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LS-DYNA Analysis for Structural Mechanics

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1. FINISH FINISH II Change Colors Create Section Cut Me PR DNA Cem Nasa B g Te ate pee Mb i meet mere TEALA om TARL DA amming Mu vene EE Isay Te dytt j gt Se ee ee te i Be m Jr 118 eee ew ee 1 Workshop XII Drop Test of Pressure Vessel beg x Workshop XII Drop Test of Pressure Vessel le y Timo 00109001 v rt Time 00064981 v t tv 3 he 2 i ny fe BE Eh le aag HE vg oe p i ie Cy e me pr a a l F la lea Y r al lt A o gt poteat i Ges yrrsnNOed At prs NR ee Geer Ges VERO OG jm out AA bl LI AA I OOF TOR Bet Part Coins ete vent tee area ed mas ss barn verre mn bes Bomnsres Clean and neat drop test against rigid wall The pressure is inward function of the plate element normals or sign of the pressure load Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute FINISH III Contour Stresses se Workshop XII Drop Test of Pressure Vessel Tie 0010001 Contours of Ettective Stress vm y Lu alse ed lege btaa wees sms mr td Op Wewet gut yr tTnOed AX re Ne v r Bomaeces As the vessel is collasped the fluid volume pushes the rubber portals outward Page 84 of 105 FINITE ELEMENT ANALYSIS f TT A Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 11 CONNECTIONS VI
2. Large Deformation of Plastics Drop Test of Composites Electronics Human Biometrics t em SS ee Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 11 of 105 FINITE ELEMENT ANALYSIS as N Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 Drop Test of Nuclear Waste Container REVO p ei S x L i Crash Analysis of Cargo Net Impact Analysis of Foams on anor rest ANALYSIS Plastic Thread Design Digger Tooth Failure Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 12 of 105 fp FINITE ELEMENT ANALYSIS Predictive Enginesring LS DYNA Analysis for Structural Mechanics 2014 Electron Beam Welding _ Pyro Shock Analysis Medical Equipment Kaman JPF AP battery Primer Pyro Shock faren ODi bes nws Oki emnent Tes tere TE Ballistic Shock Loading of Optical Equipment Hyperelastic Medical Seal Analysis Rifle Mounted Scope Tere OFF tesse Covteers of Puttes Dress jose vakse i HHHH i oa a a L Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 13 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering Blade Out Analysis Ballistic Penetration of Al Foam Panel LS DYNA Analysis for Structural Mechanics 2014 Discrete Element
3. Y TW INN Prsge Levete SA Wortehep N Bast Bed Sibe Opiihesi rAr OP Woetkwtog IV Banke Br Suda with Sade Padure Cortear of EPer twe Grows re ISe NIS T AT 3 3339407 SJ TE aJi i g aS be oter ee i Gu rt caved 40 bekk TOLERE Sor Bek wv FT 7 Rti et 4 8 es fn m fe s 6 miw arnee gas gt oe steden pl Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 98 of 105 Finite ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 14 5 1 BIRD STRIKE MODELS Figure 5 4 Various bird models used in rotating bird strike analyses lf one ever wonders what a spherical chicken looks like Image courtesy of Aerospace MGD v12 1 pdf page 101 see Class Reference Notes Aerospace Working Group Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 99 of 105 Pa DET III fr DOANA MA 7 TT FINITE ELEMENT ANALYSIS AO I INN Predictive Engineering LS DYNA Analysis for Structural Mechanic 0 14 6 REFERENCES 1 L D Libersky A G Petschek T C Carney et al High Strain Lagrangian Hydrodynamics A Three Dimensional SPH Code for Dynamic Material Response Journal of Computational Physics vol 109 no 1 pp 67 75 11 1993 2 J L Lacome Smooth Particle Hydrodynamics SPH A New Feature in LS DYNA 3 G R Liu and M B Liu Smoothed
4. 3 4 1 INSTRUCTOR LED WORKSHOP II IMPLICIT VERSUS EXPLICIT MESH DIFFERENCES Meshing for Accuracy ee te ProPcat 43 Seta i Tier DOLD OO b ter I its vernes ingit Man Oe twrenceni Dept isot fe Moc Yew Germany HM aaron Getting Hett Perfect Explict Wave Propagation Times 14857 1 3 ic fe e Solution time number of nodes time step is often one of the most important considerations in setting up an explicit analysis care should be exercised in setting up the mesh density r maset 0467171 at elema 1881 uf r A e A good implicit mesh does not typically work well for an explicit analysis Em fl T e In an explicit analysis linear elastic stresses are not often the most important analysis result Typically plastic strain energy crushing depth etc are more 4 FES Cre marg o eda LAJ Ga vri hd fa an Gr Dres Falani tas a Petals 2 Ow gt o SELLER A TETE EEI important These parameters are not as mesh sensitive town mose stout potel UYL right click sv mhich rotstor oez as linear elastic stresses and permit a much larger LIS LD PrePcer 4 J Beta Tagga pid I Curt yenas mgit Man Diirsrepi Orpen element size to be used EE AATE Sander hugse Moos Since the time step is controlled by wave propagation the Contour of cave Biren Iven mesh should be graded gradually to likewise allow a ras Q4340A8 tsler TOR smooth wave propagation through
5. Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 7 7 1 MODELING WATER WITH EOS_GRUNEISEN AND MAT NULL As basic as this may sound it is not that obvious The technique for modeling water is well described in Class Reference Notes Aerospace Working Group Aerospace MGD v12 1 pdf at page 66 Section 3 9 2 Water The entry is as simple as the graphic shown on the right The only real difficulty is ensure that one gets the units handled correctly Analyst s Note Make sure you remember to set the PART card to use the EOS law 3 9 2 Water In LS DYNA models MAT_NULL and EOS GRUNEISEN are commonly used to represent water and other liquids Some commonly used Input constants for water at 20 deg C follow MAT_NULL Mass density RO 1 e 6kg mm 3 1 0 g cm 3 1000 kg m 3 1 e 9 tonnes mm 3 9 37e 5 Ibf s 2 in 4 Dynamic viscosity MU 1 0e 3 N s m 2 often taken as 0 0 Pressure cutoff PC 100 Pa often taken as zero All other parameters in MAT_NULL should be set to zero or left blank EOS GRUNEISEN Nominal sound speed C 1500 mm ms 0 15 cm microsec 1500 m s 1500e3 mm s 59055 in s VO 1 0 unitless Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 54 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering 7 8 MATERIAL FAILURE SIMULATION 7 8 1 BASIC METHODS OF MODELING FAILURE MATERIAL VERSUS BOND FAILURE Standard failure in th
6. SURFACE TO SURFACE BEAM OFFSET SHELL EDGE SURFACE BEAM OFFSET SUMMARY TABLE FOR TIED CONTACT Recommended Usage Gluing solid mesh transitions together where the two meshes are co planar adjacent Useful for creating weld edge lines between two solid elements parts that are co planar simulates a fillet weld Welding plate or beam nodes together when the mesh is co planar and captures all six DOF Gluing solid mesh transitions when the meshes are not co planar Ideal for welding together plates beams or for plates beams onto solids whether deformable and or rigid with offsets Struc Type Constraint Constraint Constraint Penalty Penalty tural Mec 2014 e nanics Bo RR EAT Pros Cons Pros Provides smooth displacement and stress interpolation across dissimilar meshes between hex to hex or tet to hex Cons If the meshes are co planar there are no cons Pros Allows the logical modeling of edge contact between solid parts If the meshes are co planar there are no cons Cons Not to be used with plate or beam elements since rotational DOF are not correctly handled Pros Handles all six DOF s using a constrain method Cons Not designed for solid elements Pros Allows one to glue together dissimilar meshes that are offset Also one may glue deformable bodies onto rigid bodies Cons Not suitable for plate and beam connections Pros The grand slam of tied c
7. e This default formulation is efficient and generally the most robust formulation for large deformations e The example shows that under integrated elements have severe problems in bending The recommended number of through thickness elements is three 3 However fully integrated ELFORM 16 does an adequate job with one or two Computationally 3x more expensive than the default formulation ELFORM 2 e Importantly it is not always possible to use only ELFORM 16 due to computational expense and care must be taken with using the default formulation in situations where only one msme HTTP OG verkene element through thickness is possible o gt gt ne Boring ELFet and vil 4 Ml i TE 4 F i FI ti ij H S Ho i e Increasing the number of elements can be problematic due the CFL timestep condition since three elements over a narrow width of strip will always cause a severe reduction in timestep YL ALES UE 5 vege e Recommended size is 5 mm for steel and aluminum and thus yields a time step of approximately 1 us FE This section courtesy of LSTC and Paul Du Bois Hermes Engineering NV toluo ooie tm jjun eee D aoe Tr y Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 35 of 105 FINITE ELEMENT ANALYSIS Predictive Enainesring LS DYNA Analysis for Structural Mechanics 2014 5 2 2 INSTRUCTOR LED WORKSHOP
8. Please Do Not Copy or Distribute Page 59 of 105 FINITE ELEMENT ANALYSIS ri Ad Predictive Engineering 8 CONTACT 8 1 DEFINITION OF CONTACT TYPES LS DYNA was developed specifically to solve contact problems see Class Reference Notes History of LS DYNA Contact behavior is enforced by three methods i Penalty Based using finite springs see graphic ii Constraint Based where no penetration is allowed and cannot be used with rigid bodies and iii Tied Contact discussed within its own section The most commonly used approach is that of the penalty method Contact can be effortlessly implemented or it can be bewitching in complexity A reasonable treatment of contact is a multi day course in itself To start the learning process see Class Reference Notes Contact User s Guide Contact User s Guide pdf Efficient Contact Modeling Whenever possible interferences between parts should be avoided It is standard contact practice that any initial interference is removed nodes are shifted and as such sharp stress spikes can occur where parts plates overlap Setting up contact surfaces appropriately that account for plate thickness can be time consuming If necessary contact thickness can be overridden within the CONTACT Keyword card or tracked via IGNORE 1 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute LS DYNA Analysis for Structural Mechanics 2014 ci poor
9. Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 Some things to note is that a third node is not defined within the ELEMENT BEAM card since the orientation of the element is handled by the CID definition One will note that VOL and INER are both given values of 1 for simplicity since the mass of the element is then controlled by just the mass density on the material card And don t forget that a PART card is also required to tie together the SECTION and MAT cards In this example the coordinate system is fixed and does not rotate with the system 5 3 1 WORKSHOP DISCRETE ELEMENTS NON LINEAR BUCKLING ANALYSIS Femap Model LS DYNA Non Linear Buckling Results ES 7 648 02 7 0tte 02 6 373602 5 736 02 5 0990 02 44616 02 3 824002 3 187002 2 549e42 1 912e 02 1 275002 6 373003 0 0008 00 ska gis abs feteroict a Z Migs Fore lua lUpo Vase erie 336 ne Eo o t vt J ae ie j de ce fe toia imi iy Ivinisinjele TEE Vt Beh vrnmoeg gt state 1 ve i e West State 7 feat Renderer Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 42 of 105 FINITE ELEMENT ANALYSIS KI Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 6 LS PREPOST 6 1 WorksHop IV LS PREPOST WorksHor 7 amp 8 Introduction to LS PrePost Reference and tutorial materials are provided at the www LSTC com site Model manipulation is by Sh
10. Ts tia Leormeest Boers Mur v r Ed TA gt ee Wey Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 68 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering 8 7 8 7 1 TIED CONTACT FOR MESH TRANSITIONS WELDING AND GLUING TIED CONTACT OR GLUING Given the idealization difficulty of system modeling the ability to tie together different mesh densities e g hex to hex or tet to hex snap together parts along a weld line or just glue sections together e g plate edge to a solid mesh is an amazingly useful ability and LS DYNA provides a very complete Tied Contact tool box to work with The emphasis of this course to provide an overview of the basics to get started efficiently with LS DYNA a short list of recommended KEYWORDS for Tied Contact are presented that work for both implicit and explicit solution sequences When the Mesh is Co Planar Translational DOF Tied e CONTACT TIED SURFACE TO SURFACE e CONTACT TIED NODES TO SURFACE When the Mesh is Co Planar All Six DOF Tied e CONTACT TIED SHELL EDGE TO SURFACE When the Mesh is Offset All Six DOF Tied e CONTACT TIED SURFACE TO SURFACE BEAM OFFSET e CONTACT TIED SHELL EDGE TO SURFACE BEAM OFFSET The utility of using a very brief subset is that one can build up experience and confidence without the expense of trying out a rather daunting list of Tied Contact Options Proprietary Information to Pred
11. and C m s specified as CO on EOS GRUNEISEN and u is a dimensionless parameter Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 52 of 105 K gt ANSN AN EP TT i ae ME GN FINITE ELEMENT ANALYSIS kT HOVIN Predictive Engineering Mechanics 2014 Comparison between weakly compressible and compressible Fluids in LS DYNA Explicit need to be described by a constitutive material law such as MAT_NULL for example and an appropriate EOS The reason is that solving the set of Euler equations or full Navier Stokes in the presence of viscocity with a strictly explicit time integration scheme requires an equation of state to directly determine the pressure at each node point A truly incompressible algorithm requires solving a Poisson equation elliptical partial differential equation to ensure that the flow is divergence free The Poisson equation can only be solved iteratively or using Implicit time integration All this truly means is that in LS DYNA SPH Explicit a fluid that is commonly considered incompressible can be treated as weakly compressible with a simple EOS by defining only two parameters initial density and the speed of sound in the material Throughout the workshops we use MAT NULL but other material models such as MAT JOHNSON COOK Elastic Plastic Hydrodynamic etc can be used with an EOS to describe various engineering materials Page 53 of 105 Finite ELEMENT ANALYSIS
12. 181 e Rigid e Fabric Simplified Rubber was developed in early 2000 and gt Orthotropic Anisotropic 5 Conceal although a somewhat recent development it has seen wide spread usage due to its advanced formulation and EE RE i i a robustness For elastomers it is my default choice Foams e Laminated Glass e Composites e User defined Although many material models exist for metals one of the most robust models is MAT 024 or MAT PIECEWISE LINEAR PLASTICITY This material model is the standard workhorse and is the e Viscoelastic recommended starting point for elastic plastic simulation of metals and general plastics since it can also handle viscoelastic behavior i e strain rate dependency Note It is recommended practice to build a pilot model using the material law of choice and replicate the l Piecewise Linear Plastici material s experimental data E gt E Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 45 of 105 Finite ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 7 1 3 MATERIAL FAILURE AND EXPERIMENTAL CORRELATION Material Failure Simulation of material failure is a broad research avenue Prediction of brittle material failure as shown by the glass shatter patterns on the right can be extremely mesh sensitive For ductile materials the failure prediction is more robust since ferrous and non ferro
13. Copy or Distribute Page 101 of 105 FRON ering FINITE ELEMENT ANALYSIS Predictive Engin LS DYNA Analysis for Structural Mechanics 2014 o 100 elements listed in ascending order of time step find smallest o Review rigid bodies for any that might be deleted or with super small mass o Warning and error messages find Warning or Error 15 4 History PLOTS Asmare i konum ys 26001301 Nessa LS OYNA Containment krvestigation Rev 2 Component The GLSTAT file is your first stop for checking the analysis A fundamental check is that your Energy Ratio should be 1 0 0 01 This can be quickly oh Kinetic Energy checked within the ASCII GLSTT file under Energy Ratio An example of a Tola energy more complex energy plot is shown on the right The high Sliding Energy is TE sising Energy because the model is simulating a burst containment of a fragmenting X ray target with friction For more information on Energy Data see www dynasupport com under LS DYNA User s Guides and then Energy Data also see Class Reference Notes Energy Balance Total energy LS DYNA Support pdf If the GLSTAT checks out it is time to go over the MATSUM file via individual entries The internal energy should be plotted against the hourglass energy and margins of 5 or less of the peak internal energy should be observed Sliding energy GLSTAT global and sliding interface energy ASCII local via say a lot about the nu
14. Defined in Explicit Time t Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 20 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering nanics 2014 LS DYNA Analysis for Structural Mechanic 3 2 TIME STEP SIGNIFICANCE COURANT FRIEDRICHS LEWY CFL CHARACTERISTIC LENGTH e Inthe simplest case small deformation theory the timestep is controlled by the acoustic wave propagation through the material e Inthe explicit integration the numerical stress wave must always propagate less than one element width per timestep E materiai CaccousticwaveSpeed e The timestep of an explicit analysis is determined as the minimum Pmaterial stable timestep in any one 1 deformable finite element in the mesh Note As the mesh deforms the timestep can similarly change e The above relationship is called the Courant Friedrichs Lewy CFL Lengthgiement condition and determines the stable timestep in an element The CFL AExplicitTimestep condition requires that the explicit timestep be smaller than the time needed by the physical wave to cross the element Hence the numerical timestep is a fraction 0 9 or lower of the actual theoretical timestep Note the CFL stability proof is only possible for linear ATimsteper problems 0 9 AExplicitTimestep e In LS DYNA one can control the time step scale factor TSSFAC The default setting is 0 9 It is typically only nec
15. III EXPLICIT ELEMENT TECHNOLOGY B OUT OF PLANE BENDING WITH PLASTICITY Isoparametric Shell Elements e Only two element formulations are recommended ELFORM 2 and ELFORM 16 keep it simple e Number of through thickness integration points NIP controlled by user Be 44S NIP 1 Membrane Behavior NIP 2 Linearly Elastic Behavior default NIP 3 Recommended for Nonlinear Materials JF G Optimum NIP for Nonlinear Plasticity 5 e ELFORM 2 not well suited to warped geometries unless BWC warping stiffness with full projection is invoked or use ELFORM 16 Warping is something that is troublesome whether the analysis is implicit or explicit ee BITS PHS SHIN NA Teneo T Tr TE val LELA TT Lin Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 36 of 105 FiNITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 5 2 3 WORKSHOP BUILDING THE BETTER BEAM Objective The importance of mesh density and plate out of plane integration will be demonstrated through the use of this simply support I beam model half symmetry The material model is steel with a yield stress of 100 000 psi and a tangent modulus of 200 000 psi The workshop will start with a Femap model shown on the right Tasks e Setup LS DYNA Analysis Femap Analysis Set Manager with a termination time 0 05 and Output Time Interval 0 0
