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DEFORM 2D Version 8.1 User`s Manual

1. It is now possible to remove steps form a database This is called purging a database To use this for mode select purging Next use the Browse icon next to the text box labeled Old to locate a database from DEFORM 7 1 or greater database Creation information about the data base will be displayed in the text boxes below the database name The steps in the database will be listed in the Steps scroll region The steps highlighted in white will be the ones purged removed The icons None Range and All are used to select the steps to be converted The individual steps can be clicked on to highlight them or UN highlight them Once the database for purging has been found and the steps selected for purging type in the new database name in the text box labeled New Next click on the Purge Database icon You should have a new converted database 137 138 Chapter 4 Post Processor With the new release of DEFORM 2D we are proud to support OpenGL as an option for the 2D graphics rendering in our Post Processor The approach will enable the user to view the results with a much more attractive appearance 4 1 Post Processor Overview The DEFORM post processor is used to view and extract data from the simulation results in the database file All results steps that are saved by the simulation engine are available in the post processor Information which is available from the post processor include Deformed geometry including tool mov
2. Gieneral Rotation Rotahor2 C3 Geometry ah har bo fa ngle l Deg Matenal z3 Defined Constant fo in sec Movement 4 C User Routine fO 5 Stroke M Speedlimit Define Figure 49 Object movement window speed force Speed control This is the default movement control This specifies the speed and direction of a 102 tool Speed can be defined as a constant or as a function of time or stroke When an object is rigid the entire object will move at the assigned speed When the object is elastic plastic or porous each node with a movement boundary condition assigned will maintain the assigned speed Note that movement boundary conditions should never be assigned all the way around an object boundary In general no more than 1 2 to 2 3 of the boundary nodes on an object should have movement boundary conditions Symmetry planes are defined with V 0 boundary conditions normal to the appropriate surface Due to limitations of border extraction during remeshing parallel symmetry planes should be defined using at least one rigid symmetry surface instead of V 0 boundary conditions on both sides of the object Force control For force control the speed of the object is constrained such that the specified load is maintained When the object is rigid the load is the resultant load applied by a non rigid object due to the relative motion of the two objects When the object is elastic plastic or porous the load is the su
3. DE ii Design Environment for FORMing DEFORM 2D Version 8 1 User s Manual Jeffrey Fluhrer Forming Columbus Ohio 43220 Technologies Tel 614 451 8330 Corporation Fax 614 451 8325 Email support deform com Scientific lt 5038 Reed Road TM Table of Contents PREFACE TO THIS MANUAL sssssnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nnana 5 Chapter 1 Overview oDERORM cccciie tt es Aree ek atl ieee Be eta eecce 7 Tt DEFORM family Of products annie 7 122 CapabilitleS Aric teste hiiessin a aaa aa 8 1 3 Analyzing manufacturing processes with DEFORM cccceeeeeeeeeeeeeeeeeeeeeeeeetaaaes 11 1 4 Before yOu DO GIN eeee ete cece ee eeecce nett eee rete aaa a a aa 11 1 5 Geometry representation cccccceceeee eect eee eenceee steer ee teecaaeeeeeeeeeegecaaaeeeeeeeeeeeeeaaaes 12 1 6 The DEFORM Syste Maese eieiei eaea aaea a a aaa a a 13 ee RPO DFOCOSSING eieaa aa aa a a E 13 1 8 lt Gfre ting inp t data ceccedcdecertce cece eee eeetinndeceecenrceiucnecacenteuneiuneredeetoua mi veereceneeumcenneanteets 14 1 9 File sySteM vivid iia a ae ia a Tar aaaea Ar 15 1 10 Running the Simulation weve cececese esther tanita 16 Td POSt DlOCOSSOl cist weknhchakwknhakahekalahahakahakakdhahakandhahaias 17 112 0 UNIS cs ial A ee Aa a A et Oe A 17 Chapter 2 IPlesPhOCeSSOrtsx6 cut ie aie els a ren etal reread eased arte wera ieiaees 19 2 1 Simulation OOO S thee haek t
4. For example e A tool is made of H 13 H 13 is defined as a phase It should be assigned to appropriate tooling as a phase e A workpiece is made of 1040 Steel The simulation begins with the object 91 composed of 100 volume fraction pearlite 1040 is defined as a mixture of pearlite banite austenite and martensite The 1040 mixture properties are assigned to the object and the volume fraction is set to 100 pearlite under element properties 2 4 7 Object initial conditions Initial conditions can be specified for any object related state variable in DEFORM The most common initial condition specification is object temperature For heat treat problems with variable carbon content in the workpiece dominant atom content may also be specified For meshed objects initial object temperature and initial dominant atom content are specified by assigning values to all the nodes When a mesh is generated the nodes in that mesh will be assigned values from the Meshing Defaults fields under the Defaults tab in the Object window Uniform object temperature can be specified using the TEMP button on the object window Nodal values may also be specified using the Nodes Data menu Values for an entire object can be set using the initialize i icon next to the appropriate data field For non meshed rigid tools a constant object temperature may be set using the reference temperature REFTMP under the Objects Properties menu Note Using
5. User defined post processing USRVAR The user defined post processing routines have to be written using FORTRAN in the file PSTUSR FOR When user variable tracking is done the functions in this FORTRAN program are called for the steps that have been selected in the post processor The user function is evaluated at each node element of the object for which the variables are tracked The user subroutine is called at the beginning of tracking to get the variable names then at the first step to get the initial values for all variables and then called for all the steps present in the database being tracked There are three phases in the tracking process PHASE 1 The user variable function is called with the INIT flag set to to 0 This is done once before tracking is started During this phase the variables names VNAME should be defined so that they can be displayed in plots on the screen The variables for which VNAME is defined are tracked For easier identification purpose it is recommended that proper name or descriptions be assigned to VNAME This can be done when the user subroutine is called with INIT 0 as shown below IF INIT EQ 0 THEN VNAME 1 User Example 1 VNAME 2 User Example 2 VNAME 8 User Example 3 VNAME 4 User Example 4 VNAME 5 User Example 5 RETURN ENDIF 214 PHASE 2 The user variable function is then called with INIT flag set to 1 This is the second phase in whic
6. Numerous phenomenological models have been published in the area of grain modeling and controversies exist on the definitions of various recrystallization mechanisms To accommodate these models DEFORM has chosen the most popular definitions and generalized equation forms In each time step based on the time local temperature strain strain rate and evolution history the mechanism of evolution is determined and then the corresponding grain variables are computed and updated Definitions Dynamic recrystallization occurring during deformation and when the strain exceeds critical strain The driving force is removal of dislocations 50 Static recrystallization occurring after deformation and when strain is less than critical strain The driving force is removal of dislocations The recrystallization begins in a nuclei free environment Meta dynamic recrystallization occurring after deformation and when strain is greater than critical strain The driving force is removal of dislocations Because the strain has exceeded critical strain recrystallization nuclei have formed in the material so the recrystallization behaviors are different from without nuclei static recrystallization Grain Growth occurring before recrystallization begins or after recrystallization is completed The driving force is the reduction of grain boundary energy Dynamic Recrystallization The dynamic recrystallization is a function of strain strain ra
7. Process Duration fo sec Primary Die Displacement fo fo in d Min Velocity of Primary Die fo fo In Sec Max Load of Primary Die fo fo F Max Strain in Any Element fo Sec Figure 13 Stopping controls window Maximum strain EMAX Terminates a simulation when the accumulated strain of any element reaches the specified value Maximum process time TMAX Terminates a simulation when the global process time reaches the value specified Maximum stroke SMAX Terminates a simulation when the total displacement of the primary die reaches the specified value The stroke value for the object is specified in the Object Movement menu Minimum velocity VMIN Terminates a simulation when the X or Y component of the primary die velocity reaches the X or Y values of the VMIN This parameter is typically used when the primary object movement is under load control or when the SPDLMT parameter is enforced for a hydraulic press Maximum load LMAX Terminates a simulation when the X or Y load component of the primary die reaches the X or Y value of LMAX Typically used when the movement control of the primary object is velocity or user specified 28 Stopping distance MDSOBJ Terminates a simulation when the distance between reference points on two objects reaches the specified distance Stopping distance must be used in conjunction with the reference point REFPOS definition on the Objects Properties menu Simulation Contr
8. applications Appropriate for compacted sintered powders no less than 70 fully dense Accurately models consolidation and densification during forging limitations Cannot model loose powder or compaction processes 2 4 5 Object geometry DB Tod Edit General Figure 39 Geometry tool window In a DEFORM model geometry definition plays several roles Initial geometry may be read from a file or created in the geometry editor For deformable 75 objects the geometry of that is created in the pre processor is not stored in the database as the shape of the object can change during the simulation So once a database has been generated the intial geometry of the object becomes the border of the finite element mesh The Geometry Definition window is used to create import modify or view the geometry of a given object The window appears upon selecting the Geometry icon from the Objects window 2 Ta Edt General Figure 40 Geometry tool window editing Geometry formats XYR format input DIEGEO The XYR format consists of defining an X coordinate a Y coordinate and a radius for every point of the geometry defining an object An arc with the specified radius is drawn connecting the lines that would have intersected at the point defined by the X and Y coordinate The XYR Table appears directly in the Geometry window This table allows specifying and or editing an object s geometry through a number of points i
9. e Locate the 25 pin parallel port on the back of your PC This is sometimes called the LPT1 port e Plug the Security Key directly into this port e If an existing printer is also plugged into this port it must be plugged into the end of the Security Key WARNING e The Security Key keeps track of the date on your PC Make sure the date is correct before initially running DEFORM 2D Changing the date backwards or forwards may make the DEFORM 2D system inoperable INSTALLING DEFORM 2D IN WINDOWS e DEFORM 2D comes on one CD with an automatic installation program Installation can be done by following a few simple steps Important _Before beginning to install DEFORM 2D in Windows NT it is necessary for the user be logged in as the Administrator e Start up Windows NT Log in as the Administrator or with Administrator privileges e Insert the CD in the appropriate drive e The installation program should start automatically unless this version has been already installed If it does not start automatically simply start an NT Explorer window go to the CD ROM drive and double click the Setup exe file e The Welcome window comes up Click Next 236 Welcome xj e WOOO NO ETENA TE FoG PINN This program will install DEFORM 2D on your computer It is strongly recommended that you exit all Windows programs before running this Setup program Click Cancel to quit Setup and then close any programs you have running
10. 238 to run with a local hardware key dongle leave the box checked and Click Next If a network license is to be used for this installation uncheck the box and Click Next Select Lomponents x Please select the additional component s to install e f user routines are to be used select the box and Click Next Otherwise simply Click Next Select Lomponents x Do you want to setup user routine environment By setting the aa by clicking Cornpile_User_Routine bat sstseevesasneeusaseunsneaseensessaueaneansnesuuausaussuaaneuusansseeassaseueeuasuseusaeacuusauscnensauequecuaanenuanesteenncneenes e DEFORM 2D will be installed This may take a minute or two If this 239 takes longer or appears to hang up please check the available disk space Also some anti virus software has been known to slow incoming executables by scanning and can slow installation significantly e After installation select the appropriate password scheme either local password or license manager and Click Next Select Lomponents x Please choose whether you want to use local password or license manager Please note that the choice will affect all Deform applications feet e At this point the installation should be finished and rebooting the machine will complete the installation At this point Click Finish e The password will need to be installed in the case of a local password Please copy the file DEFORM PWD to
11. 34 Vs Simulation Control x Enor Tolerances Variables User Defined Node Oscillations x Current Local Time fo sec Time to Use for Function Data amp Global Time Local Time Figure 19 Simulation controls advanced window variables Current time TNOW This value specifys the current process time and the local process time The global time should not be reset during a simulation as the post processor uses this time for many post processing operations Primary workpiece PDIE The deforming object that is used to pass average strain rate AVGSTR data to the user routines for control of die speed based on the strain rate in the workpiece 35 Simulation Control xi Enor Tolerances Variables UserDefined Node Oscillations x Figure 20 Simulation controls advanced window user defined User defined variables USRDEF User defined variables are 80 character string variables which are passed to user defined subroutines Refer to User Routines for more information on how to use these variables Simulation Contro x Eror Tolerances Variables UserDefined Node Oscilations x Repeated Touching Seperation Touch after cycling Separate after cycling Figure 21 Simulation controls advanced window node oscillations Nodal oscillations OSCTRL 36 Corner oscillations Corner oscillation controls are used to control oscillation of a n
12. Click Next to continue with the Setup program WARNING This program is protected by copyright law and Garnaal Weabes Unauthorized reproduction or distribution of this program or any ee may result in severe civil and criminal penalties and be prosecuted to the maximum extent possible under law e An information window will appear asking the user to refer to this manual Click Next when finished For the proper installation of this D product please refer to the installation notes sent with this product or download them from our web site at www deform com in the user e Choose the Destination location where the files are to be installed or use the Browse button to install in a different folder Click Next It is 237 recommended to choose a drive with ample space for all the DEFORM files that may get generated over time lease select the installation path x The path for the DEFORM installation should be specified here e Select the Program Folder default recommended and Click Next The installation program copies program files This can take a minute Setup will add program icons to the alder listed below You may type a new folder name or one from the existing Folders list Click Next to continue L FORM 2D 7 1 R V7 DEFORM 3D V4 0 5 DEFORM 3D 4 01 lt Back f Nen _ Cana i e Setup then asks you if you want to install the Hardware key driver If this
13. IBM mount v cdrfs r dev device cdrom SGI IRIX systems automatically mount the CD ROM after it is inserted in the drive SUN Sun Solaris systems mount the CD ROM after it is inserted in the CD ROM drive Starting the INSTALL Script Note The installation is generally performed as an ordinary user not as root Once the CD ROM is mounted DEFORM may be installed using the following commands Change to the CDROM directory cd cdrom Run the INSTALL program INSTALL The INSTALL program will check the computer for a supported operating system If the platform is supported the script will prompt for a directory where DEFORM will be installed If the installation directory does not exist a directory will be created The appropriate platform dependent and platform independent files will be installed from the CD to the installation directory An example of a sample session is given below SCIENTIFIC FORMING TECHNOLOGIES CORPORATION DEFORM 2D V8 0 INSTALL SCRIPT Support Telephone 614 451 8313 Fax 614 451 8325 E Mail support deform com Web site http www deform com NOTE If at any time you want to stop the installation process press Ctrl C to abort the process Current directory home testinst DEFORM_DIR home testinst 2D V80 Operating system name GenericUnixOS Release version 17 Install default configuration DEFORM 2D 8 0 for GenericUnixOS y If the installation script does not work
14. NOUTINE Routine to be used USRPS1 USRPS20 The output from the functions to be given by the user VAR2 1 20 Updated State Variables 1 In the example given below the maximum mean stress is stored in the 215 first variable the maximum strain rate is stored in the second variable IF INIT EQ 2 THEN STSM STS 1 STS 2 STS 3 3 IF STSM GT VAR1 1 THEN VAR2 1 STSM ELSE VAR2 1 VAR1 1 ENDIF IF EFEPS GT VAR1 2 THEN VAR2 2 EFEPS ELSE VAR2 2 VAR1 1 ENDIF VAR2 3 VAR1 3 VAR2 4 VAR1 4 VAR2 5 VAR1 5 ENDIF In the statement to check for INIT 2 each user variable is checked with some criterion if it meets this then the value is updated else the new value is set the same as the previous value VAR1 It is very important that if the value is not updated the value is set to the VAR1 value as this allows tracking of variables across remeshing steps where data is interpolated from an old mesh to a new mesh Since this calculation is done for each step and for each node element the code should be written efficiently You should not open close files for each subroutine call as this can degrade performance The DATA statements in FORTRAN can be used to store parameters and the COMMOW block fields can be used to hold static data If files are to be opened then use UNIT numbers from 91 99 for opening these files as opening other unit numbers might clash with files opened in other parts of the progra
15. Note that both of these expressions account for the change in the cross sectional area of the specimen during the test assuming incompressible material This gives a better measure of the actual state of stress and strain the material is under 178 Tension test True o O sng l e Stress True hy Strain Gr In 7 Figure 93 Stress and strain defined for tension test All materials have a characteristic stress strain curve that determines how the material behaves structurally For most isotropic metals this behavior is of the general shape seen in Figure 5 Note that the top and bottom curves are the engineering stress strain curves for a material and the middle curve is the true stress strain curves for a given material The true stress strain curve is the same for either tension or compression but they are not the same in terms of engineering stress strain Stress Strain Curve True Tension Figure 94 Stress strain curve For simplification the stress strain curve is divided into two regions The steeply sloped region at very low strain values is known as the elastic region In the elastic region since strains are very low when the material is unloaded and the forces removed the material returns to its original shape In Figure 6 an object is deformed in uniaxial tension The change in length is shown and the corresponding position on the stress strain curve is shown In this case the 179 deformation
16. Resistance 7 Figure 7 Simulation Control window 2 1 1 Main controls Simulation title TITLE The simulation title allows you to title the problem up to 80 characters for reference purposes Simulation name SIMNAM The simulation name allows you to title the specific operation up to 80 characters for reference purposes Units UNIT The DEFORM unit system can be defined as English or Metric SI All information in DEFORM should be expressed in consistent units The unit system should be selected at the beginning of the problem setup procedure and should not be changed during a simulation or after an operation 20 Entity SI unit English unit SI unit es unit factor Time e EE a o 254 Area mm2 in2 6 4516e2 Volume mm3 in3 1 6387e4 Force N KIb 4 4484e3 Mechanical Energy N mm Klb in 1 13e5 Stress MPa KSI 6 8918 Heat Energy a BTU 1 055e6 Temperature F F 32 1 8 Conductivity T Btu sec in F 7 4764e4 Heat Flux Rate N mm sec BTU in2 sec 1 6353e3 Hoat Capacity n mm2 0 BTU nd 1158962 Convection Coefficient N sec mm C BTU sec in2 F 2 943e3 Lubricant Heat Transfer Coefficient N sec mm C BTU sec in2 F 2 943e3 Figure 8 The DEFORM units system Geometry type GEOT YP Two geometry models are currently available 1 Axisymmetric models the object as a cross section with respect to the central axis Therefore the model requires the deformin
17. TEMPN Nodal point temperature USRN1 User defined state variables Input At the beginning of Step N USRN2 User defined state variables Output At the end of Step N KNODE Node number The variable USRN1 stores the nodal variables at the beginning of the step the current value After computing a new value for the user defined variables the results should be stored in USRN2 at the end of each step For the element variables USRE1 stores the values at the beginning of the step and the updated value must be stored in USRE2 If the variables are not being calculated then the value stored in USRN1 and 202 USRE1 must be copied to USRN2 and USRE2 respectively Examples of using the user defined nodal and element variables are given below 1 The maximum principal stress is stored in the first user element value USRE2 1 and the second element variable is not used in this example IF ISTATUS EQ 1 AND KELE GT 0 THEN USRE2 1 USRE1 1 CALL USR_MAXPRN STSE PRNSTS IF USRE2 1 LT PRNSTS USRE2 1 PRNSTS ENDIF In this example the average cooling rate F min from 1300 F to 600 F is approximately calculated and the result stored in the second user nodal variable USRN2 2 At first starting time is marked when TEMPN is between AMAXteme and AMI Nreve When TEMPN is less than AMIN temp ending time is marked and elapsed time is calculated by difference of them The cooling rate is calculated as the temperature difference
18. distance across flats A gradually tapering part such as a turbine blade can be modeled by modeling several plane strain sections 12 ihe l GTO issit la Il NH EET EHE WI nithi iparanntj Hi SH HHH danre io Basic aan Sse cena tt si SSG tHe Wisapi ae i all bat Figure 3 Buckling Buckling of cylindrical parts is a fully three dimensional process and must be modeled as such if such behavior is expected An axisymmetric simulation will not show buckling even if it will occur in the actual process Figure 3 Parts which cannot be simplified to 2D must be modeled as 3D 1 6 The DEFORM system The DEFORM system consists of three major components e A pre processor for creating assembling or modifying the data required to analyze the simulation and for generating the required database file e A simulation engine for performing the numerical calculations required to analyze the process and writing the results to the database file The simulation engine reads the database file performs the actual solution calculation and appends the appropriate solution data to the database file The simulation engine also works seamlessly with the Automatic Mesh Generation AMG system to generate a new FEM mesh on the workpiece whenever necessary While the simulation engine is running it writes status information including any error messages to the message MSG and log LOG
19. lt _ Generalized shape function equation b NO Figure 104 Description of a shape function Figure 16 also shows the case of a two dimensional element 186 o x N 0 N x i x a as a Mioi 2 w REF fig 6 5 Pg 97 of Kobayashi Oh and Altan s Meta Forming and Finite Element Method Figure 105 Description of shape function After all the equations for the elements have been written out they must be combined into a single set of simultaneous equations This process is shown in Figure 17 At the end using a Newton Raphson iteration method the updated velocity can be solved for by solving a simultaneous set of equations Once this velocity update is solved for it is applied to the current velocity and velocity update is solved again iT 4 Figure 106 Construction of a stiffness matrix to solve for velocities 187 The general FEM solution process is given below 1 Input Geometry amp Processing Conditions 2 Generate Initial Guess of Velocity Field single step 3 Calculate Element Behavior Based on Velocity Field amp other variables strain temp etc 4 Calculate Force boundary conditions based on Velocity Field 5 Assemble and solve the matrix equation 6 Calculate the error 7 lf error is too large apply correction to velocity field and go to step 3 otherwise continue to step 8 8 Update Geometry 9 Calculate temperature change for this step 10 Calculate new pres
20. system The die movement can be a function of the following variables C INPUT C C NSPD USER SUPPLIED ROUTINE NUMBER 196 TIME THE SIMULATED PROCESS TIME PDIS PRIMARY DIE DISPLACEMENT VX DIE SPEED IN X DIRECTION VY DIE SPEED IN Y DIRECTION STRKX THE CURRENT DIE STROKE IN X DIRECTION STRKY THE CURRENT DIE STROKE IN Y DIRECTION FRZX DIE FORCE IN X DIRECTION FRZY DIE FORCE IN Y DIRECTION AVGSRT AVERAGE STRAIN RATE SRTMX MAXIMUM STRAIN RATE TMPMX MAXIMUM TEMPERATURE DTIME CURRENT TIME STEP 1 0 ADIQDIDAAQAIAININIANNINO The output that the user has to provide are OUTPUT UPDV THE UPDATED DIE SPEED IN THE SPECIFIED DIRECTION UPDF THE UPDATED DIE FORCE IN THE SPECIFIED DIRECTION O00000 DTIME DESIRED TIME STEP VO It is important to note that either UPDV or UPDF need to be defined but both cannot be defined at the same instance The reason for this is that defining the force determines the die speed through how fast the moving die can press the workpiece Conversely defining the die speed determines the amount of force required to push the workpiece a given distance at a given speed The die speed routines are functions which are called from the USRDSP subroutine based on the function number specified in the Object Movement controls window 197 Current Objec 1 Billet B Speed Force Press Hammer SpringLosdedDie Rotation Torsion General o Type Direc
21. 156 loading of a material This requires the user to use a kinematic hardening rule In large deformation processes like forging this is usually negligible Velocity The velocity option plots nodal velocity at each step Vector plots display magnitude and direction Magnitude is indicated by vector length and color Contour plots display only magnitude where contour color indicates velocity magnitude Temperature The temperature plot displays nodal temperature at each step Volume Fraction If transformation calculations are performed the volume fraction of the selected phase component of a mixture material is displayed Grain Size Grain size is not implemented in DEFORM release 7 0 It will be implemented in a future release Hardness Predicted hardness based on the hardness method selected in the pre processor will be displayed Dominant atom The concentration of the dominant atom usually carbon in a diffusion calculation is displayed Material The material group of a given object can be plotted In most cases this will show the object as a solid color unless multiple material groups have been defined for the same object User Variables User defined nodal variables can be stored using user defined FORTRAN subroutines Refer to the section on user subroutines for more information 157 4 5 4 Flow Net The flownet is a post processing tool that traces a pattern through deformation states The flow ne
22. A message file with the output of the compiler linker 3 A dll file or an exe file if the compilation was successful If not please refer to the error message in output file from the compiler linker For more information on user routines please refer to the section on user routines in the manual 288
23. Constant nodal temperature is specified 2 Heat transfer with environment boundary condition 3 Specified nodal heat flux Boundary condition function BCCTFN BCCFNC is used to specify time nodal value pairs for nodal boundary constraints Types of nodal boundary constraints that can be specified as time nodal value pairs include velocity force traction temperature heat and distributed heat flux BCCFNC can only be used when a node s boundary constraint function type BCCDFN or BCCTFN has been specified as a time nodal value type Diffusion Diffusion DIF 113 Dominant atom content DATOM DATOM specifies atom content at a node Atom flux CRBFLX CRBFLX specifies carbon flux or atom flux for the surface of a workpiece Boundary condition code BCCCRB BCCCRB specifies the atom transfer boundary constraint code for individual nodes User variables User node variables USRNOD User node variable values can be defined using FORTRAN subroutines Refer to User Routines for more information on the subroutines Each node value may accept both a name and a value Also an infinite number of variables may be defined A minimum of 2 user node variables will be defined by default however the user may increase this to as large number as wished The only caveat is a large number of variables defined can lead to a large database file The user specified nodal variables can be viewed initialized modified or tracked 2 4 13 O
24. DEFORM to calculate the heat generation from friction due to rotation for processes such as inertia welding Relative rotation can be defined as a constant or a function of time Modeling inertia welding is possible with DEFORM but is not a straightforward process Comparison between DEFORM results and known experimental cases should be tested before results for unknown cases are used 122 Self Contact An object can have a self contact condition imposed on itself This will allow the simulation to continue even if a fold or defect develops Self contact is defined by selecting the same object in both the Object 1 and the Object 2 list and assigning a master slave or slave master relationship to itself Caution Be careful when using the self contact condition If not monitored a fold might develop and cover itself up during the simulation allowing the user to believe that the process is acceptable when in fact it may be problematic 2 5 2 Positioning Figure 59 Object positioning window offset Offset Positioning Offset positioning is used to move the object to position by a given displacement in the chosen direction One input required is the object to be moved should be highlighted in the position table and the distance the object should be moved should be entered in the distance boxes The other option for movement is two point positions Interference positioning 123 Interference positioning moves the object to be pos
25. DTMAX Solution step size can be controlled by time step or by displacement of the 23 primary die If stroke per step is specified the primary die will move the specified amount in each time step The total movement of the primary die will be the displacement per step times the total number of steps If time per step is specified the time interval per step will be used The die displacement per step will be the time step times the die velocity Stroke per step is frequently more intuitive However time per step must be specified for any problem in which there is no die movement such as heat transfer or for any problem where force control is used Selecting time step and number of steps Proper time step selection is important Too large a time step can cause inaccuracy in the solution or rapid mesh distortion Too small a time step can lead to unnecessarily long solution times The following section provides some guidelines for selecting time steps For typical two dimensional simulations of forming operations 100 steps is generally adequate For simple simulations such as squaring up a cutoff billet as few as 25 50 steps may be appropriate For complex or semi continuous processes such as extrusion or drawing more steps may be required For these simulations the time step can be determined by the following method 1 Using the measurement tool measure one of the smaller elements in the deformimg object this must be done
26. In DEFORM the concept of flow stress is used The idea of flow stress is important in the case of incremental plasticity As a material is deformed plastically the amount of stress required to incur an incremental amount of deformation is given by the flow stress curve which corresponds to the plastic region of the true stress true strain curve In Figure 9 the concept is shown visually O D Initial stress required for an After deformation work increment of deformation is hardening increases the stress simply the yield stress level required to produce additional deformation Figure 97 Introduction to flow stress concept 181 Flow stress is strongly dependent on several state variables among these are accumulated strain instanteous strain rate and current temperature As seen in Figure 10 the flow stress curves can vary strongly with these state variables So it is important to account for these variables to accurately determine the behavior of the material Stress Strain Curve Stress Strain Curve VS VS Temperature Strain Rate oO oO Increasing Strain Rate Increasing Temperature amp With all other factors equal With all other factors equal increasing the part temperature increasing the rate of deformation decreases the stress required for increases the stress required for an increment of deformation an increment of deformation Figure 98 Variation of flow stress with strain rate and temperature In the case where
27. Processor i scesseckicessateivesitanicesseceivehsdalsaeatneceiwenndesecediedhewes vaakiednuonees 139 4 1 POSt ProceSSor OVGIVIOW iisi ioen aeiae seas deea dent cev duaddeee Aai ERARA 139 4 22 GraphiCalGiSplay x tescs avers sea ee busch ekae see butch esha Sees ceur tee eas echt batchah Pee eetuatc hah aver 140 4 2 1 Window YOUN esate A iat ated acacia La i 140 Object Display Modes ns ne a a a a sieeve E ge eaat a A E A oersyihs 141 Tree levels and TUnctiOns nenga a E a a E A aeitertameatac genres 141 Additional Post Processing Functions seeseeeeeesseeseirtttsstttiitttttstttirrnttesttttrtntttsetttnunntnneeteeenn 143 4 32 Display WINGOW AEAEE EPE et EE OEE EE E OE POE ES ETE E EEA 144 44 Graphic Wihl Sien e a a a a a eee a E E 145 4 5 Post Processing SUMMALY oeaan dined waitin 147 4 5 1 Simulation SUMMALY a cece cece cece eeeeeene ae a eaa aia e a 147 4 5 2 Object MINON g tos oe A a T a a a a a a 148 453 State Vafa ES a a ML ee Ee Le ee ea a 150 419 4c2 PIOW Nets tcscentresss vere yeaseetnersvads setae crensensuataheerenteat a a a eA 158 45 5 POINT Trackin tet esse a e a a dh ati ted eas e a e a a ei ea 164 45 6 boad OOKO ia ae ah eae a a a etd 165 AIDE ASIEDS T A E A E lt a ee Ba 166 4 5 8 Database Management c cccccceeeeeetcceee eset eeeeec nase eee eeeteeaaaeeeeeeeeteesaaeeeeeeeeteneaaaeeeeness 168 4 5 9 Nodes WINDOW visiiiec Hint seceaetiescetesiaesiieti navel arane in ANAA ined ASEE AA ANATA AA NANA
28. TR IT 6 2 Kinetics The model for recrystallization kinetics is based on the modified Avrami equation k SS ee ee ee cave where tosis an empirical time constant for 50 recrystallization fy gd e s exp O IRT 3 Grain Size The recrystallized grain size is expressed as a function of initial grain size strain strain rate and temperature dim ded e 2 emlO RT e __ 8 if r gt 2o then dhex do _ 9 Meta dynamic Recrystallization Meta dynamic recrystallization is similar to static recrystallization but with different activation criteria and material constants 1 Activation Criteria When strain rate is greater than Sss see equation 1 meta dynamic recrystallization occurs after deformation 2 Kinetics The model for recrystallization kinetics is based on the modified Avrami equation 7 ole 05 1 0 where tosis an empirical time constant for 50 recrystallization fy agd s amp egpl O i RT 11 A ade T lT EEP 52 3 Grain Size The recrystallized grain size is expressed as a function of initial grain size strain strain rate and temperature kr T aT j gt dig aydi 8 8 exp O RP c if r gt 2o then dhex do _ 12 Grain Growth Grain growth takes place before recrystallization start or after recrystallization finishes The kinetics is described by equation EA a fa tap e all _ 13 where dg denotes the grain size after gro
29. This is useful in situations where a higher density needs to be defined around a moving object such as a punch The window should be given the same velocity and direction as the punch In cases where punch velocity is not known such as a hammer forging or a load controlled press the best estimate of a constant velocity should be made 86 Note If a velocity is assigned to a window it should be repositioned as necessary before a second or third operation is performed Mesh generation When all of the Mesh parameters have been set a mesh can be generated by clicking on the Generate button When a new mesh is generated for an object that currently has a mesh the old mesh will be deleted and replaced with the new mesh BD Tool Remesh Criteria Advanced General Cj cc G A Interference Depth in as Maximum Stroke Increment fo in Mesh Maximum Time Increment 0 sec E TE Material Maximum Step Increment s E Movement nm Oo BCC BJ Property amp Advanced Figure 45 Automatic remeshing criteria window Automatic remeshing criteria Automatic remeshing Autoremesh is the most convenient way to handle the remeshing of objects undergoing large plastic deformation The Remeshing Criteria Window contains a group of parameters that control when and how often the mesh will be regenerated on a meshed object based on assignment of certain triggers There are four keywords that control the ini
30. and placing a 3x3 rectangular grid on it will yield an initial flownet that resembles Figure 76 This flownet is stored as the file seen in Figure 77 As seen in Figure 77 the grid points are first stored and the connectivity is stored in the 2 section The grid points are seen in as labeled in Figure 76a and the connectivity curves are labeled as Figure 76b 162 Figure 76 The result of placing a 3x3 flownet on a round object The points are labled in a and the curves are labeled in b CONAN Ver p BI mw 4 143 4 5 6 2 4 7 8 9 W 3 4 1 4 8 H 4 4 2 5 9 2 Figure 77 Sample pattern file corresponding to example case Compare the point connectivity to the figure above Defining a Region 163 A flow net region is defined in the display window It can be selected within an object s border or within a specified region within the object In order to define a region you must add at least three points within the object s border Once the points have been defined just select generate pattern in the pattern generation tracking window Add Points Delete Points Delete All Points 4 5 5 Point Tracking In point tracking you can track up to 200 points over the course of a simulation In order to use point tracking first select the desired starting step from the start step list in the point tracking window Next you should select the object from the object table Once this has been accomplished click on the Defi
31. and the change in volume of the object DVOLF can be invaluable in determining the progress of a transformation and aid the user in deciding whether to increase or decrease the time step for a particular transformation User variables User element variables USRELM User element variable values can be defined using FORTRAN subroutines Refer to User Routines for more information on the subroutines Each element value may accept both a name and a value Also an infinite number of variables may be defined A minimum of 2 user element variables will be defined by default however the user may increase this to as large number as wished The only caveat is a large number of variables defined can lead to a large database file The user specified element variables can be viewed initialized modified or tracked 2 5 Inter Object Definition The purpose of inter object relations is to define how the different objects in a 117 simulation interact with each other The relations table shows the current inter object relations that have been defined All objects which may come in contact each other through the course of the simulation must have a contact relation defined This includes an object having a relationship to itself if self contact occurs It is very important to define these relationships correctly for a simulation to model a forming process accurately The critical variables to be defined between contacting objects are e Friction fac
32. as unit factor Time send secon Length mm 25 4 Area mm2 na 6 4516e2 Volume mma 1 6387e4 Force E 4 4484e3 Mechanical Energy Nm ei 1 13e5 Stress MPa 6 8918 Heat Energy N mm BT 1 055e6 Temperature cC F 32 1 8 Conductivity N sec C HANTE 7 4764e4 Heat Flux Rate N mm sec BTU in2 sec 1 63533 Heat Capacity N mm2 C BTU in3 F 1 1589e2 Convection Coefficient N sec mm C BTU sec in2 F 2 943e3 Lubricant Heat Transfer Coefficient N sec mm C BTU sec in2 F 2 94363 Figure 5 DEFORM unit system 17 Note It is important to select the unit system at the beginning of the simulation Once numerical values have been entered in the pre processor the numerical values will remain unchanged even if the unit system designation is changed In Version 3 1 the Post Processor has been equipped with a feature for unit conversion for database viewing The user has four options for unit conversion If the conversion factor selected is Default then the units are picked up automatically depending on whether the database is English or SI Since there is no conversion necessary all the conversion factors are set to 1 0 in this column For the cases of converting english to SI or converting SI to english the conversion factors and units are picked up from the dialog and the values are converted and displayed in the post processor The fourth option gives the user the option of viewing the data from the
33. be plotted This variable is primarily intended for die deformation analysis Density For powder or porous materials plots the relative density distribution Theoretical maximum limit is 1 0 which means that the material is 100 dense Strain Strain is a measure of the degree of deformation in an object A detailed description of strain is available in any standard text on mechanics of materials metal forming analysis or plasticity A brief description of 154 nomenclature will be given here The measure of strain used in large deformation analysis including DEFORM is true strain which differs slightly from the well known engineering strain presented in typical engineering applications Engineering strain is defined as change in length by original length that is fine for small deformations but begins to break down when deformations become large For large deformation analysis it is better to use true strain which is defined as the sum of a large series of arbitrarily small strain increments e In Integrating this over the total change in length gives where is the true strain is the initial length and is the final length Extending this deformation into three dimensions we can assume a cube with initial dimensions xo Yo and Zo Components of strain in the x y and dx d Ey z directions can be defined incrementally as Ez Zo 28 and dz where dx dy and az are incremental d
34. be expressed mathematically as the following functional form seen in Figure 13 The top equation is simply a balance of the body forces 1st term versus the surface tractions 2nd term The manner in which this equation is solved for the velocities is seen in the 2nd equation The velocities are solved by solving for when the variation in the functional is stationary Note that there is an extra term that maintains incompressibility in the solution This is done by integrating the volumetric strain rate and multiplying by a large constant Since the total solution should be zero the solution will tend to maintain a low volumetric strain rate to keep this integral value low 183 e av Fu ds n eszdv F8u ds k a d dv 0 S plastic work surface traction change in volume work multiplied by a large penalty constant K Figure 101 Functional equation for minimum work rate principle In order to obtain a closed form solution for complex shapes we need to resort to mathematical tricks such as FEM The introductory theory for this is discussed in the following section Introduction to FEM theory The principle of FEM theory is divide and conquer First one must divide the problem into small little subproblems that are easily to formulate and after the entire problem has been divided and formulated they must all be carefully combined and then solved The manner in which a problem is divided is through a proc