16. LS DYNA Analysis for Structural Mechanics 2014 j SG KAT Predictive Engineerin s 5 1 EXPLICIT ELEMENT TECHNOLOGY ELEMENT TYPES IN LS DYNA There are many different element types in LS DYNA Point elements mass inertia Discrete elements springs dampers Beams shells Solids 20 and 3D Lagrangian Eulerian ALE Shells Thick Shells 8 noded Seatbelts and related components EFG and SPH meshless Extremely Brief Recommendations Hg trusses beams Hughes Liu Integrated Beam ELFORM 1 is default Stresses are calculated at the mid span of the beam ANN V C H Special requirements for stress output ng Mee ee dataen For solid elements the default is ELFORM 1 and uses Detailed Element Recommendations see Student s Class one point Guassian Integration constant stress Reference Notes This element is excellent for very large deformations oe Review of Solid Element Formulations Erhart pdf It is the standard recommend for explicit simulations Shall elanientsarecovercd EN Aerospace Working Group Aerospace MGD v12 1 pdf Page 34 of 105 FINITE ELEMENT NALYSIS H gt Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 5 2 ONE GUASSIAN POINT ISOPARAMETRIC SHELL ELEMENTS AND HOURGLASSING 5 2 1 INSTRUCTOR LED WORKSHOP III EXPLICIT ELEMENT TECHNOLOGY A SIDE BENDING isoparametric Shell Elements Through Thickness Default element is one Guass point in plane ELFORM 2
17. Models Available in LS DYNA rrrrnnnnrrnnnnnnrnnnnnnnrrnnnnnnsrnnnnnnsrnnnnnssnnnnnnnsnnnnnnnsnnnnnnnsnnnnnnnsnnnnnnnsennnnnnsennnnnnsennnnnnseennnn 45 7 13 Material Failure and Experimental Correlation ciisiccscsssnassvescnscvscsveninnadiucensaveceasvasanasunat eaidewi vie cnasebesavniaduasuvab oeadnnebiedenoss atannnatancsent beds 46 Pee VPN ANNEN 47 Jea SNE NNN 48 PT ANNE NNN 49 7 4 1 Modeling Elastomers vs Foams ke EE EE EE EE 49 Faar DATTEREN ODE TORTIE DELNE PO N EE RE EEE 50 7 0 WORKSHOP VI MODEUNG AN ELASTOMER BALL WITH HEX VIE 51 7 7 EQUATION OE STATE EOS MATERIAL MODELING ae 52 7 7 1 Modeling Water with EOS GRUNEISEN and MAT NULL sssmnennnnnrrnnnnnrnnnnnnernnnnnnsennnnnnnennnnnnsennnnnnesnnnnnneennnnnnesnnnnnnnennnnnnesnnnnnneeneennn 54 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 4 of 105 FINITE ELEMENT NALYSIS H gt Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 To MER NNN 55 7 8 1 Basic Methods of Modeling Failure Material versus Bond FailUre cccccsccccssscccessecccesececeececsescceeeeceseuecessuscesseeeeseuecessuscetsunees 55 MPV 56 7 10 MOREN ER E 2100 2 OE EE EE EN NN NR 57 7 10 1 Rigid Materials MAT_020 or VAL GP avs 57 740 2 Instructor Led Work nop V RBEZ TO CNRD EE EE EN E 58 TF Wo rksh p Vil Using Rigid DOIE ke 59 e CONT Te A E EN EEE EN 60 L ENN PN 60 O SEE EEE EE EE EE deep sauenetrateee ca ec E 61 BLE 61 B
18. Workshops Each Workshop is part theory part demonstration and part hands on practice Videos are provided for each Workshop allowing the student to relax and follow along at their own pace These videos cover the basics and also provide insight into the many tips and tricks that make LS DYNA the world s most complete and accurate simulation code Breaks are provided every two hours where students can pause relax and ask the instructor more detailed questions Students are encouraged to turn off their email text messaging and other forms of digital social media during class time 8 00 am to 5 00 pm ry Information to Predictive Engineering Please Do Not Copy or Distribute Page 9 of 105 2014 LS DYNA Analysis for Structural Mechanics FINITE ELEMENT ANALYSIS Predictive Engin ering 1 4 GENERAL APPLICATIONS Crashworthiness Driver Impact Train Collisions Earthquake Engineering Metal Forming Military SN ile z AMA TLE det A pS woe ee AP MT _ al i d war TE aa mr nr i gt i a ce vat JAVA t a JOE v Page 10 of 105 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute FINITE ELEMENT NALYSIS H gt Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 1 5 SPECIFIC APPLICATIONS COURTESY OF PREDICTIVE ENGINEERING Drop Test Consumer Products 4 P Crash Analysis of Seats Sporting Goods Equipment
19. eens 48 MGP INTER Ames SHS C fetteren BG Bone t hoppid hr B w re OG eee preg pm rs gt iS gt i ae NSG ZEC TRT J Ka eS u 9 le With SURFACE TO SURFACE contact Interpenetration is enforced and the slave surface nodes are immediately moved to accommodate the profile of the master surface Note One should add back in SINGLE SURFACE contact for the top tube with SOFT 2 2014 FINISH V CONTACT AUTOMATIC SURFACE TO SURFACE SOFT 2 f i de se ow Os wym Sew oe Pee on Pipe Contact Finish V 2 520702 Ke TET Tur With the Soft 2 option interpenetrations are gracefully handled i e tracked It is what makes the Soft 2 option quite useful in many contact applications Analyst Note The reason that so many contact options exist is partly due to legacy requirements and also for numerical efficiency When working with large assemblies the contact algorithm can often represent the most numerically costly part of the simulation e g gt 50 To pare down run time it can be very handy to remove the SOFT option and to explore the many other more economical contact algorithms such as NODES TO SURFACE or to remove the AUTOMATIC option Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 65 of 105 FINITE ELEMENT ANALYSIS H e Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 8 4 INSTRUCTOR LED WORKSHOP VI CONTACT NEG
20. for dynamic events is the kN mm ms kg system Stresses are then in GPa We have covered this before but it is hard to overstate the importance of getting your units straight In a dynamic analysis the mass of the system should always be checked 15 2 MESH When looking at your mesh it should look good and if it looks good it will generate a smooth stress contour This is never more so important than for an explicit analysis If this sounds odd please see Class Reference Notes Stress Visualization Desktop Engineering Stress Visualization Article March 2011 pdf Besides this Zen of meshing statement here are some bulleted items to consider e Is the mesh density sufficient to capture the mechanical response Remember one point Guass Integration e If Hourglassing is significant remesh and likewise if contact is poor high SLEOUT remesh etc e Lastly check the explicit time step Seriously a couple bad elements can completely explode the analysis personal experience that cost me a weekend This can be done easily via LSPP and viewing the D3hsp file under 100 smallest timesteps 15 3 D3ksp FiLe LS DYNA EQUIVALENT TO THE NASTRAN FO6 FILE e The d3hsp file summarizes the input in descriptive terms and can be viewed via a text editor or from within LSPP via Misc and then D3hsp View Within the d3hsp one should review o Verify mass of system find summary Proprietary Information to Predictive Engineering Please Do Not
21. hit Apply and you re done e Create your pressure load curve using the DEFINE CURVE command Set the curve to unity over time e g 0 1 and 1 1 When done this should be curve number 2 e The pressure load is finally created using the LOAD SEGMENT SET command We are setting the pressure to 5 psi by setting SF 5 Run the model and interrogate This model has Finish Il appended to its name ae mist ES 0 e To simulate the incompressible fluid behavior within the a Iam ran Pose nee ro me vessel add AIRBAG_LINEAR_FLUID to the model with renee aR sce Satin BULK 5e5 and RO 1e 4 with all other options default The segment set created for the pressure load is re used to define the enclosed fluid volume The completed card is shown on the right e Rerun model You should see the rubber portals bulge This model is noted as FINISH III Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 83 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering 10 3 1 STUDENT BONUS LS DYNA Analysis for Structural Mechanics 2014 Take the prior model and reorient the RIGIDWALL_PLANAR to make it vertical or in the XY plane Then change the INTIAL VELOCITY GENERATION to have the vessel hit normal to the XY plane or in the Z direction We are simply re orienting the impact from smashing down on the ZX plane to hitting sideways against a XY plane so to speak
22. internal energy at any stage of the analysis use CONTROL_ENERGY HGEN 2 to calculate hourglass energy In LSPP check gistat for total hourglass energy and then matsum for individual part energy How to Limit Hourglassing Apply pressures instead of point loads Refine mesh Selectively use ELFORM 16 3x computational cost D PN Fe fr H AFSAL iw AR VAA 9 dan r dar Drea d H de H wm Cr Cr a gt A M A CF D A enrn Naw R At fi Arai Ar Py a ctr 5 AVEL Sa rrONMricltary hnrormation to rredqaictive engineering r cdot D O NOT CODY OT D ISU b ULE i 7 i i EG O ren oO it i I i i LS DYNA Analysis for Structural Mechanics 2014 f4 7 3 4 x fl of Ls f2 TEST OF HOURGLASS CONTROL Fase ta Workshop II Hourglass Control e Evaluate current model for hourglassing Plot internal energy and hourglass energy e Read Hourglass Material e Attempt fix with different hourglass type e Switch ELFORM to 16 Page 38 of 105 Finite ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 5 2 5 WORKSHOP Ill MESHING FOR EXPLICIT SUCCESS MESHING FOR EXPLICIT SUCCESS START MODFEM Element Quality for Explicit Analysis Orthogonal Meshes In explicit analysis regular meshes are important to represent the wave propagation problem with minimal dispersion When the mesh is irregular the wave front will become dispersed and degrade the quality of the results Ideally mesh l
23. learn the material 1 2 3 4 5 Quality of the experience 1 2 3 4 5 If you could do one or two things to make it better what would they be General Comments When done just tear out this sheet and leave it at your desk Thank you Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 113 of 105
24. pemon ET Contact thickness Shell io midplane I 5 o amp O Physical gap Page 60 of 105 FINITE ELEMENT ANALYSIS H gt Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 8 2 GENERAL CONTACT TYPES Although there are numerous contact types given in the Keyword Manual these Classical Contact workhorse formulations are recommended Keeping Nodes on the Right Side 1 CONTACT AUTOMATIC GENERAL 2 CONTACT AUTOMATIC SINGLE SURFACE p 3 CONTACT AUTOMATIC SURFACE TO SURFACE d E The first formulation is the kitchen sink and is computationally expensive but is very robust and will enforce contact between beam elements and other a components It is a single surface formulation and only the slave side is defined it assumes that everything contacts everything else The second formulation is a less CPU expensive form of GENERAL e g edge to edge contact is not checked While the last formulation is general purpose and numerically efficient 8 2 1 ADDITIONAL OPTIONS SOFT 2 THE DEFAULT The standard contact search routine is based on nodes looking for faces i e segments Sometimes contact might be missed for a few steps and when finally engaged a large restoring force is required to separate the interfaces or contact might just not occur Additionally the standard penalty approach calculates the spring stiffness based on global material stiffnesses This can lead to contact instabilit
25. provided Femap model Inspect how contact was defined Export model using the LS DYNA translator e Open model in LSPP inspect how contact was translated i aa y and verify CONTROL cards for analysis OE e Run Analysis and contour stresses seat noes mars eee Mot LIGG Cerne be Paxil uti Cant St pA e Use the XY plot capability to verify reaction forces Would you recommend this design Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 71 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering Export to LSPP and Verify Loads Constraints and Contact Bares errr eee oe re te es De bis View Gorny stu sacar jeirga _ Mesh Transition TIED ORDRE VU AEII Assemity 1 FEM Porta Geom Parts Putt si SOS BGO Seer Ge rrns0ed 4 0 paa O90 147020 This image created by Application Model Checking General Checking Contact Check Highlight the Contact and hit the Check button Keyword Commands Used a ml Ar QPriicriir lt EBE D p GL AGA amp I Mechanics 2014 Run Implicit Analysis and Verify Load nie N UDE sen Er kun vri goe gerrsey at yona i Wesn Transuion ED SURFACE To ng i ak Bado Sumas joe Tore Esi pt cers Bodd aa 41448 ite Tews CES gar earl eee y 77200 ih GJ ML Peete Paet Partere mommersont 40 Mesh Transition TED SURFACE TO SURFACE AE 1 After contour stresses make an XY plo
26. restart file is written and LS DYNA continues A plot state is written and LS DYNA continues Dump contents of ASCII output buffers Write a plot state and terminate Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 32 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 4 6 WorksHop I LS DYNA GETTING STARTED EXAMPLE This workshop uses the LSTC Getting Started Example material and a LS DYNA model has been prepared This material can be found in the Students Class Reference P 70 e 05 Pa Alumumim 1 100 0 density 2700 kg m Notes folder modulus of elasticity 70 2 09 Pa Poisson Ratio 03 Goals coefficient of expansion 23 6e 06 m m K heat capacity 900 J kg K thermal conductivity 220 Wim K e Open Windows Notepad and build LS DYNA Keyword deck by hand entry Use comma separated format The vertical displacement due to a 70 0e 05 Pa pressure load can be calculated by e For each command consult the Keyword Manual e Analyze your model e Post process the results within LS PrePost PI _ 70e 05X1 _ Aj E 70e 09 e If time exists proceed to other examples Oc 04 m df apes omens vern BOG DER of set wart e tes Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 33 of 105 FINITE ELEMENT ANALYSIS CUA SONY TSN f ee
27. sectional area of the coupon The true stress strain response accounts for the necking of the cross section and can be elastically stated as shown on the graph on the right This method has its limitations and once the coupon starts to neck locally this approach is no longer valid and an iterative approach FAO must be used to calculate the true stress strain response E E In 1 6 l lo In many simulations it is not exactly critical to have the necking f a 1 6 Ao response accurately characterized since once the material starts to o neck we only have the end point data available and hence we draw a straight line from the initiation of necking to failure Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 44 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 7 1 2 REVIEW OF MATERIAL MODELS AVAILABLE IN LS DYNA The broad array of material models in LS DYNA can be Major Categories over whelming In the material manual they are listed in LS DYNA manual Vol II R7 0 pdf numerical order based on their insertion into the code Hence the elastic material model MAT 001 was the first material model developed These earlier models are e Elastic Heart Lung Tissue well validated since they have been used extensively e Elastic Plastic e Acoustic material over the years Later material models e g MAT
28. that there is a lot going on with LS DYNA md Internal Angles e Mesh surface and check Explicit Time Step see Model tip Data Contour Show Model Data Contour Note that recone the time step is in milliseconds given the unit system and ke that the element time step is defined by its shape Young Modus Property Dota Change elastic modulus from 70 to 35 and re contour pieanina Area time step Note change and then un do CTRL Z within Femap Setup Analysis Manager for LS DYNA Analysis The sene an analysis will run for 8 milliseconds with results sets at NA Wave Propagation Paampia intervals of 0 01 Make sure to select a Load for the Analysis Program 28 LS DYNA analysis Export to the same directory as the Femap inii Type 9 Poke Tria Dynamics model file While doing this verify the load application and the constraint set there ain t any Run Analysis Using VisQ ok cancel Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 23 of 105 FiNITE ELEMENT ANALYSIS fi NAF Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 Femap to LS DYNA with Mass Scaling Basics continued ee SR N Tasks fn Carn av hare Run LS DYNA model file using LS DYNA in rat et Co e Take a look at the Analysis Output and find the time step listing One will note that it is reduced by 0 9 from what Femap calculates The reason for this is to ensure that
29. the field variables for a given particle i with N j neighbors in the support domain is given by Lui and Lui 3 W is the smoothing function interpolation kernel and can take on many different forms depending on the type of problem being studied e g the cubic spline function is popular 77 is an Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Continuity Equation N Dp OW j J Conservation of Momentum Dv gf a OW j pe Let pe tt ax Conservation of Energy N De 1 25 Dt 32m j 1 pj y p Pi tmy oP 1 70P g 4P H p l Page 90 of 105 Pa q IN AC SSN VT HH AN NW FINITE ELEMENT ANALYSIS KS Il WAAR Predictive Engineerin a artificial viscosity term and H is an artificial heating term The general idea is to use a finite number of neighbors within a radius of influence also known as the smoothing length on the central element The graphic on the right depicts how the smoothing length can be visualized for a SPH mesh The method converts a set of partial differential equations PDE into a J D set of ordinary differential equations ODE The ODE s can be integrated in time with many different schemes in LS DYNA a multi step fractional step explicit method is used This means that there is a stability condition on the time step size CFL Otmin 4 my CTV is a constant and is typicall
30. 001 e Measure maximum displacement at the end of the beam and record this value on the table below Then increase mesh density in web record maximum displacement Lastly increase Plate Integration Points 5 and record maximum displacement Extra Task Open up LS DYNA deck in LSPP File Open Mesh Density LS DYNA Keyword File and look at the Keyword SECTION ot 1 Ler t ies a dese Aner A integration points are defined read the manual if necessary for clarification Go back to one element thru the web and change the element type to full integration fast Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 37 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering EP III I gt AUNSN RN 3 TN 5 2 4 WORKSHOP II HOURGLASS CONTROL HOURGLASS lsoparametric Shell Solid Elements and Hourglassing All under integrated isoparametric elements one Guass point have hourglassing present It is a non physical zero energy mode of deformation Fully Integrated formulations do not hourglass Additionally tetrahedron and triangular elements do not hourglass but are overly stiff in many applications Control Hourglass or Hourglass to set hourglass control Use default unless additional documentation is consulted e g see Review of Solid Element Formulations Erhart pdf Class Reference Notes Solid Elements Hourglass energy should be less than 10 of the
31. 22 NNN NVE 62 S3 WORKSHOP IX NEBE NN 63 8 3 1 Student Bonus Option Contouring Interface Pressures Ja 63 8 3 2 Workshop IX Comparison of Results sesenoseeneseesssersssrrssrrrssrerssrressrresrrrssreessrrossereseeessteesstrosrersterssteosstrosreessrersstrossereseeesseeeseeres 64 S4 INSTRUCTOR LED WORKSHOP VI CONTACT NEGATIVE SLIDING INTERFACE ENERGY Jeep 66 MENE NTN 67 8 5 1 Beam and Edge to Edge Contact MN vvrvrvrvrsreeeee 67 Boa NNN 67 Oe VPN EDO TOEL E ONTACT naien E E ar eE a a a he 68 ST TIED CONTACT FOR MESH TRANSITIONS WELDING AND GLUING sass serestosatencaensuieasaasaneasens nnavianateieciaas E aE EAA aa 69 L Hc Bs hess Or GUNE sesinin inasin NE EENES O ETE EEE EEEE NEEE AE EEEE 69 Go ONM ARE rO aE O T E E A 70 8 9 WORKSHOP XI A TIED CONTACT FOR HEX TO TET MESH TRANSITIONS TIED SURFACE TO SURFACE ccccccesecccseseeeecceeeeeeeeeeceteneseeeeeeeees 71 LNR 73 8 10 WORKSHOP XI B TIED CONTACT FOR GLUING THINGS TOGETHER BEAM OFFSET ccccceseccccseccccescccenecscesceceessceeeecsseuecsseeeseeensessueseseees 74 8 10 1 Instructor Led Bonus Workshop Bad Energy with Tied Contact ccccccccsssccccssececesccceescecceececasceseeneceseaeceseuecesaueeeseecessuncesseness 75 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 5 of 105 Predictive En gin de g LS DYNA Analysis for Structural Mechanics 2014 DENN 76 9g 1 GENERAL MASSAND STIFFNESS NNN 76 LVS 76 9 1 2