35. cycles per second 3 Current Die Stroke This value is the amount of the stroke length for which the die or punch is in contact with the workpiece In the case of a die moving in the Y direction the current die stroke should have a minus sign and the magnitude should be the distance from the top of the stroke to the current position of the die 4 Direction Direction is used to designate a direction in which the object s stroke will be applied 107 5 Connecting Rod Length As seen in Figure 52 the connecting rod length can have an influence on the speed of the ram If the length of the connecting rod is known it can be input as a field If it is not known it can left as zero and it s contribution to the ram speed will not be considered Crankshaft Connecting Rod Figure 52 Sketch of a simple direct crank drive The Current Die Stroke specifies the displacement of an object from simulation start with a movement control boundary constraint MOVCTL It is valid for any object with movement control applied to it For example you designate the movement type as mechanical press with a total movement of 8 inches If the process is to be started mid stroke just set the Y stroke component to 4 inches The stroke of the primary object PDIE can be used to define movement control e simulation time step size DSMAX e object movement MOVCTL e simulation termination criteria SMAX VMIN LMAX Rotational movement 108 T
36. deformation 4 Define the Material Define thermal properties for the material For most steels the files STEEL_E KEY or STEEL_S KEY contain reasonable thermal properties These files can be loaded from the FILE gt LOAD gt KEYWORD menu on the main preprocessor window 5 Define the Workpiece 1 Define Object Type For most simulations plastic object type is suitable 2 Define the Geometry Geometry can be defined from a 2D IGES OR DXF file or by entering table data Workpiece geometry requirements e The x 0 line is the centerline of the part If the part is solid it must be located on the centerline If it is hollow the left edge of the part should be positioned at the internal radius e Geometry must be defined counterclockwise e Always check the geometry 1 Mesh the Object Typical progressions should use 1000 to 1500 elements When in doubt more elements will tend to give more accurate results Typical weights e Curvature_0 9 e Strain Rate_0 7 e Strain 0 5 e Temp_0 1 Define Thermal Boundary Conditions For solid parts define heat exchange with the environment on all faces except the centerline For hollow parts rings define heat exchange with environment conditions on all faces 2 Initialize Object Temperature Set the initial object temperature to the furnace soak or preheat temperature 250 1 Complete Simulation Controls 1 Define Number of Steps A typical transfer operation can be simulated in
37. elastic deformation can be neglected as in the case of bulk metal forming the Levy Mises flow rule can be used to relate the stress tensor to the strain rate tensor This flow rule is shown in Figure 11 The coefficient is a function of state variables and the material This relation allows one to express stress in terms of rate of deformation Oo r oe a j Figure 99 Levy Mises flow rule In calculating metal flow the minimum work rate principle is a cornerstone for accurate calculation This principle is defined below Minimum Work Rate Principle the velocity distribution which predicts the lowest work rate is the best approximation of the actual velocity distribution 182 This principle states that the material should always flow in the path of least resistance This is shown in Figure 12 where there are three different upset cases and the amount of friction between the workpiece and the tool determines the flow pattern of the material In the case of no friction there is no resistance for the material from flowing straight out uniformly In the case of high friction there is much resistance from flowing outward so a barreling behavior is observed Initial Geometry i No friction Moderate Friction High Friction Figure 100 Minimum work rate principle Note for each case the actual velocity is the one which incurs the lowest work rate for the workpiece This minimum work rate principle can
38. files e A post processor for reading the database file from the simulation engine and displaying the results graphically and for extracting numerical data 1 7 Pre processing 13 The DEFORM preprocessor uses a graphical user interface to assemble the data required to run the simulation Input data includes Object description Includes all data associated with an object including geometry mesh temperature material etc Material data Includes data describing the behavior of the material under the conditions which it will reasonably experience during deformation Inter object conditions Describes how the objects interact with each other including contact friction and heat transfer between objects Simulation controls Includes instructions on the methods DEFORM should use to solve the problem including the conditions of the processing environment what physical processes should be modeled how many discrete time steps should be used to model the process etc Inter material data Describes the physical process of one phase of a material transforming into other phases of the same material in a heat treatment process For example the transformation of austenite into pearlite banite and martensite 1 8 Creating input data There are several ways to enter data into the DEFORM pre processor Depending on the requirements of a particular problem a combination of the following methods will frequently be used Manual
39. is a fully automatic optimized remeshing system tailored for large deformation problems DEFORM HT adds the capability of modeling heat treatment processes including normalizing annealing quenching tempering aging and carburizing DEFORM HT can predict hardness residual stresses quench deformation and other mechanical and material characteristics important to those that heat treat 1 1 DEFORM family of products DEFORM 2D 2D Available on all popular UNIX platforms HP SGI SUN DEC IBM as well as personal computers running Windows NT 2000 XP Capable of modeling plane strain or axisymmetric parts with a simple 2 dimensional model A full function package containing the latest innovations in Finite Element Modeling equally well suited for production or research environments DEFORM S3D 3D Available on all popular UNIX HP SGI SUN DEC IBM platforms as well as personal computers running Windows NT 2000 XP DEFORM SD is capable of modeling complex three dimensional material flow patterns Ideal for parts which cannot be simplified to a two dimensional model DEFORM PC PC Available on personal computers running Windows 95 98 or NT 2000 XP Capable of modeling two dimensional axisymmetric or plane strain problems Suitable for small to mid sized shops starting in Finite Element Modeling DEFORM PC Pro Pro Available on personal computers running Windows 95 98 or NT 2000 XP A powerful two dimensional modeling package cont
40. it back to it s original name Warning Make sure that the simulation is finished before renaming it back or risk losing all the work lf you are unsure rename it back to a different name than the original name Step 3 Execute the Simulation Engine This is done by opening a dos prompt and changing to the directory where the problem is located A dos prompt can be accessed by either selected a shortcut from the Start Menu or by typing cmd in the Run menu Once the dos prompt is open it will look like the Figure 127 Let s assume that the dos prompt starts in the C directory and the problem we want to run is the C Settings and Documents Test directory To navigate from the C directory to the end directory type the following cd Settings and documents test and the current working directory will become Settings and documents test To then run the new version of DEFORM 2D make sure that the file FOROO3 is in this directory After this execute the new engine by calling the executable in the DEFORM 2D directory An example is seen in Figure 128 284 Figure 127 A new dos window Figure 128 Running a simulation from a dos window 285 Appendix M Finer Points on Using Force Controlled Dies Objective In many simulations force controlled dies are used in order to simulate real world tool loading conditions As seen in Appendix E these can be used in order to simulate spring loaded dies The purpose of this
41. menu functionality is duplicated in a control bar at the bottom of the object tree jas ccrrem guide AGRA Lam a afa q Toggle object on off displays mesh geometry or both depending on which is available and selected Defaults to mesh if neither is selected amp Toggle mesh on off C Toggle geometry on off gt Toggle item on off may be any item such as slicing a curve or graph etc Display contact nodes 4 Toggle transparency 4 3 Display Window The display window is used to graph data and to aid in the analyzing of the simulation The display window is shown below i x Figure 67 Post Processor display window 144 Most of the common graphical control features in the display window are accessed from the buttons surrounding the simulation heading box and viewport along the top of the window The viewport is the specific drawing area in which graphics are displayed for the current step It is also referred to as the data display box The simulation heading box is used to display information of the current database The simulation title is displayed along with the disk path and name of the database currently loaded Also it lists the current step number date and time The data display box is used to display the selected graphical data for the problem Clicking on the right mouse button in the display window shows a shortcut to other options such as view manipulation refresh fit plot options capture ima
42. number of elements to be generated in a mesh is controlled by the value of number of elements in keyword MGNELM If the value of thickness elements results in a mesh that contains more than the value specified in MGNELM elements the value of MGTELM will be scaled down so that the mesh contains approximately MGNELM elements If the value of MGTELM results in a mesh that contains fewer than MGNELM elements the remaining elements will be distributed to other user specified mesh density controls curvature strain strain rate and temperature 82 DB Tod Remesh Criteria Advanced General g pe fa System Setup C User Define er General Weight Factors Meshwindow Tolerance Coating col Boundary Curvature _ j 828 Bz Movement E Generate Mesh Detault Setting Show Geometry Figure 43 Advanced mesh settings weighting factors Mesh weighting factors The weighting factors or parameters system defined mesh density for boundary curvature temperature strain and strain rate specify relative mesh density weights to be assigned to the associated parameter Temperature strain and strain rate densities are assigned based on gradients in these parameters not absolute parameter values That is a region with a rapid temperature change in a particular direction will receive more elements that a region with a uniform high temperature Boundary curvature based weighting factor MGWCUV The Boundary Curvatu
43. number of nodes increases Thus it is desirable to have a large number of small elements high density in regions where large gradients in strain temperature or damage values are present Conversely to conserve computation resources it is desirable to have a small number of relatively large elements in regions where very little deformation occurs or where the gradients are very small Other issues related to mesh generation e Too coarse a mesh around corners may cause mesh degradation and remeshing problems e Too coarse a mesh in regions with localized surface effects ie high damage along a surface may cause peak values to decline due to interpolation errors during remeshing amp Tool Remesh Criteria Advanced General Type Geomety System Setup User Define bad General Weight Factors Mesh window Tolerance Coating E Material prs Mesh Parameters Movement Number of Elements 250 a Thickness Element f4 E Size Ratio f2 SB Generate Mesh Defaut Setting Show Geometry Figure 42 Advanced meshing options general settings Basic mesh controls Number of elements MGNELM 81 The number of mesh elements represents the approximate number of elements that will be generated by the system The Automatic Mesh Generator AMG takes the value for MGNELM and generates a mesh that will contain approximately the same number of elements The error between the number of specified elements a
44. of temperature and atom content 38 Thermal expansion EXPAND The coefficient of thermal expansion defines volumetric strain due to changes in temperature It can be defined as a constant or as a function of temperature For elastic bodies temperature change is defined as the difference between nodal temperatures and the specified reference temperature REFTMP o T T where amp is the coefficient of thermal expansion To is the reference temperature and T is the material temperature For elasto plastic bodies the thermal expansion input in the pre processor is the average value of thermal expansion and the FEM calculates the instantaneous tangential value from the average value ef a AT gt Aethrrev where a is the tangential coefficient of thermal expansion and T is the material temperature 2 2 3 Thermal data Thermal data is required for any object in the heat transfer mode 39 Plastic Elastic Thermal Diffusion Grain Hardness Elec Mag Advanced Themalconductviy Tem A A Heatcapacty m A A Enisity ers A o Figure 23 Material data window thermal Thermal conductivity THRCND Conduction is the process by which heat flows from a region of higher temperature to a region of lower temperature within a medium The thermal conductivity in this case is the ability of the material in question to conduct heat within an object The value can be a constant or a function of tem
45. pstusr2 f PC_pstusr2 f PC_pstusr2 als PC_pstusr2 xps Project file USR_DEF_PST2 gui USR_DEF_PST2_Absoft70 gui for Absoft Version 7 0 PROCEDURE Compile USR_DEF_PST2 gui to generate a Dynamic Link Library USR_DEF_PST2 dll Step by Step If you can find Compile_DEF_PST_USR bat in the current directory you can compile the user routine by simply click on that batch file and copy the USR_DEF_PST2 dll to DEFORM2D 8_0 Usr directory To generate USR_DEF_PST2 dll follow these steps 1 Double click USR_DEF_PST2 gui USR_DEF_PST2_Absoft70 gui if using Absoft 7 0 compiler Absoft Pro Fortran compiler will open automatically 2 Click on icon or in the menu bar Click ToolsaBuild to build USR_DEF_PST2 dll 3 After finishing with the set up of the project customize pstusr2 f and rebuild USR_DEF_PST2 gui 4 Copy USR_DEF_PST2 dll to the DEFORM2D 8_0 Usr directory 209 Compiling user routines for UNIX platforms The user routines are called for each node element for every step during the simulation and efficient coding practices should be followed to minimize simulation time Do not open or close data files during each subroutine call as this can degrade performance significantly The USRDEF field in the pre processor can be used to store a limited number of parameters If you require more space than what is available in USRDEF then open the data files in the user subroutines and store a static variable ina COMMON block so
46. sides of the centerline of a part If a part lies on the centerline symmetry can be added by clicking on the add option and picking the region of the part that touches the centerline If the part does not lie on the centerline there are two ways in which to mirror the part 1 Click the Point Axis button under the Add tab and specify the centerline of the part by selecting the proper object setting point to 0 0 and set the axis to the centerline axis 0 1 Click Apply to see the symmetry 2 Click the Copy Mirroring Plane button and copy an existing symmetry line from an already mirrored object to an unmirrored object Click Apply when finished 149 g Symmetry Definition x C ddd Delete 1 TEST Mirror 1 2 TOP_DIE Mitror 1 3 BOT_DIE Mirror 1 3 BOT_DIE Miror 1 a Figure 70 Copy mirroring plane window 4 5 3 State Variables In order to plot state variables the variable and the component of the variable must be selected Also one of the scaling types global min max of all objects for all simulation steps local min max of all objects for the particular step and user defined which defaults to the global values must be selected For user defined the min max values can be entered in the input fields provided to the right of the window Then the type of contour line shaded vector and the class of objects to be plotted can be selected and finally specific objects can be selecte
47. simulation engine Note All pre processor steps should have a negative step number Number of simulation steps NSTEP The number of simulation steps to be run defines the number of steps to run from the starting step number The simulation will stop after this number of simulation steps will have run or if another stopping control is triggered to stop the simulation Hence if the starting step number is 35 NSTART and 30 steps NSTEP are specified the simulation will stop after the 65th step unless another stopping control is triggered first Step increment to save STPINC The step increment to save in the database controls the number of steps that the system will save in the database When a simulation runs every step must be computed but does not necessarily need to be saved in the database Storing more steps will preserve more information about the process consequently it will require more storage space Primary die PDIE The primary die is the object for which the stroke is measured for any values which refer to the die stroke For example stopping criteria based on primary die stroke or die velocity which is specified as a function of stroke are both keyed to the primary die movement The primary die is usually assigned to the object most closely associated by the forging machinery For example the die attached to the ram of a mechanical press would be designated as the primary object Step increment control DSMAX
48. steps are appropriate 1 Assign the Primary Die The top die or punch should be the primary die This will generally be object 2 2 Calculate the Stroke per Step Estimate the distance the top die will move from the point it contacts the workpiece Divide this value by the number of steps and enter this value in Stroke per Step If you are unsure of total punch stroke add 10 or 15 extra steps This will overshoot the goal and you can back up a few steps to get the ending shape 253 3 Set Stopping Controls optional If you know the exact distance the punch will move enter this value under stopping controls If no value was entered the simulation will stop when all steps have been completed 4 Set substepping control Under Advanced Step Controls set Strain per Step to 0 025 1 Save the Data Save a keyword file Go to Database generation Check the data If there are any yellow or red flags resolve them then generate the database Exit the preprocessor and start the simulation 2 Running a Second Operation 1 Identifying the endpoint of the first operation After the simulation is completed go to the Post Processor and check the results Identify the step at which the first operation will be completed and make a note of this step number 2 Loading Simulation Results Into the Preprocessor Return to the preprocessor and load the appropriate step from the database 3 Simulate Chilling During Transfer to
49. such a lap is detected and you would like to continue the simulation you may try the following alt Modify the geometry to remove the lap and continue the simulation This will require remeshing and interpolation to maintain the strain temperature and damage history 2 Declare the master slave relationship to itself thus a closed lap will continue the simulation process e Adie geometry defined by a closed loop must have the starting stopping point away from the contact zone between the die and workpiece If this is not the case it is possible for a node to think it has penetrated the die at 132 this seam and lead to subsequent serious problems during remeshing e If for any reason a node has penetrated one of the dies the remeshing will become problematic This can be evaluated by looking at the FEM MESH of all objects at the step just prior to remeshing A node that is inside the die surface will move back to the die surface after remeshing and interpolation of boundary conditions but an element that had an acceptable geometry can be highly distorted during this process e Ifthe user sets a problem with very large time steps and little to no substepping criteria this can lead to a problem resulting from a mesh distorting severely during the first step Time step size should be small enough to allow for multiple steps between remeshing In the case of simple or developmental problems 40 to 50 steps are reasonable In the case o
50. that the file does not have to read each time the user subroutine is called After the FORTRAN code has been modified a new FEM engine can be build using the INSTALL2D script which is located in the DEFORM_DIR or using the script build_ fem which is in the DEFORM_DIR USR directory If the INSTALL2D program is being used the code in DEFORM_DIR will be altered you must have write permissions If you wish to build a local copy of the FEM engine code then copy all files from the DEFORM_DIR USR directory to your local directory Then run the script build_fem using the following command gt build_fem This builds a new copy of the FEM engine DEF_SIM EXE in the local directory After this process is completed simulations using the new user defined routines can be run using the local copy of the FEM engine Running the modified FEM engine for UNIX platforms If the FEM engine is built in the DEFORM directory with user routines all users have access to the same user routines If a local copy of the FEM engine is to be built and run then the DEF_ARM COM script has to be copied to the local directory and the calls to DEF_SIM EXE have to be modified to call the local copy of the program In place of the calls DEFORM_DIR EXE DEF_SIM EXE replace it with DEF_SIM EXE where DEF_SIM EXE is the local copy of the FEM engine When simulation jobs are submitted using the GUI or text based main program the alias DEF_ARNM is used to start the scri
51. the DEFORM2D V8_0 directory where the installation was made and the program should be ready to run 240 Setup has completed installing DEFORM 20 Do you want to restart your computer now esserennsnnsenstnanseanesnnsensnsatnransannenasnvannetnaensensenvansenssnenrannsensensananne C No will restart my computer later Click Finish to exit DEFORM 2D setup TROUBLESHOOTING When you are troubleshooting the installation of DEFORM it is recommended to open an MS DOS prompt from the Start Menu and change directory to where the DEFORM files are located For testing 2D type run the file DEFORM2 COM by typing the name of file in the DEFORM2D V8_0 directory in the MS DOS prompt This will show the exact error message in the MS DOS window Error The message Security Parameters do not match please contact Scientific Forming Support Personne is displayed Problem Your DEFORM 2D password has expired Solution Contact Scientific Forming Technologies Corp for a new 241 password file DEFORM PWD Error The message Hardlock Key is not found is displayed Problem 1 The Security Key cannot be located on the system by DEFORM 2D This is a probably a result of either the Security Key not plugged in to the parallel port tightly or not on the system at all Solution 1 Check the back of your PC If the Security Key is not plugged in locate the parallel port usually LPT1 and plug the Security Ke
52. the direction to X and Generate BCC s the direction to Y and Generate BCC s on the same nodes Then change Repeat this process for all other rigid deformable contact pairs NOTE The weld contact interface must NOT have n n boundary conditions 256 7 Define the rest of the preprocessor settings including all interobject relationships as you normally would 257 Appendix B Running DEFORM in text mode DEFORM contains text based modules which can be used to set up and run simulations in automatic mode without going through the graphic user interface GUI The text based preprocessor DEF_PRE EXE can be used to assemble input data and generate a DEFORM database It contains most of the same functionality of the graphic interface The job can be submitted by calling the simulation control script DEF_ARM_CTL COM Assembling input data The preprocessor can be controlled by redirecting a text input control file to the program C deform2d v7_2 DEF_PRE EXE lt DEF_PRE_INP txt Where DEF_PRE_INP txt contains the following lines lt CR gt 2 1 DEF_COMMANDS KEY lt CR gt E E Y lt CR gt Which are the user inputs if the text based system were run in interactive mode The file DEF_COMMANDS KEY contains a series of Action Keywords which trigger the preprocessor to perform a series of options The file name is the users choice Action keywords are documented separately It also can contain standa
53. the specified type and direction click the Initialize BCC s button In version 7 0 if the previous method of defining the boundary conditions at the nodes was used it will still be shown as boundary conditions at the nodes Deformation boundary conditions Velocity BCC Velocity of each node can be specified independently in the x y and z directions Velocity boundary conditions are normally set to zero for symmetry conditions see section on symmetry in this manual but may also be set to a specified non zero value for processes such as drawing in which a workpiece is pulled through a die NOTE If parallel symmetry planes are to be defined velocity boundary conditions can only be used on one plane A rigid surface should be defined on 98 the other Force BCC Force boundary conditions specify the force applied each node The force is specified in default units For die stress analysis the force that the die exerted on the workpiece can be reversed and interpolated onto the dies by using the interpolation function Refer to the tutorial labs on die stress analysis for a detailed procedure for using force interpolation to perform die stress analysis Caution should be used in specifying force boundary conditions If the part is remeshed the total force acting on the object will change as the number of nodes changes Where possible it is better to define a rigid surface attach the nodes to that surface then apply a force to that
54. this approximation will tend to over estimate temperature loss as the die surface will not heat up during the simulation This effect can be compensated for by reducing the inter object heat transfer coefficient IHTCOF For any object defined as a mixture the initial volume fraction VOLFC and maximum volume fraction transformed VOLFS must be assigned for all volume fractions In general VOLFC and VOLFS should be initialized to the same value The volume fraction initialization is under the Object Data Elements dialog under the Transformation tab 2 4 8 Object properties 92 k2 Deformation Thermal Fracture Hardness Heating User General oO Average Strain Rate 0 1 1 s Creep Calculation Geometry Limiting Strain Rate 0 0007 t s NotActive is 2 l Active Mesh E Volume Penalty EP Initial Guess Use Material C Vanable C Plastic Solution Movement Previous Step Solution Figure 47 Object properties window Miscellaneous object parameters which affect either thermo mechanical behavior of the object or numerical solution behavior are specified in the Object Properties menu or the Object Advanced menu Deformation properties Limiting strain rate LMTSTR The limiting strain rate defines a limiting value of effective strain rate under which a plastic or porous material is considered rigid Average strain rate AVGSTR The average strain rate is a characteristic average value of the effective stra
55. track down what went wrong Message File The information generated about each simulation step is written to the message file The file for the current problem is listed in the Message File text box When a simulation stops check the Message file for information on why the simulation terminated 3 3 Email the Result This function allows DEFORM to send an e mail notification of the completion of a simulation If Yes is selected the e mail address to send to is required as well as the name of the company SMTP mail server 3 4 Starting the simulation The simulation is started by clicking the Simulation Start button This initiates a series of operations to run the simulation and generate new meshes as necessary Run time information will be written to the Problemld MSG and Problemld LOG files e Execution information including convergence information for each step and simulation error messages can be found in the MSG file e Information on simulation and remeshing execution times and fatal errors can be found in the LOG file or in the command window where DEFORM was executed from 3 5 Add to Queue Batch Queue This will allow the simulation specified in the simulation window to be added to the DEFORM queuing system which will run multiple jobs in a consecutive manner Once the simulations are added to the bat
56. volume fraction depends on carbon content c State variables are simplified Incubation time TICF starting volume fraction VOLFN not used anymore Additions and Enhancements to the Inverse Heat Transfer Template 52 Diffusion is added 53 Symmetrical plane definitions 54 Allow heat treatment medium temperature specified as function of time 55 Allow to deactivate certain transformation for particular operations Additions and Enhancements to the Inverse Heat Transfer Template 56 Allow one heat transfer zone to contain two or more segments on the boundary 57 On line checking of currently best heat transfer coefficients 58 Convenient restart using results from previous optimization 59 Final simulated thermal history is compared with experimental measurements 222 223 System Installation UNIX and Linux Warning In this release we have changed the name of the password file from DEFORM IDF to DEFORM PWD in order to be consistent with the PC version If you install the password file as DEFORM IDF the installation will not work OVERVIEW In order to load the DEFORM 2D system on your machine you need the version of the operating system given in Table B 1 and a FORTRAN compiler if you need to use user routines optional Approximately 100 120 MB of disk space will be required for this installation In this release each platform s installation requires a platform independent file DEF2DV80 TAR Z and a
57. 1 PEM 0 1 YS 10 EFEPS PEM FIP 10 PEM EFEPS PEM 1 RETURN END Discussion In this very simple model the flowstress is merely a function of strain rate The three lines of added code can be seen using the comments in the code This creates a very simple equation for the derivative with respect to strain rate and the derivative with respect to strain is zero Every time a flowstress value for an element is required this routine is called It then computes the flowstress for the element and the derivatives and returns the values as PEM YS and FIP 2 The flow stress depends on the strain index PEN strain rate sensitivity index PEM the effective strain STRAIN and the effective strain rate EFEPS The value of effective strain can be the element strain or from a user defined state variable In the example given below the effective strain comes from a user defined state variable that stores the current strain This example also illustrates the concept of using the user defined state variables to calculate flow stress STRAIN USRE1 1 IF STRAIN LE O STRAIN 1 E 5 PEN 0 15 PEM 0 1 YS 10 STRAIN PEN EFEPS PEM FIP 10 STRAIN PEN PEM EFEPS PEM 1 YPS 10 PEN STRAIN PEN 1 EFEPS PEM User defined movement control USRDSP DEFORM supports control of the die movement control for machines which cannot be controlled using the movement mechanisms given in the DEFORM
58. 10 to 20 steps 2 Select the Primary Die Enter object 1 only object defined as the primary die 3 Calculate the Time per Step Divide the total transfer time by the number of steps 2 Save the Data Save a Keyword file Go to Database Generation Check the data If there are any yellow or red flags resolve them then generate the database Exit the preprocessor and start the simulation 3 Loading Simulation Results Into the Preprocessor to Define Second Operation Return to the preprocessor and load the last step from the database 4 Define Material Data for the tools Specify thermal data for the tool material 5 Define the Tools 1 Assign Tool Names optional For reference during pre and post processing 2 Define Tool Geometry Import or define geometry for the upper die punch and lower die The geometry rules detailed above for the workpiece all apply Furthermore For multi piece tools draw a single tool boundary defining all inserts knockouts etc The geometry can be separated later for die stress analysis Refer to the manual or contact tech support if there is more than one moving tool for a given station Extend the tool geometry slightly across the centerline For tools with a sliding clearance between the punch and die increase the OD of the punch to slightly intersect the die Refer to the manual or training material for more details Put a slight flat on the tip of any pointed punches While it is not s
59. 3 Rest on dies 4 Forge 5 Repeat for multiple forging blows 1 Create a new problem folder directory Each DEFORM problem should reside in its own folder However a given problem may contain many operations all in the same database file 2 Start the DEFORM preprocessor 3 Set Basic Simulation Controls The simulation controls will be set for the first operation simulating chilling during the transfer from the furnace to the press 1 Problem Title optional Descriptive title for the problem will be displayed on the screen during pre and post processing 2 Operation Name Operation name 3 Unit System Select English or SI units This will change many default values and affect how material data is imported 4 Select Axisymmetric or Plane Strain An axisymmetric part can be completely defined by rotation of a 2 dimensional cross section or significant details can be captured in a 2D section for example a pinion gear where fill in the teeth is not significant An average pitch diameter which gives the same cavity volume should be used Buckling problems are not axisymmetric problems An axisymmetric 249 simulation will NEVER show buckling or bending even if it will occur in production Refer to the manual for more information 5 Select Simulation Mode For simulating transfer of the workpiece from the furnace to the press only heat transfer will be modeled so turn on heat transfer and turn off
60. DEFORM Support Website for Windows Machines There is now the possibility to compile user routines for Windows platforms using the SFTC website The location of the website is as follows and is available to only current customers of DEFORM http support deform com 2d support fortran eT EFORM 2D Windows FORTRAN Compilation Microsoft Internet Explorer Bile Edit yew Favorites _ Help l Heak GAl Compile this def_usr f DEFORM 2D v8 0 0 User Routine crs this def_usr f PELO Compile this pstusr2 DEFORM 2D v8 0 2 User Routine DEFORM 2D v8 0 2 Post Processor Library Information provided in the Users Area is company confidential and animal gt ae e e ee D Internet Figure 129 The DEFORM webpage for compiling user routines Figure 129 shows the webpage where the user routines are compiled There are various versions of DEFORM listed on the website and the appropriate version should be 287 selected The left half of the webpage are the user FEM routines that can be compiled and the right half are the user post processing routines that can be compiled To compile a user routine click the appropriate Browse button and load the fortran file that should be compiled After this click the Submit File button and the website will guide you to download a zip file This zip file will contain the following information 1 The original fortran file you submitted 2
61. DEFORM can be installed by performing the taks 1 Create the installation directory mkdir usr deform 2D V80 227 2 3 Switch to the installation directory cd usr deform 2D V80 Uncompress and untar the installation files from the CD zcat cdrom 2DV80_GenericUnixOS TAR Z tar xvf zcat cdrom DEF2DV80 TAR Z tar xvf Installing the password file The password for running DEFORM 2D on the current system has to be setup in the file DEFORM PWD This password file can be obtained from your distributor Installing DEFORM 2D components Optional 1 2 228 Go to the DEFORM 2D directory cd usr deform 2d v80 Optional Modify the command procedure file DEF_MSH COM which controls the activation of other FEM pre or post processors if necessary In DEFORM 2D System several commercially available FEM pre and post processors i e PATRAN I DEAS can be directly activated This is done by DEF_MSH COM Since the activation of these processors is site dependent modifications may be necessary Please check with your system administrator for the procedure to activate these processors and follow instructions given in DEF_MSH COM to make necessary changes Note The GUI version does not use the above features Optional Do not copy DEF_USR FOR from an old version of DEFORM Update DEF_USR FOR provided with this version Changes are documented in the file DEF_USR FOR Modify the FORTRAN source DEF_USR
62. DEMAX The maximum element strain increment limits the amount of strain that can accumulate in any individual element during one time step If a non zero value is assigned to DEMAX a new sub step will be initiated when the strain increment in any element reaches the value of DEMAX Volume change per step DVMAX During a deformation time step elements typically experience a change in volume Over time this volume change generally results in volume loss The volume loss generally increases with increasing step sizes and increasing total height reduction i where refers to a height reduction per step and H refers to the height of an object For problems where volume loss is significant the volume loss also can be controlled by specifying the maximum amount of volume change that an 23 individual element or an object can experience during a time step If a non zero value is assigned a new sub step will be initiated when the ratio of the volume change to the original volume of any element exceeds the specified value Temperature change per step DTPMAX The maximum temperature change increment limits the amount that the temperature of any node can change during one time step If a non zero value is assigned a new sub step will be initiated when the temperature change at any node reaches the value of DIPMAX The maximum minimum time step are the largest and smallest time step allowable with the temperature based sub stepping S
63. FOR which contains user defined material properties routines and die velocity routines if necessary The file is in the USR directory 10 dummy material property routines from UFLOW1 UFLOW10 are included in DEF_USR FOR To replace these routines refer to subroutine UFLOW1 for instructions 10 dummy die speed routines from DIESP1 DIESP10 are included in DEF_USR FOR To replace these routines refer to subroutine The user defined variable subroutine USRUPD may be used to specify the USRNOD and USRELM variable values As an example USRELM 1 stores the maximum principal stress Instructions on what is to be done is given inside this subroutine A user defined damage criteria also exists in the DEF_USR FOR To use these subroutines refer to the routines Optional Do not copy PSTUSR FOR from an older version of DEFORM Update PSTUSR FOR provided with this version Changes are documented in the file PSTUSR FOR Modify the Fortran source PSTUSR FOR which contains user defined routines for state variables tracking if necessary The file is in the USR directory 10 dummy state variable routines from USRPS1 USRPS10 are included in PSTUSR FOR To replace these routines refer to subroutine USRPS1 for instructions 5 If no change is made to DEF_USR FOR goto step 9 6 To link DEF_USR FOR with the DEFORM simulation engine run INSTALL2D INSTALL2D Select Option 3 The updated FEM simulation execution image DEF_SIM EXE will b
64. IF Diffusion with the environment BCC Specifies diffusion of the dominant atom through the boundary elements bordered by the indicated nodes Environment dominant atom content and surface reaction rate are specified under the Simulation Controls Processing Conditions menu Environment content and reaction rate for various regions of the part may be modified by using diffusion windows The new keyword for this is ECCATM Fixed atom content BCC Specifies a fixed dominant atom content at the given nodes Atom flux BCC Specifies a fixed dominant atom flux rate over the elements bordered by the indicated edges This is now specified using an edge definition starting in version 7 0 Atom flux may be defined as a constant or as a function The new keywords for this are ECCATM and ECAFLX Advanced Diffusion BCC The purpose of this boundary condition definition is to allow the user to have the flexibility to specify all the various types of diffusion boundary conditions on the same edge The user can either specify a user subroutine number or a local diffusion definition If the user wants to specify a user routine the User Routine Number should be specified The User Routine number specified will correspond to the subroutine the boundary condition will correspond to Refer to User Routines for more information on how to use these user defined boundary conditions If the routine number is left zero the user may then define a local defined bounda
65. NA nies 168 4 5 10 Elements Window i giacieistneseletiaeciniiatel fied ciel aieeidiadieievies dtievivieliawedd daa ellage aie 170 4 5 ODjSCtECGES sutvessa he ened ese ned bere ened at bie ened ai teace a Ae oan 170 4 512 MIGWPDOM chee ik Ain etl ai eat a ead a et eh he 171 4 5 13 Data Extractioninewissnide Musee ee eae ae ee ee a ee a 172 4 5 14 State variable distribution between 2 points cece eeeceeeeeeeeeeeeeetaeeeeeeeeeteeetaeeeeeees 174 Chapter 5 Elementary Concepts in Metalforming and Finite Element Analysis 177 Chapters User ROUNES i aciseccst Aci iese eane Ee reheat nena Sees 189 ROME VIO WE seh da teh octet ccc E tented eben neon E OE E nn teen savage Made 189 User Defined FEM Routines cccccccccceeeeeeeeeeeeeccaneeeeeeeeeeeeecaaeeeeeeeeeeeecaaeeeeeeeeeeeeeeaaaes 189 Summary of subroutines and calling structure of user defined FEM routines ccceeeeeeeeeeeeee 190 User Defined Post Processing ROUtINGS ccececeeeeeeeeeeeeeeeeeaeeeeeeeeeeeeecaaaeeeeeeeeeteeeaaaes 192 6 1 User defined FEM fOutines siictecctccetetetecetac ctecetes E etude tac tate tet eteceten 192 6 2 User defined post processing routines ccccceccccceeee cette eeeeeceneeeeeeeeeeteetaaeeeeeeeenteee 214 Release NOLS itic i Shaqns eta a a aa E E EEEa teea wade pe RERE Ea 218 System Installation UNIX and LINUX cece eee eeeeeneee teeter eeeeeceeaaeeeeeeeeeeeeeeeaaees 224 Installing Java for the 2D
66. Next Station Consider the transfer time between stations Refer to the beginning of this section for guidelines on running heat transfer simulations 4 Changing Tool Geometry Go to the Geometry editor delete the tool geometry not the whole object and import or create new tool geometry for each tool 5 Positioning Objects From Interobject reposition the tools against the workpiece using interference 6 Generate Contact Initialize and generate contact boundary conditions 7 Reset Simulation Controls Determine total steps and stroke per step as described above 8 Reset Stopping Stroke If the stroke stopping control was used reset the stroke to zero on object movement controls and reset the stopping control under simulation controls 9 Write The Database 254 Writing an old database will append data to the end of the existing database It will overwrite any steps after the step that was loaded 10 If the appropriate ending step is not saved If you encounter a situation where say step 90 is not formed enough step 100 is formed too much and there are no steps saved in between you can load step 90 change the save interval to 1 save every step then rerun the last 10 steps of the simulation to get the proper stopping step 255 Appendix A Running an inertia weld simulation in DEFORM DEFORM 2D includes special features to simulate uniform rotation and distortion about the Z axis The torsional dis
67. PHASTF MIC eeeeenneeeeeeeeeeernresseeserrrrtsserrrrrrrrssetrrrnresserreenn 62 2 3 2 Kinetics model TTTD MIC aaaea aeaaea ai aaa Ei EET 63 2 3 3 Latent heat PHASLH MIC cceeceeceeeeeeeeeeeeeneeeeeeeaeeeeseaeeeeecaaeeesecaeeeesssaeeeessieeeeesaes 67 2 3 4 Transformation induced volume change PHASVL MIC ceeceeeceeeeeeeeeeeettteeeeeeeeeteea 68 2 3 5 Transformation plasticity TRNSFP MIC 0 eect ee eet eeeeeeeeeeeteetaeeeeeeeeeneea 69 2 4 Object Detinition s t2wwieie ei Alea aa a ets 69 2 4 1 Adding deleting Obj CtSi ic t ieuseidiievcieiewe ennaa aa a a ie alin Aaa 71 24 2 Object name OBINAM renye tuces neat E E eee atoadh E at eet oon ee eek 71 243 Pimay Die PDI E ti encc wie tas aimed aim cnumbedmbanehinimdmuent aceite 72 2 44 Object type OBULY P sees tint cee eateasteiate a thi a a RST 73 246 OBL i GEOMEY aa cea wei ais ee aah ies Sess adeiaaser aaa ai E 75 PR R ObjecumMeshinGiers sets Mate Me easter Sides Meade tia tteus Meat Mhiattua daa tee tea aad ee eae 80 2 5 Inter Object DEMON gazcee caves ceed estexvcavviveete dee seeeatvivessevedesvestviseed weeeniaavinedeeveriniatiaen 117 275 1 Mer OBjECE IMLS ACE aoe tas fas Setens cavashae a datenecasagedavacesstecers E ace Meade verasans See stearety 118 2 522 POSITIONING gic ii nants Maes aint Haare eet ea ee aa eee ae 123 2 5 3 Inter object boundary CONCITIONS cee ee eeeeeteee eee ee tte e eee e eee eeeaaeeeeeee
68. PRZ maintains a specified normal pressure or shear traction across the face of the elements lying between the selected boundary nodes Deformation Boundary condition code BCCDEF BCCDEF specifies the deformation boundary condition in X Y and Z The code values are 0 Node force specified X Y or Z component of node velocity constrained corresponding to the X Y or Z component of BCCDEF 2 Constrained node tractions specified by PRZ 3 Node movement control defined n Node is in contact with object number N Note There is no significance to 112 the X Y or Z component of contact Contact values are stored in the first free component starting with Z then Y then X Boundary condition functions BCCDFN BCCDFN specifies if the value of a deformation boundary constraint nodal velocity force or traction associated with a particular node is to be specified as a constant or as a set of time nodal value data Thermal Temperature NDTMP NDTMP specifies the nodal temperature to be applied to individual nodes Heat NDHEAT NDHEAT specifies the nodal heat to be applied to individual nodes Heat flux NDFLUX NDFLUX specifies the distributed nodal heat flux to be applied to individual nodes The heat flux constraint will be applied to the element faces lying between the selected boundary nodes Boundary condition code BCCTMP BCCTMP specifies the heat transfer boundary constraint code for individual nodes 1