32. 3 stresses are only provided at the centroid and integration points Hence one will note significant differences in stresses due to lack of Jacobian extrapolation from the integration points out to the nodal points Of course if your mesh is fine enough the differences will be small A trick to overcome this limitation in solid meshes is to skin the solid with very thin layer of plate elements and then take your stresses from this layer This technique is well known and leveraged within the implicit community for obtaining high quality stresses for strain gauge and fatigue work Ir aar ATFs bka Drea al 5 gra Lae im Cr rch APA aa va fr PD l rnacn Ra Alat Cc Proprietary Information to Predictive Engineering Please Do Not Cc r Distribut Page 107 of 105 AAS VF n ee T FINITE ELEMENT ANALYSIS KSI Il TAR Predictive Engineering 2014 16 1 IMPLICIT KEYWORD CARDS AND RECOMMENDATIONS This algorithm was essentially developed for implicit analyses It is super expensive for explicit and not recommended However keep in mind that with the BT and DT CONTACT MORTAR contact card option one can always turn it off and switch to another contact formation for the explicit run BCSLIB EXT Boeing solver that is recommended for LSOLVR 6 implicit solutions for your standard plate beam CNRB CONTROL IMPLICIT SOLVER hex solid model I SOLVR 10 For large tetrahedral models the iterative solver performs well just like Nastran Not a big f
33. 342 m s and has a density of 1 000 kg m The viscosity of water is 0 001 Pa s e Run explore and then change mu 1 000 e SPH can also be used for a sloshing analysis Analyst s Note SPH doesn t need hourglass control but if a default value is applied see CONTROL_HOURGLASS it will get used Since the Null material has no shear stiffness the default hourglass coefficient can lead to significant energy losses Given this feature avoid the use of CONTROL_HOURGLASS for SPH simulations and apply hourglass control directly to the part of interest Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 95 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 14 4 SPH Wor KSHopP III VERIFICATION This workshop courtesy of Kirk Fraser compares the SPH method against the standard FEM method and discusses a common numerical difficulty with SPH method known as Tensile Instability This introduction is not meant to be anywhere complete but just to get the student started in how to debug their SPH models and what they might want to look out for while interrogating the model If this subject is of greater interest LSTC provides a two day course on the SPH method and the course notes can be viewed within Class Reference Notes SPH LSTC SPH Short Course Notes pdf Three models are provided IIIA FEM Method IIIB Tensile Instability and IIIC Recommen
34. 4 Bes vr ETFS es HAO LOCO AN CE Ur FDaCepwa ee HQ er Hes nisma baissas kranene hyrule wren 0 771308 qan GOAN ORAM Laem IG A bn ite eters With AUTOMATIC and SOFT 2 the correct contact behavior is noted Interpenetration between surfaces is noted which should never happen Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute LS DYNA Analysis for Structural Mechanics 2014 FINISH II CONTACT FORCE TRANSDUCER w ASCII outputs RCFORC amp RWFORC 1E 6 2 msandmn t e Pipe on Pipe Contact Finish pep Contact Forces E 6 o K 0 Es a m Although _SINGLE_SURFACE is used one can still obtain surface to surface contact forces The rigid wall forces are also reported with the ASCII option RWFORC Note that the rigid wall force is much greater than the tube to tube force since it represents the combined force of both tubes hitting the ground floor Page 64 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering FINISH III SECTION SHELL Thickness 50 eet LOTE 8 erie rere eet With SINGLE SURFACE contact initial interpenetrations are not instantly removed but automatically tracked This is equivalent of setting the IGNORE 1 option LS DYNA Analysis for Structural Mechanics FINISH IV CONTACT AUTOMATIC SURFACE TO SURFACE LS
35. A JOINTS BOLTS AND SPOTWELDS 11 1 JOINTS or CONSTRAINED JOINT To model the motion and likewise large deformation in engineering systems one needs joints LS DYNA has a very sophisticated set of commands that will allow one to model many types of common joints e g hinges spherical bearings etc If time permits we ll do a simple model pg een joint transl 3 tranls Cylindrical joint 2 transl 2 rot Planar joint Translational joint 1 transl 2 rot 2 transl 3 rot Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 85 of 105 FINITE ELEMENT ANALYSIS RAT IN is Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 12 LOAD INITIALIZATION BY DYNAMIC RELAXATION AND IMPLICIT ANALYSIS 12 1 INITIALIZATION OF GRAVITY BOLT PRELOAD AND OTHER INITIAL STATE CONDITIONS Stress Initialization Given that explicit analysis work often involves timesteps in the range of microseconds one can image the challenges of using an explicit approach to obtain quasi static or static stress states in structures subjected to uniform constant loading There are many applications where the start of the explicit analysis requires the initialization of steady state loads within the structure Here s a short list rotating equipment e g fans turbine blades or rotating flywheels pressurized vessels or tires bolt preloads shrink fit parts or spring mounted structures under con
36. ATIVE SLIDING INTERFACE ENERGY Contact sliding energy has three contributions i interfacial forces ii energy dissipated due to friction FS 0 0 and iii energy dissipated by contact damping on the Contact Card VDC 4 0 0 In a well defined model the sliding interface energy SLEOUT should be positive and perhaps no more than 10 of the total internal energy of the model However a common numerical pathology for contact is to generate negative sliding energy and is a red flag for that particular contact Numerically negative sliding energy is typically generated by i parts sliding past each other not friction and the penalty method has difficulty maintaining the surfaces apart interpenetrations and ii rough mesh large time step etc where the contact behavior has trouble pushing the surfaces apart cleanly and can get numerically lost in which direction to push the surfaces apart Analysts Note Itis common practice to report Sliding Energy in comparison to the analysis internal energy and also to provide a plot of individual Sliding Energy for each contact SLEOUT How to Fix when it is more than a couple of percent of internal energy but even then it depends Eliminate initial penetrations check for redundant contacts reduce the time step scale factor CONTROL_TIMESTEP TSSFAC lt 0 9 refine the mesh set contact card options back to default except SOFT 1 and IGNORE 1 explore the use of the DEPTH option
37. Analysis for Structural Mechanics 2014 3 FUNDAMENTAL MECHANICS OF EXPLICIT ANALYSIS 3 1 TIME STEP SIGNIFICANCE Flowchart for LS DYNA explicit C start gt If t 0 then initialize o 0 1 0 v w t 0 t 0 a t 0 m f f cvt 0 Compute internal forces mY gyri a E m mY ms o F E 0 0 At0 fa B 0 av Compute external forces Gr Calculate accelerations a m fet g cy Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 19 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 3 1 1 EXPLICIT TIME INTEGRATION e Very efficient for large nonlinear problems CPU time increases only linearly with DOF e No need to assemble stiffness matrix or solve system of equations e Cost per time step is very low e Stable time step size is limited by Courant condition e Time for stress wave to traverse an element e Problem duration typically ranges from microseconds to tenths of seconds e Particularly well suited to nonlinear high rate dynamic problems e Nonlinear contact impact e Nonlinear materials e Finite strains large deformations Time step CONTROL TIMESTEP At Simulation time CONTROL TERMINATION Pie Output time to d3p ot files States DATABASE BINARY D3PLOT Figure 1 How Solution Time and Result Outputs Are
38. CONTACT If anything this little dialog is to remind myself to be careful with Tied Contact s with OFFSET As mentioned the Offset option indicates that the algorithm is using the penalty method to enforce the locked motion between parts When there is penalty one has the opportunity to create negative sliding interface energy This behavior killed a rather simple analysis It was a bit amazing how it completely changed the behavior of the structure The fix is just to change the contact to BEAM OFFSET The two models are provided a 3 amp mep i ei gt E O at 5 ia Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 75 of 105 FINITE ELEMENT ANALYSIS o o Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 9 DAMPING 9 1 GENERAL MASS AND STIFFNESS DAMPING In dynamics there often can be some oscillations that the analyst would prefer to have damped out or to account for viscous behavior of some materials see Material Damping By default LS DYNA is undamped 9 1 1 DAMPING_OPTION Introduces Rayleigh proportional damping based on c alm ng p k e The mass damping constant a is specified by DAMPING GLOBAL DAMPING PART MASS and DAMPING RELATIVE e The stiffness damping constant p is activated by DAMPING PART STIFFNESS Mass damping is for low frequency response rigid body modes while stiffness damping is more effective at h
39. DIES The implementation of rigid bodies open doors to making your models run faster and allows you to focus on what is important and avoid getting distracted For complex system level models the use of rigid bodies is invaluable and if desired can always be switched later on to deformable What You Will Learn e How Rigid Bodies work within a simulation and how easy it is to switch to deformable to gather deformation and stress information e Defining a fixed movement i e punch movement as a load case e Getting more familiar with the LSPP Interface for making model updates Sve iy ee S Cope pee ae Student Led Workshop I Switching Rigid Bodies to Deformable Bodies Dim al The pendulum model starts out rigid and then is switched to deformable at the areas vee 2 last moment prior to impact See Class Reference Notes LSTC General eg DA Examples Manual and Examples EXAMPLES DEFORMABLE TO RIGID pen a no fy This example provides insight in how to do a Restarts See Class Reference Notes Keyword Manuals LS DYNA manual Vol I R7 0 pdf Section RESTART INPUT DATA Two files are provided that covers the complete run in the directory noted above Run the regular model and then perform a restart A small movie file is provided to show how the process works see Workshops Student Led Workshops gt me e T E gur at T Imam Proprietary Information to Predictive Engineering