69. RO03_PUR DB Browse Type Step Time C Die stroke Figure 82 Database management window The database management window has the purpose of providing database purging 4 5 9 Nodes window The nodes window will display information on the nodes of the currently selected object This information includes position state variables and boundary conditions A different node can be selected through the node text box or by selecting a node graphically in the display window The information will change as the step number displayed changes in the display window 168 Figure 83 Nodes data window 169 4 5 10 Elements window The elements window will display information on the elements of the currently selected object A different element can be selected through the element text box or by selecting an element graphically in the display window The information displayed will change as the step number displayed changes in the display window Ti Element Data TEST total of elements 246 x Element jj 3 276 280 oK 279 275 Cancel Deformation Hardness Transformation Heating rman Highlight Elem Figure 84 Elements data window 4 5 11 Object Edges Some values are defined on the boundary of each object These values are known as element edge data The value for these conditions is available in the object edges window In many cases boundary conditions act upon the surface of an objec
70. Requirements ABSOFT Pro Fortran 7 0 or above version 7 0 7 5 or 8 0 Files provided by SFTC 1 Libraries DEF_SIM_USR lib 2 Project files DEF_SIM_USR gui for Absoft 7 5 or above DEF_SIM_USR_Absoft70 gui for Absoft 7 0 3 Sample fortran source file def_usr f PROCEDURE Compile def_usr f and link this library with the DEF_SIM_USR_LIB lib provided by SFTC As result an executable file DEF_SIM exe will be produced SFTC provides two project files and one FORTRAN file that can be used as templates Step by Step If you can find Compile_DEF_SIM_USR bat in the current directory you can compile the user routine by simply click on that batch file and copy the DEF_SIM exe to the folder where DEFORM 2D is installed To build DEF_SIM exe manually follow these steps 1 Double click DEF_SIM_USR gui DEF_SIM_USR_Absoft70 gui if you are using Absoft 7 0 Absoft Pro Fortran compiler will open automatically 2 Click on icon or in the menu bar click on Tools gt Build to build DEF_SIM exe 3 Copy DEF_SIM exe to the DEFORM2D V8_0 directory do not forget to make a backup copy of the original DEF_SIM exe Note An alternative to compiling user routines on a local compiler is to use the DEFORM webpage This is available to all current DEFORM customers Please refer to Appendix N for more details 208 Windows building procedure for FEM routines Requirements ABSOFT Pro Fortran 7 0 or above Files provided by SFTC
71. T f e Temperaire miceli My M Stwess indret Fa F Tanfomiat on n Transfimatcn Terit Fati Figure 1 Relationship between various DEFORM modules 1 3 Analyzing manufacturing processes with DEFORM DEFORM can be used to analyze most thermo mechanical forming processes and many heat treatment processes The general approach is to define the geometry and material of the initial workpiece in DEFORM then sequentially simulate each process that is to be applied to the workpiece The recommended sequence for designing a manufacturing process using DEFORM e Define your proposed process e Final forged part geometry e Material e Tool progressions e Starting workpiece billet geometry e Processing temperatures reheats etc e Gather required data e Material data e Processing condition data e Using the DEFORM pre processor input the problem definition for the first operation e Submit the data for simulation e Using the DEFORM post processor review the results e Repeat the preprocess simulate review sequence for each operation in the process e Ifthe results are unacceptable use your engineering experience and judgment to modify the process and repeat the simulation sequence 1 4 Before you begin Before you begin work on your DEFORM simulation spend some time planning the simulation Consider the type of information you hope to gain from the analysis Are temperatures important What about die fill Press loads Material defor
72. The convection coefficient is required for convection heat transfer calculations The convection coefficient may be specified as a constant or as a function of temperature View Factor calculation This is a checkbox that will perform self heating and radiation heating from other bodies when the view factor box is checked 31 Heat Transter Diffusion Induction Constant ok Environment Atom Content Cancel Constant 1 69 atm Function of Time Define Constant fie 005 in sec C Function of Temperature C Function of Atom Figure 16 Process condition window diffusion data Environment atom content ENVATM MIC The percentage atom content of the dominant atom usually carbon for diffusion calculations Reaction rate coefficient ACVCOF DIF The surface reaction rate with the atmospheric atom content for diffusion calculations Heat Transter Diffusion Induction Constant ox Interface Penalty Constant Te 010 Cancel Mech to Heat Conversion 0 107 Time Integration Factor 0 75 Boltzman Radiation Constant 3 306e 015 Figure 17 Process condition window constants 32 Boltzman constant BLZMAN The Boltzman constant is required for radiation heat transfer calculations Default values for English and SI are set automatically In radiation heat calculations the nodal temperature will be automatically converted to absolute temperature Rankine Kelvin based
73. UX or a dynamically linked library Windows 3 This shared library can be called by going to the User Variable tracking window seen below To select the library click on the library tab and select the library that was built After this go back to the tracking window and press the Track Data button 4 After the data has been tracked go to the State Variables window and select the USR tab and then the state variables can be plotted to User Variables The only difficultly is in editing the FORTRAN file This requires a slight knowledge of the FORTRAN language and a compiler available on the computer one is working on Please refer to Appendix N if using a Windows machine and a compiler is not available Note User defined Post Processor routines can only use data that was saved in the database If a very coarse step increment was made variables having a cumulative effect can have considerable error 6 1 User defined FEM routines This section contains a description of the different FEM user routines available in the current release of DEFORM 2D The skeletal code for user routines is stored in DEF_USR FOR or def_usr f that has the FORTRAN functions that the FEM engine calls if a user routine is to be used The user routines calculate the specified values and returns output values User defined data USRDEF The user defined data USRDEF field in the pre processor can be used to store data that can be used to specify parameters for the us
74. VE TERMS Fill in the form After this click submit button you can see the download page c Click download hp ux runtime environment for the Java 2 platform version 1 3 1 10 PA RISC to download installation file to your hard disk d Follow the instruction shown to install 3 Check PATH by typing env If it doesn t include java path add it by setenv PATH path to java ie opt jre1 3 bin PATH Cutting template configuration 1 After installed cutting template go to 2d_cutting directory 2 cd CONFIG modify directory ini file it requires 2 values for DEF_DIR and USR_PROB_DIR DEF_DIR the absolute path of 2d_cutting ie home deform 2d v80 TOOLS 2d_ cutting USR_PROB_DIR the absolute path of PROBLEM directory of user usually under your account ie home myAccount PROBLEM 3 cd 4 type Machining_Template bat to run template Setup a user account 1 Make sure the default login shell is C shell csh We will assume the DEFORM 2D user name is user1 and the login directory is disk1 user1 2 Log into the user account and edit C shell login command file cshrc to 230 include the following two command lines setenv DEFORM_DIR usr deform 2d v80 source DEFORM_DIR CONFIG COM The first command line defines the global symbol DEFORM_DIR to be the DEFORM 2D directory The second line executes the DEFORM configuration file CONFIG COM Note The user can use any shel
75. _ARM_CTL COM DEFORM_DEMO B The Bindicates that the simulation should be run in Batch mode 260 Appendix C Inserting DEFORM Animations in Powerpoint Presentations Based on Powerpoint 97 running on Windows 98 platform other variations may be slightly different Legend Comments in square brackets parentheses are instructions Underlined comments are actual key strokes The Process Arrange suitable directory structure for example POWERPOINT file in same directory as DEFPLAY EXE and presentation files in subdirectories immediately below Open POWERPOINT file and go to page where animation is to be inserted insert object create from file orowse_ find DEFPLAY EXE in the browse window and select it ok locate new object icon on page perhaps drag it to the bottom left corner right click on icon edit package package object edit command line type DEFPLAY EXE presentation_file_full_path e ok file update file exit where presentation_file_full_path is for example d work presentation extrude extrude pre right click on icon action settings mouse click action on click none action settings mouse over action on mouse over none right click on icon custom animation timing start animation animate 1 seconds after previous event 1 seconds is optional custom animation effects entry animation and sound no effect custom animation chart effects none custom animation play settings o
76. a toggle selection e Show geometry normal vector displays vectors normal to each surface facet e Make transparent e Show backface backface shows the interior or back surface of rigid objects The Material Data menu allows access to the material properties window same window as the preprocessor A meshed rigid object will contain both mesh data for temperature calculations and rigid surface geometry data for contact with deforming objects The mesh and geometry data menus allow control of the mesh and geometry surface display The Mesh Data menu controls display of the object surface mesh description e Show Mesh Hide Mesh shows or hides the display of the object surface mesh Change shade color changes the element fill color e Change line color changes the color of the lines delineating element edges The Geometry Data menu controls the display of the surface geometry description Show Geometry Hide Geometry shows or hides display of the surface geometry e Change shade color changes the surface facet fill color Change line color changes the color of lines delineating facet edges Additional Post Processing Functions When various post processing functions state variables load stroke curves slicing etc are displayed the respective icons will be added to the object tree Right clicking on these icons allows editing of their respective properties Object Control Bar 143 All right mouse
77. after a mesh has been generated Estimate the maximum workpiece velocity for most problems this will be the die velocity For extrusion problems it will be the die velocity times the extrusion ratio Divide the result of 1 by the result of 2 and take about 1 2 of this value as the time step This is a rough estimate so extreme accuracy is not critical n Fa The number of steps is given by VA where n is the number of steps x is the total movement of the primary die V is the primary die At velocity and is the time increment per step If there is insufficient information available to calculate the total number of steps three alternatives are available 1 A general guideline of 1 to 3 height reduction per step can be used 24 Specify an arbitrarily large number of steps and use an alternative stopping control such as time or total die stroke Make a good estimate of the number of steps required for the given step size then specify about 120 of this value Allow the simulation to overshoot the target then use a step near but not at the end as a final solution Simulation Control 1 x General Advanced Advanced2 OK Step Definition Cancel User System M Auto Control Parameters Maximum Strain in Workpiece per Step 0 025 Maximum Volume Change inElement O Maximum Volume Change inWorkpiece 0 Figure 11 Advanced stepping menu 1 2 1 3 Advanced Step Controls Strain per step
78. ain rate is defined as the instantaneous plastic strain rate Stress Stress is defined as the force acting on a unit area of material Assume a unit cube of material Forces or stresses acting on the faces of the cube can be resolved into normal perpendicular to the face and shear along the face Shear stresses can further be resolved into two components along arbitrary orthogonal axes Thus the complete stress state can be Oz Oy 0 defined by three normal stress components and and and six Ory Tyr yz Fry Izz Orz shear components and Through equilibrium conditions it may be shown that the components Og O acting in the same plane are equivalent That is ia cs it eid Ozz Orz and Thus the complete stress state can be represented by 3 normal components and 3 shear components As with strain by mathematical analysis it is possible to orient three orthogonal axes such that the shear components of the stress along these axes is 0 The resultant normal stresses acting on these axes are termed principal stresses DEFORM uses the von Mises stress to define the characteristic effective stress The effective stress is defined as Q z o1 02 02 03 03 01 where 71 72 and 73 are the principal stresses For most metals the effective stress is indicative of the onset of plastic flow Back Stress Back Stress is defined as the translation of the yield surface caused by
79. aining most features available on DEFORM 2D DEFORM HT Available as an ad on to DEFORM 2D and 3D In addition to the deformation modeling capabilities DEFORM HT can model the effects of heat treating including hardness volume fraction of metallic structure distortion residual stress and carbon content 1 2 Capabilities Deformation Coupled modeling of deformation and heat transfer for simulation of cold warm or hot forging processes all products Extensive material database for many common alloys including steels aluminums titaniums and super alloys all products User defined material data input for any material not included in the material database all products Information on material flow die fill forging load die stress grain flow defect formation and ductile fracture all products Rigid elastic and thermo viscoplastic material models which are ideally suited for large deformation modeling all products Elastic plastic material model for residual stress and springback problems Pro 2D 3D Porous material model for modeling forming of powder metallurgy products Pro 2D 3D Integrated forming equipment models for hydraulic presses hammers screw presses and mechanical presses all products User defined subroutines for material modeling press modeling fracture criteria and other functions 2D 3D FLOWNET 2D PC Pro and point tracking all products for important material flow infor
80. al calculations to solve the problem The simulation engine reads input data from the database then writes the solution data back out to the database As it runs it creates two user readable files which track its progress Log LOG files Log files are created when a simulation is running They contain general information on starting and ending times remeshings if any and may contain error messages if the simulation stops unexpectedly Message MSG files Message files are also created when a simulation is running They contain detailed information about the behavior of the simulation and may contain information regarding why a simulation has stopped 1 11 Post processor The postprocessor is used to view simulation data after the simulation has been run The postprocessor features a graphical user interface to view geometry field data such as strain temperature and stress and other simulation data such as die loads The postprocessor can also be used to extract graphic or numerical data for use in other applications 1 12 Units DEFORM data may be supplied in any unit system as long as all variables are consistent ie length force time and temperature measurements are in the same units and all derived units such as velocity are derived from the same base units This task can be simplified by using either the British or SI system for the default unit system Entity SI unit English unit SI unit
81. al variation more careful study of friction is warranted If there is little variation then the typical values are adequate Friction windows FRCWIN Friction windows allow the user to specify different friction coefficient values for different contact regions of the same object pair The friction window defines a friction coefficient for the specific area that is defined in the display window The friction coefficient specifies the friction encountered by any object in contact with the workpiece The three friction models allowed are constant shear coulomb and tau friction All types of friction can be defined as a constant value or as a function of pressure or time Note If there is not a friction window assigned for portions of objects that are in contact The global friction coefficient assigned in the inter object interface will be used Interface heat transfer coefficient IHTCOF The interface heat transfer coefficient specifies the coefficient of heat transfer 121 between two objects in contact This can be specified as a constant or a function of time or interface pressure The interface heat transfer coefficient is generally a complex function determined by the interface pressure amount of sliding and interface temperature If this data is available it can be entered as a table If no data is available values of 0 004 english or 11 SI should give reasonable results Separation criteria SEPRES The separation crite
82. also be considered as flow stress The metal starts flowing or deforming plastically when the applied stress reaches the value of yield stress or flow stress The DEFORM material database has been implemented with around 145 material flow stress data sets Additional materials will be included as they are available The material database contains only flow stress data data for a material in the plastic region Thermal and elastic properties are not included in the material database Note Flow stress data is compiled from a variety of sources and it is only provided as a reference data set Material testing should be performed to obtain flow stress data for critical applications Flow Stress FSTRES DEFORM provides different methods of defining the flow stress These forms are shown below Power law 41 g Flow stress Effective plastic strain Effective strain rate c Material constant n Strain exponent m Strain rate exponent y Initial yield value Tabular data format Flow stress Effective plastic strain Effective strain rate T Temperature This method is most highly recommended due to its ability to follow the true behavior of a material The user is required to enter the values of effective strain effective strain rate and temperature for which the user has flow stress values Interpolation methods Linear interpolation This method takes a linear weighted average between tabular flow stres
83. alue This is the default which does not have to be changed in almost all cases e System In the system defined steps mode each sub step is saved to the database and is treated as a step This option is primarily used for debugging purposes e Auto In temperature based sub stepping the DTPMAX value controls the time stepping 26 General Advanced Advanced2 oK Control Parameters Maximum Temperature Change per Step 0 Minimum Temperature Time Step a Maximum Temperature Time Step tb t it S Maximum Sliding Error as Minimum Deformation Time Step Maximum Deformation Time Step PP Y Figure 12 Advanced stepping menu 2 2 1 4 Stopping controls The stopping parameters determine the process time at which the simulation terminates A simulation can be terminated based on the maximum number of time steps simulated the maximum accumulated elemental strain the maximum process time or maximum stroke minimum velocity or maximum load of the primary object A simulation will be stopped when the condition of any of the stopping parameters are met If a zero value is assigned to any of the termination parameters other than number of steps NSTEP the parameter will not be used If no other stopping parameters are specified the simulation will run until it has utilized all of the specified steps 27 Simulation Control Process Parameters Die Distance General
84. angle NOTE Idle rolls can be defined by specifying torque control with a very low torque value 2 Axis of Rotation is specified by a vector originating at the point center and through the point direction Rotation direction is defined by the right hand rule That is positive rotation is clockwise as viewed from the center point looking towards the direction point Ral Speed Force Press Hammer Rotation 0O Type a Angular Velocity BS Mesh C Taga rat C Energy Figure 54 Object movement window rotational torsion element case Movement control user subroutines Complex die movement can be defined using user defined FORTRAN subroutines Please refer to User Routines for a description of how to implement user defined subroutines 2 4 12 Object node variables 110 Node Data TEST total of nodes 280 x Node fl aeae feo ox Deformation Thermal Diffusion Heoting User ea Displacement f0 fo 1 2 aw www Do fp 0 aja fee Po Po Po sa Dimec F P po a Furcionsec ooo ooo o M Highlight Node F Show Node No Figure 55 Object node data window The nodes window displays all available information about nodes All information can be modified and many of the variables can be plotted Features of the display window include Node number The number of the node for which information is being displayed A node may be selected either by keying in the value or by using the select i
85. area to be meshed with an appropriate mesh density There are two important facts that should be noted 1 There must be at least two mesh density windows The reason is that the value density level is compared to another window s density value The mesh density window must intersect the object s boundary Defining mesh density windows 1 Select a window number under the mesh density window header Up to 10 different windows can be defined 2 Click Geo button to enable the geometry editor 3 Add Points click button to add points Create a window by defining 3 or more points in the desired area 4 Once a window is defined its relative mesh density is entered in the box under the Parameters header 5 A velocity for the mesh window can also be defined in the x and or y direction These values are also found under the Parameters header 6 Be sure to set the weight of user defined areas to a non zero value under weighting factors Mesh density windows have the following data associated with them points The Points represents the total number of points that make up the mesh density window density The Density is the desired density value for a given window velocity The Velocity is the velocity of the window This allows the window to move with the dies The velocity can be in the X direction the Y direction or a combination of the two Mesh density window movement A constant velocity can be assigned to the mesh density window
86. ary condition window Boundary conditions specify how the boundary of an object interacts with other objects and with the environment The most commonly used boundary conditions are heat exchange with the environment for simulations involving heat transfer prescribed velocity for enforcing symmetry or prescribing movement in problems such as drawing where a part is pulled through a die shrink fit for modeling shrink rings on tooling prescribed force for die stress analysis and Contact between objects in the model In version 7 0 some of the boundary condition definitions have been changed from a node based definition to an element edge based definition The purpose for changing from a node based definition to an edge based definition is to reduce ambiguity at corners If heat exchange with environment is defined on an edge and heat flux is set to zero at an adjacent edge there is an ambiguity at the corner If the corner node is set to heat exchange with the environment then the definition at the edge with one heat exchange BC and one heat flux BC is not clearly defined The purpose of the edge definition is to eliminate this problem in any case where the boundary condition acts over the length of an element edge such as pressure heat flux and atomic diffusion from the environment 97 Defining object boundary conditions Boundary conditions are specified and enforced at nodes or element edges in the finite element mesh The basic procedu
87. bject action activate contents check box hide while not playing ok save powerpoint file file save Some platform powerpoint version combinations may give warnings of OLE 261 object that may contain viruses this may be removed by tools options general general options uncheck box macro virus protection 262 Appendix D Adding Gas Trap Calculation to a Simulation In 2D gas trapping can be predicted if the file DEF_GAS DAT is added to the directory where a simulation is running The contents of the file DEF_GAS DAT is unimportant in that the file is merely a flag to indicate that gas trapping is to be performed The gas trapping is modeled as a perfect law for any time a boundary of a deformable object traps a region of a rigid object When a volume is closed off by contact with a single body See Figure 112 a pressure is applied to the surface of the body which increases as a perfect gas law At the end slight underfill can be noted in the workpiece by highlighting the contact nodes Figure 113 Inthe case that the boundary of the deformable traps a split between two objects there will be no trapping even if the two objects are flush or overlapped If a gas trap simulation is run delete the files DEF_GAS DAT and DEF_GAS INI in the case of running a simulation that does not use gas trapping The file DEF_GAS DAT is a flag used activate gas trapping The file DEF_GAS INI is a file output by the program and s
88. bject element variables 114 ie Element Data TEST total of elements 246 Elemet aee Ci C Deformation Hardness Transtarmation Heating Grain User macs Eai onn ff Creer msn 0 Damage 9 vein 4 Stress Component Normal p zP g Shen 0 fp fi Yiehi Conporart Normal zz TEY j O N N I Highlight Elem Figure 56 Object element data window Deformation Material group MTLGRP MTLGRP specifies the material number associated with each element Relative density DENSTY DENSTY specifies the relative density of the material at each element DENSTY is used when a porous material with relative densities less than 1 0 is being simulated If no value is specified for density it is assumed to be 1 0 The flow stress of porous objects should be specified for the fully dense material Effective strain STRAIN STRAIN specifies the value of total effective strain at the centroid of each element Elemental strains are interpolated between meshes during remeshing procedures Damage DAMAGE DAMAGE specifies the damage factor at each element The damage factor can be used to predict fracture in cold forming operations The damage factor 115 increases as a material is deformed Fracture occurs when the damage factor has reached its critical value The critical value of the damage factor must be determined through physical experimentation Damage factor Ds is de
89. by fs mk where f is the frictional stress kis the shear yield stress and mis the friction factor This states that the friction is a function of the yield stress of the deforming body Coulomb sliding Coulomb friction is used when contact occurs between two elastically deforming objects could include an elastic plastic object if it is deforming elastically or an elastic object and a rigid object objects generally to model sheet forming processes The frictional force in the coulumb law model is defined by fs up where fs is the frictional stress p is the interface presssure between two bodies H and _ is the friction factor There must be interfacial pressure between two bodies for frictional force to be present If two bodies contact each other however there is no force pressing the bodies together there will be no resulting friction Tau shear stress The Tau model of friction lets the user set the shear stress between two objects in contact due to friction The value of shear stress the user may set can be a constant or a function of time For contact between two plastic or porous objects the frictional stress is calculated using the flow stress of the slave object Common Question What is a good value for a friction coefficient Answer The lubricant used on the tooling plays a large role in the amount of friction that exists between the tooling and workpiece The friction in turn affects the metal flow at
90. c Thermal Diffusion Grain Hardness Elec Mag Advanced Jominy Curve A Jominy Distance vs Cooling Time Phase Hardness Figure 29 Material data window hardness There are two methods in which the hardness of a object may be determined after a cooling operation The first method is by specifying the hardness of each phase HDNPHA in a mixture and DEFORM will use the mixture law to determine the hardness of each element The second method is to use experimental results from the Jominy curve and cooling time vs distance to determine the hardness during cooling The method of calculating the hardness can be specified for each object in the Object Properties menu Hardness of each phase HDNPHA The hardness of each phase material group can be specified The hardness of each phase may be a constant or may vary with respect to atom content The hardness of the object will be calculated based on the volume fraction of each phase in the element and on the hardness of each phase Jominy curve JOMINY The hardness vs distance for the Jominy test specimen must be specified here This data is to be defined only for the mixture material MSTMTR Cooling time HDNTIM The cooling time vs distance for the Jominy test specimen must be specified here Using the JOMINY data and the HDNTIM data DEFORM will calculate the 55 hardness of the object during cooling 2 2 8 Advanced Features Plastic Elasti
91. c Thermal Diffusion Grain Hardness Elec Mag Advanced MechtoHet 09 oo BoyFoce D mm ik Figure 30 Material properties window advanced Fracture Data FRCMOD FRCMOD specifies the damage model that one wishes to use for damage calculation and for element deletion Currently the DEFORM fracture model only supports element deletion however in the future element splitting will be implemented There are 10 different models to choose from Cockroft amp Latham is the damage model that is used to calculate damage in DEFORM It is also possible to write a user subroutine which can be used for the damage model e Cockroft amp Latham e McClintock e Freudenthal e Rice amp Tracy e Oyane e Ayada e Osakada 56 e Brozzo e Zhoa amp Huhn e Maximum effective stres ultimiate tensile strength e User routine If the Maximum effective stress ultimiate tensile strength model is selected the ultimate tensile strength UTSDAT has to be defined as a constant or a function of temperature Mechanical Work to Heat FRAE2H Mechanical work to heat specifies the fraction of mechanical work converted to heat The conversion fraction would typically be 0 9 to 0 95 The default value is 0 9 and unless the user has a good feel for this value this value should not be changed Force per unit volume FPERV The following equation is used to calculate the body force for porous materials F f ptaav where F is forc
92. c heating correction In other words adiabatic heating at the higher strain rates artificially heated and softened the material causing an apparently lower flow stress If no clear cause can be determined find data that does not exhibit this reverse strain rate sensitivity Dangerous process conditions Flow stress strain Lower your penalty constant of plastic objects to 250 000 to 500 000 using a constant value PENVOL This may lead to volume loss if the value is much lower than 100 000 for typical engineering materials Reduce your time step This advice applies particularly for elastic plastic materials A very small time step can frequently allow the DEFORM system to get through a tough region of convergence After a large number of nodes are in contact with dies and the simulation is in progress a larger time step can be resumed For the sake of guidelines very simple developmental problems should run about 50 steps Simple to average problems should run about 100 steps This might include a typical blocking operation or a very simple finisher Very complex operations such as high reduction extrusions or piercing should run well over 100 steps with 200 being common for industrial problems This may be accomplished through either controlling the time step or a control modifier that will lead to substepping such as DEMAX or SLDERR In the case of cold materials that exhibit little to no strain rate sensitivity this is one of t
93. c type Tms Tm 50 Table form The transformation start and 50 level temperature are inputted as a table format by depending on carbon content and stress levels This model is not currently available for the current release of DEFORM Diffusion type function Volume fraction is represented by the Avrami equation as follows Er 1 exp fr T fs om fe C t fs Om f Om where f T andfc C are the functions of temperature T is the mean stress and C is the carbon content The power n depends on the kinds of the transformation and f T can be expressed the following simplified formula T Am 4 Ars T T fr T an 1 Ar3 AT6 where the coefficients from Anto Ay are determined by using 50 transformed fs o line of TTT diagram and fc C describe the stress and carbon content dependency of transformation respectively as follows fs Om exp Asom fo C exp Ac1 C Ace The coefficients As is specified according to the stress dependency of TTT curves Ac and Ace are determined by carbon content dependency Diffusion type function and table This model is not currently available for the current release of DEFORM Martensitic type function The volume fraction of diffusionless type martensite transformation depended on temperature stress and carbon content is introduced by modifying the Magee s equation as follows 65 Em 1 exp yiT y2 C Co 310m 325 Ya 0 Here is the m
94. cal damage value Therefore to limit volume loss an extremely fine mesh should be used in any region where fracture is expected The FEM simulation is temporarily stopped to perform element deletion The stopping may be triggered by a given number of steps or whenever the damage value in a specified number of elements exceeds the critical value 95 Fracture step FRCSTP The step interval at which the simulation should be stopped to perform element deletion If no elements are above the critical damage value none will be deleted Fracture elements FRCNEL The number of elements which must be above the critical damage value for the simulation to be stopped to perform element deletion A typical value is around 4 Fracture method FRCMTH At the writing of this manual only the element deletion method of fracture has been implemented Hardness properties MIC Material hardness predictions can be based on e Volume fraction of various phases e Jominy curve data e Cooling time Hardness data for a material can be entered in the Material Properties menu Hardening model HDNRUL A description of the hardness prediction method is given there Referenced Start temperature referenced end temperature Upper and lower temperature values for Jominy or cooling time hardness prediction curves 2 4 9 Object boundary conditions 96 2 TOP_DIE i 3 BOT_DIE Thermal gt Del All BCCs Figure 48 Object bound
95. ch they are listed consecutively in the Batch Queue window see below The Batch Queue window accessed from the main DEFORM window orders the jobs in the queue and lists the problem names and the paths From the Batch Queue window the queue can be submitted and modified Once a problem is finished it is removed from the Batch Queue list and the next job in the batch can be submitted by pressing the Submit Queue button 128 Batch queue setup Figure 62 Batch queue window 3 6 Process monitor Figure 63 Process monitor The process monitor displays the status of any simulations running on the CPU The process will not be displayed while remeshing is occurring The Process Monitor reads the DEFORM status file to determine what simulations are running and what simulations are stopped If this file gets corrupted in any way the process monitor may have problems In order to remedy this problem the user needs to recreate the status file This can be done by running the INSTALL2D script for 2D and the INSTALLSD script for 3D These files are found in the main 2D and 3D directories respectively under the main DEFORM directory The user needs to have write access to this directory when running these programs When the user runs the INSTALL2D or INSTALL3D programs the user will be presented with a number of options The user should select the first option to generate the status file This should solve the problem with the Process M
96. con and mouse picking a node Show node numbers Toggles graphic display of all node numbers Initialize values i icon Initialize the specified variable value on all nodes in the object Plot variable Produces contour or vector plot of selected node variables Line contour Shaded contour Select line or shaded contour display of node variable values Slicing Displays sliced object geometry Refer to the description of the slicing function in the postprocessor for more details Save AMGGEO Saves the object geometry in AMGGEO format Volume 111 Calculates and displays the volume of the mesh Position The coordinates of the node are displayed The values can be modified to slightly adjust the position of nodes where boundary conditions were not properly enforced This should be done with EXTREME caution For features such as boundary extraction and mesh generation the database must be saved and the newly saved step read into the preprocessor before the adjusted coordinates can be used Deformation Displacement DRZ Displacement stores the displacement of each node since the last remesh For elastic objects a displacement may be specified for interference fits The elastic recover of the object will cause the appropriate stress values to be developed Velocity URZ URZ is the X Y and Z velocity components of each node Force FRZ FRZ specifies the value of the constant nodal force at individual nodes Pressure PRZ
97. contact surfaces Typical values using constant shear only 0 08 0 1 for cold forming processes 0 2 for warm forming processes 120 0 2 to 0 3 for lubricated hot forming processes 0 7 0 9 for unlubricated surfaces Most processes are not extremely sensitive to friction and the typical values listed above are perfectly adequate For processes which are very sensitive to lubrication conditions friction values may be determined by experimentation Note e Constant Shear sticking friction is used mostly for bulk forming simulations e Coulomb sliding friction is used for sheet metal forming operations since it most closely resembles the type of friction encountered in this process e Tau friction can be used if the user needs to specify the shear stress on a surface Remarks Two simple ways of gauging the sensitivity of the process to friction Would you expect significant variation in the part depending on whether lubricant is applied well or applied poorly in production If you would not then the typical friction values listed above should be adequate If you are still unsure run two DEFORM simulations with say a 20 pct variation in friction conditions from the typical values For lubricated cold forming you might run one simulation at 0 08 and one simulation at 0 12 Compare the results such as load versus stroke or final geometry particularly the parameters you identified as critical If there is substanti
98. correct behavior of the process To select a user defined material model the user needs to select User under the Material properties window for a specific material group and then define a routine number for that material group This routine number will determine which subroutine is called for that material group The inputs to the USRMAT subroutine are the stress components at the previous step strain components increment time increment and other elemental variables including deformation gradient and rotation tensor The user may also use user defined elemental values for this constitutive routine DSTRAN 4 Total strain increment at t n 1 2 and rotated by ROT1 DFGRO 2 2 Deformation gradient F t n w r t t 0 DFGR1 2 2 Deformation gradient F t n 1 w r t t 0 ROT1 2 2 Rotation tensor at time n 1 2 STRESS 4 Stress at the start of increment EPX Effective plastic strain at the start of increment TOLDG Temperature at the previous increment TNEWG Temperature at the current increment TREF Reference temperature The user material routine is responsible to compute the stress components and tangent modulus at the end of the time increment for the Newton Raphson solution procedure If the user changes the effective plastic strain as an internal variable it can be updated using variable EPX STRESS 4 Stress at the end increment DSAVE 4 4 Tangent modulus at the end of increment EPX Effective plastic strain at the e
99. ct that has movement defined as a user model This routine is called at the beginning of each step 3 USRUPD Description This is the user defined nodal and element variable subroutine This routine allows the user to calculate special state variables and store them for each node and element These variables can be viewed in the Post Processor or be used during the simulation in flow stress calculation User Nodal variables are updated only at the end of a converged step User Element variables are updated at the beginning of each iteration and at the end of a converged step The purpose for this is that the most current user element variable can be fed into the user defined flow stress routine 4 USRDMG Description This routine allows the user to calculate damage of a material This routine is called at once every step 5 USRZRT Description This routine is added for convenience to complement USRRAT This routine is called whenever INCUBT is called 6 USPM This subroutine allows the user to specify parameters for densification of a porous material model This routine is called before stiffness matrix generation at the beginning of each iteration 7 USRCRP Description This routine is used to define creep rate and its derivative as a routine This routine is available for only elasto plastic materials This is called upon the beginning of each iteration 8 USRBCC Description This routine is used to allow the user to specify specia
100. ction Window 166 Step The step list will show all steps that are to be used in the Post Processor highlighted Selection The selection method for the step list in the Post Processor None No steps are selected for use in the Post Processor Toggle Remeshing Toggle Remeshing will select deselect the remeshing steps from the step list for use in the Post Processor Increment This is the previous DEFORM method of step selection The increment of steps is out of the total number of steps not just the saved steps Increment Saved This will select an increment of steps but the increment will be out of the saved steps For example An Increment value of 5 in Increment Saved mode will select every 5 saved steps between the starting and ending step for inclusion into the Post Processor All Steps All steps will be selected for use in the Post Processor Increment The Increment specified here will be used in the increment and increment saved step selections Start Step The starting step for the increment range End Step The ending step for the increment range 167 Increment The increment to be used in the range specified through the starting and ending steps 4 5 8 Database Management Deest aixi i Puge Merge Convert Style i Al None une ___Dreraion tating RM2D PROBLEM SpKe FOROOZDB Browse Bemeshing Tie SPIKE HOT FORGING No of Steps To fi z P PROBLEM Spike FO
101. cutting template HP UX 11 0 only eeeeeeeeeeeeeeeeee 229 NT 2000 XP Installation Installation NOteS ccc ccceeeeeeeeeseeeeeeeeeeeeeeteeeesneeeeeeees 236 Chapter 7 Quick start tutorial sccsi2 5 ceteweste steam cedraee abate nots ae chee etic 244 A Cold FOMInG suite ee ata eae 244 fi2 lt HOt FOMing eiie i dna wah a a a 249 Appendix A Running an inertia weld simulation in DEFORM ccceeeeeeeeeees 256 Appendix B Running DEFORM in text mode cc eeeeeeeeeeeeeeeeeneeeeeeeeeeeeeeenaaees 258 Appendix C Inserting DEFORM Animations in Powerpoint Presentations 261 Appendix D Adding Gas Trap Calculation to a Simulation s e 263 Appendix E Modeling of a Spring Loaded Sliding Die 0 0 0 2 eeeeeeeeeeeeeeteeeetteees 266 Appendix F Using the Inverse Heat Transfer Template c seeeeeeeeeeeeeeeeneees 271 Appendix G THE DEFORM ELASTO PLASTIC MODEL eceeeeeeeeeeeeteees 272 Appendix H Die Stress Analysis Theory ccccccccceceneeeeeeeeeeeeeeenaeeeeeeeeeeeenenaaees 275 Appendix I Running creep simulations in DEFORM 2D seeen 276 Preface to this manual This manual describes the features and capabilities of the DEFORM 2D system It also contains a description of the inputs and actions required to setup problems and run simulations If you have not used DEFORM before we would recommend that you go through the lab manuals first for an introduction on how to u
102. d YPS derivative of flowstress as a function of strain 1 The flow stress depends on the strain rate sensitivity index PEM and on the effective strain rate EFEPS GATE Eee TRA PA AAP ASSES ADDRESS RARARE ARRAS OAD AAEE AEE LESCOL OCR E RES SUBROUTINE UFLOW1 YS YPS FIP TEPS EFEPS TEMP 194 GAARA SEES AE EASAREAEEARARAES SS SERARAAASRRAAAAE SESE S RALARSEAAAAEL SET SES C C C C CPEE EAA EAE EKE EEEE EEA E EEE EE EEEE IMPLICIT REAL 8 A H O Z INTEGER 4 I N C C USER DEFINED VARIABLES C CHARACTER 80 IUSRVL COMMON IUSR IUSRVL 10 TO READ DATA 10 RESERVED LINES READ IUSRVL LINE NUMBER DATA1 DATA2 DATAS TO WRITE DATA 10 RESERVED LINES WRITE IUSRVL LINE NUMBER NEWDATA1 NEWDATA2 NEWDATAS KKK END KKK DESCRIPTION THIS ROUTINE IS USED TO DEMONSTRATE THE IMPLEMENTATION OF MATERIAL ROUTINE ALL THE REAL VARIABLES SHOULD BE DOUBLE PRECISION THE DEFINITION OF ARGUMENTS ARE DESCRIBED AS FOLLOWS INPUT TEPS EFFECTIVE STRAIN EFEPS EFFECTIVE STRAIN RATE TEMP TEMPERATURE OUTPUT YS FLOW STRESS YPS DERIVATIVE OF FLOW STRESS W R T TEPS FIP DERIVATIVE OF FLOW STRESS W R T EFEPS NNN ND AANA NANAAMNAAMNAAMNAAMNAAMNAMNAAMNOAMNOAMNOAMNONOKNONdNKNNKNdNN NO COMMON ELMCOM RZE 2 4 URZE 2 4 STSE 4 EPSE 4 EFEPSE EFSTSE TEPSE RDTYE TEMPE 4 DTMPE 4 DAMAGE 195 USRE1 1500 USRE2 1500 USRNE 1500 4 NODEE 4 KELE KELEL KGROUP C This code added for example
103. d omitted by toggling them on off in the object list Clicking on the OK button plots the state variable in the current viewport 150 xi _Type Line contour Shade contour Solid contour Elemental contour Vector plat f Deflection Scaling f Local Steps glabal f User global Object global inf C T Muttiselection T Histogram Bin width Sampling ratio Figure 71 State variables window Plot type Line contour Shows the state variable selected as a line contour plot Shaded contour Shows the state variable selected as a shaded contour plot Solid Contour Shows the state variable with each element shaded with a constant color with very discrete color transitions of the color bar This makes it easy to extract values from each element and to visualize low and high value regions Elemental Contour 151 Shows the state variable with each element shaded with a constant color with very smooth color transitions of the color bar This makes it easy to visualize low and high value regions Vector Plot This plots variables as vector quantites i e with a scale and a direction Only certain variables are applicable to be plotted in this manner such as velocity and displacement Advanced Plotting Options The advanced plotting options changes different plotting viaues such as pixel resolution vector size etc Scaling Local current step There is a different minimum and maximum value f
104. database in units that are not English or SI The user is free to enter the conversion factors and the units corresponding to the conversion factors There is no user type unit conversion for temperature since the temperature conversion is not a simple multiplication 18 SPIK Chapter 2 Pre Processor ISIE HOT FORGING SGL 1 OITAREPO Step 1 e n Ready msee DEFORM D Preprocessor Figure 6 The DEFORM 2D Preprocessor 2 1 Simulation Controls The Simulation Controls window can be found by clicking a button in the Preprocessor See Figure 6 Options defined under Simulation Controls See Figure 7 control the numerical behavior of the solution Main controls details with specifying the simulation title unit system geometry type etc Stopping and step controls are used to specify the time step the total number of steps and the criteria used to terminate the simulation Processing conditions like the environment temperature convection coefficient can be specified under Processing conditions Certain advanced features are explained in the Advanced controls section 19 gt gt Simulation Control x Simulation Title cs Engish SPIKE HOT FORGING aaa _ owa ener Incremental Steady State OPERATION l i Mode Operation Number fi 4 f Hest T Meshnumber M F i Defomato amy ri i Axisymmetric F Diffusion Plane Strain Torsion Fh sss F Heating
105. der extract meshes with degenerate elements triangular 21 Picking nodal and element information after interpolation of state variables now works correctly Object Boundary Conditions 22 Edge BCC now works correctly in the case of multiple mesh boundaries Material Properties 23 The pasting of numbers to the flow stress table has been improved to have higher precision 220 24 The phase transformation kinetics dialog has been consolidated into the phase transformation dialog Inter Object Properties 25 Fixed problem of failing to delete self contact relation in inter object dialog 26 The friction user routine number of inter object is now saved into the database 27 Heat transfer coefficient as a user routine is now available 28 Inter object relations for one non rigid object is now allowed 29 Friction window re ordering is now allowed Database Generation 30 The warning for the 0 005 force convergence for elasto plastic simulations has been removed 31 When defining either distance per step or time per step the other is now set to zero Simulation 32 Simulations can now be submitted to a remote license server 33 Floating licenses can be monitored remotely now 34 Fixed bug of user lost MPI processor information without clicking enter or tab on table in environment dialog 35 Spaces in the directory name are now legal for the batch queue Post Processing 36 Unit conversion is now availabl
106. different annealing treatments However for a given material with a given annealing treatment critical damage value at fracture is reasonably repeatable Damage value can be used in two ways 1 Evaluating alternatives In problem solving a job that is known to fracture or in analyzing a job where ductile fracture is known to be a risk Several alternatives can be analyzed in DEFORM The alternative with the lowest damage value is the best alternative for minimizing the likelyhood of fracture 2 Comparing a design to a known critical value Critical damage values can be estimated from prior experience with a given material on a part that is known to fracture Running a DEFORM simulation of a process known to cause stretch cracking in the part will give an upper bound value for damage Running a simulation on a part made of the same material that is known not to crack will give a good lower bound value The ideal part is a marginal process that is one that cracks occasionally but not on every part If the peak damage value from the DEFORM analysis corresponds with the fracture site on the part this will give a good estimate of the critical value Designs with a damage value 10 to 20 or more below this value should be safe from fracture if material and anneal conditions are the same Displacement For small deformation problems only plots the nodal displacement value For large deformation the displacement since the last remesh will
107. divided by the elapsed time Here CURTIM is the current time in the simulation which can be accessed from the COMMON block CLOK COMMON USER_DATA AMAX_TEMP AMIN_TEMP ADIF_TEMP DATA AMAX_TEMP AMIN_TEMP ADIF_TEMP 1300 600 700 IF ISTATUS EQ 1 AND KNODE GT 0 THEN IF TEMPN LT AMAX_TEMP AND USRN1 1 EQ 0 AND TEMPN GT AMIN_TEMP USRN2 1 CURTIM USRN2 2 0 ELSE IF TEMPN LT AMIN_TEMP AND USRN1 2 EQ 0 THEN USRN2 1 CURTIM USRN2 1 USRN2 2 ADIF_TEMP CURTIM USRN1 1 60 ELSE USRN2 1 USRN1 1 USRN2 2 USRN1 2 ENDIF ENDIF In many situations the flow stress may be a function of a user defined variable In the example given below the value of strain is stored in the user variable and can then be used in the USRMTR routines to calculate the flow stress of the material IF ISTATUS EQ 1 AND KELE GT 0 THEN C C Strain time increment strain rate C USRE2 1 USRE1 1 DTMAXC EFEPSE C 203 C Calculate max principal stress and if greater than current value C store in the user element value C USRE2 2 USRE1 2 RETURN ENDIF C IF ISTATUS EQ 1 AND KNODE GT 0 THEN USRN2 1 USRN1 1 USRN2 2 USRN1 2 RETURN ENDIF User defined damage models USRDMG User defined damage models can be implemented for calculating damage or for use with the fracture module of DEFORM where elements can be deleted when their damage values exceeds a certain value To use the damage model select the fracture
108. e case of brick elements the elasto plastic model is valid for all levels of strain applications Provides a realistic simulation of elastic recovery springback and strains due to the thermal expansion Useful for problems such as bending where springback has a significant effect on the final part geometry Also useful for residual stress calculations Object type must be elastic plastic for creep calculations limitations Does not model strain rate sensitivity and as such is inappropriate for hot materials undergoing large deformations Requires more solution time than rigid plastic and may have difficulties with convergence NOTE If flow stress is defined for multiple strain rates the flow stress of an elasto plastic material is evaluated at the strain rate value specified in limiting strain rate under object gt properties 74 Porous Porous objects are treated the same as plastic objects compressible rigid visco plastic materials except that the material density is calculated and updated as part of the simulation The material behavior is modeled similar to plastic objects but the model includes the compressibility of the material in the formulation The limiting strain rate LMTSTR and the flow stress FSTRES must be specified at the fully dense state The material density is specified at each element DENSTY Objects with changing material densities such as materials used in powder forming should be modeled as Porous objects
109. e generated in the DEFORM 2D EXE directory 7 If no change is made to PSTUSR FOR goto step 9 8 To link PSTUSR FOR with the DEFORM 2D post processor run INSTALL2D INSTALL2D Select Option 4 The updated post processor execution image DEF_PST EXE will be generated in the DEFORM 2D EXE directory For user variable tracking in the GUI post processor a shared library DEF_PST2 SL will be generated in the DEFORM 2D USR directory 9 The installation of the optional modules is complete To run the program you must create a valid password file in the current directory See section for more information about the password file Installing Java for the 2D cutting template HP UX 11 0 only 1 Before install java environment go to website http www hp com products1 unix java patches index html This webpage provides information on how to detect an existing java environment on each HP system and which patch to be applied before install new java Cutting template recommends using Java 1 3 If your system already has java installed check the version by typing java version Since java 1 4 may not be compatible with java 1 3 If you already has java 1 4 installed and have difficulty running template Please try to install java 1 3 229 2 To install java 1 3 a Go to the website http www hp com products1 unix java java2 sdkrte1_3 downloads license_rte_1 3 1 10_pa risc html b Read the terms check ACCEPT ALL OF THE ABO
110. e deformable object contacts the surface of another deformable object a relationship between the two objects must be established to keep the objects from penetrating each other This relationship is referred to as a master slave or slave master relationship When two objects are contacting each other the contact nodes move with the master surface as long as the two objects are in contact The slave nodes are considered to be in contact with the master object as long as the nodal forces indicate a compressive state When a slave node develops a tensile force the node is considered to have separated from the master object F Inter Obiect P Deformation Thermal Heating l Friction Window _ Ghose Friction Type bint Shes Constat E Coulomb Function F iTime C Constant Tau l 4 M UseRn f x Contact method Penalty C Conforming coupling Separation Criteria System Default fi Separation Density fo Figure 58 Inter object settings window Friction FRCFAC The friction coefficient specifies the friction at the interface between two objects The friction coefficient may be specified as a constant a function of time or a 119 function of interface pressure The friction types allowed are constant shear coulomb friction and constant shear stress Constant Shear sticking Constant shear friction is used mostly for bulk forming simulations The frictional force in the constant shear definition is defined
111. e distance the punch will move total stroke Divide this value by the number of steps and enter this value in Stroke per Step If you are unsure of total punch stroke add 10 or 15 extra steps This will overshoot the goal and you can back up a few steps to get the final result 3 Set stopping controls optional 246 If you know the exact distance the punch will move enter this value under stopping controls If no value was entered the simulation will stop when all steps have been completed 4 Set substepping control Under Advanced Step Controls set Strain per Step to 0 025 1 Save the Data Save a Keyword file Go to Database Generation Check the data If there are any yellow or red flags resolve them then generate the database Exit the preprocessor and start the simulation 2 Running a Second Operation 1 Identifying the endpoint of the first operation After the simulation is completed go to the Post Processor and check the results Identify the step at which the first operation will be completed and make a note of this step number 2 Loading Simulation Results Into the Preprocessor Return to the preprocessor and load the appropriate step from the database 3 Changing Tool Geometry Go to the Geometry editor delete the tool geometry not the whole object and import or create new tool geometry for each tool 4 Positioning Objects From Interobject reposition the tools against the workpiece u
112. e in the post processor 37 Graph smoothing is now available 38 Shear angle can now be plotted from the Simulation Summary window 39 Point tracking and flow net have more options for their display 40 Micro structural variables and user variable can now be point tracked 41 The flow net capability has been improved to handle concave shapes 42 Added 2D torque angular velocity and angle rotated to load stroke graphing 43 Add 6 more levels to user defined color editor 44 Stroke can now be placed on the y axis for load stroke curves 45 New viewport options have been added 46 Increase step combobox pull down list length to display larger number of entries 47 Implemented vector plot for principal stress strain strain rate 221 48 Line contour show geometry for object without mesh 49 User specified range for state variables is stored independently for each variable Miscellaneous 50 Multiple resolutions now available for printing Additions and Enhancements to the Simulation Engine 51 Improved phase transformation kinetics models a Allow simultaneous modeling of competing A gt B A gt C phase transformations The model utilizes an Avrami formulation augmented with physics based factors such as interfacial area between mother and child phases b Equilibrium volume fraction This can be used to compute volume fraction of precipitation as well as transformation like Austenite gt Ferrite where equilibrium
113. e of error can not be caught Below are a few common geometric errors and how they are corrected by DEFORM Note Clockwise Counterclockwise orientation is NOT checked in geometry checking GEOMETRY ERROR DEFORM CORRECTION Duplicate points Remove the duplicate point Adjacent points are collinear Remove the collinear point s Corner radius is so large that at least Reduce the corner radius so that both one tangent of the tangent points lies outside the points lie within the tangent line segments tangent line defined by the adjacent points Arc interference at adjacent points Adjust the radii of the points so that the common Arc interference at adjacent points Adjust the radii so that the common tangent point same arc orientation becomes the intersection point of the two opposite arc orientations tangent point lies on the line connecting the points 78 ene arcs projected on the common tangent line Line entity with zero length Remove entity Arc entity with zero radius Remove entity Adjacent entities cross Modify entities so that the intersection point becomes the ending point of one entity and the starting point of the other entity Unconnected adjacent entities Add a line segment to connect the entities Importing existing geometries Geometry may be imported from a neutral file a DEFORM native graphics file AMGGEO or created using the geometry editor When importing IGES files use the mouse to se
114. e simulations or to skip through the settings This interface is extremely streamlined to construct a large variety of simulations in a very brief time 3 DEFORM MO2 An interface to allow the user to construct many successive operations at the initial setup 4 Heat treatment interface This allows the user to construct many successive heat treatment simulations with minimal effort 5 Inverse heat transfer interface This allows the to determine the heat transfer coefficient at the boundary of an object by using actual thermocouple data coupled with iterative simulation results 6 Optimization interface This allows the user to perform optimization simulations of either preform shape or strain distribution 7 Machining interface This allows the user to perform two dimensional cutting simulations operations with ease 218 Additional capabilities 1 Simulation graphics are now available through the interface 2 There is now a three dimensional viewer for post processing that can be utilized for all DEFORM TOOLS users Improvements in the interface Geometry and Display 1 Anew geometry editing dialog with many new options has been added 2 Many points can be selected at once by clicking and dragging on the displayed points in the geometry window 3 A scale has been added to the display window as seen in the figure below 4 Acenterline has been added to the display window for axisymmetric simulations 5 Geometry now
115. e transformation and a few relational properties such as latent heat and volume change 61 2 3 1 Transformation relation PHASTF MIC In DEFORM the manner in which transformation is defined is in terms of transformation relationships The basic unit for transformation relationships are phases Phases can be grouped together to define a mixture A mixture corresponds to a material such as AISI 1045 or Ti 6Al 4V For each phase defined there may be a transformation relation to any other phase that is defined For example in the case of low carbon steel austenite has a relationship to pearlite since austenite may form pearlite upon the proper cooling conditions Also upon proper heating conditions pearlite can convert to austenite Thus in DEFORM to specify the relationship of austenite converting to pearlite one needs to select the austenite as Material 1 and the pearlite as Material 2 and then click the Phase 1 Phase 2 relationship This will then allow the user to define the kinetics of the transformation the latent heat of the transformation volume change of the transformation etc Heat ererated by Deformation efermacion Therma Sqanion Heat Transfer F Pi va Latent Fi Heat f e Temperaire mhced Fa F Tan formiat on Trcufoanatcn Flati ranm orta ation Figure 31 Relationship between various DEFORM modules 62 2 3 2 Kinetics model TTTD MIC 5 ui mntermaterialiBase Mother Phase Ch
116. e user to generate a mesh for the current object The user has two methods of controlling mesh density e System Defined method uses a system of weights and assigned windows to control the size of elements during the initial mesh generation and subsequent automatic remeshings e User Defined allows the user to specify certain areas on the object to have higher element densities relative to other areas of the object during the initial mesh generation only this density specification is not referenced during automatic remeshing Mesh density refers to the size of elements that will be generated within an object boundary The mesh density is primarily based on the specified total number of elements and Point or Parameter mesh density controls The sample grid resolution and the critical point tolerances also affect the mesh density but to a lesser extent than the other parameters Mesh density is defined by the number of nodes per unit length generally along the edge of the object The mesh density values specify a mesh density ratio between two regions in the object They do not refer to an absolute number of nodes So at least two different density regions must be specified 80 A higher mesh density more elements per unit area volume offers increased accuracy and resolution of geometry and field variables such as strain temperature and damage However in general the time required for the computer to solve the problem increases as
117. e with unit of Klb for english and N for SI fva is the force per unit P l volume and is the material density 57 2 2 9 Material data requirements Guidelines 1 An isothermal forming problem with rigid dies and a rigid viscoplastic workpiece Td Werigiecs Ces veraa Od Foses OOO x Youngs moos o Poisons Ratio OOOO S Thermal Expansion Heat Capacity ooo o y O msy SSCSC S 2 A Non isothermal forming problem with rigid dies and a rigid viscoplastic workpiece a e a MaterialData FlowStess X YoungsModulus PoisonsRaio O S T P bansion e x gt O a a a a 3 Heat transfer analysis Cd wee w Flow Stress Youngs Modulus O 58 Posos OOOO Thermal Expansion Heat Capacity Coupled analysis non isothermal with thermal expansion Elastic dies and elasto plastic workpiece po Workpiece fies MaterialData Flowsiess x SSCS FYoungsModuus x J x Poisons Ratio O O Oxo Oooo el T Expansion e T E S E Decoupled die stress analysis isothermal O wwe MaterialData y O O Fowsiess xX StS Vomgsvoas x PoisonsRaio O JO Oox o o C T Expansion Haca OOOO S O woy O SSS Decoupled die stress analysis non isothermal Ooo O I OWopee ies Material Data o 59 Youngs Modulus Expansion Heat Capacity 60 2 3 Inter Material Data The purpose of inter material data is to defi
118. ean stress is the effective stress When the martensite transformation start temperatures under carburized conditions and applied stress palpi v3i vr 3 1 p pa and are given can be determined and and are identified if temperatures for martensite start Tmsand for 50 martensite Eu 0 aes Tmso at an are provided respectively Diffusion type simplified A simplified Diffusion function is defined by a function of the following form ooo where T average element temperature Ts starting temperature of the transformation Te ending temperature of the transformation This formula is a good first approximation for a diffusion based transformation The coefficients can be obtained using dilatation temperature diagrams Diffusion type recrystallization The volume fraction of recrystallization is usually defined by the equation including the time for 50 recrystallization as follows vaa where b is material constant and n is the exponent whose value depends upon the underlying mechanisms and t s is the time for 50 recrystallization Q a S ae dgexp pr where a m and n are material constants Q is activation energy R gas constant T absolute temperature and is a prior plastic strain obtained after an operation 66 of forming and ab is an initial grain diameter specified as object data This model is not currently available for the current release of DEFORM Melting and solidification type This m
119. ected steps This makes it easier to track evolution of a variable over several steps but sacrifices resolution on a single step User defined The user can specify maximum and minimum contour levels This is particularly useful for state variables exhibiting small regions with extreme values Resolution of the remaining area may be lost because of autoscaling to an extreme peak Resetting the maximum and minimum values to more reasonable values will wash out the peak values but give much better resolution to intermediate values Interpreting state variables Damage Damage generally relates to the likelihood of ductile fracture in a part The specific definition of damage is dependent on the method of calculation selected in the pre processor Damage is NOT a good indicator of fracture in tooling Stress components should be used for die failure analysis Damage particularly the Cockcroft Latham damage model the default damage model in DEFORM has been shown to be a good indicator of certain types of tensile ductile fracture cracking due to deformation by stretching such as chevron or surface cracking in extrusions or cracking on the outside surface of an upset It is not a good indicator of fracture in compression such as splits perpendicular to die motion due to extreme heading reduction 153 The damage value at which fracture initiates varies substantially from material to material and can even vary for a given material with
120. ed flow stress routine Please refer to User Routines for a description of how to implement user defined flow stress routines Flow stress database The DEFORM material database contains flow stress data for around 145 different materials The flow stress data provided by the material database has a limited range in terms of temperature range and effective strain Warning If simulation conditions of the material exceeds the bounds of the strain strain rate or temperature defined in the tabular data the program will extrapolate based on the last two data points which may lead to loss of accuracy Yield function type This functionality supports anisotropy There are three different types of yield functions available Von Mises This is the default setting This specifies a isotropic material model Hill s quadratic FGHLMN This allows the user to specify anisotropic settings using the FGHLMN format of the Hill s quadratic method 44 5 HII s Quadratic x F fos G fos H fos Cancel L iG M j5 N hs C Function Figure 25 Hill s quadratic FGHLMN input screen Hill s quadratic R value This allows the user to specify anisotropic settings using the R value format of the Hill s quadratic method 5 HIIl s Quadratic x Constant ox ROIR fi R45 Ray 1 Asa Ay fi Cancel C Function Figure 26 Hill s quadratic R value input screen Hardening model HDNRUL MIC Currently two models for hard
121. eformations in the x y and z directions Ezy Shearing components of strain can be defined incrementally as 2o dz f yo and where szy vz and z are shear strains in the xy yz and zx planes respectively In a two dimensional analysis the yz and zx components of shear strain are assumed to be zero Through various mathematical techniques which are beyond the scope of this discussion it is possible to define so called principal axes on which all components of shear strain are zero The strains measured along these axes are termed principal strains It is frequently useful to have a single characteristic strain value to describe the degree of deformation DEFORM uses a value common to metal forming analysis known as the effective or Von Mises strain Eyz Ezg E 1 2 2 3 3 1 i 3 PORE where and are principal strains and is the effective strain For porous materials there is also a volumetric component of strain This change in volume relative to initial volume is stored as mean strain 155 For elasto plastic materials the type of strain saved is the total plastic strain Strain Rate Strain rate is a measure of the rate of deformation with respect to time The units are strain per second where strain is a dimensionless value The components of strain rate are defined in the same manner as the components of strain Str
122. ements and deformed mesh at each step Contour plots Line or shaded contours display the distribution of any state variables including stress strain temperature damage and others Vector plots displacement and velocity vectors indicate magnitude and direction of displacement or velocity for every node at each step throughout the process Graphs of key variables such as press loads volumes and point tracked state variables Point tracking to show how material moves and plots of state variables at these points Flow net showing material flow patterns on a uniform grid Generally a very good predictor of grain flow patterns in the finished part Graph of any state variable between two points that can be specified by the user These points can follow the boundary or linearly follow the line formed between the points State variable geometry and image data can also be extracted in a number of neutral formats for use with other programs 139 SPIKE HOT FORGING Ql OITAREPO Step 1 BEAL 1100 COLD 70F BlvIMesh Elem 246 QM TOP DE LOMGeo S OMGe gt Q MB0T_DIE COM Geo Figure 64 DEFORM 2D Post Processor 4 2 Graphical display 4 2 1 Window layout The postprocessor has three windows one to display information one to manipulate the view and one to control the information that is displayed Display Window The display window is the main postprocessor window It is the
123. ening are supported kinematic and isotropic For an isotropic model as a material yields and plastically deforms the yield surface expands uniformly or isotropically Thus the yield strain in all directions is the same However for a kinematic model the yield surface shifts as the material yields The kinematic hardening model is required if the Bauschinger effect is to be modeled This is valid only for the elasto plastic objects under small deformation Creep CREEP MIC Creep is defined as the time dependent permanent deformation under stress that usually occurs at high temperatures It is common in applications where the material undergoes cyclic loading or where stress relief is of interest DEFORM 45 only supports creep calculations for elasto plastic objects The methods for defining creep in DEFORM are given below Perzyna s model mE rc E 1 where B fuicity effective stress S Flow stress m Material parameter E Effective strain rate This model is known as Perzyna s model It is a formulation for elastic viscoplastic flow In this method creep will not occur until the effective stress exceeds the yield strength of the material If the effective stress is less than the flow stress the resulting strain rate is zero Power law 3 ao hi hee 3 where fluidity effective stress S Flow stress m Material parameter Effective strain rate This model is known as the power law I
124. ently selected only a line of points will be shown After a state variable is picked from the state variable window reclicking the Calculate button will show a graph of the distribution between the two points State Variable Distribution Y L x Figure 89 State variable distribution between two points 176 Chapter 5 Elementary Concepts in Metalforming and Finite Element Analysis Definition of stress strain and strain rate Stress is the measure of force applied to a unit area of material This variable is of importance in forming in that material deform change shape different amounts depending on how much stress they are under There are several definitions of stress Engineering Stress force per unit area measured on the original undeformed shape True Stress force per unit area measured on the deformed shape These two definitions are shown in Figure 1 as a comparison In general the true stress is more interesting for the engineer in analyzing a forming process True stress will indicate plastic yielding and other issues with better accuracy than engineering stress Force 100KIb Force 200KIb Initial CS Area 1 sq in Final CS Area 2 sq in Engineering Stress 100kib 1 sq in 100ksi Engineering Stress 200kIb 1 sq in 200ksi True Stress 100kIib 1sq in 100ksi True Stress 200kIb 2sq in 100ksi Figure 90 Demonstration of concept of stress Strain is a measure of the total accumulated deformatio
125. er the directions are dictated by numerical convenience Contact conditions are first assigned to the Z direction If that position is occupied by another value conditions are assigned in the Y then X directions Refer to the BCCDEF section under Node Properties for more information 99 Thermal Boundary Conditions Heat exchange with the environment BCC This boundary condition specifies that heat exchange between element faces bounded by these nodes and their environment should occur The contact boundary condition determines whether exchange will occur to the ambient atmosphere or to a contacting object In version 7 0 this boundary condition is specified on the element edges rather than on the boundary nodes This will reduce the ambiguity upon defining symmetry planes On a corner element the two edges will be defined consistently as opposed to the case where the nodes were defined and one of the edges was ambiguous The new keyword for heat exchange is ECCTMP Default heat exchange with the environment occurs to the ambient environment as described above However heat exchange windows may be specified using the heat exchange windows icon Heat exchange for nodes within these windows is controlled by the parameters set for each window Heat flux BCC Specifies an energy flux per unit area over the face of the element bounded by the nodes Units are energy time area This is defined in terms of edge definition starting with vers
126. er routines The purpose for importing data for user routines through this method is that this data can be stored within a keyword file or a database and can be made unique to an individual simulation This data can be accessed in the Simulation Controls Advanced Controls menu Ten lines are assigned for user defined data Each 192 data should be separated by space and user can input as many of data in each lines unless they don t exceed 80 columns In the user routines the following code lets the user access the USRDEF values common block through the variable IUSRVL CHARACTER 80 IUSRVL COMMON IUSR IUSRVL 10 To read and write data to the USRDEF variable the following sections of code can be used C GC TO READ DATA 10 RESERVED LINES C READ IUSRVL LINE NUMBER DATA1 DATA2 DATAS C C TO WRITE DATA 10 RESERVED LINES C WRITE IUSRVL LINE NUMBER NEWDATA1 NEWDATA2 NEWDATAS The screen where this information can be set is seen in the figure below Simulation Control i x Enor Tolerances Variables User Defined Node Oscillations 2 DEFORM SIMULATION 3 DEFORM SIMULATION 4 DEFORM SIMULATION 5 DEFORM SIMULATION DEFORM SIMULATION 7 DEFORM SIMULATION 18 DEFORM SIMULATION 9 DEFORM SIMULATION 10 DEFORM SIMULATION Figure 108 User defined variables dialog User defined flow stress routines USRMTR If the flow stress models in DEFORM are not applicable for a process a user de
127. erated Grid Spacing This is the distance DX and DY between each grid point in the X and Y directions Angle This will determine the angle at which the grid will be drawn in degrees Circular Grid The circular grid can generate a field of circles of a given radius and distance apart within the desired region Circular patterns are typically used to monitor directional orientation of flow If a circular pattern is selected you must specify the grid origin circle radius center to center distance between circles number of segments in the circle and whether clipped circles should be included The circular grid is controlled through the following parameters Origin This is the origin in X Y coordinates at which the grid will begin to be generated Radius Specifies the radius of each circle Center Center Specifies the vertical and horizontal distance between each center of neighboring circles No Segments Sets the number of line segments the circles will be composed of The circles are actually constructed of three or more line segments default is 12 Inc Clipped Includes any partial circles that were clipped by the region s boundaries default is Yes Offset Curve The offset curve will draw an identical surface at a specified distance within the objects border The border offset pattern is typically used to capture tendencies toward lap formations If a border offset is selected you must specify the distance the border is
128. erial recovers its original form compeletly upon removal of the force causing the deformation The elastic material behavior is specified by a Young s modulus YOUNG and a Poisson s ratio POISON Elastic tools are used if the knowledge of the tooling stress and deflection are important throughout the process If maximum stress or deflection information is required for die stress it is recommended that rigid dies be used for the deformation simulation then a single step die stress simulation be used t is important to note that the elastic formulation in DEFORM is meant only for small deformation and no rotation Thus we would not recommend using the elastic formulation for the modeling of roller Refer to the die stress tutorials in the online help for more information applications When used to model tooling the elastic model can provide continuous information on tool stress and deflection Also useful in rare situations when tooling deflection can have a significant influence on the shape of the part limitations When used to model elastic dies during deformation simulation time is increased often for very limited gains in information If yield stress for the 13 tooling is exceeded stress and deflection results will be incorrect However in most cases if tooling yield stress is exceeded this represents an unacceptable situation and tooling deformation beyond yield is not useful Plastic Plastic objects are modeled as r
129. esh The procedure to perform a manual remeshing is as follows Procedure 1 Open the preprocessor 2 Select the step from the database where remeshing is to be performed and load this in the pre processor If the object will not remesh at the last step it may be necessary to remesh at an earlier step 3 Select the object to be remeshed 4 Extract the border of the object may be done automatically 5 If the part geometry is to be modified such as trimming flash or punching out a web it may be done at this point using the geometry editor 6 Adjust mesh windows or other mesh parameters as necessary 7 Generate a new mesh 8 Interpolate data from the old mesh to the new mesh 9 Interpolate boundary conditions from the old mesh to the new mesh unless e Dies are being changed at the same time the part is being remeshed 90 e The mesh visibly distorts on remeshing e A negative jacobian error occurs immediately when the problem is restarted 10 Generate a database and start simulation If after remeshing the mesh visibly distorts or the dies change regenerate the mesh again and interpolate data but not boundary conditions If boundary conditions are not interpolated it is necessary to recreate all velocity heat transfer interobject or other boundary conditions If there are no changes to the geometry such as trimming the part then the simplified manual remeshing icon can be used this extracts the border and show
130. ess called meshing In Figure 14 an axisymmetric body is being upset between two flat dies There is a grid that has been superimposed on the figure of the workpiece This grid is the mesh that represents the body being deformed Each rectangle represents a portion of material in this case each rectangle corresponds to a ring for which the equation in Figure 13 can be easily solved Each rectangle is called an element and the intersection of any grid lines is called a node An element corresponds to a region of material and a node corresponds to a discrete point in space The solution for the equations in Figure 13 are the velocity at each node which are shown as vector arrows the right side of Figure 14 In additions to the bottom equation of Figure 13 there are boundary conditions that should be specified in order to provide a unique solution to the problem In this problem the velocity of the top set of nodes is determined by the downward speed of the die as well as the friction model between the workpiece and the die The boundary conditions on the left side of the die is specified as a centerline condition meaning that the nodes are not allowed to move either right or left The bottom nodes also have a symmetry condition meaning that they are not allowed to move up or down These three boundary conditions allow the mesh to behave as the actual part 184 Figure 102 2D mesh of upset test Note This mesh is extremely coarse for the sake
131. eteeeaaeeeeeeeeteeenaaaeeeeees 124 2 6 Database Generation ce ieee nS aaa ee 125 Chapter 3 Running Simulations wdadye a enacctnactene a autien kaGeien meats 127 3 1 Interactive and batch Modes isiin niaaa iiaiai ieas tiesai 127 B12 ETE E E A A A A A E 127 ere E Emall AEE c l AAA E OREA P AOE POES EA OOE EOE EEEO EOT EOE EEE EO E OE 128 3 4 Starting the simulation naiiai aaaea aeaniee aiaa ana iaiT 128 3 5 Add to Queue Batch Queue sseesssssssssssrrsssssssrenrrrsssesrrenrnntssesrrennnntssesrneennnnssent 128 3 6 Process MONT iai 129 8 7 Stopping a simulati eta eikanenandhansiandhanniandhanntadhanahaidio 129 3 8 Troubleshooting Problems cc ccccceeeeeeeeecneeeeeeeeeeeeecaeeeeeeeeeeeeccaaeeeeeeeeeseessaaaeeeeees 130 3 8 1 Simulation aborted by USER nena a a a a aa a 131 3 8 2 Cannot remesh at a negative step eseeesssesseirettecetetrtttttttttirtttaetttttrnntascettennnnnscereennn 131 3 8 3 Remeshing is highly recommended cccccecceeeeeeeeeeeeeeeeeecaeeeeeeeeteeeaaeeeeeeeeteeeniaeeeeeeess 131 3 8 4 Negative Jacoba Nisia iaiia a a a a aa AA 132 3 8 5 Solution does NOt Converge a e E E 133 3 8 6 Stiffness matrix is non positive definite cece eee ee eeetee teeter eeeeeaaeeeeeeeeteesaaeeeeeees 135 9 0 7 gt ZETOPIV Obeactet e e etary Md ects N tee camily E sia actinic ws oun etuerying 136 3 9 Database Management as icchecstdestectecbtee a a a a Mec tieedtvatdeetaent tes 137 Chapter 4 Post
132. even if the flow stress is retrieved from the DEFORM material database Flow Stress Extrapolated value should equal the initial yield stress Plastic Strain Figure 118 Extrapolation of flow stress data to determine the initial yield stress Object data e Set the EP initial guess under Objects Properties Deformation to Previous step solution e lf there is a change in operation e g moving the part from one station to another initialize the velocity for the part under Objects Nodes Data Deformation This will improve the initial guess of the velocity solution e f moving the part from one set up to another allow the part to relax its stresses by placing a few springback steps between operations Solution procedure e Always use Newton Raphson iteration method or BFGS iteration method The user can select the different methods under Simulation Controls Iteration It is useful to try switch iteration methods when either 273 one fails to converge The force error norm can be increased two orders of magnitude larger than the velocity error norm This is suggested only when the solution fails to converge due to non stationary force error norm behavior The value can be changed under Simulation Controls Iteration It is recommended to reduce the value after convergence has been achieved Elasto plastic convergence is very sensitive on time step size By selecting a time step size too large size depends on the simulat
133. ew spindle The screw spindle transmits the rotation through the threads which have pitch angles between 13 and 17 degrees to a linear movement of the main ram On contact with the workpiece the complete kinetic energy of the flywheel and the ram is transformed into useful work work on the workpiece and losses elastic deformation work in the workpiece and the frame of the structure and friction The elastic deformation work results in a reaction force in all the press parts lying in the force transmission path The Screw press Energy method will mimic the movement of a screw type press on the selected die In a screw press a flywheel is taken to a given speed and a clutch is engaged Once the clutch is engaged the screw press begins to draw energy to drive the screw from the flywheel Once the flywheel energy is expended the stroke is over and the movement will stop The resultant load due to inter object contact is calculated for all objects with a MOVCTL boundary constraint Screw controlled movement can only be specified for rigid objects Motion of which is controlled by screw press parameters can only be applied in the X Y X or Y directions The data required to run a screw press driven tool is 105 1 Blow Energy The Blow Energy is a measure of the total energy that the flywheel will contain when the desired speed has been reached and prior to engaging the clutch The units for blow energy are klb inch in English units and N m
134. f this is not done the FEM engine cannot write to the status file and hence exits To restart the simulation first go to the DEFORM_DIR run INSTALL2D and select the option to regenerate the status file Note If the user gets the message Command not found the user should run the INSTALL2D by typing INSTALL2D This will force the operating system to override the paths and force the system to run only the file in the current directory 3 8 2 Cannot remesh at a negative step The FEM engine prints this message and exits when a remeshing has just taken place and in the current step a negative jacobian is encountered so remeshing has to take place again Every remeshing introduces error in the solution as data is transferred interpolated from an old mesh to a new mesh If this is done at every step then the simulation results may not be accurate So as a check to prevent remeshing at every step the FEM engine stops a simulation if this condition is encountered Also this prevents the DEFORM system from encountering a neverending loop The reasons for this could be that the time step DSMAX DTMAX may be large as might happen in extrusions where the ram speed might be low but the velocity of the extrudate might be very high causing severe mesh distortion near the die radius Another example would be in a forging when material starts to flash and the elements near the flash region get severely distorted To avoid this problem the time step ca
135. f very complex industrial problems 200 to 300 steps are not excessive A complex industrial problem running 25 steps with no substepping is an excellent formula for disaster e If substepping is disabled in a 3D simulation great care must be taken to use sufficiently small time steps This means that any time a node displacement calculates a node position inside a rigid object the node is pushed back to the die surface This is not a bad assumption if the node displacements are small however if the node displacements are large this assumption may lose its validity These suggestions are intended as general guidelines and may not solve all of this class of problem If all of these areas have been investigated and subsequent attempts to run your problem fail we would recommend sending us a keyword file for further investigation 3 8 5 Solution does not converge There are two common reasons for a solution not converging 1 The material has a large rigid body motion Much of the deforming body has a very low strain rate or is rigid 2 The material is not strain rate sensitive In cases where a problem will not converge the following checklist should help with the troubleshooting process This will help with the most common cases e Increase your Force Norm or Velocity Norm up to one order of magnitude The Force Norm may in fact be raised as high as 1 or even eliminated for a few steps This should not lead to significant error bu