40. FINITE ELEMENT ANALYSIS VG N Predictive Engineering LS DYNA Analysis for Structural Mechanics An overview of the core analysis features used by LS DYNA to simulate highly nonlinear transient behavior in engineered structures and systems LSTC Livermore Software QD Technology Corp iH Er a AS M 4 i AN FINITE ELEMENT ANALYSIS I Predictive Engineering 2014 Acknowledgements These notes were constructed from numerous sources but special thanks should be given to the following people Technical Support Team at Livermore Software Technology Corporation LSTC With special mention to Jim Day LSTC Philip Ho LSTC External to LSTC we have Paul Du Bois Hermes Engineering NV And DYNAmore Gmbh Germany Trademarks LS DYNA and LS PrePost are registered and protected trademarks of LSTC Femap is a registered and protected trademark of Siemens PLM Software Disclaimer The material presented in this text is intended for illustrative and educational purposes only It is not intended to be exhaustive or to apply to any particular engineering design or problem Predictive Engineering nor the organizations mentioned above and their employees assumes no liability or responsibility whatsoever to any person or company for any direct or indirect damages resulting from the use of any information contained herein Page 2 of 105 FINITE ELEMENT ANALYSIS PG N Predictive Engineering LS DYNA Analysi
41. MENT NALYSIS H e Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 18 FLUID STRUCTURE INTERACTION AND MULTI PHYSICS IN LS DYNA Fluid Structure Interaction with LS DYNA Multiphysics See Class Reference Notes Multi Physics LS DYNA Multi Physics ppsx Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 110 of 105 PA AT PX AN SN FINITE ELEMENT ANALYSIS kX AA Predictive Engineering 2014 19 LS DYNA RECENT DEVELOPMENTS Recent Developments and Roadmap 12t International LS DYNA User s Conference June 5 2012 Paa R p per nder sk sep sl sg sg Zanda secr Sor Orn See Class Reference Notes LS DYNA Recent Developments LSTC 2012 Conference Recent Developments pdf Page 111 of 105 FINITE ELEMENT NALYSI Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 END End of LS DYNA Analysis for Structural Mechanics Class Notes Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 112 of 105 FINITE ELEMENT ANALYSIS 9 i Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 Your comments would be welcomed On a scale of 1 to 5 where 1 means not satisfactory and a 5 indicates that it was very satisfactory How were the class notes and the workshops 1 2 3 4 5 Did the instructor do a good job in presenting the material 1 2 3 4 5 Was the pace of the class adequate to
42. Method for the Drop Test of Hand Held Mining Industry Electronics Hm matet bueyes V INE Be Be a PSC FALCON AMORE REV 4 7 DEG tomer High Speed Spinning Disk Locomotive Fuel Tank Containment Locamotive Fuel Tank Crushing Analysis Spinning Dea Buret Containment Temes 003001 Tees aa Conimers of Maximum Principal Strees p avd ipt 43 m ne 90821321 at oomi 270068 maser HHT G7 at abnt 129707 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 14 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 Airplane 16g Crash Analysis Impact Analysis of Safety Block Device Snap Fit Analysis Piastic Assemb y Snap Fit Tone 12 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 15 of 105 FINITE ELEMENT ANALYSIS N Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 16 of 105 FRON ering FINITE ELEMENT ANALYSIS Predictive Engin LS DYNA Analysis for Structural Mechanics 2014 2 IMPLICIT VERSUS EXPLICIT ANALYSIS LS DYNA is a non linear transient dynamic finite element code with both explicit and implicit solvers 2 1 WHAT WE ARE SOLVING Explicit only works when there is acceleration dynamic whereas an implicit approach can solve t
43. NASupport com and Keyword Manual LS DYNA User s manual SECTION_SOLID parameter ELFORM EQ 2 fully integrated S R solid intended for elements with poor aspect ratio accurate formulation EQ 1 fully integrated S R solid intended for elements with poor aspect ratio efficient formulation EO constant stress solid element default ae EQ fully integrated S R solid ij 1 2 EQ 3 fully integrated quadratic 8 node element with nodal rotations 3 3 EQ S R quadratic tetrahedron element with nodal rotations m D 1 point tetrahedron m 1 point nodal pressure tetrahedron EQ 15 2 point pentahedron element EQ 16 or 5 point 10 noded tetrahedron EQ 17 10 noded composite tetrahedron DSINI penlahodroan sem er In NOUIGIESS COM CONTROL SOLID ESORT 1 po I CE pm Me yee mer VEN Amen Sarto tert LS DOYNA Tene 0 00000909 Centours of Effective Stress wn rm ns 57 876 et come mans 016 5 at slemme bat i TPE er pees Gus INAO090S 1 yo T p et RIES A Skin EI n tt fo et vat nt tt Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 51 of 105 ot ee III fr DOANA MA 7 TT FINITE ELEMENT ANALYSIS H I INN 7 7 EQUATION OF STATE EOS MATERIAL MODELING An equation of state is required for materials that undergo significant deformation can be very large plastic deformation or a compressible fluid The Cauchy stress tens
44. NG TEN 30 ar BU IN IRN NANIA neni E E E EE E EE O 30 ae AO E E E EE 30 EG OUN E EN E rer cr er Tre te rer eer er ker re tr 31 44 REFERENCE MATERIALES AND PN 32 25 SUBMITTING BOM ANALYSIS JOBS AND SENSE SWITCHES and 32 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 3 of 105 Predictive En gin aarin g LS DYNA Analysis for Structural Mechanics 2014 AO WORK MOPE CS DINA GETNNG p 33 gt EPLENE ENE 34 SL FET 34 32 ONE GUASSIAN POINT ISOPARAMETRIC SEL ELEMENTSAND FIOURGLESSING crsccarssianervrgeswsnimutennvegitonescqrtanctaperenposatanesnisweasouuternaapnisaberndancpapomnenes 35 5 2 1 Instructor Led Workshop Ill Explicit Element Technology A Side BENding cccccccscsseseccceceeeseccceeeeessececeeeeeeeeeeeseeeuseeeeesseeeees 35 5 2 2 Instructor Led Workshop Ill Explicit Element Technology B Out of Plane Bending with Plasticity cccsccccsceessseeeseeeeeeees 36 S23 Sr OE EEE EEE ENE 37 5 2 4 Workshop li ed Ge ae EEE EE EEE EE 38 5 2 5 Workshop III Meshing for Explicit Success Meshing for Explicit Success Start modfem rrrrrrnnnnnnnnnnnnrrrnnnrnnnnnnnenrrrrnnnnnnnnnneneee 39 5 3 SCALAR ELEMENTS NNN ENN 40 5 3 1 Workshop Discrete Elements Non Linear Buckling AnalysiSj rrrrrnnnnnnrrnnnnnnnnnrrnnnnnnnnnrrnnnnnnnnnernnnnnnnnsernnnnnnnnsernnnnnnnesernrnnnnesesensnnnn 42 BTV 43 61 VEV NNN 43 EPLENE 44 LPEN 44 7 1 1 NNN NTT TN 44 7 1 2 Review of Material
45. Not Copy or Distribute Page 25 of 105 FINITE ELEMENT ANALYSIS PG 3 N Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 Femap to LS DYNA with Mass Scaling Basics continued Tasks Go back to the Femap model file and open up the Meshing Toolbox Pane Decrease the mesh sizing on the right hand side curve in the middle by four increments Although we are making the mesh size larger i e the timestep should increase one will note that the explicit time step will decrease due to non uniform shaped elements used to transition the mesh This is more reflective of FEA reality where the mesh is rarely uniform Operator Eory ode aber 16 De prte Eig y i j gt abe t i ae r yeza nea pman i sees tv EN Vy amp 7 t eV pul Set Model Vata to contour pg TR DK a eh i de a et ved i l m JU O LJ E wy Si si gt Ne NA vee va SELEN Coin NY ier Med w Detete 2 0 hardetetatio etamin Agped vi Export Model to LS DYNA analyze and create a plot as in the steps above Apply mass scaling to arrive at an explicit time step of 0 0334 ms See LS DYNA Keyword CONTROL_TIMESTEP and insert this keyword into the Femap Analysis Set Manager see graphic andrerun the model Note keywords can elis ts be entered in a simple comma og separated format as shown in the Peber Based Hate Parte graphic on the right and when the din india deck is exported they are inserted into the LS DYNA an
46. S DYNA Analysis for Structural Mechanics 2014 14 1 3 TYPES OF SIMULATIONS WITH SPH e Impact and ballistics e g bird strike e Fracture and fragmentation e Fluid structure interaction e g sloshing e Linear and non linear vibrations e Microstructure evolution e Heat transfer e And many more 14 1 4 COMMON KEYWORDS FOR SPH e CONTROL SPH e SECTION SPH e CONTACT AUTOMATIC NODES TO SURFACE with SOFT 1 is recommended e All EOS and most MAT_ see Keywords manual for details 6 and 7 cards can be directly used e Most of the standard keywords work for SPH e Node sets need to be used to define contact boundary conditions etc Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 93 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 14 2 SPH WORKSHOP I GETTING STARTED This example courtesy of Kirk Fraser is geared toward demystify the process of creating and running a SPH model The concept is that any box sphere cylinder etc can be used to create a SPH mesh Once the mesh is created the model is setup and analyzed Start Up e Open the Femap model SPH SPH Workshop 1 SPH 1 Ball and Plate Example Setup for SPH modfem and then fire up the movie file Goals e Get familiar with the concept of creating a SPH mesh e The procedure is pretty simple and offers flexibility e Visualize your SPH spheres e Convert mode