136. fined by Dy Zde where is the tensile maximum principal stress is the effective stress and de is the effective strain increment Stress components STRESS Defines the stress tensors of each element of an object In a plane strain model Or _ Oy _ Cz _ Try X1 is the value of X2 is X3 is and X4 is In an axisymmetric f Or _ Ig Trz model X1 is the value of X2 is X3 is and X4 is Yield surface translation tensor YLDS MIC YLDS specifies the yield surface translation tensor for kinematic hardening Hardness MIC Hardness HDNOBJ HDNOBJ1 specifies hardness and HDNOBJ2 cooling time from high temperature to low temperature for each element Transformation MIC Volume fraction VOLFC VOLFC specifies the initial volume fraction of a phase material in an element at the beginning of a simulation In addition throughout the simulation VOLFC stores the volume fraction of all phases in each element per step The volume fraction is determined from the keyword TTTD which specifies the model or data used in calculating the volume fraction of each phase It is important that the user specifies the necessary input for the keyword TTTD or else the volume fraction VOLFC will not be calculated for the object The user must input the type of diffusion model and at least two Time Temperature curves the beginning of the transformation and the end of the transformation Volume fraction limit VOLFS VOLFS s
137. fined flow stress can be calculated during the simulation The flow stress can be a function of strain strain rate temperature user node and user element variables The flow stress subroutine should return the following information 1 The flowstress of the element at the current state condition 2 The derivative of the flowstress with respect to total effective plastic strain 193 3 The derivative of the flowstress with respect to total effective plastic strain rate A maximum of 100 flow stress routines can be defined in this program In the pre processor Material Properties the flow stress FSTRES type selected should as User routine as seen in Figure 109 and a routine number can be specified by selecting the icon to the right of the User routine line This routine number NPTRTN is passed to the user defined flow stress subroutine to control branching to the specified UFLOW module 5 Material Material List Mapka Material 1 Yield function type f Von Mises z Hardening tule isotopic l Figure 109 Specifying flowstress as a user defined method Examples of using the user defined flow stress subroutine are given below Note that only the additional code to the skeleton of the routines is shown in order to save space in the text except for example 1 Recall that only three values need to be returned as mentioned above YS yield stress FIP derivative of flowstress as a function of strain rate an
138. fness matrix is defined by geometry and material properties When the user sees a message non positive definite stiffness or Zero pivot this is caused by a stiffness matrix that has a zero value This problem is usually caused by a material property having a zero value that is related to the stiffness or resistance to flow heat or deformation For a given type of simulation there is a property that is most likely to lead to this problem It is as follows e Heat Transfer Heat Capacity and or Thermal Conductivity e Elastic Young s Modulus e Plastic Deformation Flow Stress e Heat transfer problems can be identified by the information in the message file The iteration information will contain the heading Temperature Error Norm in the section just prior to the problem being terminated e Plastic deformation problems can be identified clearly by the information in the message file The iteration information will contain the headings Force Error Norm and Velocity Error Norm in the section just prior to the problem being terminated These messages will also be seen during the elastic die stress type of problem 3 8 7 Zero pivot Rigid body motion can lead to the zero pivot error This leads to the velocity norm increasing and a resulting simulation failure This typically results from the lack of adequate boundary conditions and can be resolved by properly defining these For a 2 D case there are two possible geometric modes Axis
139. for SI units 2 Blow Efficiency The Blow Efficiency represents the fraction of the total energy that will be converted to deformation energy The rest of the energy is absorbed through the clutch mechanism friction and the machine frame There are no units for this quantity 3 Moment of Inertia The Moment of Inertia is the moment of inertia of the flywheel The English units of inertia are lof sec2 inch and the SI units are kg m2 The mass moment of inertia for a circular disc with the Z axis perpendicular to the center is KS 2B w where Eris the total energy of the flywheel and is the angular velocity in radians per second 4 Ram Displacement The Ram Displacement specifies the distance per revolution of the flywheel that the screw will advance This helps in determining the linear velocity of the ram The English units for Ram Displacement are inch revolution while the SI units are mm revolution If only the pitch angle and diameter of the spindle is known the Ram Displacement mdsin O can be calculated using where where d is the diameter of spindle 0 and j is the pitch angle of the spindle Hydraulic press To use the hydraulic press model the user must input two parameters 1 Speed The speed of the press can be input as a constant or as a function of time or stroke 2 Speed Limit The speed limit of the hydraulic press is also entered in the familiar table format as a function of load See Example Lab 21 Hydraulic P
140. g geometry to be axially symmetric and in the first quadrant and fourth quadrant ie X gt 0 In addition the system assumes that the flow in every radial plane is identical Figure 9 2 The plane strain model assumes that the geometry to have an unit depth with both front and back faces constrained The simulation assumes that the objects will behave identically in any given cross section across the width and height of the object Figure 9 Simulation modes TRANS DEFORM features a group of simulation modes that may be turned on or off individually or used in various combinations Heat transfer simulates thermal effects within the simulation including heat transfer between objects and the environment and heat generation due to deformation or phase transformation where applicable Deformation simulates deformation due to mechanical thermal or phase transformation effects Transformation simulates transformation between phases due to thermomechanical and time effects Diffusion 21 simulates diffusion of carbon atoms within the material due to carbon content gradients Grain simulates recrystallization and grain growth Heating simulates heat generation due to resistance or induction heating This feature is not activated in the current release L i gz Figure 9 Axisymmetric and plane strain cases For compatibility with old keywords and databases before version 6 0 the keyword SMODE old
141. ge etc If mode is clicked a view manipulation toolbar appears This tool bar can be moved by dragging it to other parts of the screen Note that this toolbar is dockable and if dragged to any side of the screen will combine with that given side 4 4 Graphic Utilities F Fle Mode Viewport Display Model Step Tools Window View Option Help se dalngean Flaga lnl taal a Step 4 ah a lt an gt ey y EE Oj Be xl BBB Figure 68 Graphics utilities Multiple viewport control The viewport control icon allows the display of from one to four viewports Each viewport can display a separate data set The primary viewport is indicated with a green border Commands to modify the object view or to change displayed will only affect the primary viewport View sizing by zoom or pan can be copied to all active viewports using the Same As This icon in the graphic utilities window Select The select button is a general pointing utility It performs several functions which vary with context It can be used to report coordinates of an arbitrary point to select a node or an element to change the primary viewport and many similar functions 145 Dynamic zoom The dynamic zoom dynamically changes the size of the region of the object which fills the active viewport The view can be changed by left clicking the mouse in the active viewport then rolling the mouse backward or forward to increase or decrease the amount of the object which is displa
142. generation Running simulations describes how to run simulations and also how to handle errors that occur during simulations Post Processor describes post processing results from simulations and how to interpret results User Routines describes user FORTRAN routines in detail DEFORM allows the user to write FORTRAN programs to describe the flow stress die speeds damage accumulation and other features as well as defining and storing new variables which can be tracked in the post processor along with the standard DEFORM variables Release Notes contains release notes Installation Notes for Unix and NT 2000 contains installation notes Chapter 1 Overview of DEFORM DEFORM is a Finite Element Method FEM based process simulation system designed to analyze various forming and heat treatment processes used by metal forming and related industries By simulating manufacturing processes on a computer this advanced tool allows designers and engineers to e Reduce the need for costly shop floor trials and redesign of tooling and processes e Improve tool and die design to reduce production and material costs e Shorten lead time in bringing a new product to market Unlike general purpose FEM codes DEFORM is tailored for deformation modeling A user friendly graphical user interface provides easy data preparation and analysis so engineers can focus on forming not on learning a cumbersome computer system A key component of this
143. graphical display for all results information including geometry and meshes contour and vector plots and graphs Graphic Utilities The graphics utilities window provides view manipulation and other utility functions for the object window Features include zoom and pan measurement utilities multiple viewport controls printing and animation creation utilities The graphics utilities window also contains step control buttons to continuously play through the database to single step forward or backward or to jump to the beginning or end of the database Control Window The post processor controls is used for selecting the specific data set to 140 be displayed in the postprocessor window and for extracting solution data from the database and writing it to text files Object Display Modes DEFORM has 3 different object display modes as seen in Figure 65 Single Object mode the selected object is displayed All other objects are hidden Multi Object mode the selected object is displayed in solid color All other objects are transparent User Object mode the user can set the display mode on transparent or off for each object independently Simulation SiH OPERATION 1 Step 1 E 01 3511 260 2020F 700 EB v Mesh Elem 16489 Gv 2 Top Die o tOM Geo Poly 328 iv 3 Bottom Die tO Geo Poly 328 Q 4 Object 4 v Geo Poly 2 User object Mode Multi object Mode Single object Mode
144. h all user variables have to be initialized to their starting values This is called at the first step in the list of steps which are being tracked ISTEP equals to the starting step for each node element in the object IF INIT EQ 1 THEN If the initial value of a variable is zero the this is defined using the following code Here variable 5 is used VAR2 5 0 If the maximum value of a variable is being tracked for example temperature then this value can be set to Here variable 5 is used VAR2 5 10000 and then checked and increased if temperature at any step is greater than this PHASE 3 The user variable function is called with the INIT flag set to 2 in the phase in which all calculations of the user variables are done This function is called for all steps for each node element of the object and the user is expected to update the values of the state variables based on the inputs passed to this program The inputs to the function are TNOW CURRENT Time RZ Element center Coord Dimension 2 TEMP Temperature EFEPS Effective Strain Rate TEPS Total accumulated Strain EFSTS Effective Stress DAMG Damge Factor RDTY Relative Density STS Stress Tensor Dimension 4 EPS Strain Rate Tensor Dimension 4 TSR Strain tensor VAR1 1 20 Initial State Variables IOBJ Object number NUMNP Total number of nodes NUMEL Total number of elements ICURNE Current node element when INIT 2
145. has a shading near the border in order to show the inside versus the outside Shading displayed on the inside of the geometry indicates correct counterclockwise orientation for closed bodies 219 6 There are now primitive geometry definitions available in the geometry definition 7 Geometry can now be created through a series of boolean operations 8 Fixed the problem in transformation data initialization display 9 Improved the picking in element and edge initialization Object Positioning 10 When positioning objects the window definitions such as mesh density windows will be positioned accordingly with the body 11 Multiple objects can be coupled together when positioning This will allow the user to position many objects simultaneously 12 Mouse driven positioning is available Objects can be dragged using the mouse Object Movement 13 Spring loaded dies are now available 14 The screw press model now has a template for multiple blows 15 The problem of not showing asterisk for the picked axis in object movement has been fixed Object Meshing 16 Mesh density windows can now be reordered manually 17 When saving point tracking data directly to file the format is now all ona single line in order to be excel friendly 18 Absolute mesh density is available now by setting the number of elements to zero 19 Thickness elements are now saved to keyword and database files 20 DEFORM 2D can now read and bor
146. he hardest cases to gain convergence In fact there should be a very slight strain rate sensitivity even in the cold forging world A user may help with convergence by creating an artificial strain rate sensitivity This is not far from reality and may be done by adding a data set of flow stress at a higher strain rate with slightly higher flow stress data See Figure 11 2 for an idea of how to handle this type of issue Adjusted data for strain rate 10 0 fs DOG d im a A p eA in _ Y i SER EEPE O Actual data for strain rate 1 0 LL strain In a few cases convergence problems can be caused by a course mesh in an area with high local deformation such as under the corner of a punch during a piercing operation In these cases generate a finer mesh and set the remeshing criteria to have a higher bias towards boundary curvature and strain rate These suggestions are intended as general guidelines and may not solve all nonconvergence problems Although DEFORM has excellent convergence behavior for most problems the occasional problem will occur where the user experiences some difficulty If all of these attempts fail we would recommend sending us a keyword file for further investigation 3 8 6 Stiffness matrix is non positive definite DEFORM uses the finite element method to solve problems of plastic 135 deformation heat transfer and elastic deflection When using this method a material stif
147. he information can be extracted to one file or multiple files A good time to implement this option is when information for more than one step is desired Data can be written to one file or multiple files labeled name0001 DAT name0002 DAT etc Data File The is the name of the file by default it is labeled DEFORM DAT This file can be renamed or browse can be used to find a existing file Extract Once the desired information has been selected press the extract button to extract the information View By clicking on the view option the file that is located in the data file box can be viewed 4 5 14 State variable distribution between 2 points 174 SY Distribution Between 2 Points Straight Line Following Boundary gose Stat ay 08235 7 es I Follow abject i X Remove Sampling Points 10 Figure 88 State variable distribution between 2 points This feature allows the user to specify two points and to plot a given state variable distribution between those two points The state variable distribution can either linearly interpolate between the two points or follow the boundary of the object Step 1 Click on the SV distribution button in the Post Processor Step 2 Select whether to interpolate along a straight line or to follow the boundary Step 3 Pick two points on the object to interpolate along Step 4 Click the Calculate button 175 If no state variable is curr
148. he modified post processor The GUI post processor looks for the shared library DEF_PST2 SL first in the current working directory then in the users HOME directory under the subdirectory DEFORM2 and then in the DEFROM_DIR USR directory It reads this shared library and displays the list of existing variables which can be tracked In User Variables dialog the routine number the object for which tracking is to be done and the option to track at the node or element can be selected to carry out tracking Once tracking is carried out all the data is stored in a post processor database PDB file Variables can then be plotted by selecting the variables in the State Variables menu 217 Release Notes for Version 8 1 Overview These release notes are organized as follows e Overview of available interfaces e Additional capabilities e Improvements in the interface If there are any questions about the information contained in this document please contact Scientific Forming Technologies Corporation Please review this document as it is a general overview of the improvements and exciting new features contained within this new release Overview of available interfaces There are many new interfaces for the DEFORM system A description of them is as follows 1 The standard DEFORM 2D interface of Pre Processor Post Processor and the Main menu 2 DEFORM F2 An open hybrid interface to allow the user to either follow an ordered list to creat
149. hei let heheh late lett l hiatal ahah eles 19 21 Main COntrOlSs 4 t tchen no ela ek eh at ee ee a ae Ek abe Sat 8h bee adh ee 20 22s SIEP COMUONS xe sists sade e era E E A E A aE 22 213 Advanced Step Control si d scsscedouees cet sous teceumdayeth sean n aea a a a aea ed a 25 2 14 Stopping CONOIS e e a AA a a a Ag oe a a a ET 27 Re REONE OIDI LO EAEE cate AE A at Se tat a et 29 2 1 6 Proc ssing ANd ONS sacs eon A ana ae aai aaa a ee a i ele ek 31 2017 Advanced Control Siisera aeaa aa a tia ATAA eet aaa cet eae detect 33 2 2 Mate nial Data areira aa aa a viet ex iereaeee 37 2 2 1 Phases and mixtures MSTMTR MIC seseseeeeeeeeeesseesirrrrsseerirrrrtrssetirrrrrssetrrrnnesserrnennn 37 2 22 Elastic data ensinan aita a A A A add ed E eel 38 2 2 8 Thermal dat enesis nadn n a A E A E A A N a ae 39 2 2 4 Plastic Datan a a et ae a rn Bee ae 41 2 2 5 DIMUSION O Fe LE ORE AE E tN AEE EE E A Ge E AR 47 2 2 6 Grain growth recrystallization model eeeesseeseeeeeeeseeeiirttttsetttrtrttsstttirnttttsttttnrnnnnsetteen nn 50 2 2a Hardness data MIC kenuri e a ne e e aeae aere ayete ea eg 54 2 2 8 Advanced Feature Shei ioed a a aaao aiaa AeA 56 2 2 9 Material data requirements nneeeeeeoeeeeneeeeeeeeenretteeetetrrtttscertetratttecettrtntttaccreeenannaeertennnt 58 2 3 Inter Material Data 0oeeeeeeeeeenennnnesssessserrrtsssessttrnnntsseerrrennntsssetnnennnnsasennnennnnnsnent 61 2 3 1 Transformation relation
150. hould not be changed during a simulation 263 Volume of trapped air Figure 112 A trapped volume under compression The red circle shows where the air is trapped as the workpiece is being extruded 264 Final trapped volume Figure 113 The final trapped volume The final volume is small but it can be easily seen as slight underfill by the highlighted contact nodes 265 Appendix E Modeling of a Spring Loaded Sliding Die Using Force Controlled Objects Note This method is no longer recommended since there is now a spring loaded die movement control in DEFORM 2D Overview A simulation of a spring loaded sliding die can be broken down into three typical phases of sliding die movement 1 Force on the sliding die is below the preload die is stationary resting ona stop or another die 2 Force on die exceeds preload die begins moving under spring load control 3 Die hits a stop forming process completes with die stationary Note Depending on the type of sliding die being modeled this behavior may or may not be fully realized in any particular simulation For example some pneumatic springs don t require the modeling of a preload In such a case the first phase can be omitted Methods for modeling sliding dies in DEFORM Option 1 Make the sliding die the primary die use load and or stroke stopping controls to stop the simulation when die starts Preload exceeded or stops motion spring goes solid then cha
151. ick on the interior density specification button and enter the desired density value Now click on the Add Points button and click within the object to place the density values A yellow point should appear with the density value next to it To delete the interior densities click on the Delete Points button and select the points you wish to delete Combined density The Combined Density Specification allows a density definition of both surface and interior density values DB Tod Remesh Criteria Advanced General o Type fe System Setup C User Define Mesh General Weight Factors MeshWwindow Tolerance Coating E Windows Parameters Material Window 1 4 Pts Element Size f in pz Velocity ae fo fo in sec Bcc Use Primary Die Yelacity Generate Mesh Default Setting Show Geometry Figure 44 Advanced mesh settings mesh windows Mesh density windows The Mesh density window concept is similar to a user defined mesh density Where the window crosses the workpiece border a specified density value is assigned However the mesh density window is used for remeshing user defined mesh densities are not It can also be assigned a velocity and it can be defined in an area where the workpiece has not yet been deformed through The mesh density window specifies an area in space which will move with and object 85 during deformation This area has a mesh density definition applied to it and will cause the
152. ickness of object at the initial and current configuration respectively In this definition the plane is only allowed to move parallel to the reference plane therefore all the points in the object will have same thickness strain Volume penalty constant PENVOL The volume penalty constant specifies a large positive value that is used to enforce volume constancy of plastic objects The default value of 10 is adequate for most simulations If the value is too small unacceptably large volume losses may occur If the value is too large the solution may have difficulty converging Elasto plastic initial guess ELPSOL The convergence of an elastic plastic solution is dependent on the initial guess of the stress strain state Three initial guess solutions are available e Plastic solution Uses the purely plastic deformation data to generate the initial guess e Elastic solution Uses the purely elastic deformation data to generate the initial guess e Previous step solution Uses the elasto plastic solution from the previous step to generate the initial guess The previous step solution seems to give the best convergence in most cases If 94 convergence is poor for a particular problem the elastic or plastic problem should be tried Creep solutions CREEP MIC Activates creep calculations for a particular object For more information on creep calculations refer to Creep CREEP Reference point REFPOS Point on object used
153. igid plastic or rigid viscoplastic material depending on characteristics of materials The formulation assumes that the material stress increases linearly with strain rate until a threshold strain rate referred to as the limiting strain rate LMTSTR The material deforms plastically beyond the limiting strain rate The plastic material behavior of the object is specified with a material flow stress function or flow stress data FSTRES applications When used to model workpiece provides very good simulation of real material behavior Accurately captures strain rate sensitivity limitations Does not model elastic recovery springback and is therefore inappropriate for bending or other operations where springback has a significant effect on the final part geometry Does not model strains due to thermal expansion contraction Cannot capture residual stresses Elasto plastic Ela Pla Elasto plastic objects are treated as elastic objects until the yield point is reached Then any portions of the object that reach the yield point are treated as plastic while the remainder of the object is treated as elastic In the elasto plastic deformation the total strain in the object is a combination of elastic strain and non elastic strain The non elastic strain consists of plastic strain creep strain thermal strain and transformation strain depending on the characteristics of materials Detail of different material models can be found in chapter 6 In th
154. ild Phase AUSTENITE SCr SCN BANTE cn 7 dauf AUSTENITE SCr SCN gt MARTENSITE SCr BAINITE SCr gt AUSTENITE SCr SCN ARTENSITE SCr gt AUSTENITE SCr SCN Kinetics Heat Volume Plasticity Model Diffusion TTT Curves gt B Thermal Direction None 7 Figure 32 Transformation kinetics definition window A kinetics model is a function that defines the conditions and manner in which one phase may transform into another The amount of data required is often considerable as in the case for a full TTT diagram so unless necessary often using coefficients for a function can suffice A model defines one relationship only so many relationships are required for such cases as steel where many phases can be produced There are two classifications for kinetics models diffusion type transformations and diffusionless type transformations The system is designed for both ferrous and nonferrous metals Using carbon steel as an example the austenite ferrite and austenite pearlite structure changes and vice versa are governed by the diffusion type transformation The transformation is driven by the diffusion processes depending n the temperature stress history and carbon content The diffusionless transformation from austenite to martensite involves a shear process which depends on the temperature stress and carbon content Diffusion type TTT table form Temp Stress Atom This type defines a TTT diagra
155. in rate An approximation of this value should be given at the start of the simulation A reasonable approximation can be obtained from lt Eavg h 93 where V is the initial velocity of the primary die and h is the maximum height of the workpiece DEFORM automatically maintains the ratio between average strain rate and limiting strain rate Generally the value of limiting strain rate should be 0 1 If the limiting strain rate is too small the solution may have difficulty converging If itis too large the accuracy of the solution will be degraded Generalized plane strain control ZSTR Generalized plane strain control allows certain object to have thickness direction deformation for plane strain element The thickness direction deformation can be controled either by prescribed velocity or traction in thickness direction This option is available for elasto plastic material with both velocity and traction control and for rigid plastic material with velocity control only The object lies between two bounding planes which may move as rigid bodies with respect each other thus causing strain of the thickness direction of the object Let Po Xo Yo be a fixed point in the reference planes The length between Pand its image in the other plane P is to Ouz where tis the initial thickness and Ouzis change in length in thickness The thickness strain is define as z ln t to where t and tare the th
156. in distance calculation for the Stopping Distance stopping control Refer to Stopping Distance in the Simulation Controls Stopping Step Stopping Controls subsection Thermal properties Reference temperature REFTMP For elastic objects the reference temperature is the temperature on which thermal expansion calculations are based That is thermal strains are given by Equation Coefficient of thermal expansion is set in the Material Properties Elastic menu Truncation temperature TMPLMT The Truncation Temperature is the maximum nodal temperature allowed at any point in the object If the calculated temperature exceeds this value it will be reduced to this value Stopping temperature OTPRNG The stopping temperature sets an upper and lower temperature limit which if exceeded will stop the simulation The user has the option of enforcing this limit if any single node exceeds the temperature or only if all nodes exceed the temperature Fracture properties Ductile fracture of a deforming workpiece can be modeled in DEFORM If the fracture function is turned on material separation will be modeled for any elements which exceed a critical damage value specified in the Material Properties Advanced Fracture menu This feature is useful for modeling shearing and blanking machining fracture of deformable installation fasteners pop rivets and other applications Fracture is modeled by deleting any elements which exceed the criti
157. increased to capture high changes in mesh gradient over short distances Node addition parameters MGERR The node addition parameters specify the maximum distance and angle error permitted between the object boundary and its associated grid element side The distance and angle tolerances are used to capture critical boundary geometry that might otherwise be lost when the mesh is generated If a object is required to capture very small features the maximum distance can be decreased or if a node needs to be placed on a shallow angle the angle error can be decreased as well Rarely will the user ever have to change these values Manual remeshing During the course of a DEFORM simulation extensive deformation of plastic or porous objects may cause elements in those object meshes to become so distorted that the mesh is no longer usable negative Jacobian If this condition occurs the simulation will abort and an error message will be written to the ProblemID MSG file To continue a simulation after a mesh has become unusable the object must be remeshed Remeshing is the process of replacing a distorted mesh with a new undistorted mesh and interpolating the field variables strain velocity damage and temperature etc from the old mesh to the new mesh In most cases remeshing and interpolation occurs automatically without user intervention It is also possible to manually regenerate a mesh on an object and interpolate the data from the old m
158. ing the point numbering button in the geometry display window If the current connectivity is clockwise either after drawing or after importing it can be reversed The geometry reverse function reverses the current connectivity of the object by clicking the Reverse button Edges The die starting and stopping point must be away from the contact zone unless points are on the axis of symmetry Tooling which crosses the center line should do so at 90 degrees other angles may lead to non convergence In case of a pointed punch a very short line segment should be added at the center Blended fillets 77 The connectivity between blended fillets is ill defined in IGES format To avoid problems it is helpful to define a very short line segments between arcs Blended fillets can cause DEFORM 2D to continuously give an incorrect geometry message even once the geometry has been checked and corrected To correct this simply add an extremely small line segment between the two fillets End points The radius of the first and last points must be zero Clearance fits Tooling with close clearance fits should be drawn to overlap slightly Failure to overlap tooling may allow nodes to slip between the punch and the die and cause problems when the mesh regenerates A negative jacobian error in the message file will result Geometry checking Always check geometry DEFORM has a checking algorithm that checks for geometric errors but every typ
159. input The pre processor menus contain input fields for nearly every possible data input in DEFORM The user can enter view or edit any of these values Discussions of each field are contained in the reference section of this manual Keyword file input Most of the data fields in the DEFORM pre processor correspond directly to a DEFORM keyword Individual keywords describe very specific information about a particular object characteristic simulation control material characteristic or interobject relationship Keyword data can be saved in a keyword KEY file A keyword file is a human readable ASCII representation of DEFORM simulation data 14 The typical format of a keyword is keyword name keyword parameters default data data data A keyword file may contain a complete simulation data set or it may contain only one or a few specific keywords Assembling keyword files When a keyword file is read into the pre processor only the specific data fields listed in that keyword are changed the remainder is unchanged Thus it is possible to assemble a complete set of problem data by loading one keyword file that contains only data for one object another keyword file that contains material data etc To save specific elements of a keyword file it is necessary to save the entire file then use a text editor such as Notepad vi emacs or equivalent to delete unwanted information The keyword file load and save features
160. ion convergence may be very difficult By reducing time step convergence in many cases may be improved Strain Definition The calculated strain components are of the plastic strain and the effective strain is the effective plastic strain Advice on Predicting Springback 274 To calculate the residual stress or springback during unloading one of two methods may be used If the amount of springback or residual stress is the chief concern remove the dies put enough constraint on the workpiece to prevent rigid body motion run a one step simulation If the user wishes to observe the material response during the unloading then reverse the direction of the primary die run multiple small steps Appendix H Die Stress Analysis Theory Still under construction 275 Appendix I Running creep simulations in DEFORM 2D Creep is slow continuous deformation with respect to time The strain instead of depending only on the stress is a function of temperature and time To run creep stress relaxation simulations in DEFORM the main issue is acquiring the material data There are several common laws available for the creep modeling that can be seen in the material data section If a specimen is under a constant tension and a given temperature creep will give a changing strain over the total amount of time See Figure 119 There are three different modes of creep primary secondary steady state tertiary In Figure 119 the sca
161. ion 7 0 The previous method is supported in 7 0 but may not be supported in versions after 7 0 The keywords for heat flux are ECCTMP and ECHFLX Nodal heat BCC Specifies a heat source at the given nodes Units are energy time Temperature BCC Specifies a fixed temperature at the given nodes Advanced Temperature BCC The purpose of this boundary condition definition is to allow the user to have the flexibility to specify all the various types of heat boundary conditions on the same edge The user can either specify a user subroutine number or a local heat transfer definition If the user wants to specify a user routine the User Routine Number should be specified The User Routine number specified will correspond to the subroutine the boundary condition will correspond to Refer to User Routines for more information on how to use these user defined boundary conditions If the routine number is left zero the user may then define a local defined boundary condition where the environmental temperature the convection coefficient the emmisivity and the heat flux needs to be specified the edge All four of these variables may be defined as either constants or functions To apply a local user defined boundary condition set the variables you want set the local defined number to a unique value and apply this to a set of element edges The 100 new keywords for local edge definition are ECCDEF ECTMFN and LOCTMP Diffusion Boundary Conditions D
162. is completely elastic After the tensile forces are removed the material will return to the original shape Elastic plastic material Elastic Range Figure 6 Diagram of elastic deformation The second region of a stress strain curve is known as the plastic region This region comprises strains just above the elastic range and appear on the curve as the less steeply sloped region on curve In this region the material does not recover any the deformation that occurs The only recovery that occurs is the accumulated elastic strain In Figure 7 a specimen under tension deforms first elastically and then plastically The loading curve in figure 7 first follows the elastic loading curve and then follows the plastic curve When the material is unloaded and the forces are removed from the specimen the material follows the elastic curve down When the material is completely unloaded the deformation left over is the permanent deformation of the body Elastic plastic material Plastic Range Permanent Deform ation A hk Recovery Figure 95 Diagram of plastic deformation 180 In DEFORM the stress and strain used in the stress strain curves are the known as the effective stress and effective strain The equations for these values are seen below in figure 8 a Effective von Mises Stress 7 sgia Oy Ho 0Y Ho oY ty t Effective Strain p lle e e ay e 4 Figure 96 Equations for effective stress and strain
163. itioned towards the reference object so that they interfer Common Question What is a reasonable value of Interference Answer The interference should be a small fraction of the height of the smallest element in the mesh before generating inter object boundary conditions Rotational positioning Rotation positioning allows the user to rotate any object To use this option select the object that is to be rotated Select the direction clockwise counter clockwise the center of rotation and the total angle that the object will rotate 2 5 3 Inter object boundary conditions Inter object boundary conditions identify nodes of a slave object that are in contact with a master surface Contact conditions are automatically updated by DEFORM but it is necessary to define initial contact conditions to assist with the initial solution step When inter object boundary conditions are generated DEFORM checks a tolerance band defined by the tolerance distance around all master surfaces Any nodes falling within this tolerance band or nodes which are inside the object are considered to be in contact with the surface and their position is adjusted if necessary so they are on the surface of the master object Note If master object geometry is improperly defined clockwise instead of counterclockwise or if the tolerance band is set too wide error messages will be generated 124 2 6 Database Generation Jatabase Generation O
164. its own folder However a given problem may contain many operations all in the same database file 2 Start the DEFORM preprocessor 3 Set Basic Simulation Controls 1 Problem Title optional Descriptive title for the problem will be displayed on the screen during pre and post processing 2 Unit System Select English or SI units This will change many default values and affect how material data is imported 3 Select Axisymmetric or Plane Strain An axisymmetric part can be completely defined by rotation of a 2 dimensional cross section or significant details can be captured in a 2D section for example a bolt with a hex or Torx amp trade head Buckling problems are not axisymmetric problems An axisymmetric simulation will NEVER show buckling or bending even if it will occur in production Refer to the manual for more information 4 Select Simulation Mode For cold isothermal simulations deformation mode should be turned on yes heat transfer and all other modes should be turned off 4 Define the Material Define Plastic material properties for the workpiece material Material data can be loaded from the DEFORM material database Be careful to select a material with data in the temperature range you will be simulating 244 5 Define the Workpiece 1 Define Object Type For most simulations plastic object type is suitable 2 Define the Geometry Geometry can be defined from a 2D IGES OR D amp F file o
165. l csh bsh tcsh but the C shell file must have the above lines Also the settings should be active for all shells not just interactive shells You may log out the system at this time Next time you log into the system the above command lines will be executed automatically If you decide to stay in the system at this time you need to execute cshrc manually since its contents have changed To do that enter source cshrc To verify the definition of DEFORM_DIR you may enter printenv or setenv from the keyboard The system will display the definition of DEFORM_DIR and DEFORM_USER DEFORM_DIR usr deform 2d v80 DEFORM_USER disk1 user1 System execution The following procedure may be used to run the DEFORM 2D system 1 2 Log into the DEFORM 2D user account from an X terminal Invoke the DEFORM 2D System by issuing DEFORM Text based interface DEFORM2 Graphical based system Program modules in DEFORM 2D System can also be invoked independently by issuing DEF_AMG Automatic Mesh Generation Module DEF_PRE Input Preparation Module DEF_SIM DEFORM 2D Simulation DEF_PST Simulation Results Post processor DEF_MO2 Multiple Operation system DEF_BQ2 Simulation Queue 231 Installation related problems Simulation aborted by the user Simulation stops after one step with the message SIMULATION ABORTED BY USER If the simulation status file protection is not se
166. l boundary condition settings to a given object This is called upon the beginning of each iteration 9 USRMAT Description This routine is used to allow the user to specify a unique material property for a given object This is called upon the beginning of each iteration 9 USRMSH Description This routine is used as a general purpose routine that has access to many internal variables within DEFORM This routine is advocated when other routines cannot satisfy the needs of the user This routine is called at the beginning and end of each step 10 USRBCC2 Description This routine is used to allow the user to specify special boundary condition settings to a given object This is called upon the beginning of each iteration 191 User Defined Post Processing Routines In the post processor user defined post processing routines can be used to calculate field variables using the steps stored in the database The manner in which these values are computed is based on creating a shared library file to compute variables based on the variables stored in the database To implement user defined post processing variables 1 The file in the USR subdirectory of DEFORM 2D should be copied to a local directory and the file PSTUSR FOR UNIX or pstusr f Windows can be edited The manner in which to edit this file is discussed in a later section of this document 2 After editing this file can be compiled and linked as a shared object file UNIX LIN
167. ld G New JCADEFORM2D PROBLEM Spike SPIKE DB Browse Figure 60 Database generation The simulation data set entered into the preprocessor can be written as a new database or appended to an existing database file The information will be written as a negative step indicating that it was written from the pre processor and not the simulation engine In an existing database any steps higher than the current step will be overwritten at this time The simulation database will be checked as it is written Data errors Errors are serious problems with the data set that will prevent the simulation from running These errors are marked with red flags in data checking and must be resolved before the database can be written Data warnings 125 Warnings are conditions which may cause undesirable solution behavior but will not prevent the simulation from running Warnings are marked with yellow flags If warnings exist each one should be carefully checked and the source identified Some warnings represent unusual but valid data situations If this is the case they can be ignored and the simulation can be run 126 Chapter 3 Running Simulations Simulation Option Figure 61 Simulation options window 3 1 Interactive and batch modes DEFORM is typically run in Batch mode In some cases it is desirable to watch the iteration behavior in the message file while the simulation is running For example a simulation
168. le is not correct in that the secondary creep generally has a much larger range of time compared to the other two modes Secondary creep is the only mode that is modeled and fitting experimental data to a power law curve does this as below Bo where g strain rate B n material constants o stress Many of the available forms are just fancier versions of this basic form known as the power law curve Itis easy to fit data to this curve by plotting log log curve and fit the curve to a linear slope to obtain both B and n or whatever form is being used a Strain m gt Time Figure 119 Strain versus time response for a specimen under constant load at a given temperature exhibiting creep behavior Note the three different regions of response in the strain time curve l Primary creep Il Secondary Steady State creep and Ill Tertiary creep 276 To run a creep simulation the following requirements must be fulfilled e The workpiece should be made elasto plastic e Creep has been activated in the object gt properties gt deformation window See Figure 120 Average Strain Rate 0 5 1 s Creep Calculation Limiting Strain Rate 0 005 is NotActive Active Volume Penalty 70 msec DEFORM 2D Preprocessor Figure 120 Object properties window where creep is activated e A creep model with non trival data has been defined any of the given is sufficient In the case of user routines the
169. lect the object you wish to import Click on any line segment in the object Any segments connected to this object will also be selected and highlighted Note It is necessary to use the mouse to select the object to be imported even if there is only a single object in the drawing file Creating geometries Objects can be created in tabulated form When creating objects keep in mind that it is very difficult to define complex geometric shapes by adding and moving points For complex objects it is suggested that you enter the geometry in tabular form It is also possible to enter the geometry graphically and then modify it from the table option or vice versa Multiple boundaries It is possible to create an object with multiple internal holes in the 2D pre processor Geometry can be entered for each surface in the X Y R format or by importing IGES format files The point numbering for the hole geometry must be clockwise opposite the normal DEFORM numbering system The Check Geometry feature will ensure that objects are oriented properly relative to each other However the outside object must still be oriented properly When importing an IGES file multiple boundaries may be selected for a single object by pressing the Shift key on the keyboard and selecting the boundaries with a mouse 79 2 4 6 Object meshing Tool Remesh Criteria Advanced General Figure 41 Object meshing window The Mesh Generation window allows th
170. liding error SLDERR The sliding error is used to control the movement of nodes of a slave object which are in contact with a master object Sliding error limits the distance a contacting node of a slave object can move from the adjacent master object in a single time step The value of sliding error should be between 5 and 10 of the smallest side length of the smallest element Slave nodes which are in contact with a master surface slide along the master surface as the object is deformed However when the slave node approaches a corner on the master surface the direction of the nodal velocity may cause the node to shoot past the corner during a time step Once the node has separated from the master surface it will continue to move in the direction of its separation velocity until the time step is completed When a new time step is generated the node is forced back onto the master surface along the shortest normal connecting the node and the master surface The length of this normal is referred to as the normal distance error The sliding error limit causes a new time step to be initiated whenever a slave node s normal distance error exceeds the specified value for SLDERR An alternate approach to this problem is to specify the contact release method OSCTRL under Simulation Controls Advanced Controls Step definition STPDEF There are three modes for defining steps e User In user defined steps mode the steps correspond to the NSTEP v
171. ll terminate and a message will be written to the DEFORM message file If direct iteration is specified as the iteration method the specified number of iterations will be performed If the solution has not converged another series of iterations will be performed If the solution has still not converged the simulation will terminate and a message will be written to the DEFORM message file 30 Simulation Control xj Heat Transfer Diffusion Induction Constant OK Environment Temperature Cancel f Constant 68 F Function of Time f Define Convection Coefficient Constant 7 7e 006 Btu sec in 2 F Function of Temperature ff Define I View factor calculation Figure 15 Process condition window heat transfer data 2 1 6 Processing conditions The processing conditions menu contains information about the process environment and constants related to general solution behavior Environment temperature ENVTMP Environment temperature is used in radiation and convection heat transfer calculations and represents the temperature of the area in which the modeled process is taking place The environment temperature may be specified as a constant or as a function of time Heat transfer to this temperature is considered to occur from any nodes not in contact with another object unless heat exchange windows are used No radiation shape factors are accounted for Convection coefficient CNVCOF
172. located with the current installation of DEFORM 2D usually in a directory such as C DEFORM2D V8_1 If it is not there look for a file named DEF_SIM EXE Compiling User Routines on the DEFORM Support Website for Windows Machines There is now the possibility to compile user routines for Windows platforms using the SFTC website The location of the website is as follows and is available to only current customers of DEFORM http support deform com 2d support fortran 211 Microsoft Internet Explorer Compile this def_usr f DEFORM 2D v8 1 User Routine PAAR S RRNA ROTI Hie Comments Suggestions Contact 7 se eee SOUR pe e Figure 111 The DEFORM webpage for compiling user routines Figure 129 shows the webpage where the user routines are compiled There are various versions of DEFORM listed on the website and the appropriate version should be selected The left half of the webpage are the user FEM routines that can be compiled and the right half are the user post processing routines that can be compiled To compile a user routine click the appropriate Browse button and load the fortran file that should be compiled After this click the Submit File button and the website will guide you to download a zip file This zip file will contain the following information 1 The original fortran file you submitted 2 A message file with the output of the compiler linker 3 A dll file or an exe file if
173. lve problems of large deformation and AMG Automatic Mesh Generator to automatically provide an optimized remeshing capability In most cases the meshing and remeshing runs very smoothly There are cases though where a simulation will not continue due to a negative jacobian unacceptable mesh at a step immediately after a remeshing operation In most cases these can be easily identified from one of the following areas e Any time geometry is imported into DEFORM using IGES in the case of 2D it is subject to a number of issues that could make it illegal Overlapping of endpoints in blended fillets duplicate points overlapping lines and other problems can occur DEFORM has a geometry checking functionality that should always be used on created or imported geometry If this is neglected a small mismatch during the simulation can lead to a node which has no mass sticking in this area and leading to subsequent remeshing problems If the problem stops with the negative jacobian message read a previous starting step into the preprocessor and check all geometry of dies this includes checking for the orientation of the die geometries by looking at the vertex numbering If these recognize an error this is most likely the culprit The error can be corrected and rerun from that step e A closed forging lap will usually lead to this problem Look at your progressions carefully and see is there is a small area where a lap has formed and closed If
174. m The mesh number should always be incremented when there is a change in the mesh If a remeshing step has been purged from a database then user variable tracking will not work with the database Compiling user routines After the code has been modified the new TEXT based post processor and the shared dynamic library for the GUI post processor have to be generated using the INSTALL2D program which is located in the DEFORM_DIR or using the script build_pst which is in the DEFORM_DIR USR directory If the INSTALL2D program is being used the code in the DEFORM_DIR will be altered If you wish to make a local copy of the code then copy all files from the DEFORM_DIR USR directory to your local directory Then run the script build_pst using the following command gt build_pst 216 This builds a new copy of the post processor DEF_PST EXE in the local directory and also builds DEF_PST2 SL a shared library that can be used with the GUI post processor After this process is completed then the new variables can be accessed from the text based and GUI post processors In the GUI based post processor when tracking of user variables is done a post processor database PDB is generated for the values of the tracked variables If the same data is to be viewed again in the post processor after loading the database the post processor database can be loaded to view the data This saves the time required to track these variables again Running t
175. m of the nodal loads of all nodes movement boundary condition codes cn ou TN iae Se 8 ae Sy BCL ANS oe y Current Die Stroke b nt es jyanced Speed Limit Delne Figure 50 Object movement controls press hammer 103 Hammer energy Hammer forging operation is controlled by energy During a working stroke the deformation proceeds until the total kinetic energy is dissipated by plastic deformation of the material and by elastic deformation of ram and anvil when the die and ram faces contact each other During hammer forging operation only a portion of the kinetic energy of ram is used for the plastic deformation of workpiece The rest of the energy is lost through anvil and machine frame The blow efficiency IB is defined by _ Wu 1B Er where Wy is the energy consumed for the plastic energy of workpiece and E the total kinetic energy of ram There are basically two types of hammer one is anvil type hammer and the other counter blow hammer The formulations and assumptions used for the two types of hammer forging operations are given below 1 Anvil Type Hammer In an anvil type hammer the workpiece together with the lower die set is placed on an anvil which is stationary In a simple gravity drop hammer the ram is accelerated by gravity and builds up the blow energy Therefore the blow energy Er is calculated by Er mrgH where mris the mass of the ram g the acceleration due to gravity a
176. m whose independent variables are average element temperature effective stress and dominant atom content In the case of 63 steel dominant atom content is the weight percentage of carbon in the metal at each element Using tabular data DEFORM is trying to solve an Avrami equation which has the form 1 exp kt where is the volume fraction transformed tis the time and k and nare constants n being the Avrami number In terms of TTT data two curves are required in order to solve for k and n If only one curve is input to DEFORM the user must provide the Avrami number Transtermation from 1 2 Time Stress 300 0000 Fae 2 C1044 O C2 D444 B FE4 1 Li Fu fi 14 BOH agay rr a i oO 2 i E B 2 b eoi 5 297 4 a 7 i amp 4 4 5 4554 1 a I H i I 1 3510 V a s E E B a A S E E O A E O O E E E A S E T A E E a E a a a S E E 0 797 O Ali 1 609 2 807 L006 5 203 Time Figure 7 2 shows an example TTT diagram in DEFORM In the case below two Curves are used to define the percent transformed for a given dominant atom content Each curve has a value at which an amount of transformation is defined The curve to the left has been defined in which starting pct of the transformation from austenite to bainite The curve to the right has been defined in which ending pct of the austenite to bainite transformation 64 Martensiti
177. mation Contour plots of temperature strain stress damage and other key variables simplify post processing all products Self contact boundary condition with robust remeshing allows a simulation to continue to completion even after a lap or fold has formed 2D Pro Multiple deforming body capability allows for analysis of multiple deforming workpieces or coupled die stress analysis 2D Pro 3D Fracture initiation and crack propagation models based on well known damage factors allow modeling of shearing blanking piercing and machining 2D Heat Treatment Simulate normalizing annealing quenching tempering and carburizing Normalizing not available yet Heating a ferrous alloy to a suitable temperature above the transformation range and cooling in air to a temperature substantially below the transformation range Annealing A generic term denoting a treatment consisting of heating to and holding at a suitable temperature followed by cooling at a suitable rate used primarily to soften metallic materials In ferrous alloys annealing usually is done above the upper critical temperature but the time temperature cycles vary both widely in both maximum temperature attained and in cooling rate employed Tempering not available yet Reheating hardened steel or hardened cast iron to some temperature below the eutectoid temperature for the purpose of decreasing hardness and increasing toughness Stress relieving Heating t
178. mation patterns Ductile fracture of the part Die failure Buckling Can the part be modeled as a two dimensional part or is a three dimensional simulation necessary Having a definite goal will help you design a simulation which will provide the information most vital to understanding your manufacturing process 11 1 5 Geometry representation T I gz Figure 2 Axisymmetric and plane strain examples DEFORM simulations can be run either as two dimensional 2D PC Pro or three dimensional 3D models In general 2D models are smaller easier to set up and run more quickly than 3D models Frequently the added detail of a 3D model is not worth the additional time required over a 2D simulation if the process can reasonably be represented in 2D There are two 2D geometry representations axisymmetric and plane strain Axisymmetric geometries assume that the geometry of every plane radiating out from the centerline is identical Plane strain requires that there is no material flow in the out of plane direction and that flow in every plane parallel to the section modeled is identical Figure 2 illustrates axisymmetric and plane strain models Objects that are closely approximated by axisymmetric or plane strain models can also be modeled in 2D by neglecting minor variations For example if the head shape is not critical a hex head bolt can be modeled as axisymmetric by defining a head radius which maintains constant volume radius 0 525
179. meshings of the object For a value of 15 for RMSTEP the object will be remeshed at least every 15 steps This is helpful when the simulation stops prematurely because of a negative jacobian error Before the mesh becomes unusable the object can be remeshed Advanced mesh options These criteria need not be changed except for very rare cases Among these cases are objects with very fine details objects requiring very steep gradients in mesh density etc Before changing these values the user may want to consult the staff at SFTC to make sure that changing these values will perform the task that the user requires D Tool Remesh Criteria Advanced General bi Geometry System Setup C User Define wr General Weight Factors Meshwindow Tolerance Coating amp Grid Resolution Material X Divisi os af m Yose E A Movement Generate Mesh Detauit Setting Show Geometry Figure 46 Advanced mesh settings tolerances Grid resolution MGGRID When an object is meshed in 2D a sampling grid is required to discretize density of the mesh throughout the starting geometry Grid resolution specifies the spacing of the sampling grids which are used to sample mesh densities Increasing the value of Xdivision or Ydivision will result in sharper gradients between areas of differing mesh density In the case of blanking where a very high mesh gradient is required over a narrow region these values may need to 89
180. mode FRCMOD as User Routines in Materials Properties Advanced and specify the user routine number to be called in the subroutine USRDMG The damage routines are functions USRDM1 onwards with the inputs being as follows STS STRESS EFSTS EFFECTIVE STRESS EFEPS EFFECTIVE STRAIN RATE DAMAG PREVIOUS ACCUMULATED DAMAGE STRLMT STRAIN LIMIT DTIME TIME INCREMENT The output is the new value of damage DAMAG NEW VALUE OF ACCUMULATED DAMAGE The routine USRDM1 has an example on how the above routine is to be used 1 The default damage model in DEFORM is the normalized Cockroft and Latham model in which damage is computed as given below DNT DSQRT STS 1 STS 2 2 4 STS 4 2 S1 STS 1 STS 2 DNT 0 5 S2 STS 1 STS 2 DNT 0 5 PRNSTS S1 IF PRNSTS LT S2 PRNSTS S2 DAMAG DAMAG PRNSTS EFEPS DTIME User defined material models USRMAT The user defined material model USRMAT can be used to define a unique constitutive model This will provide flexibility for models which require constitutive equations different than those provided by the default material 204 models For example in the case of molten glass or polymers the constitutive models for rigid plastic or elasto plastic models are not sufficient in certain process conditions This routine allows the user the flexibility to apply a constitutive model to capture instances where the built in material models don t capture the
181. n a region of material has undergone Mathematically the two definitions of this are seen as follows Engineering Strain Change in Length Original Length True Strain Sum of incremental strains In final length initial length In Figure 2 the calculated strains for both an upset and a tensile test are shown Note that the Engineering strain gives rather round numbers for doubling or halving the length of a test specimen The advantage of true strain is that itis a more accurate measure of the actual length change in the material and is used to determine stress in DEFORM 177 Strain rate is a measure of the instantaneous rate of deformation a region of material is experiencing This quantity measures a rate of change of the strain at a point of a material per unit time H 2 mena A m gt Engineering Strain 0 5 Engineering Strain 1 True Strain 0 69 True Strain 0 69 Figure 91 Demonstration of concept of strain In Figure 3 the engineering stress and strain are shown as closed form expressions for a compression test Note that both of these quantities fail to account for the increase in area of the test specimen due to barrelling Compression test Engineering o F Stress Ai a ae Ah Engineering Eeng Strain ho Figure 92 Engineering stress and strain for a compression test In Figure 4 the true stress and strain are shown as closed form expressions for a tension test
182. n be reduced the number of mesh elements can be increased or the mesh density in the area where distortion occurs can be increased The way in which to check for this is to plot the node velocities in the Preprocessor It is not recommended for the displacement of the nodes each time step be larger than the edge length of the elements 3 8 3 Remeshing is highly recommended Remeshing is Highly Recommended because of Unbalanced Mismatch between Master and Slave is a message that occurs when the size of the elements on the slave and master surface are not proper When specifying master slave relationships between objects the following rules should be adhered to e the slave is the softer material e the slave should have a finer denser mesh than the master 131 This mesh is very important in the region where the slave and master contact each other If the mesh on the master is much denser than the slave s mesh in a region where they contact the results of the simulation will not be accurate If the ratio of the number of elements on the contact surface between the master and slave is greater than 3 1 then the message Remeshing is highly recommended because of unbalanced mismatch between master and slave is printed as a warning in the message file This will reduce the accuracy of the solution and steps should be taken by the user to change the mesh densities on the objects 3 8 4 Negative Jacobian DEFORM uses the finite element method to so
183. n the XYR format X and Y are the x and y coordinates of the point and R is the radius of the point if it is to define a curved line Line Arc format input DIEGEO 76 Line Arc format is similar to XYR format in that it can define arcs but it is more entity oriented The XYR format defines the connecting points and the connection type but the Line Arc format defines the lines and arcs that make up the object not the connections The primary reason that the Line Arc format is used is because IGES files are formatted in the Line Arc scheme AMGGEO format input The AMGGEO format is the mesh generators internal format for handling geometries This format can specify geometry as a set of connect points the XYR format the line arc format and as a set of boundary nodes Geometry rules There are several conventions that must be followed when creating or editing object boundaries Orientation The endpoints of line segments are defined numerically For all die definitions all objects should be numbered such that the die block is on the left and open air contact zone on the right as you move along the points in the order Failure to follow this orientation may cause any of the following problems e object won t mesh e mesh distorts when boundary conditions are applied e object positioning error using interference positioning Direction Objects must be defined counter clockwise CCW The orientation direction may be checked us
184. nd H is the ram dropping height In a power drop hammer the ram is accelerated by steam cold or hot air pressure in addition to gravity The total blow energy is given by Er Mrt 9 Pm A H where A is the piston area and pm is the indicated steam oil air pressure on the piston The velocity of ram vz is calculated by 2Er mT Vr The plastic deformation energy during a small time increment At is calculated by 104 AEp Lr amp s where L7is the deformation load at the ram and As is the ram travel during At After the increment the blow energy is adjusted by AE Er t At Er t a The simulation is repeated until the blow energy Er becomes zero The characteristic values of Anvil type hammers are given in the following table Hammer type E kN m ft Ibf nB Vs m sec ft sec nB min 1 nH Free Drop Hammer 40 29 440 0 3 0 6 4 5 13 16 4 40 0 2 0 3 16 11 780 0 3 0 6 4 5 13 16 4 35 0 2 0 3 100 73 600 0 3 0 6 4 5 13 16 4 55 0 5 63 46 370 0 3 0 6 4 5 13 16 4 60 0 5 Power Drop Hammer 50 36 800 0 8 0 9 5 8 16 4 26 3 80 250 0 45 0 55 40 29 440 0 8 0 9 5 8 16 4 26 3 450 0 45 0 55 250 184 000 0 8 0 9 5 8 16 4 26 3 55 240 0 5 100 73 600 0 3 0 6 5 8 16 4 26 3 55 240 0 5 Screw press energy The unique characteristic of a screw press is the method of driving it A motor drives a flywheel which is either directly connected or can be connected to a scr
185. nd of increment The routine USRMAT has an example on how the above routine is to be used 1 This example shows the user material routine applied to a elastic constitutive model Notice that tangent modulus stress components and plastic strain were updated in this subroutine YM 1000 PV 0 3 THIRD 1 3 C C Elastic tangent modulus Cc S1 1 PV 1 0 2 0 PV S2 1 PV S1 S3 YM 1 PV S4 S3 2 S5 S3 1 2 PV S6 S5 PV S7 S5 S6 C 205 G DSAV DSAV DSAV DSAV DSAV DSAV DSAV DSAV DSAV DSAV DSAV DSAV DSAV DSAV DSAV DSAV E E e e A a a a a a d a d d d d Gs N en E S SR FEN es AEN pe oe AWAN ABER BWWWBNNNFREHE Store elastic tangent modulus in DSAVE BOU AMNH Ww Nn e BWNHERWNE Se H1 D Il n S6 S6 J OOOO A Total stain increment STRAN 1 H2 DSTRAN 2 H3 DSTRAN 3 H4 DSTRAN 4 Cc G Calulate elastic stress Cc TI STRESS 1 S7 H1 S6 H2 S6 H3 T2 STRESS 2 S6 H1 S7 H2 S6 H3 3 STRESS 3 S6 H1 S6 H2 S7 H3 T4 STRESS 4 S4 H4 Cc C new stress at the end of increment G STRESS 1 T1 STRESS 2 T2 STRESS 3 T3 STRESS 4 T4 C No effective plastic strain C EPX 0 0 User defined boundary conditions USRBCC User defined boundary conditions USRBCC can be implemented to model special boundary conditions not available in standard DEFORM Currently use
186. nd the number of generated elements is typically on the order of ten percent When the mesh is generated the specified total number of elements is used in conjunction with the Point and Parameter controls to determine the mesh density Element size ratio MGSIZR The maximum size ratio between elements is one of several ways to control the mesh density during automatic mesh generation AMG by specifying the ratio of node densities For a value of 3 for MGSIZR the largest element edge on an object will be roughly 3 times the size of the smallest element edge on the same object If equal sized elements are desired then Size Ratio 1 If SizeRatio 0 the element size ratio will not be a factor in the mesh density distribution Number of thickness elements MGTELM The max thickness ratio is one of several ways to control the mesh density during automatic mesh generation AMG The number of elements in thickness direction represents the approximate number of elements that will be generated by the system across the thickness direction of any region of the part The Automatic Mesh Generator AMG takes the value for MGTELM and generates a mesh that will have that number of elements across the thinnest portion For instance if MGTELM is set to 4 the AMG will try to have 4 elements across the thickness of the geometry The thickness direction of an object is perpendicular to a branched centerline axis for each region of the part The total
187. ne Material Points button You can add the points that you wish to track in the display window Point Trac king Figure 78 Point Tracking initial window 164 Figure 79 Point tracking tracking option window 4 5 6 Load Stroke The graphs window is used to generate load speed torque angular velocity and volume vs time or stroke plots for the objects Multiple plots can be generated on the same graph If time is used as the x axis then the graph can be used for selecting steps Clicking on a point on the graph will load up the closest saved step from the database of the list of steps which are displayed on the step list The default object that is selected is the primary die and the default load is the Y Load Figure 80 Load stroke window 165 It is possible to plot a load stroke curve for one object by selecting the object in the object table It is also possible to plot the load stroke curve for the primary die In order to do this turn Follow PDIE on By default when one plots a load stroke curve for a multiple operation problem All load stroke curves will appear on the plot it is possible to plot one at a time In order to do this turn Follow Oper on 4 5 7 Steps The step options such as adding and subtracting steps from the step list are accomplished from within this window By default when DEFORM loads up only positive steps are displayed in the step list Figure 81 Step Sele
188. ne the relationships between the phases of a mixture As defined in the material data a mixture is defined by the user as a Set of phases The relationships between the phases is defined in terms of the following transformation characteristics e Transformation kinetics model e Latent heat of transformation e Transformation induced volume change e Transformation plasticity The purpose of this section is to give the user an understanding of how to properly define a transformation relationship between two phases This section will explain in how DEFORM handles the above concepts Transformation is a crucial concept in metal forming and heat treatment Figure 7 1 illustrates the coupling between temperature deformation transformation and carbon content Transformation is modeled by defining the volume fraction for each possible phase in each element of a meshed object For low carbon steel object each element may contain different volume fraction of martensite bainite pearlite or austenite Each phase is defined by its own set of material properties These material properties define the plastic behavior of the phase the thermal properties of the phase and possibly if using an elastic plastic material the elastic properties of the phase The relationship between the transformation from one phase to another is defined by the inter material data This relationship is defined in terms of a kinetics model in order to determine rate of phas
189. ned by considering how the spindle shaft is threaded V o ad sin where Vo The output translational velocity of the die Rotational speed of the flywheel d diameter of the spindle 6 pitch angle of the spindle threads This can be implemented in the following code DATA ENERGY 10000 0 eff 0 2 MI 10 PI 3 14159 diam 1 0 pitch 0 1 C This calculates the change in the energy between steps e_change FRZY STRKY eff C This updates the energy value ENERGY ENERGY e_change C This makes sure that the energy doesn t go negative if ENERGY LT O THEN ENERGY 0 0 endif C This computes the rotational speed based on the current energy rot_spd SQRT 2 ENERGY MI C This converts angular speed to rotations per second rot_spd rot_spd 2 Pl C This calculates the tranlational velocity of the screw press V_out rot_spd PI diam sin pitch C This updates the value UPDV V_out User defined node and element value USRUPD The user can implement subroutines that can calculate 100 nodal and 100 elemental values during the simulation for each node element of the objects in the simulation The inputs are all state variables and the outputs are the values for USRNOD and USRELM The variables can also be used in the flow stress 201 routines to model flow stress as a function of new state variables The subroutine USRUPD is called to calculate the nodal and element values
190. ng the specified image format Animate Writes images of all selected steps to a an image file using the specified image format Steps may be selected or deselected using the Steps option on the post processor controls window 4 5 Post Processing Summary The post processor controls window is divided into two sections The top sections consists of links to several sub windows which access virtually all post processor data display and extraction functions The bottom sections contain hot link icons which display several of the most commonly used functions 4 5 1 Simulation Summary This is very similar to the old DEFORM simulation summary The step can be selected using the step list and then the object can be selected using the up down arrow buttons in the object field The concept of operation number is going to be added to DEFORM until then all the operations have the number 1 After changing the object if the step changes the object does not change The up down arrow keys can be used to browse through the step list 147 Simulation Summary Window 4 5 2 Object Mirroring 148 2 Symmetry Definition Mirroring Options Add Delete F Copy Mirroring Plane System Define Pick a mirong edge Point Axis Object 1 TEST Mi No fo Point fi fi Axis fi fi d Figure 69 Object mirroring window The purpose of object mirroring and symmetry is to allow the user to visualize the both
191. nge movement controls and restart Option 2 Use artificial elastic spacer s to allow the spring loaded die to react against deformable body and allow simulation to run through More initial setup time but less intervention during run time Option 1 described Phase 1 See Figure 114 a Set object 2 velocity control b Object 4 primary die no movement control c Stop on load preload on object 4 d Step control by time primary die is not moving Phase 2 see Figure 115 a Object 4 load control Direction should be direction load is applied not direction of movement b If movement of object 4 is limited stop on stroke can be set 266 Figure 114 Sketch of spring loaded die simulation with spring loaded die set with a stopping criteria based on load 267 Figure 115 Sketch of spring loaded die simulation with spring loaded die set with movement type based on load Option 2 described Using an artificial elastic spacer See Figure 116 a Create a thin elastic object 5 in this case with about 10 20 elements b Make object 5 slave to both objects 3 and 4 c Set movement on object 4 to load control with the load as the preload d Run the simulation When load exceeds preload die will automatically move up 268 Figure 116 Sketch of spring loaded die simulation with spring loaded die set with movement type based on load and an additional elastic body 5 that provides a reaction force for
192. ns Vy 0 for the top and bottom of the workpiece and Vx 0 at the centerline Add creep material data This data is rather difficult to obtain since it is a pure material property and not obtainable without experimental testing Turn on creep in the object properties window The simulation should run fairly quickly and the stress should relieve rather quickly The stress results can be obtained by point tracking 279 Appendix J On Manually Importing Material to DEFORM Still under construction 280 Appendix K Generating a Circular Geometry With a Hole This case involves the two features of generating a circular geometry and adding an internal hole To create a circular geometry go to the geometry window of the desired object 1 Click the Edit tab and select the Line Arc format radio button as seen in Figure 123 2 Set the type to Arc 3 The first point X1 Y1 is the start of the arc The second point X2 Y2 is the center of the arc The angle is the amount of sweep of the arc Input the following values 1 0 for X1 Y1 0 0 for X2 Y2 and 360 for the angle This will yield the result seen in Figure 124 Current Objec 1 Workpiece a Tool Edit al Gener o i a lu fi aj Wih Current Boundary TT fs Geo Format ee Te G XR 3 a f Moen e H s gw 3 Insert 3 Del x Del All O ww 70 msec DEFORM 2D Pre processar Figure 123 Setting the geometry type to Line Arc 4 Inc
193. nw gid QG vse EI Figure 65 Detail of Object Tree showing object mode selection icons Tree levels and functions The right mouse button menu has functions associated with each level of the object tree The object tree levels are shown in Figure 66 141 otal objectis 4 3 Ai Figure 66 Levels in the object tree Right mouse selections at each level accesses a context appropriate menu The Problem Data menu contains the following commands e Turnon all objects e Turn off all objects e Turnon all workpieces Turns on any object which is not rigid Turns off all rigid objects e Turnon all dies Turns on any object which is rigid Turns off all other objects Turn on transparency for all e Turn off transparency for all e Turnon backface for all backface shows the interior or back surface of rigid objects e Turn off backface for all The Object Data menu contains some or all of the following commands 142 depending on object type e Turnon this only turns on the selected object and turns off all other objects Turn off turns off the selected object e Show contact node highlights any nodes which are in contact with any master object This is a quick way to display contact This is a toggle menu selection Select it once to turn the contact node display on Select it again to turn the display back off e Show BCC highlights any node with constrained velocity boundary conditions This is also
194. o a suitable temperature holding long enough to reduce residual stresses and then cooling slowly enough to minimize the development of new residual stresses Quenching A rapid cooling whose purpose is for the control of microstructure and phase products e Predict hardness volume fraction metallic structure distortion and carbon content e Specialized material models for creep phase transformation hardness and diffusion e Jominy data can be input to predict hardness distribution of the final product e Modeling of multiple material phases each with its own elastic plastic thermal and hardness properties Resultant mixture material properties depend upon the percentage of each phase present at any step in the heat treatment simulation DEFORM models a complex interaction between deformation temperature and in the case of heat treatment transformation and diffusion There is coupling between all of the phenomenon as illustrated in the figure below When appropriate modules are licensed and activated these coupling effects include heating due to deformation work thermal softening temperature controlled transformation latent heat of transformation transformation plasticity transformation strains stress effects on transformation and carbon content effects on all material properties 10 Heat t eretated by Deformation eformacien TEA LA Heat Transfer r p 7 j Ao Carbon Content Latnt 5 Heat 7
195. ode between adjacent line segments of a surface If the number of oscillations exceeds the limit the node will be locked for a fixed number of sub steps Repeated touching separating When slave nodes touch and seperate from a master surface after two oscillations the nodes are made to touch for the sub step The touching seperating control can be used to make the node seperate from the surface for the sub step after a specified number of oscillations 2 2 Material Data In order for a simulation to achieve a high level of accuracy it is important to have an understanding of the material properties required to specify a material in DEFORM The material properties that the user is required to specify is a function of the material types that the user is utilizing in the simulation This section describes the material data that may be specified for a DEFORM simulation The different data sets are e Elastic data e Thermal data e Plastic data e Diffusion data e Grain growth recrystallization model e Hardness data e Fracture Data FRCMOD This section discusses the manner in which to define each of these sets of data and which type of simulation each of these are required for 2 2 1 Phases and mixtures MSTMTR MIC Material groups can be classified into two categories phase materials and mixture materials For example a generic steel can exist as Austenite Bainite Martensite etc During heat treatment each of the above phase
196. odel is not currently available for the current release of DEFORM User routine This model is not currently available for the current release of DEFORM 5 ui intermaterialBase Mother Phase Child Phase AUSTENITE SCr SCN BANTE 6C 3 da Transformation AUSTENITE SCr SCN gt MARTENSITE SCr BAINITE SCr gt AUSTENITE SCr SCN ATENSITE SCr gt AUSTENITE SCr SCN Kinetics HeatVolume Plasticity Laer Canaan e Volume Change T emp Atom A S Figure 33 Transformation induced volume and latent heat window 2 3 3 Latent heat PHASLH MIC Latent heat accounts for the net energy gain or loss when a phase change occurs from one phase to another Latent heat may be a constant value a function of either temperature or a function of the dominant atom content The energy release due to the latent heat can prolong the time of transformation A positive sign on the latent heat value means that the transformation acts as a heat source and a negative sign means that the transformation acts as a heat sink 67 2 3 4 Transformation induced volume change PHASVL MIC Volume change may be the result of a phase transformation This volume change may induce stresses in the transforming object and will certainly affect the final dimensions after processing The volume change due to transformation is induced by a change in the lattice structure of a metal The transformation strain is used mainly to acc
197. of clarity When the velocity at node points have been determined their coordinates need to be updated The manner in which we update the nodal coordinates is by integrating the velocity over the time step of the current step In Figure 15 the nodal positions are shown as updated from the previous stage A simple principle of note are clear from this figure If the nodal velocities change direction or magnitude over very small time periods a small time step size is required to correctly predict this behavior i x t At x t v At y t Atj y t v At tese smmm ee Figure 103 Updating nodal coordinates after a completed calculation The problem that now must be addressed is how to solve the equation in Figure 13 over a discrete set of points since the nodal values define the velocities only at discrete locations The way in which to solve this problem is to define shape functions over the elements as a manner of providing a velocity field that satisfies the compatibility requirement continuous over the entire body Figure 15 shows a general equation for a shape function whose purpose is to define the velocity profile over an element based on the nodal velocities A one dimensional case is shown in Figure 16 as a simple linear function The advantage of an equation of 185 this form is that compatibility is maintained when the same nodes for any shared element edge define the velocity over that edge D plx D2 x
198. offset The offset curve is controlled through the following parameter Offset Distance The offset distance is a positive value specifying how far inside the region the identical border should be positioned User Defined If you wish to create your own initial pattern or use a previously generated 161 pattern you may do so by reading in a flow pattern file A pattern file consists of a list of point coordinates and a list of connectivity sets The points are points of intersection within the flownet The type of grid is determined by the connectivity list This list determines each curve separately as the number of points in a sequential pattern If the starting and ending point indices are the same the curve is closed The user defined pattern must be read by a pattern file The pattern generated can be saved to this file by setting the save option to yes If the pattern is being saved the file name must be specified in the pattern File text box The material point data format is Numpt 1 X 1 Y 1 Numpt X Numpt Y Numpt NumCv 1 CvSz 1 pt 1 pt CvSz 1 NumCv CvSz NumCv pt NumCv pt CvSz NumCv where Numpt Number of material points X i X coordinate of ith material point Y i Y coordinate of ith material point NumCv Number of curve CvSz i Number of points in ith curve pt Point index of curve refers to indices in first list Example Case Taking a round billet from the SPIKE KEY file in the DATA directory
199. ol x Solver Iteration Method Cancel Skyline Newton Raphson C Sparse Direct Iteration Convergence Error Limit Velocity Error 0 001 Farce Error joo Band Width Optimization W Deformation Maximum Iterations per Time Step 200 Figure 14 Iteration controls window 2 1 5 Iteration controls The iteration controls specify criteria the FEM solver uses to find a solution at each step of the problem simulation For most problems the default values should be acceptable It may be necessary to change the values if non convergence occurs Iteration methods ITRMTH e Newton Raphson The Newton Raphson method is recommended for most problems because it generally converges in fewer iterations than the other available methods However solutions are more likely to fail to converge with this method than with other methods e Direct The direct method is more likely to converge than Newton Raphson but will generally require more iterations to do so Temperature solver SOLMTT The skyline solver uses the skyline storage method in conjunction with Gaussian elimination to store temperature matrix data This method is recommended for most problems Initial guess INIGES 29 Initial guess generation improves the convergence behavior of the first step of the solution It should be used for almost all problems Bandwidth optimization DEFBWD TMPBWD Bandwidth optimization improves solution time by optimizing the
200. ome of the above situations will not arise if DEFORM was working and suddenly stopped working In most situations the license has probably expired and a new license has to be obtained from Scientific Forming Tech Corp Mesh generator does not work One of the problems if DEFORM 2D is not installed properly is that in the GUI the mesh generator will not work and in the text based main program the pre 232 processor and post processor cannot be invoked To confirm that this is the problem try to mesh a very simple geometry In the terminal the following message will be displayed when trying to generate a mesh DEF_AMG command not found On some systems the above message may not be printed but a dialog box with the following message can appear MESH GENERATION ERROR The KEY file generated by the mesh generator could not be found This implies mesh generation failed at some state Possible reasons could be 1 Incorrect geometry check orientation 2 Insufficient resources to run AMG 3 Insufficient memory array sizes This problem can occur if the environment variable DEFORM_DIR is not set in the proper place in the cshrc file The variable must be defined for interactive and non interactive shells If it is not defined for non interactive shells then the variable DEFORM_DIR is not defined when the mesh generator is executed The shell returns with the message that the command is not found Also it is very important that the cshrc unde
201. on should be to use mesh density controls to place a smaller mesh in the offending region If problems are still occurring then interference depth can be used Maximum stroke increment RMSTRK Anytime the maximum stroke increment is exceeded by the stroke increment of the primary die since the last remeshing step a new remeshing step will be initiated Maximum time increment RMTIME Anytime the Maximum Time Increment Value of Elapsed Time has elapsed since the last remeshing step a new remeshing step will be initiated The keyword RMTIME controls the initiation of a remeshing procedure based on the process time measured from the last remeshing It is the value of process time allowed to elapse between remeshings of an object For a value of 10 for RMTIME the object will be remeshed at least every 10 seconds This is helpful when the simulation stops prematurely because of a negative jacobian error Before the mesh becomes unusable the object can be remeshed The elapsed process time between remeshings will not be used to determine when the object is remeshed Maximum step increment RMSTEP Anytime the Maximum Step Increment Number of Steps has occurred since the last remeshing step a new remeshing step will be initiated The keyword RMSTEP controls the initiation of a remeshing procedure based on the number of simulation steps measured from the last remeshing It is the value of 88 simulation steps allowed to elapse between re