47. Sos A orakel Bites Stress rs ree P morae e a O O EEE U as gg Morkahog KIV mit apiet Turies Spar Up Sez ar ais i i were a a Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 89 of 105 FINITE ELEMENT ANALYSIS PN Predictive Engineering 2014 LS DYNA Analysis for Structural Mechanics 14 SMOOTHED PARTICLE HYDRODYNAMICS SPH 14 1 INTRODUCTION A short introduction video for this section can be found in Workshops SPH Introduction to SPH Modeling 14 1 1 ALITTLE BIT OF THEORY SKIP THIS IF YOU DON T LIKE MATH Kirk Fraser Sr Staff Engineer Predictive Engineering Smoothed particle hydrodynamics SPH was developed in the 1970 s by Monaghan Gingold and Lucy for astrophysics problems Monaghan has published an enormous number of papers on the SPH method Libersky et al 1 were the first to apply the method to solid mechanics problems Lacome 2 was one of the first to implement SPH in LS DYNA Mesh based methods do a great job for all kinds of engineering calculations When the deformation gets really large mesh based methods start to fail due to negative element volume excessive mesh distortion and or mesh tangling within contact region which then causes problems with the explicit time step and so on and so forth SPH is a Lagrangian based mesh free method that can handle unlimited plastic deformation The rate of change of
48. TI PHYSICS IN LS DYNA ssssseseseeesesesessesesesesesensesesesesesseseseseseseesesesesesee 110 19 LODINA RECENT DEVELOPMENT ririri nen E tonnes teahassirnanossaiaeeasstanreniiaataeieceacassetsaisuagas 111 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 7 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 END N 112 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 8 of 105 FINITE ELEMENT ANALYSIS Predictive Enginesring 1 1 1 LS DYNA Analysis for Structural Mechanics 2014 INTRODUCTION WHAT THE STUDENT CAN EXPECT This class is directed toward the engineering professional simulating highly nonlinear transient dynamic problems involving large deformations and contact between multiple bodies What this means in more layman terms is that we will provide a realistic foundation toward the practical usage of LS DYNA Prot pr 1 2 riet WHAT WE COVER Explicit FEA Mechanics The technology of creating accurate nonlinear transient FEA models How to do your own research to create more advanced simulations Our condensed experience and that of our colleague s toward inoculating you against repeating our mistakes How WE DO IT The class covers the basics in a hands on manner as taught by an engineer that has had to live by what they have killed Each day will have six to eight
49. TN UNN 76 9 1 3 Material Damping e g elastomers and foams EEE 77 9 1 4 Student CE EEE EEE EE EE EE avireetedee wa a ot 77 9 2 INSTRUCTOR STUDENT LED WORKSHOP VIl SG EN NN EAN ANTEO REES 78 JE PURE O T PE E E A EE AN E AA E E NE EE 79 10 LOADS CONSTRAINTS AND RIGID NN 80 10 1 DN T cutscenes ten 2 aw ge oo ents perc ated odie so been unease rd es deennemue eecenecrannnne 80 10 1 1 Initialization Loads cca edie tens vcd treed cereus atiasnnesoy cw ins dhivpn ed edanwase nds annie vcehas dvatedeseddeniasebairenedineaibaseeosenesedeetiunenaanensie eas beeneealecntnsekeeeeiiaes 80 10 1 2 PN NNN 80 DI NNN 80 10 2 WORKSHOP APPLYING MOVING NNN 81 10 3 WORK HOPF AIE DROP TE TOFPRE NENNE 82 VL NNN 84 11 CONNECTIONS VIA JOINTS BOLTS AND SPOTWELDS sccsscsdsiccnisuceticcvacetaiedponnnabeadacncsnanetinbendaded cbiwasqabeadieavebiecatnesndeiateass 85 11 1 VOUS OR CON a RUINED NN 85 12 LOAD INITIALIZATION BY DYNAMIC RELAXATION AND IMPLICIT ANALYSIS ccc ec ccecscscscsceceseeeeeeeeeseeeecuees 86 12 1 INITIALIZATION OF GRAVITY BOLT PRELOAD AND OTHER INITIAL STATE CONDITIONS asset eessaark antdne 86 12 2 WORKS ROP AII DYNAMIC NNN 87 13 IMPLICIT EXPLICIT SWITCHING FOR BURST CONTAINMENT i eeeeanunanenennnnnnnnnnnnnnnnnnenvnennnnnnnnnnnnnnnnnnnnnnvnensnnnnnnnunnnnnnnnenene 88 13 1 HIGH SPEED ROTATING EQUIPMENT CONTROL ACCURACY Vea 88 13 1 1 Workshop XIV Implicit Explicit Turbine Spin UpP ssssssssseesssenssseresserssresssersssrreseerssrerssrre
50. added mass my choice is MSSCL 2 DATABASE_EXTENT_BINARY BEAMIP 4 amp STSSZ 3 This is very useful to check your model for mass scaling effects To contour the added mass see LSPP Fcomp Misc Time Step Size whereas in this case it is the added mass Please note it is really mandatory if you are going to be aggressive with your mass scaling to contour this item and be aware of where you are adding mass to your structure Page 105 of 105 FINITE ELEMENT NALYSIS H e Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 15 9 ETC I m a big fan of building stupid simple itty bitty test models to evaluate a proposed behavior A standard downfall of many simulations is an attempt to model all the physics out of the gate without prior evaluation of the effects of individual items in brief the more complex the model the more heinous is the debugging Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 106 of 105 FINITE ELEMENT ANALYSIS IC AVALIA RA mn larm Lan mm f Aim Me JE Predictive Engineering 16 IMPLICIT CHECK OUT AND RECOMMENDATIONS Implicit analyses are generally much more difficult to obtain convergence and that is often the downfall of its usage To truly get spun up to speed on implicit the student should start by reading see Class Reference Notes Implicit Analysis LSTC Implicit Class Notes by Morten Jensen 2012 Draft pdf For implicit
51. ah bodies within the simulation but at a fraction of the numerical cost of dragging around a fully deformable body For example the model on the right is of a deep drawing operation and only the plate is deformable ar e Note Rigid bodies cannot have constraints applied to them To constrain a rigid body the CMO flag is set within the MAT RIGID card For a very nicely done reference please see Class Reference Notes Rigid Bodies LS DYNA Intro Class Chapter 9 Rigid Bodies pdf Other Common Usage Rigid Links and Joints eater Nastran multi point constraints MPC equations of which their two most common flavors are the RBE2 and RBE3 elements are translated into two different LS DYNA formulations Our discussion will just focus on the RBE2 translation The RBE2 is translated into a rigid body where the nodes are placed into a group and then constrained rigidly per the number of dependent DOF s specified in the RBE2 element The inertia or mass properties for this nodal rigid body are obtained from the elements attached to the nodes of the rigid body Although this may sound a bit odd coming from the implicit world in explicit mechanics everything needs a bit of mass to enable its calculation Hence for the rigid link to behave correctly it borrows mass from its attached elements and two node CNRB s should be avoided The LS DYNA card that is used is CONSTRAINED NODAL RIGID BODY CNRB with the CMO card speci
52. all impact force RWFORCE via PADD on XY Plot Dialog Lastly if one has time setup model to show contact pressure see Student Bonus Option 8 3 1 STUDENT BONUS OPTION CONTOURING INTERFACE PRESSURES LS DYNA doesn t automatically generate interface pressures developed during contact To obtain this information three items are required i DATABASE_BINARY_INTFOR DT time interval must be set ii Print flag s on card 1 of CONTACT must be set to SPR 1 and or MPR 1 and iii and upon analysis LS DYNA Program Manager one must use the Advanced tab and include the Interface Force s provide your own filename option This creates a separate binary file can then be read by LS PrePost as a separate post processed item just load the filename specified above Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 63 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering 8 3 2 WORKSHOP IX COMPARISON OF RESULTS START FINISH CONTACT AUTOMATIC SINGLE SURFACE SOFT 2 CONTACT SINGLE SURFACE EITE Ea TT ee Maap AEIIRTTRE me WALT DW adagio tte tata at oe Geers 106 m ne Stee ie oe oe Gow 106 ape See oe Contact Swan a l Pipe on Pipe Contact Fintan amp amp Teve 820100085 Yy A a i lap i 3 s is v vg ug lA lt lt e P TE E a Ka si 8 KL ogoenro ufe
53. alysis file x Dotsint 4 WerDetetals Hosen Supped gt Date ara Sues 0 nrDeesake Perey Sood O Oeltted 4 Nealeteter nede Gapped M Fleeweex hane F re g amp siaem Resy Memes 1711 Enmspets 1614 Peel Itt Cond Geo COR TWOL_TURESTER A mr Marval Centro Start Text Or _ Ship Sterdars End Tene Ce Prev mote oe Cancet Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 26 of 105 FINITE ELEMENT ANALYSIS RI Hi Predictive Engineering 2014 Femap to LS DYNA with Mass Scaling Basics continued The following task is to get comfortable reading the LS DYNA output Although this information can be found in the d3hsp and Btn em Sec i oe ie VEE frr Lori r messag files it is a bit easier to grab it directly off of the screen 28 33000602 de 2 Atoz oie a fie n i 3 t 6 GTS0E 02 dt 3 ME O2 write d3plot file The information we are looking for is the percentage increase of at 1 aE on at 3 Be rite Fete tiis r A s write G mass that the DTMS option within the CONTROL TIMESTEP has EEEREN EEEN tis 5 7 4 L added to our model In this example we have added mass of 10 t 3 00S1E 01 dt 3 206 02 urite a3plet File cpu Keen te SONO acon TS iaooe 16 9 M nb A klag por sere GaS 1796 nanesecands Objective I eyiuanedicne tine t Sipin 7s eet WNO ears estimated total clock tine ver Ohra O s
54. an of auto stepping It will sometimes help but CONTROL IMPLICIT AUTO IAUTO 1 often is slower than just specifying a small DTO within the CONTROL IMPLICIT SOLUTION card Recommended Only for Pure Implicit Analyses where Stress Recovery in the Elastic Range is Important Since for Explicit Analyses it Generates 4 to 8x larger D3Plot Files due to Integration Point Stresses A negative number dumps out all integration point MAXINT 3 stresses DATABASE EXTENT BINARY This dumps out all the integration point stress data for NINTSLD 8 solid elements Very useful for implicit work if you would like to something that approaches a normal linear stress result This command will correctly extrapolate the integration point stresses for ELFORM 20 shells ELFORM 18 solids LSPP LS PrePost v4 1 Extrapolate 1 and aligns well with Nastran type element results with MAXINT 3 Note For shells one can use 1 or 1 only for solids is 1 required Page 108 of 105 Finite ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 17 DISCRETE ELEMENT METHOD Discrete Element Method DEM Smooth Particle Ne allie SPH and Arbitrary Lagrangian Eulerian ALE Kirk Frase bler ve em See Class Reference Notes DEM Predictive Engineering Discussion of LS DYNA Meshfree Methods pptx Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 109 of 105 FINITE ELE