202. on the main pre processor menu load or save an entire data set To load partial keyword files use the Keyword Load option from the File menu Other file inputs Various data types particularly part geometries and material data can be read from appropriate format files Modifying problem data Solution or input step data from any stored step in a database file can be read into the pre processor modified and either appended to an existing database or written to a new database file Viewing specific problem data Most problem data stored in the database file is accessible in the post processor However certain specific information such as boundary conditions or inter object contact conditions are displayed differently in the pre processor When debugging a problem which is not running properly it is sometimes useful to use the pre processor data display to view this information 1 9 File system The primary data storage structure is the database file The database file stores a complete set of simulation data including object data simulation controls material data and inter object relations both from the original input and from selected solution steps The sequence of information storage in a database file is shown in Figure 4 The pre processor uses an ASCII format file called the keyword file to create inputs 15 S 0 D L L U E T T l l G D N N Figure 4 DEFORM database structure Each DEFORM problem has an a
203. on the selected English or SI units Interface penalty constant PENINF A large positive number used to penalize the penetration velocity of a node through a master surface The default value is adequate for most simulations It should be at least two to three orders higher than the volume penalty constant PENVOL Mechanical to heat conversion UNTE2H A constant coefficient to relate units of heat energy e g BTU to mechanical energy e g klb in Appropriate constant values are automatically set for English and SI units Time integration factor TINTGF The time integration factor is the forward integration coefficient for temperature integration over time Its value should be between 0 0 and 1 0 The value of 0 75 is adequate for most simulations 2 1 7 Advanced controls 33 Simulation Control xj Enor Tolerances Leth oK Figure 18 Simulation controls advanced window error tolerances Error tolerances Geometry error GEOERR This value is an estimate of the error between discretized objects The default value for this is sufficient Contact release method CNTERR In certain cases the present contact algorithm does not release nodes that are touching a master surface within the time step This option allows the contact condition for a slave node to be released if it moves away from the master boundary by a prescribed distance This value can be used as an alternative to the sliding error SLDERR
204. onitor Note the behavior of the process monitor is erratic on some operating systems 3 7 Stopping a simulation 129 A simulation may be stopped using the Abort buttons in the process monitor The simulation will be stopped after the current step is completed Killing a simulation process Since the Abort Stop command will only stop a simulation after the current step is completed substantial time may be required for the simulation to stop To kill a simulation immediately the process DEF_SIM EXE must be killed directly from the operating system On Windows 95 98 NT press ctrl alt delete on the keyboard to bring up the task manager Find the DEF_SIM EXE process in the process table and click on the End Process button On Unix from a terminal window type the command gt ps ef grep DEF_SIM EXE a process table will be displayed Find the process named DEF_SIM EXE and find the associated process id should be a number up to 5 digits under the column PID Use the command gt kill 9 PID where PID is the process ID number 3 8 Troubleshooting problems In order to determine why a simulation has not achieved a finished solution a bit of expertise is required in simulation of forming processes The three areas in which information can be obtained to determine why a simulation has unexpectedly stopped are the following files e Message file e Log file e Database file The message file is an iteration by iteration acc
205. ons friction and heat transfer data etc Note To replace an object geometry definition without deleting movement controls and inter object relationships it is possible to delete only the object geometry from the geometry window This is useful for changing die geometries when performing two or more deformation operations on the same workpiece When redefining an object in this manner it is extremely important to initialize and regenerate inter object boundary conditions It may also be necessary to reset the stroke definition in Movement controls to 0 2 4 2 Object name OBJNAM 71 a aes o gt Import Object Name Mworkpiece Geometry C Rigid Mosh Plastic e Material Object Type Bute Ty M Porous Movement Elasto Plastic BCC g Temperature 12150 F Property 7 Primary Die amp Advanced E Save Figure 38 Object general properties window The workpiece and each piece of tooling must be identified as a unique object and assigned a hard coded object number and name The object name is a string of up to 64 characters It is highly recommended that this be set to something meaningful ie punch die workpiece 2 4 3 Primary Die PDIE The primary die specifies the primary object for the simulation The primary object is usually assigned to the object most closely controlled by the forming machinery For example the die attached to the ram of a mechanical press would be designated as the prima
206. or every step Global all steps The same minimum and maximum value will be used for every step Global user defined The same minimum and maximum value will be used for every step which the user can define Object Limits The Object Limits allows the user to set different minimum and maximum values for different objects This is only activated for line contours User Variables User defined variables allows one to plot any user defined variable in the post processor Usage State variable plots display contour or vector plots of each of the state variables 152 Line contours display colored contour lines at each contour level Shaded contours fill the entire object geometry with color representing solution values The data ranges from a specified minimum to maximum data values The colors can be modified by selecting the Options Colors Shaded Contours option from the topline menu on the controls window Colors can be changed by double clicking on the Base contour colors color block and selecting a new color from the base pallet Scaling The minimum maximum range of contour plots can be based on Local The maximum and minimum state variable values for the current step are used This provides better resolution for a single step but will cause colors to shift over multiple steps making it difficult to track the evolution of variables Global The maximum and minimum state variable values are taken from all sel
207. or more details e Puta slight flat on the tip of any pointed punches 245 e While it is not strictly necessary it is convenient to make object 2 the punch or moving object 1 Define Press Movement for the Punch In general press speed will not influence simulation results for cold forming simulations A constant press speed of 10 in sec or 250mm sec is generally adequate Set the direction typically 90 degrees for punch on top The stroke value should generally not be changed by the user 1 Define Interobject Data 1 Inter Object Relationships The workpiece should be slave to both tools For well lubricated cold forming a friction factor of 0 08 is reasonable 2 Object Positioning Using interference with the workpiece as the reference object position both tools in contact with the workpiece For extremely small parts a smaller interference tolerance may be necessary to prevent excessive tool workpiece overlap 3 Generate Contact Boundary Conditions The default value of tolerance is adequate 2 Complete Simulation Controls 1 Define Number of Steps e For very limited deformation such as a square up use 50 steps e For average deformation such as heading use 100 steps e For problems with a large amount of deformation such as extrusion use 200 steps Save every 5 to 10 steps 1 Select the Primary Die Enter the object number for the punch generally object 2 2 Calculate the Stroke per Step Estimate th
208. ount for the structure change during the transformation and is in the form of i DBrs sbi where Bry is the fractional length change due to transformation from phase to phase J oy is transformation volume fraction rate bij is the Kronecker delta and a amp j is the transformation strain rate A positive sign in the volume change means there is a increase in volume change and a negative sign means there is a decrease in volume over the transformation 5 ui intermaterialBase Mother Phase Child Phase AUSTENITE SCr SCN EANITE Sch al Transtomation AUSTENITE SCr SCN gt MARTENSITE SCr BAINITE SCr gt AUSTENITE SCr SCN ATENSITE SCr gt AUSTENITE SCr SCN didi Kinetics Heat Volume Plasticity Transfomation Plasticity 2 1 5Xph E E 5y Coefficient Ki Constant 4780005 Figure 34 Transformation plasticity window 68 2 3 5 Transformation plasticity TRNSFP MIC As a material undergoes transformation it will plastically deform at a stress lower than the flow stress This phenomenon is known as Transformation Plasticity The change of the dimensions of a part due to transformation plasticity occur in combination with the dimension changes due to transformation induced volume change In DEFORM the equation for transformation plasticity is as follows 3 ar gkrsh Ea bssij where a Transformation plasticity strain tensor Ky Transformation pla
209. ount of the simulation It shows how close each iteration is to converging to the final solution by calculating a relative error norm between successive steps for both nodal velocities and nodal forces There is also information given on node contact being generated and also if there is a sudden stop For slightly more information on what an iteration is and why it is necessary please review the introductory section on fem simulation and the metal forming process The log file is an account of the module execution Message file messages If a simulation stops early it is recommended to check the end of the message file to see why the simulation stopped While a simulation is run under the batch mode of operation there are three places in which the end of operation may be indicated The message file is where the simulation will indicate a normal stoppage of the FEM module If there is an abnormal stoppage in simulation due to an illegal operation in the FEM module or in the mesh generation this will be indicated in either the LOG file or in the command window where DEFORM was 130 intially called This may be also accompanied by a core file which should be deleted as soon as possible since they often consume a large amount of disk space 3 8 1 Simulation aborted by user When DEFORM is installed the permission for the status file which monitors simulations running on the machine should be set using the command chmod 777 DEFORM STA I
210. pecifies the volume fraction limit of a phase in an element of an object VOLFS is only stored in the database at the beginning of a new phase 116 transformation ex Austenite gt Pearlite or Austenite gt Martensite The intent of VOLFS is to assure that the volume fraction amount transformed from Austenite gt Pearlite does not exceed the volume fraction of Austenite prior to transformation It should be noted that VOLFC is different than VOLFS in that VOLFC stores the volume fraction of the phases every step Typically the user will only be concerned with inputting volume fractions for VOLFS at the beginning of the simulation Grain size GRAIN Current this is not implemented Incubation time TICF TICF consumption of incubation time specifies the fraction of time that has occurred before the transformation has started It is calculated for diffusion type transformation as follows TICF where is the time increment and is the incubation time at temperature The variable total is temperature dependent If TICF reaches the transformation starts Volume fraction change DVOLF DVOLF specifies the change in volume fraction of all the different phases that resulted from the transformation during each time step DVOLF of each phase is initially set to zero in a simulation DVOLF is determined by for each step where f is the volume fraction of a particular phase DVOLF is used in calculating the latent heat due to transformation
211. perature a function of atom content or a function of temperature and atom content Heat capacity HEATCP The heat capacity for a given material is the measure of the change in internal energy per degree of temperature change per unit volume This value is specific heat per unit mass density The value can be a constant or a function of temperature a function of atom content or a function of temperature and atom content Emmissivity EMSVTY The emissive power E of a body is the total amount of radiation emitted by a body per unit area and time The emissivity of a body is the ratio of E E where Epis the emissive power of a perfect blackbody For a more complete description of the properties of emissivity consult any source dealing with heat transfer The value can be a constant or a function of temperature 40 Material Material List 1100 COLD 70F 20C 1 Plastic Elastic Thermal Diffusion Grain Hardness Elec Mag Advanced Fowstess S E27 2 Cosap No Model Yield function type Yon Mises a Unit Conv Hardening tule Isotropic Figure 24 Material data window plastic 2 2 4 Plastic Data For studying the plastic deformation behaviour of a given metal it is appropriate to consider uniform or homogeneous deformation conditions The yield stress of a metal under uniaxial conditions as a function of strain strain rate and temperature T can
212. platform specific file Table 1 The installation script INSTALL located on the CD ROM will install the required files on your system The platform independent file contains the manuals labs examples and other other utilities The platform specific file contains the DEFORM executables and Python HP USERS The two HP tar files are compiled for the same operating system HP UX but are for different operating system releases HP Tru64 Be te 0 opve0 OSF1_V4 0 TAR Z Alpha IBM PPC aK 7 3 2DV80_AIX_3 TAR Z 2DV80_LINUX_2 4 20 Linux x86 Red Hat 7 2 50 7 TARZ SGI MIPS IRIX64 6 5 2DV80_IRIX64_6 5 TAR Z 224 Sun Sparc Solaris 2 6 2DV80_ SUNOS _5 6 TAR Z Table 1 Files for different platforms 225 Installing DEFORM 2D The first step in the installation is to mount the installation CD ROM Mounting a CD ROM makes the files from the CD available for use in the file structure of the system On some systems SGI Sun this is accomplished automatically by an auto mount daemon On other systems this task must be performed manually In most cases administrative privileges root are required to mount a disk Note The CD must be mounted in a manner such that long filenames are available otherwise the installation script will not work properly The DEFORM 2D installation disk is created using the ISO9660 format with both Rock Ridge and Joliet extensions Mounting the CD Note With few exceptions these
213. pt DEF_ARM_CTL COM which in turn runs DEF_ARM COM When using a local copy of the FEM engine copy DEF_ARM_CTL COM toa local directory and change the alias for DEF_ARM to point to the local copy of DEF_ARM_CTL COM This alias is defined in the DEFORM_DIR CONFIG COM and a line in the cshrc after the source DEFORM_DIR CONFIG COM redefining the alias should work In the cshrc file the following modifications can be made 210 setenv DEFORM_DIR disk1 deform 2d v60 source DEFORM_DIR CONFIG COM Old alias alias DEF_ARM DEFORM_DIR COM DEF_ARM_CTL COM New alias which is a local copy of DEF_ARM_CTL COM alias DEF_ARM HOME DEF_ARM_CTL COM Also in the local copy of DEF_ARM_CTL COM the following calls should be replaced DEFORM_DIR COM DEF_ARM COM with the local version of HOME DEF_ARM COM After this has been done simulations can be run using the local copy of the FEM engine and jobs can be started using the user interface One problem that can occur is that if the cshrc has an exit for non interactive shells and the new definitions are after this then they will never be defined when running a simulation Place the new command to run the local copy of DEF_ARM just after the definitions for the regular version of DEFORM Running the modified FEM engine for Windows platforms If the FEM engine has been built for Windows the only way in which to utilize it is to swap it with the current engine The current engine with be
214. r defined boundary conditions are only supported for the case where there is no contact and the edge is free The inputs to the routine are seen below which allow the user to make use of various quantities including nodal temperature and user defined node variables If any quantity is not provided in this group the user can always compute it in user defined nodal variables and import it into this subroutine Input NODE1 NODE2 edge node number IELEM element number of current edge NBCD 2 2 boundary condition code NDIE contact condition 0 non contact n contact to n object 206 RZ 2 2 coordinate of nodes DRZ 2 2 displacement of nodes USRNOD NUSRN I user defined node variables node number user node1 and node2 to get the values NUSRN number of user defined node variables ENVTEM environmental temperature or film temperature TEMO 2 previous step temperature TEMC 2 current step temperature CURTIM current time As in the other user defined routines the user can write an arbitrary number of subroutines so long as the subroutines are defined and the call statements are defined In each boundary condition window in DEFOR M the user can define a function number which allows the user to use a special subroutine for any type of boundary condition the only exception is in the case where contact would exist For example if the user would want to write a routine to define the heat flux over a certain portion of
215. r by entering table data Workpiece geometry requirements e The x 0 line is the centerline of the part If the part is solid it must be located on the centerline If it is hollow the left edge of the part should be positioned at the internal radius e Geometry must be defined counterclockwise e Always check the geometry 1 Mesh the Object Typical progressions should use 1000 to 1500 elements When in doubt more elements will tend to give more accurate results Typical weights e Curvature_0 9 e Strain Rate_0 7 e Strain 0 5 e Temp_0 1 Define Boundary Conditions For solid parts define the velocity in the X direction along the centerline to be 0 No velocity boundary condition is required for hollow parts 1 Define the Tools 1 Assign Tool Names optional For reference during pre and post processing 2 Define Tool Geometry Import or define geometry for the punch and die The geometry rules detailed above for the workpiece all apply Furthermore e For multi piece tools draw a single tool boundary defining all inserts knockouts etc The geometry can be separated later for die stress analysis Refer to the manual or contact tech support if there is more than one moving tool for a given station e Extend the tool geometry slightly across the centerline e For tools with a sliding clearance between the punch and die increase the OD of the punch to slightly intersect the die Refer to the manual or training material f
216. r the users HOME directory must have these definitions If etc cshrc has the definitions then it may not work An example of a cshrc file taken from an HP is given below with the incorrect definition of the DEFORM environment variables Default user cshrc file bin csh initialization Usage Copy this file to a user s home directory and edit it to customize it to taste It is run by csh each time it starts up Set up default command search path For security this default is a minimal set set path usr local bin usr local lib skip remaining setup if not an interactive shell if USER 0 prompt 0 exit set history 100 set ignoreeof set prompt hostname whoami cwd date not in correct place setenv DEFORM_DIR disk1 deform 2d v60 233 source DEFORM_DIR CONFIG COM In the above file the DEFORM_DIR variable is set for all interactive shells but there is an exit command before the variables can be set if the shell is a non interactive shell This will cause the problems with the mesh generator and simulation engine To avoid this problem move the statements above the if exit statement For security this default is a minimal set set path usr local bin usr local lib new place for the DEFORM_DIR setenv DEFORM_DIR disk1 deform 2d v60 source DEFORM_DIR CONFIG COM skip remaining setup if not an interacti
217. ration Return to the preprocessor and load the last step from the database 5 Set Simulation Controls 252 1 Operation Name optional 2 Select Simulation Mode We will now simulate the forging operation so turn deformation on yes 6 Define Material Data for Workpiece Assign plastic flow data for the workpiece material Be sure the material selected covers the proper temperature range including any deformation heating and die chilling 7 Assign Top Die punch Movement Press behavior may play a role in results Consult the manual or SFTC tech support for more information on press behavior Set the direction typically 90 degrees The stroke value should not be changed unless a mechanical press model is used 8 Define Interobject Data 1 Inter Object Relationships Assign a friction factors For lubricated hot forging values of 0 2 to 0 3 are typical For non lubricated hot forging values of 0 8 to 1 0 are typical 2 Object Positioning Using interference with the workpiece as the reference object position both tools in contact with the workpiece 3 Generate Contact Boundary Conditions The default value of tolerance is generally adequate 9 Complete Simulation Controls 1 Define the Number of Steps For very limited deformation such as a square up or buster use 50 steps For average deformation such as heading use 100 steps For problems with a large amount of deformation such as extrusion 200 or more
218. rd keywords to define simulation controls time stepping stopping controls etc An important function of action keywords is to trigger the input of other keyword files which can include geometry definition boundary conditions etc Sample contents of the DEF_COMMANDS KEY file Contents of an actual file will be defined by the user 258 KFREAD DEFAULT KEY CURSIM 1 SIMNAM Solution DTMAX 0 001 DTPMAX 10 0 01 100 STPINC 10 KFREAD DEF_MESH KEY KFREAD DEF _EDGE_BCF KEY NDTMP 1 0 70 0 TMAX 10800 ENVTMP 2130 KFREAD AIR_BC KEY USRSUB 1 1 GENDB 2 DEFORM DEMO DB This file Reads DEFAULT KEY which contains default problem settings Sets the operation number to 1 Sets temperature substepping and save increment Reads DEF_MESH KEY Reads DEF_EDGE_BCF KEY which contains boundary condition definitions Sets the temperature of all nodes to 70 degrees Sets simulation time Sets environment temperature Loads AlIR_BC KEY which contains convection coefficients for air Defines a user subroutine to be used Generates a database called DEFORM_DEMO DB Running a Simulation A simulation can be executed by running it directly from the command line calling the DEF_ARM_CTL COM simulation control script The inputs are DEF_ARM_CTL COM problem_id B 259 Where problem_id is the database file name with the DB extension stripped In the case above we would run the simulation for DEF_DEMO DB with the line F DEFORM2D 7_2 DEF
219. re for setting any boundary condition except Contact is the same 1 Select the appropriate condition type 2 Select the direction where applicable 3 Select the nodes to which boundary conditions will be applied 4 Apply the boundary conditions The selected nodes will be highlighted To apply the boundary conditions click the Generate BCC s button Colored markers will highlight the nodes to which boundary conditions have been applied To delete specific boundary conditions select the start and end nodes and click the Delete BCC s button To delete all boundary conditions of the specified type and direction click the Initialize BCC s button Plane Select a node on a plane All nodes on that plane will be selected Surface Patches Click the surface patches icon Surfaces will be extracted based on a 30 angle between adjacent element faces Selecting any node within a given patch will select all nodes on that patch Regions Points defining a closed freeform region are defined Any nodes within the region will be selected This feature should be used with caution because it is relatively easy to inadvertently select unintended nodes To apply the boundary conditions click the Generate BCC s button Colored markers will highlight the edges to which boundary conditions have been applied To delete specific boundary conditions select the start and end nodes and click the Delete BCC s button To delete all boundary conditions of
220. re weighting will apply a higher mesh density to curves on the objects boundary If MGWCUV is greater than 0 the boundary area with curves will receive a higher mesh density in that area If MGWCUV is set to 0 this weighting criterion is ignored The values from all the mesh density keywords are combined during the mesh generation process to create a mesh density distribution within the geometric boundary Strain base weighting factor MGWSTN 83 To keep a fine mesh in areas of high strain this weight can be adjusted Strain rate based weighting factor MGWSTR If there are areas on the deforming object which see high strain rates and localized deformation then using this weight will put a fine mesh in areas where there is a high strain rate gradient Temperature based weighting factor MGWTMP This weight can be used to specify fine elements in areas of high temperature gradients User defined windows weighting factor MGWUSR The user defined windows weight is used in conjunction with Mesh Density Windows User defined distribution weighting will apply a higher mesh density to areas with a specified density window If this parameter is set to 0 the mesh windows are ignored during automatic remeshing Note When an object is deformed the user defined mesh window will move according to the velocity component assigned to that window This window will carry the mesh density weight with it throughout the simulation User defined me
221. reases The flow stress data must have a reasonable description for the initial yield stress particularly in the case of low deformation simulations such as heat treatment This is where the elastic part of the stress strain curve intersects with the plastic part of the curve If the flow stress data is only defined for high strain values DEFORM will extrapolate the yield stress and this value may not be close to the actual yield stress Thus valid results are unlikely and convergence difficulties are possible Thus having some flow stress data at low effective plastic strain values may aid convergence See Figure 118 for an example of extrapolation of the initial yield stress In order to provide guidance to users who are not familiar with modeling elasto plastic materials we offer the following suggestions a When using the function form y Ce e yO it is accurate for yO to be equal to the initial yield stress If yO 0 the initial yield stress will be poorly represented b When using a table form the program will extrapolate interpolate the flow stress and use that as the initial yield stress If extrapolation is expected be sure 212 that the slope of the flow stress in the small strain region is reasonable i e extrapolated value should be the same as the initial yield stress Some modifications may be needed in the small strain region like adding one more point to correct the slope These modifications should be made
222. rement the boundary number in the geometry window and select the second boundary See Figure 125 5 Set the geometry type to Arc and set the curve as follows 0 5 0 for the first point 0 0 for the second point and 360 as the angle At this point a mesh can be generated which will have a hole in the middle See Figure 126 Note The exterior boundary was counter clockwise while the interior boundary was clockwise 281 Figure 125 Incrementing the boundary number and selecting the second boundary 282 Figure 126 A circular result with a hole 283 Appendix L Launching the Simulation Engine from a Command Prompt Windows only Purpose Sometimes a new engine is given to a user for a special application that is not covered in a release version The user can use this document to see how to run the engine without having to overwrite the current engine Step 1 Place the new engine in the installation directory of DEFORM 2D being careful not to overwrite the current engine When receiving the engine it must be located in the directory where DEFORM 2D is installed The current engine named will be named DEF_SIM EXE so be sure not to copy the new executable with that name to the install directory of DEFORM 2D Step 2 Rename a current database to the name FOROO3 in the necessary problem directory This is the name of the database while a simulation is running After the simulation is completed be sure to rename
223. rent types of User Routines will be outlined below as to their purpose and how they are implemented Later in this chapter each one of these routines is explained in greater detail on how to implement each subroutine To implement the user routines you must have a FORTRAN compiler installed on your system or you must use the DEFORM Support website Windows only Note The manner in which the User Routines are compiled and linked is slightly different between Windows and UNIX Linux platforms These differences are outlined in detail later in this chapter User Defined FEM Routines User Defined FEM Routines are FORTRAN subroutines in which the user can change internal routines within the DEFORM FEM engine to achieve very specialized functions within DEFORM These subroutines can then be compiled and linked to provided object code to generate a custom built FEM engine All the available subroutines are contained in a file named DEF_USR FOR UNIX or def_usr f Windows This file is a text format file containing all the available FORTRAN subroutines To compile this file run the script file DEF_INS COM 189 Unix or follow the instructions below Windows At this point the FORTRAN file will be compiled and liked to the object code named DEF_SIM OBJ UNIX and DEF_SIM_LIB lib Windows This will then generate a new FEM engine named DEF_SIM EXE In the case of UNIX platforms this whole process is shown in Figure 107 Currently user routines e
224. required routine should have the routine compiled and the simulation should run the special FEM engine e There is either a non zero stress state on the part relaxation case or an applied traction to the body creep e Constrain the workpiece with velocity boundary conditions alone as the penalty method of contact can give some numerical error in the stress solution for creep cases Simple example To test the functionality of the creep model a simple case can be constructed by running the UPSET KEY in the DATA directory A few changes are required to get this simulation to run better 277 e Change the object type to elasto plastic e Change the total displacement to a small distance of 0 04 mm e Change the material law to something simple For example a simple case of linear hardening model gives very easy to hand verify stress values in the workpiece In this case the equation o 2000e 10 was used See Figure 121 Figure 121 Flow stress data for example case e Make the friction between the tools and workpiece zero This will yield a uniaxial stress condition 278 Figure 122 UPSET KEY object view After the simulation is finished a stress relaxation simulation can be performed The following changes need to be made to the last step simulation Add more steps to the simulation Increase the time step size Delete the rigid objects Add fixed velocity boundary conditio
225. ress Simulation for an example of a simulation using the hydraulic press model Mechanical press The Mechanical Press type replicates the cyclic motion of a mechanical press The Mechanical Press option simulates the motion of objects driven by a mechanical press The DEFORM parameters required to simulate the motion are the total displacement of the press Dtot relative to the current displacement Dcur and the number of strokes per unit of time S Using these parameters DEFORM can compute the die speed at any point Motion of which is controlled by mechanical press parameters can only be applied in the X Y X or Y directions 106 General O Equipment Direction Geomety C Hammer x CX E C Screw press cy Cy Mesh Mechanicalpress Other Arct p ze aran TET O E ra Ez iaitu O w Movement 2 n Library H Strokes fo fsec g Load BCC Connecting rod length 0 i a Sai BS save Property Current Die Stroke Speed Limit amp i Define Advanced Venne Figure 51 Mechanical press definition The equation to derive the die speed is The parameters required to specify the movement of a mechanical press are 1 Displacement The Displacement for the mechanical press represents the total stroke of the press per cycle In English units this is inch per cycle in SI units this is mm per cycle 2 Strokes per time The Strokes per time represents the frequency of the press blows This is a measure of blows per second or
226. ria defines how the nodes at the inter object interface will behave when acted upon by a tensile force Three ways of defining the separation criteria exist They are 1 Default This setting will cause normal separation when the contacting node experiences a tensile force or pressure greater than 0 1 2 Flow stress This setting will cause nodal separation when the tension on the contact node is greater than a given percentage of flow stress of the slave object This percentage must be input by the user in the Separation Criteria box 3 Absolute pressure This setting will cause nodal separation when the tension experienced by the node is greater than the input pressure This pressure must be indicated in the box marked separation criteria Separation Density SEPDEN Separation density is used to model the behavior of porous objects that have not been fully compacted It defines the separation criterion of contacting nodes involving porous objects Unless the density of the material is greater than density nodal separation is not considered Relative rotation FRCROT Relative Rotation is used in axisymmetric simulations only This specifies the rotation difference between two objects about the axis of symmetry The units are radians second For example if a top die is rotating while moving downward the interface between the top die and the billet should have the same angular speed rad sec of the top die applied to it This enables
227. riable is fetched from our USRDEF fields the initial height of the billet READ IUSRVL 1 HI The die displacement can be computed by the following equation S D D The stroke is computed by the following code STRK STRKX STRKX STRKY STRKY STRK DSQRT STRK Example Case 2 In the case of a screwpress the rotational energy is converted to translational motion to form a part The process ends when the energy stored in the flywheel runs out or when the clutch on the drive mechanism is disengaged Each step the amount of energy may change due to energy being consumed by deforming the workpiece The total energy is an intial condition and the change in the current energy needs to be computed each step by E E AE where Eo Energy after previous step E Energy at current step 199 200 AE Change in energy over previous step The change in energy can simply be calculated by the following equation _ Fid n AE where AE Change in energy over previous step F Die force over previous step d Distance traveled over previous step n The efficiency of the process Based on the current energy the translational speed of the die can first be computed by calculating the rotational speed of the flywheel 2E I w where Rotational speed of the flywheel Eo Energy of current step Moment of inertia Using the rotational speed the translational speed can be simply determi
228. rmation states The flownet window allows the user to apply a pattern to an object and observe how the pattern deforms as the simulation progresses As the mesh deforms so does the pattern Howevere unlike the FEM mesh the pattern remains intact throughout the remeshings Thus the flownet is much like physically etching a pattern on a cross section of a workpiece and having the ability to view the workpiece at various stages of the forming process The start step list will contain all of the steps currently inthe display window Select the starting step for defining the flow net and then select the object if you want to have the flow net In order to generate a pattern for the given object click on the flownet patterns A pattern can be tracked backwards by selecting a later step in the database as the starting step then selecting an earlier step as the ending step Rectangular Grid The rectangular grid option will generate a grid composed of perpendicular lines within the desired region Rectangular patterns are typically used when the material texture is of interest This pattern is very similar to the grain flow which would be seen if a cross section of the part were etched If a rectangular pattern 160 is selected you must specify the grid origin orientation angle and line spacing in X and Y The grid can be controlled by the following parameters Origin This is the origin in X Y coordinates at which the grid will begin to be gen
229. ry condition where the environmental atom content the reaction rate coefficient and the atom flux needs to be specified the edge All three of these variables may be defined as either constants or functions To apply a local user defined boundary condition set the variables you want set the local defined number to a unique value and apply this to a set of element edges The keywords for this are ECCATM ECAFLX and LOCATM 2 4 10 Contact boundary conditions Contact boundary conditions are applied to nodes of a slave object and specify contact between those nodes and the surface of a master object see master slave relationships under the Interobject data section If a node is specified to be 101 in contact with a particular object it will placed on the surface of that object If this requires changing the position of that node it will be changed as necessary Contact boundary conditions are generated under the Interobject Contact relation CNTACT section Contact boundary conditions can be displayed for a given object using the Objects Boundary Conditions Advanced Deformation BCC s icon 2 4 11 Object movement controls Movement controls can be applied to rigid objects and boundary nodes of meshed objects The surface defined by these nodes can be thought of as a rigid surface During the simulation the constrained nodes will move synchronously in the speed and direction defined by the movement controls Translational Movement
230. ry die Characteristics of the primary die can be used to control various aspects of a simulation including 1 Simulation time step size DSMAX 2 Object movement MOVCTL 3 Simulation stopping criteria SMAX VMIN LMAX The primary die is defined as a checkbox as seen in Figure 38 This selection is valid for only one object in a simulation 72 2 4 4 Object type OBJTYP The object type defines if and how deformation is modeled for each individual object in a DEFORM problem Rigid Rigid objects are modeled as non deformable materials In the deformation analysis the object geometry is represented by a geometric profile DIEGEO Deformation solution data available for rigid objects include object stroke load and velocity The geometric profile is used for all deformation analysis and the mesh for the rigid object is used for all thermal transformation and diffusion calculations applications When used for the modeling of tooling the rigid definition increases simulation speed over elastic tooling by reducing the number of deformable objects and hence the number of equations which must be solved Negligible loss of accuracy for typical simulations except in cases where tool deflection is significant limitations Stress and deflection data for the dies is not available during deformation This data can be obtained at selected single steps by performing a single step die stress analysis Elastic An elastic mat
231. s data points Linear interpolation in log log space This method takes a linear weighted average between tabular flow stress values in log log space If the user inputs a value at zero strain a linear average between the flow stress value at the zero strain value and the flow stress value at the next highest strain value is linearly interpolated Using this method the initial yield stress can be defined at a plastic strain of zero The flow stress values are always interpolated linearly with respect to temperature Warning If simulation conditions of the material exceeds the bounds of the 42 strain strain rate or temperature defined in the tabular data the program will extrapolate based on the last two data points which may lead to loss of accuracy Flow stress for alumnium alloys Type 1 A sinh aa e F Plate where A Constant a Flow stress n Strain rate exponent AH Activity Energy R Gas constant Tabs Absolute temperature Flow stress E Effective strain rate Flow stress for alumnium alloys Type 2 Age SH FT ate where A Constant n Strain rate exponent AH Activity energy R Gas constant Tabs Absolute temperature Flow stress Effective strain rate Linear hardening o Y T A H T A 43 where A Atom content T Temperature Effective plastic strain Flow stress Y Initial yield stress H Strain hardening constant User defin
232. s can transform to another phase So any material group that can transform to another phase should be categorized as a phase material The mixture material is the set of all phases for an alloy system and an object can be assigned this mixture material if 37 volume fraction data is calculated 2 2 2 Elastic data Elastic data is required for the deformation analysis of elastic and elasto plastic materials The three variables used to describe the properties for elastic deformation are Young s modulus Poisson s Ratio and thermal expansion 5 Material Material List 1100 COLD 70F 20C 1 Plastic Elastic Thermal Diffusion Grain Hardness Elec Mag Advanced Youngs Modus Constant foo PoitsorisRaio Comat zis Thermal Expansion ee r Figure 22 Material data window elastic Young s modulus YOUNG Young s Modulus is used for elastic materials and elastic plastic materials below the yield point It can be defined as a constant or as a function of temperature density for powder metals dominant atom content for example carbon content or a function of temperature and atom content Poisson s ratio POISON Poisson s Ratio is the ratio between axial and transverse strains It is required for elastic and elasto plastic materials It can be defined as a constant or as a function of temperature density for powder metals dominant atom content for example carbon content or a function
233. s the mesh generation dialog After meshing when exiting interpolation of state variables and boundary conditions is carried out Meshing objects with multiple boundaries The most difficult feat in meshing an object with multiple boundaries is to correctly define the geometry The user should carefully refer to the previous section on defining multiple boundaries It is imperative that these recommendations be followed very carefully to successfully mesh an object with multiple boundaries Once this geometry is correctly defined meshing the object is performed in the same manner in which a solid object would be performed One point to be careful of is that if the object is very thin with respect to the characteristic size the user should be careful to specify a large number of elements and possibly boost the grid resolution in the advanced meshing parameters MGGRID 2 4 6 Object material Any object which has a mesh defined must also have a material assigned to it The material data can be defined in the Materials data section of the pre processor Assignment is made through the Object Material dialog Either phase or mixture materials may be assigned to each object In general phase materials which are not components of an alloy system will be assigned individually An alloy system mixture will be assigned to the appropriate objects as a mixture and relative volume fractions of the constituent phases should be assigned under element data
234. s velocity if necessary 11 If stopping criteria has been reached END otherwise go to step 3 and repeat the process This concludes this short summary of the FEM process in metalforming For more information on FEM theory please consider reading the following list of references 1 Kobayashi S Oh S I and Altan T Metalforming and the Finite Element Method Oxford University Press 1989 2 Przemieniecki J S Theory of Matrix Structural Analysis Dover Publications 1968 3 Zienkiewicz O C and Taylor R L The Finite Element Method McGraw Hill 1989 188 Chapter 6 User Routines This chapter explains the various user routines available in the DEFORM system in the FEM Finite Element Method engine and the post processor Examples on how to use each type of routine how to compile the code and how to run the modified FEM engine and post processor are also covered Prerequisites The user should have at least a rudimentary understanding of the FORTRAN language This section is not meant to be an introduction into the FORTRAN language rather it is meant to explain how to build the user routines and how to implement them within DEFORM For more information on the FORTRAN language please refer to many books or the documentation that was included with your compiler Overview There are two different types of user routines available e User Defined FEM Routines e User Defined Post Processing Routines The two diffe
235. se the system and how to run different types of simulations The labs for DEFORM 2D DEFORM HT are provided as PDF Portable document format documents which can be viewed using Adobe Acrobat provided with DEFORM All keywords which are used in DEFORM 2D are documented in the keyword reference manuals which is also provided as a PDF document All documents can be accessed from the help menus in the main program pre processor and post processor Overview of DEFORM presents an overview of the DEFORM family of products Analyzing manufacturing processes with DEFORM describes how to use DEFORM products to analysize manufacturing processes The DEFORM system introduces the DEFORM 2D system and describes the components that make up the system Simulation Controls describes the options to control the numerical behavior of the system Material Data describes the different material parameters that are required for simulations Inter Material Data describes inter material data which can be used to describe phase transformation related effects in the heat treatment system Object Definition describes the definition of objects loading geometry generating meshes setting boundary conditions etc Inter Object Definition describes how relations betwen objects are to be set the interface fiction and interface heat transfer coefficients Database Generation describes database generation and the errors and warnings during database
236. section is to explain the pitfalls that can occur while trying to simulate force loaded dies in terms of obtaining good results and improving convergence of the solution Theory In reality there is no such thing as an ideal step function It takes time no matter how small for things to change If a sudden load is applied there must be a time span over which things occur as a ramp function In the case of applying a load to a deformable object there are generally two ways in which a body may respond to a given amount of force The body may increase its reaction load by strain hardening or increase its reaction load by strain rate hardening In the case of a high load the final deformed shape may be quite different than the initial shape The problem with a step function is that over one step the body may have to deform much to achieve equilibrium with the applied load Also with two different possible ways in which to react can place much pressure on the simulation engine Solution As implied with the above statement on step functions if there are no step functions then the solution must be to use ramp functions This is the key to getting all of these simulations using force control to converge nicely The time step size may be very small ideally it should be realistic to the process but as long as the deformation is spread over an ample number of steps a good solution will result 286 Appendix N Compiling User Routines on the
237. sh density When a user defined mesh density is selected the density values are set through the Display Window By selecting a user defined mesh density the relative mesh density definition button becomes active After clicking this button the user will see the Display Window through which the mesh densities can be set The density value is used to specify a weight to be given to an area Note that the actual number only has meaning in relation to another density point For example a point with a weighting of 4 will have a mesh that is two times as dense as a point with a weighting of 2 One can also choose between setting the density values as boundary or interior points If a mistake is made Delete will delete the current point shown in red and Delete All will delete all density values set Note For more detailed instructions see DEFORM tutorial Lab 6 Mesh Generation for Dies in SPIKE Boundary density The boundary density specification is used to place a density value on the boundary of an object Enter the desired density in the Density box in the Display window Now select the Add Points button and click on the object s boundary A green point should now appear with the density value shown next to it To delete a value select the Delete Points button and click on the point you wish to delete 84 Internal density The internal density specification is used to set a density value for the mesh inside the object s boundary Just cl
238. sing interference 5 Generate Contact Initialize and generate contact boundary conditions 6 Reset Simulation Controls Determine total steps and stroke per step as described above 7 Reset Stopping Stroke If the stroke stopping control was used reset the stroke to zero on object movement controls and reset the stopping control under simulation controls 8 Write The Database Writing an old database will append data to the end of the existing 247 database It will overwrite any steps after the step that was loaded 9 If the appropriate ending step is not saved If you encounter a situation where say step 90 is not formed enough step 100 is formed too much and there are no steps saved in between you can load step 90 change the save interval to 1 save every step then rerun the last 10 steps of the simulation to get the proper stopping step 248 7 2 Hot Forming When simulating hot forming it is important to simulate all steps of the process including transfer from the furnace and resting on the die since the temperature loss due to transfer from the furnace and from die chilling can influence flow behavior The procedure for simulating a multi station process is detailed at the end of this section This section will outline the setup procedure for the following operations 1 Set uniform object temperature to simulate full furnace soak 2 Cool in air to simulate transfer from the furnace to the dies
239. ssociated problem ID and should be created in its own folder or directory For every problem the DEFORM system creates four types of files that are generally accessible to users Database DB files The database file contains the complete simulation data set for input data and each saved simulation step The information is stored in a compressed machine readable format and is accessible only through the DEFORM pre and post processors As the simulation runs data for each step is written to the end of the database file If the step being written is specified as a step to be saved information for the next step will be appended after the current data step If the step is not specified to be saved and a solution is found for the next step the data for the current step will be overwritten by the data for the next step Keyword KEY files Keyword files contain specific problem definition data which is read by the pre processor and used to create an input database file A keyword file may contain a complete problem definition or it may contain only specific information about for example a specific object or material The information is stored in ASCII format and can be read and edited with any text editor such as Notepad vi or emacs A keyword reference is available which describes the data format for each keyword 1 10 Running the simulation Simulation engine The simulation engine is the program which actually performs the numeric
240. steps must be performed as root The devices and mount points used in the examples may vary from system to system Consult a System Administrator for details about a specific system If the directory where the CD is to be mounted does not exists create it A typical mount point for a CD is cdrom This directory can be created using the command mkdir cdrom The CD directory will be referred to as cdrom in this installation procedure If it is different substitute the site dependent directory name Load the release CD ROM in the CD ROM drive and mount the CD ROM using the following commands to use this you must be logged in as root Platform Specific Mounting Instructions Compag TRU64 mount r dev device cdrom or mount t cdfs dev device cdrom as needed to mount the CD with long filename support To properly mount a DEFORM CD on HP UX the following procedure must be followed This is a summary of instructions detailed at http www faqs org faqs hp hpux faq Section 5 3 8 Create or alter etc pfs_fstab to include a line as follows dev dsk cOt0d0 CDROM pfs rrip xlat rrip 0 0 Where dev dsk cOt0d0 is the device and CDROM is an existing directory where you will be mounting the device Start the pfs daemons with the following commands nohup pfs_mountd amp nohup pfsd 4 amp Mount the drive pfs_mount dev dsk cOt0d0 CDROM Note You must use pfs_umount to unmount a disk mounted with pfs_mount 226
241. sticity coefficient from phase to phase J i Volume fraction rate h z 2 1 z sj Deviatoric stress tensor The only data that the user needs to provide for this relationship is the transformation plasticity coefficient The other terms are automatically calculated by DEFORM The transformation plasticity coefficient may be a function of temperature A general range for Ky for steel is given below e austenite ferrite pearlite or bainite 4 13 10 MPa e austenite martensite 5 21 10 MPa e ferrite amp pearlite austenite 6 21 10 MPa 2 4 Object Definition The objects window contains all the object specific data such as the geomtery the mesh boundary conditions movement and inital conditions for all the objects in a simulation 69 70 Figure 35 Preprocessor with the object list with a red box mee a a Figure 36 Preprocessor with the object properties window with a red box 2 4 1 Adding deleting objects Total object s 3 alg Be 48 2 Figure 37 Insert and Delete object buttons with a red rectangle To add an object to the list of objects click on the Add Object button This will insert a new object into the first available object number To delete an object select the appropriate object and press the Delete Object button This will delete all entries associated with the object including movement controls inter object boundary conditi
242. structure of the matrix equation being solved It should be used for multiple deforming body problems Convergence error limits CVGERR A deformation iteration is assumed to have converged when the velocity and force error limits have been satisfied The error norm values for each iteration step are displayed in the message file If the message file shows that the force and velocity error norms are getting small but not dropping below the error limits the simulation may be continued by increasing the error limits to the smallest value in the message file This will decrease the solution accuracy so the simulation should be allowed to run a few steps then the values should be reduced again For die stress or press load calculations where extremely accurate force or load values are required the load accuracy may be improved by decreasing the force error limit This will increase simulation time but give more accurate results Note It should be remembered that the accuracy of the flow stress data will have more impact on the accuracy of die stress and press load predictions Maximum number of iterations ITRMXD ITRMXT When Newton Raphson iteration is being used the specified number of iterations will be performed for each iteration segment until the solution has converged At most 30 iterations will be performed during a Newton Raphson segment If the solution does not converge in the specified number of iterations the simulation wi
243. style isothermal non isothermal heat transfer is read and the corresponding TRANS mode switches are set in the pre processor x General Advanced Advanced2 x Starting Step Number Poo y Cancel Primary Die TOP_DIE Solution Steps Definition With Equal Die Displacement fo o02 In With Equal Time Increment p Sec Figure 10 Simulation step controls window 2 1 2 Step controls The DEFORM system solves time dependent non linear problems by generating 22 a series of FEM solutions at discrete time increments At each time increment the velocities temperatures and other key variables of each node in the finite element mesh are determined based on boundary conditions and thermomechanical properties of the workpiece materials Other state variables are derived from these key values and updated for each time increment The length of this time step and number of steps simulated are determined based on the information specified in the step controls menu Starting step number NSTART If a new database is written the specified step number will be the first step in the database If data is written to an existing database the preprocessor data will be appended to this database in proper numerical order and any steps after the one specified will be overwritten The negative n flag on the step number indicates that the step was written to the database by the pre processor not by the
244. surface Pressure BCC The pressure boundary conditions specifies a uniform or linearly varying force per unit area on the element faces connecting the specified edges In version 7 0 and above only normal pressure is supported If a tangential component of pressure is required the user is recommended to use force boundary conditions Two values for the normal pressure are required the first value is the beginning value of pressure from the beginning point where pressure is set the second value is the value at the end of where the pressure is specified The pressure is linearly interpolated between the start and the end The keywords that replace the old definition of pressure are ECCDEF and ECPRES Displacement and shrink fit BCC A specified displacement can be specified in any direction for each node This is frequently used for specifying shrink fit conditions between a die insert and a shrink ring More information on this is available in the section on die stress analysis in this manual Movement BCC The movement of specific nodes on an object can be specified If the movement boundary condition is specified object movement controls must also be specified Advanced deformation BCC The Advanced boundary condition displays interobject boundary contact conditions on a given object This is the same information displayed in the Inter Object BCC s window There is no physical significance to the x y or z components of contact Rath
245. t could result in reduced accuracy of load calculations e If the simulation is being run with principal die movement under load or energy control run a couple of steps under speed control to allow the solution to stabilize before continuing under the original mode e Increase your limiting strain rate to 1 50 or 1 100 of the average strain rate This should not cause any significant effect on solution accuracy If you have an extremely difficult case to converge this value may be 133 134 lowered to 1 10 of the average strain rate for a few steps then reset to a more normal value Over the years we have recommended that the limiting strain rate should be 1 100 to 1 1000 of the average strain rate If this value is set too low it will result in an artificially lower load calculation Check your material data versus your process conditions to insure that no strange material properties are being passed to the FEM engine Be particularly aware of extrapolation issues For example if your process conditions are in an area that is outside of the defined flow stress region this reverse strain rate sensitivity create a problem that is almost impossible to allow DEFORM to converge on an accurate solution This may be handled by re evaluating your raw data and adjusting it as required Since it is highly unlikely that a material has a lower flow stress at a higher strain rate the common cause for this type of data is the lack of an adiabati
246. t is a very classical method for describing steady state or secondary creep Baily Norton s model Kma t Qa 46 where g Effective stress Tabs Absolute temperature K n m Q r Constants BD tuicity S Flow stress Effective strain rate This model is known as Baily Norton s model The user should make sure that K and Q are in the proper units so that the strain rate is defined as second The nodal temperature will be converted to absolute temperature inside the FEM engine Soderburg s model where g Effective stress Tabs Absolute temperature K n C Constants Effective strain rate Tabular data This method is not currently available for this release User Routines Please refer to User Routines for a description of how to implement user defined creep routines 2 2 5 Diffusion data 47 Add Dette Remove Tiara aS J Save in lib Plastic Elastic Thermal Diffusion Grain Hardness Elec Mag Advanced Figure 27 Material properties window diffusion DEFORM allows the user to model the diffusion of the dominant atom at this point carbon in an object The user only needs to specify the diffusion coefficient for the diffusion For the simulation of carburizing process normally performed before quenching the Laplace equation is used for the diffusion model oC _ Dx Ot Ox Ox where C is the carbon content and D is the diffusion coefficient Diff
247. t properly then the message SIMULATION ABORTED BY USER will appear when trying to run a simulation If the status file is corrupted for any reason a new status file can be generated using the INSTALL2D script 1 Go to the DEFORM 2D directory cd usr deform 2d v80 2 Run the script INSTALL2D and select the option 1 to create a new status file INSTALL2D Invalid program copy In order to run DEFORM on your computer a valid password file for the computer is required This file ensures that DEFORM will work only on a single computer between the dates in the license agreement If DEFORM is installed on a computer for which a valid password is not present then DEFORM will not work The license file is stored in the DEFORM_DIR directory in the file DEFORM IDF This file is created when the system is installed or when a new password is entered The file has the company name and also one line for each product that is licensed Possible reasons for getting an INVALID PROGRAM COPY message The license has expired The version of DEFORM that is installed is different from the one that is licensed e The computer on which DEFORM is installed is different from the one that DEFORM is licensed on The environment variable DEFORM_DIR does not point to the proper directory DEFORM IDF exists but there is invalid data in this file e When copying this file from a PC the Ctrl M characters were appended at the end of each line S
248. t rather than on a node or an element such as a pressure This is one such case where the definition is edge based The data for this information is available in the object edges window 170 Figure 85 Object edges window 4 5 12 Viewport The viewport options can all be changed from within the Viewport Options window These options will only be applied to the current Viewport in the Display Window Many different options are available through this window 171 Figure 86 Viewport options window 4 5 13 Data Extraction 172 i2 TOPDIE RIGID 7 3 BOT_DIE AIGID 6 amp Figure 87 Data extraction window Data Type Information can be written out in a keyword format to an output file The following items listed below can be extracted Simulation Controls Object Data User Defined Variables Material properties Inter Object Data Furthermore specific keywords from object data can be selected as well as the objects that the data is to be extracted for Output The information can be extracted to the terminal of a file 173 Steps Single steps or all of the steps can be selected To select a specific step highlight the step in the step scroll down menu towards the right side of the screen If 5 or 6 steps are desired and every step in the database is not desired Go to the steps option in the Post processor select the steps desired Go back into the data extraction window and select all for steps Files T
249. t window allows the user to apply a pattern to an object and observe how the pattern deforms as the simulation progresses As the mesh deforms so does the pattern however unlike the FEM mesh the pattern remains intact throughout the remeshings Thus the flownet is much like physically etching a pattern on a cross section of a workpiece and having the ability to view the workpiece at various stages of the formation process The start step list will contain all of the steps in the display window currently loaded by default Select the starting step for defining the flow net and then select the object you want to have the flow net In order to generate a pattern for the given object click on the flownet patterns It should be noted that flownet patterns can be generated for plastic and porous objects How to define Pattern Generation x Statin Eng Ste Sa is Feil Ce tan 0000 ooo 1 naig oe oe will be tracked F Ending step P Figure 72 Flow Net Window initial 158 Figure 73 Flownet pattern generation x Grid Detinition Grid Amount Number of Grid xB g TE C Space Figure 74 Flownet grid settings window 159 Flow Net ee xj Advanced Option You can save the starting and ending pattern and the flow net result for later annalyzation Figure 75 Advanced flownet settings The flownet is a post processing tool that traces a pattern through defo
250. te temperature and initial grain size which change in time It is very difficult to model dynamic recrystallization concurrently during forming Instead the dynamic recrystallization is computed in the step immediately after the deformation stops Average temperatures strain rate of the deformation period are used as inputs of the equations 1 Activation Criteria The onset of DRX usually occurs at a critical stain O Eg A2 y 1 where p denotes the stain corresponding to the flow stress maximum Zy ay E exp Of RP e __ 2 2 Kinetics The Avrami equation is used to describe the relation between the dynamically recrystallized fraction X and the effective strain fea Sys 8 where O o s denotes the strain for 50 recrystallization Sys ady explO RT c 4 3 Grain Size The recrystallized grain size is expressed as a function of initial grain size strain strain rate and temperature dim a2 te 2 exp O RT c if zex do then drev do _ 5 51 Static Recrystallization When deformation stops the strain rate and critical strain are used to determine whether static or meta dynamic recrystallization should be activated The static and metal dynamic recrystallization is terminated when this element starts to deform again 1 Activation Criteria When strain rate is less than static recrystallization occurs after deformation Ess Aexzpl hada
251. the boundary the user would select a portion of the boundary to have heat flux condition The user would give the heat flux a function number and when the heat flux is computed for that section of the boundary this routine would be called and the user would need to provide a heat flux value As seen below when the heat flux is computed the subroutine number is found and when heat flux is computed ITYPE 4 the user can compute heat flux All the values below can be computed except for friction coefficient MODEL subroutine number function number IMODE simulation type 1 deformation 2 heat transfer 3 diffusion ITYPE output type IMODE 1 1 pressure 2 friction coefficient IMODE 2 1 environmental temperature 2 convection coefficient for free surface or lubricant coefficient for contact surface 3 radiation coefficient 4 heat flux IMODE 3 1 environmental atom content 2 surface reaction coefficient 3 atom flux Output Variable user defined boundary coefficient or value The user needs to specify the function number as a negative value anytime a user defined boundary condition routine is used The output variable for each different combination of output type and mode corresponds to the list above For example if heat exchange with the environment is defined IMODE 2 ITYPE 1 the user would need to supply envionmental temperature as the output variable Windows building procedure for FEM routines 207
252. the compilation was successful If not please refer to the error message in output file from the compiler linker 212 For more information on user routines please refer to the section on user routines in the manual 213 6 2 User defined post processing routines User defined post processing can be used to generate plots of user variables after running a simulation It uses the steps that are stored in the database and any type of variable can be plotted in the post processor for these steps The calculation of this variable is done using a FORTRAN program PSTUSR FOR which is stored in the DEFORM_DIR USR directory It is important to note that these variables do not affect the results of the simulation There are 10 user defined routines each of these can be used to calculate 20 different user variables After the code for these variables has been specified the user defined routines have to be linked to the TEXT and GUI post processors using the INSTALL2D program or running the script build_fem in the DEFORM_DIR USR directory The script compiles the program PSTUSR FOR and also links this with the TEXT post processor and creates a shared dynamic library for the GUI post processor Some applications of user variables are to evaluate the micro structure after the simulation to predict the hardness yield strength of different regions of the forged part to evaluate failure using a critical damage value calculate the cooling rate etc
253. the spring loaded die 4 269 Figure 117 Sketch of spring loaded die simulation with spring loaded die set with movement type based on load and an additional elastic body At this stage the material has filled beneath the sliding die and is pushing the sliding die upward 270 Appendix F Using the Inverse Heat Transfer Template Purpose The purpose of this template is to aid in the estimation of heat transfer coefficients based on simulation results being optimized with experimental temperature data Procedure Please refer to the heat transfer template lab available in the Htlabs pdf file included with the documentation 271 Appendix G THE DEFORM ELASTO PLASTIC MODEL In general the elasto plastic material model should be run in a very similar manner as the rigid plastic material model Some differences are discussed in the following section Material Properties In addition to the flow stress data the material is also required to have Young s modulus YOUNG and Poisson s ratio POISON If thermal expansion and contraction is to be considered the thermal expansion coefficient must also be present Note elastic and elasto plastic materials in DEFORM deal with thermal expansion differently see Thermal expansion EXPAND for more details In the elasto plastic model the flow stress at zero strain represents the yield stress for the material As the accumulated effective plastic strain increases the yield stress inc
254. tiation of a remeshing procedure RMDPTH RMTIME RMSTEP RMSTRKk for an object When the remeshing criteria of any of these keywords has been fulfilled or the mesh becomes unusable negative Jacobian the object will be remeshed During the simulation if an object satisfies any of its remeshing criteria anew mesh is 87 generated the solution information from the old mesh is interpolated onto the new mesh and the simulation continues Maximum interference depth RMDPTH The maximum Interference Depth is used to start a remeshing procedure If any portion of a master object penetrates an slave object beyond the depth specified under RMDPTH remeshing will be triggered The interference depth controls the initiation of a remeshing procedure based on the depth of interference between a slave object and a master object The depth of interference is the depth an element edge of the slave object crosses the surface of a master object The object to be remeshed must be a slave object The interference depth parameter should be used with extremely sharp corners where the corner radius is nearly the same size as the adjacent element edge length The remesh depth should be set to roughly half of the element edge length Too large an interference depth may cause excess volume loss Too small a value may cause too many remeshings leading to slow run times and excessive interpolation error If mesh penetration is occurring the first course of acti
255. tion Geomety Speed Cx e Fence cy Gy Mah COhe ief N beg wars Sed prs C Defined Const ant fp in sec Movement User Routine fi H BCC Curent Die Stroke J Speed Limit BS fo fo ie P i Define 150 msec DEFORM 2D Pre processor Figure 110 Specifying speed using a user routine To use the values for AVGSRT STRMX the primary workpiece has to be specified as the object whose average and max strain rate are required The reason for this is that many different object can be deforming at different rates at a given step This is the keyword PDIE 2 in Simulation Controls Advanced Controls in the pre processor Example Case 1 198 The die speed routine in DIESP1 controls the speed based on a user specified value for the average strain rate The value of the average strain rate is specified using the USRDEF fields C C THE DIE SPEED OF THIS ROUTINE IS DETERMINED BY C C WHERE SR IS THE APPROXIMATED STRAIN RATE DURING C AN UPSETTING PROCESS C HIIS THE INITIAL BILLET HEIGHT READ IUSRVL 1 HI STRK STRKX STRKX STRKY STRKY STRK DSQRT STRK C C FIND the Current Height C WRITE 6 TMPMX HJ HI STRK UPDV AVGSRT HJ The goal of this routine is to define a die velocity by the following equation V H S where V Output die velocity O Average strain rate Hinitia Initial billet height S Current die displacement initial At the beginning of this code a va
256. tor e Interface heat transfer coefficient e Contact relation e Separation criterion Also covered in the inter object controls is object positioning and generation of inter object boundary conditions 2 5 1 Inter object Interface The inter object interface defines what objects can contact each other and how contacting objects will behave while in contact Contact relations inter object boundary conditions friction and heat transfer relations are set here for each object pair x Fiiction Interface Heat K TOP DIE NJ TEST 03 0004 MBOT_DIE N TEST 03 0004 Cancel Apply to all Contact BOC Tolerance Master 3 BOT_DIE amp l s Spo gt Sammi e f Edt Ji Initialize Figure 57 Inter Object window Contact relation CNTACT 118 The contact relation parameter is used to set the Master Slave relationship between workpiece dies and deformable bodies The Slave object should be the softer of the two materials and should also have the finer mesh In the case of two objects consisting of the same material either can be the slave although the object expected to elastically deform the most should be defined as the slave Setting a No Contact relation causes the objects to be invisible to each other and allows them to pass through each other uninhibited CNTACT should be specified for every pair of deformable objects that may contact each other during the simulation Note When a node from on
257. tortion mode uses a different element formulation which considers out of plane shear strains r Jand z as well as the 3 normal rz shear strains that are considered in a normal axisymmetric problem To simulate the inertia weld process the following adjustments should be made 1 Under Simulation Controls set Geometry GEOTYP to Torsion Be sure both Heat Transfer and Deformation are set to Yes 2 Enter the geometry for the weld zone for both deformable objects 3 Each deformable object should be backed by a rigid object One will be moving the other will be stationary 4 The rotation of the rotating part is controlled under the Movement Controls gt Rotation tab The rotation can be controlled by constant velocity constant torque or by flywheel inertia for flywheel controlled weld equipment 5 The translational loading force is assigned under translation controls as normal 6 Contact between the deformable object and the rigid backing object must be defined manually using n n boundary conditions which lock the nodes into position on the master surface This is done using Advanced Deformation Boundary Conditions L For each deformable rigid contact interface select the nodes on the deformable object along the contact zone with the rigid Enter a BCC code n in the Boundary Conditions window where n is the object number of the rigid contact a object Set
258. trictly necessary it is convenient to make object 2 the punch or moving object 1 Mesh the Tools 251 Use around 400 elements Use user defined density with 3 at the contact surface and 1 on the back side of the die 2 Assign Tool Material Be sure the proper material is assigned to both the tools and the workpiece 3 Assign Tool Temperature Set the uniform tool temperature before forming begins 1 Define Interobject Data 1 Inter Object Relationships The workpiece should be slave to both tools The interface heat transfer coefficient should be about 0 004 for English units or 10 for SI units 2 Object Positioning Using interference positioning position the workpiece on the bottom die Leave the top die away from the workpiece during this operation 3 Generate Contact Boundary Conditions The default value of tolerance is adequate 2 Complete Simulation Controls 1 Define Number of Steps A typical die resting operation can be simulated in 10 to 20 steps 2 Select the Primary Die Enter object 1 as the primary die 3 Calculate the Time per Step Divide the total transfer time by the number of steps 4 Define Operation Name optional 3 Save the Data Save a Keyword file Go to Database Generation Check the data If there are any yellow or red flags resolve them then generate the database Exit the preprocessor and start the simulation 4 Loading Simulation Results Into the Preprocessor to Define Forming Ope
259. usion coefficient DIFCOE The diffusion coefficient can be defined by the following methods Method 1 Constant value for diffusion coefficient Method 2 Diffusion coefficient is a function of atom content and temprature Matrix format 48 D KA t 6 13 where A is the atom content D is the diffusion coefficient and t is time Method 3 Diffusion coefficient is a function of temperature and atom content Tabular format D C T exp C2 TA 6 14 where D Diffusion coefficient A Atom content C Coefficient 1 which is a function of temperature C2 Coefficient 2 which is a function of temperature T Absolute temperature Method 4 Diffusion coefficient is a function of temperature and atom content Tabular format D C1 A exp Co A T 6 15 where D Diffusion coefficient A Atom content C Coefficient 1 which is a function of atom content C Coefficient 2 which is a function of atom content T Absolute temperature 49 2 2 6 Grain growth recrystallization model 5 Grai bata alx PekStan m z E Strain Rate Boundary i Temp C Cancel Kinetics iTerap 4 f Gran Size Temp 4 Kinetics items 7 pr Gram Size itt erp l a Kinetics Temp E Gram Size itt emp pi Static Recrystallization F Meta dynamic Recrystallization F Grain Growth Grain Size iTemp fes Figure 28 Material properties window grain growth
260. ve shell if 6 USER 0 prompt 0 exit set history 100 set ignoreeof set prompt hostname whoami cwd date 234 Final comments Unix is type case sensitive Most of the Unix commands are in lower case Please note that all the main DEFORM system files and commands are in upper case In this document we have briefly explained how to load and execute DEFORM System If you need further technical assistance please contact us at the following address numbers Scientific Forming Technologies Corp 5038 Reed Road Columbus Ohio 43220 2514 USA Phone 614 451 8313 Fax 614 451 8325 Email support deform com Web www deform com 235 NT 2000 XP Installation Installation Notes INTRODUCTION The following pages describe the installation steps that need to be performed in order to use DEFORM 2D These steps include ensuring the proper amount of memory installing the Security Key device installing the DEFORM 2D program files and troubleshooting should you run into problems INSTALLATION REQUIREMENTS Operating system Windows NT 4 0 Windows 2000 or Windows XP Hard drive space required 150 MB INSTALLING THE SECURITY KEY DEVICE e This Security Key allows the DEFORM 2D system to be highly portable while still allowing only one system to be operable at any time The actual software can be installed on as many computers as you like but each DEFORM system will be inoperable without the Security Key
261. which in turn calls USRSV1 USRSV2 etc based on the value of NPRTRN the material group number of the current element If nodal values are being calculated the branching based on the material group number will not work if an object is composed of more than one material group The advantage of using these variables instead of doing the same procedure using user defined post processing is that these values are calculated for each step in the database whereas user defined post processing is only for the steps that are stored in the database Data that is passed to the user variable subroutine are stored in COMMON blocks as detailed below Common block USRCTL KOBJ Object number KSTEP Step Number N ISTATUS 0 the beginning of the step 1 the end of the step Common block ELMCOM RZE Four corner coordinates URZE Velocity STSE Stress EPSE Strain rate EFEPSE effective strain rate EFSTSE Effective stress TEPSE Total effective strain RDTYE Density TEMPE Temperature DAMAGE Damage value DTMPE Temperature rate USRE1 Element user state variables Input At the beginning of Step N USRE2 Element user state variables Output At the end of Step N USRNE Nodal user state variables 1 2 at 4 nodes NODEE Connectivity KELE Global element number KELEL Local element number KGROUP Material group number Common block NODCOM RZN Nodal point coordinates URZN Nodal point velocities DRZN Nodal point displacement
262. which is not converging well can be stopped before it runs through all iterations Running the simulation in interactive mode will display message file information directly to the screen so it can be viewed in real time In Batch mode simulation certain platforms such as HP and SUN buffer the message file information by a certain amount until the system will write to the message file If the system were to crash on the first few iterations nothing may be written to the message file since the system would not have a chance to write the buffered iterations Interactive mode can be used to print the iterations that lead up to an early crash 3 2 Relevant files Database The current database is listed in the Database text box The database a binary file is used by the Simulation Engine to read in the data defining the problem When the problem is run the Simulation Engine adds each subsequent step to the database Log File The Log file lists information on the process switching Anytime DEFORM 2D switches from the Simulation Engine to the Automatic Mesh Generator AMG 127 or any other program it will be logged as an entry into this file When a problem occurs with a simulation the log file can help
263. wth ag and m are materials constant and Qgis an activation energy Retained Strain When recrystallization of a certain type is incomplete the retained strain available for following another type of recrystallization can described by a uniform softening method a 1 0 AK Sa 14 Temperature Limit The temperature limit is the lower bound of all grain evolution mechanisms Below this temperature no grain evolution occurs Average Grain Size The mixture law was employed to calculate the recrystallized grain size for incomplete recrystallization d K o dy tl Apa do 15 Model Dependency on Temperature and Strain Rate DEFORM allows different constants and coefficients for the equations at different temperatures or strain rates The data are linearly interpolated NOMENCLATURE 53 T_Temperature K R_Gas constant t Time d_Initial grain size drex_Recrystallized grain size _ Effective strain c Critical strain p Peak strain o 5_Strain for 50 recrystallization 5 _ Effective strain rate to5_Time for 50 recrystallization Z Zener Holloman parameter a 19 Material data b 2 Material data C g Material data n 8_Material data m gs Material data Q g3 Material data a O ma O s Material data kg Kma ks Material data _Material data 2 2 7 Hardness data MIC 54 Close G Regular 1100 COLD 70F 200 1 Plastic Elasti
264. xist for flow stress definition movement control calculation of two nodal values USRNOD calculation of element values USRELM and for other models For example there are many different methods for a user to control the movement of a rigid body within DEFORM e g constant velocity mechanical press hammer press movement speed as a function of time However there are some cases where a slightly more specialized movement control is required such as movement based on variation of state variables of the workpiece This can be performed using user routines since these variables are available when the movement of the rigid die is calculated Performed by Script file DEF_INS COM Compile User Subroutine DEF_USR FOR FEM Engine object code DEF_SIM OBJ User Subroutine object code DEF_USR 0o New FEM Engine DEF_SIM EXE Figure 107 Description on how to compile link a new FEM engine Summary of subroutines and calling structure of user defined FEM routines Here is a list of the different subroutines available to the user With each routine is a brief description of its purpose and the frequency of it being used by DEFORM 1 USRMTR Description This routine allows the user to calculate flow stress of a material This routine is called at the beginning of each iteration 2 USRDSP 190 Description This routine allows the user to calculate the die speed of a rigid obje
265. y into this port If the Security Key is plugged in remove it and re insert it making sure that it is completely inserted and try running DEFORM 2D again Error The message Computer clock is not correct is displayed Problem The computer s internal time and date have been changed since DEFORME 2D was last run Solution Check the time and date and make sure that they are correct If they are both correct then DEFORML 2D was run at least once with a newer time and date Once DEFORM 2D have been run the time and date cannot be set back If they are not correct and display an earlier time or date update them to the current time and date and try running DEFORM 2D again QUESTIONS PROBLEMS If you have any questions comments or problems installing DEFORM 2D contact Address 242 Scientific Forming Technologies Corporation 5038 Reed Road Columbus OH 43220 2514 USA Phone 614 451 8330 Fax 614 451 8325 E mail support deform com Or visit our website at http www deform com 243 Chapter 7 Quick start tutorial 7 1 Cold Forming When simulating cold forming it is important to simulate all steps of the process since the work hardening effects of early steps can influence behavior of later steps The procedure for simulating a multi station process is detailed at the end of this section 1 Create a new problem folder directory Each DEFORMA amp trade problem should reside in
266. yed Zoom Window The zoom window function allows close up inspection of a small region of the currently display object or graph The zoom region is selected by clicking and holding the left mouse button while dragging the mouse to enclose the selected region with the displayed box Pan Pan adjusts the region filling the active viewport without changing the size of the displayed object Measure The measure feature will display net distance and x and y component of distance between two selected points The measure is performed by clicking and holding on the first point then releasing over the second point The measurement marks are not erased until the viewport is refreshed and as such are also convenient for marking arbitrary reference points on the screen which will maintain their location through view changes Refresh The refresh icon redraws the screen removing any measurement marks and updating any changes made to the color pallet Fit all Fits all displayed objects or graphs inside the current viewport Same as Copies the view size of the primary viewports to all other active viewports Print Prints to a postscript printer or creates a postscript file of the current step Print all steps Prints all selected steps to a postscript printer or file Steps may be selected or deselected using the Steps option on the post processor controls window 146 Capture image Writes the current screen image to a file usi
267. ymmetric and Plane Strain simulations In the case of an axisymmetric simulation only the y direction needs constraint In the case of a plane strain simulation both the x and y directions need to be constrained for the meshed objects For the case of rigid objects these do not need any constraint since they act more as boundary conditions Extrapolation of data Many of these problems are not the result of bad data or the user neglecting to input the data properly The problem has to do with a data set that does not cover the process being modeled This being the case the available data is extrapolated to the process window In this case the material needs to be updated to include data in the actual process window or adjusted best estimate to insure that values at or below zero can not occur when these critical properties are included in the stiffness equations See Figure 11 3 for a further description 136 Heat capacity vs Temperature Preblem area with data extrapolated ae Heat Capacity Temperature These suggestions are intended as general guidelines and may not solve all of this class of problem If all of these areas have been investigated and subsequent attempts to run your problem fail we would recommend sending us a keyword file for further investigation 3 9 Database Management Database Purging
268. ype Geometry C Angular Velocity 35 Mesh Taqa a Current Angle Figure 53 Object movement window rotational plane strain case Rotational movement controls are applicable only in the case of plane strain and torsional formulations Rotational movement is defined by an angular velocity about a fixed center of rotation This movement type causes only rotation Unless otherwise specified translation is constrained The rotational speed is controlled through the Controlling Method option and the point at which the object is rotated about is set through the Center of Rotational Movement Rotational Motion can be applied to simulate rolling or any type of movement where an object will rotate about a fixed axis Rotational Motion can only be applied to Rigid objects Rigid objects can have both Rotational and Translational movement simultaneously 1 Controlling Method The objects rotation can be controlled by an Angular Velocity or a Torque Select the required control and enter the value for the rotation just below e Torque The Torque movement type will apply a rotational motion about the defined axis at a specified torque The torque can be specified as a constant or as a function of time or angle e Angular Velocity Angular Velocity will apply rotational motion about the defined axis at a specified angular velocity in radians per second The angular velocity can be specified as a constant or as a function of time or 109

DEFORM 2D Version 8.1 User`s Manual

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