55. analyses used for the initialization of explicit runs it is recommended to use the CONTACT_ birth option BT to turn off all non essential contacts until the start of the explicit run Likewise use BOUNDARY_SPC_NODE or SET BIRTH DEATH to lock down any parts of the structure that are not relevant to the implicit initialization These two steps will greatly facility a fast and efficient implicit kick off For troubleshooting LS DYNA implicit analyses don t be shy about locking down SPC ing large parts of your structure and ripping out contacts and nonlinear material laws Once you have something running it is a lot easier to add in complexity step by step by step than struggle with behemoth that is taking 30 minutes to finally error out LS DYNA also can automatically switch to explicit if the implicit solver is struggling to find convergence see Class Reference Notes Implicit Analysis LSTC Implicit Class Notes by Morten Jensen 2012 Draft pdf page 42 It may sound attractive but don t really expect it to perform miracles since it most likely has to return to the implicit solution to finalize the run and most likely it would just fail to find convergence again please note that most typical LS DYNA runs are so highly nonlinear that often times it is a miracle that the implicit run even works A little thing to note is that LS DYNA has near identical element formulations to that of standard implicit codes but as of this writing Fall 201
56. asticity approach available in MAT 024 Data is wae estimated from the presented curve and corrected to true E ma stress strain up to the point of necking After necking a uy PENTIL Ml straight line is drawn to the ultimate failure point The final S PN processed true stress strain curve is shown on the right ON The data spreadsheet can be found within the Workshop JJ file folder 0 0 05 0 1 0 15 0 2 Strain Goal Get Comfortable With Constitutive Modeling te ope amt Run initial model Elastic Plastic Failure Start dyn and me oaa oo mcd range Lt investigate the current material law Plot von Mises and min 203220 at olema 687 10810 08 _ max 300633 at elem 670 Plastic Strain History Plots Change material law to Piecewise Linear Plasticity using Excel Spreadsheet or PDF file in Workshop Directory and rerun model Note correct format for entering plastic strain Compare results check hourglass energy balance and validate material law model zt GR GO D D e u ee neve 112393 buseo ret D Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 47 of 105 FINITE ELEMENT ANALYSIS Predictive Enainesring LS DYNA Analysis for Structural Mechanics 2014 7 3 STRAIN RATE SENSITIVITY OF METALS e This mechanical metallurgical behavior is due to the movement of dislocations within the crystalline ee ea eee curves for various metallic Austenitic Steel alloys
57. avior in a birth death manner For example one can apply constraints to all secondary structures that are not relevant or in the case of a turbine analysis not spinning to ensure that the implicit analysis runs smoothly and then remove them i e death once the explicit analysis starts up Likewise this can be done with contact behavior within the model to avoid numerical difficulties during the implicit solve Both of these tricks can dramatically speed up the implicit solution without affecting the accuracy of the simulation Analyst Note The implicit to explicit switching can be a bit tricky What is recommended is that one switches the simulation to explicit prior to desired end point of the implicit simulation For example if the implicit end point is 1 0 and the implicit time step is 0 25 then the curve used to control the switch from implicit to explicit could be set to any time point after 0 75 and before 1 0 e g 0 9 and the explicit on switch set to the end time of the implicit simulation e g 1 000001 13 1 HIGH SPEED ROTATING EQUIPMENT CONTROL ACCURACY For structures that rotate it is recommended that the CONTROL ACCURACY option OSU 1 and INN 2 be set The OSU option adds additional terms to the stress update and improves the accuracy of the simulation while the INN option sets invariant node numbering to ensure the accurate calculation of element forces within elements that are become highly twisted and o
58. correctly fundamental contact modeling problems VDC 20 Contact is often noisy and adding 20 damping can be a nice option to smooth things out It is B one of those tweaks that is often times worth investigation once you have the model working ISYM 1 If you have symmetry faces via SPC s please be aware of this option Page 103 of 105 TANN Z J IN KAT TRY FINITE ELEMENT ANALYSIS K Predictive Engineering 2014 15 7 CONTROL CARDS WITH RECOMMENDATIONS Commonly used options are shown in the table below For dynamic structural only analyses this option provides a CONTROL_BULK_VISCOSITY TYPE 2 mild smoothing of oscillations with little performance or energy cost If you have small penetrations in your model this option IGNORE 1 makes good sense but don t expect to help you with large modeling contact errors ISYM 1 Symmetry Control Calculates hourglass energy and sliding interface energy Although it adds computational expense it should be added and checked and then one can delete it later CONTROL HOURGLASS IHO 4 amp QH 0 05 Improved formulations and the default value of 0 1 can often be lowered if needed ESORT 1 Ensures highly twisted elements don t cause harm to your CONTROL SHELL simulation E Del highly di h Reh NFAIL1 1 amp NFAIL 1 eletes ig y distorted elements prior to them causing harm to your simulation Automatic sorting of tetrahedron and pentahedron elements to treat degenerate tetrahedron an
59. d pentahedron elements as tetrahedron formulation 10 However most LS DYNA models don t have tetrahedrals but it is included for completeness CONTROL_CONTACT CONTROL_ENERGY HGEN 2 amp SLNTEN 2 CONTROL_SOLID ESORT 1 Just admit it you ll going to use some mass scaling If so don t DT2MS negative forget to contour the added mass to verify it didn t get to crazy see below for recommendation on contouring added mass ERODE 1 Just good practice when using solid elements If the element CONTROL_TIMESTEP Page 104 of 105 N FINITE ELEMENT ANALYSIS KZ SF VINNA predictive Engineering ad ctural Mechanics 2014 becomes highly distorted to the point of a negative volume it ll be deleted without killing the simulation If one is using RB2 or 3 elements from a Nastran model or directly using CNRB s this command will add plot only elements to the d3plot file and allow visualization of the elements CONTROL RIGID PLOTEL 1 or 2 15 8 DATABASE CARDS WITH RECOMMENDATIONS This is the minimum recommended set Please note if you have rigidwalls in your simulation you should also have RWFORC enabled Beam elements are isoparametric elements and have integration points setting BEAMIP 4 covers the default beam formulation STSSZ 3 is to dump out added mass information and then also check MSSCL 1 or 2 to indicate incremental or GLSTAT MATSUM I ON SLEOUT amp SPCFORC percentage increase of
60. ded for the student to compare and explore the SPH method The workshop movie file provides all the steps and a bit of discussion Along with learning about tensile instability the student will learn how to post processes SPH results and create comparison graphs between principal stress and contact force FEA Mesh Benchmark SPH Default FORM 0 SPH FORM 7 z m z EEE i Ge Se wt Oy eee See amp ne we a a i sol Poet 2 Se wee Oe l SS ee 5 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 96 of 105 ANN FINITE ELEMENT ANALYSIS KL Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 14 4 1 SPH VERIFICATION lll WORKSHOP BONUS At the end of the prior workshop the student should have made graphs of the maximum principal stresses and contact forces between the FEM SPH Tensile Instability and SPH Recommended In particular the contact force graph will have quite a bit of numerical noise LSPP provides a Filter option to remove such noise The student should explore this option since it is invaluable in the interpretation of dynamic results Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 97 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 14 5 SPH WOorksHop IV BIRD STRIKE The Bird Strike workshop essentially leverages all the prior worksh
61. e i LS DYNA Projectile Analysts Through Al Foam Panel Time 0 00048995 De e PE ooo IG AETS 06953 JU 2 B7TS BOVE Tar r om sham 5 D La S amp E a Ay ey ae OF ae AAO E o AEE ai RENA EE rT A Pree Y Bo TOE 40 83 ee ooo ge atu Jun rrnanoneT JYUlked quat 0 153551 044531 00040090 0 471190 dA h 16 152 pA Je EE atu Gus ranmi Come select pn angie rgrt cieh to eda Port Rereterer Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 62 of 105 FINITE ELEMENT ANALYSIS Predictive Enainesring LS DYNA Analysis for Structural Mechanics 2014 8 3 WorKSHOP IX UNDERSTANDING BASIC CONTACT MECHANICS Often times the challenge to modeling contact is not setting up the contact Keywords Discussed model but checking the results In this workshop the goal is to verify the contact paTABASE behavior and plot the contact force for each tube The contact behavior should ASCII GLSTAT RCFORCE SLEOUT make good engineering sense RWFORC Workshop Tasks _BINARY_INTFOR e Run model Pipe on Pipe Contact Start dyn and look at contact behavior e Investigate logical contact behavior and change to Automatic and try using RIGIDWALL GEOMETRIC ELAT SOFT 2 FINISH I T e Measure contact forces between the parts CONTACT FORCE TRANSDUCER and set ASCII file parameters RCFORCE amp RWFORCE 1e 6 FINISH II e Plot rigid w
62. e modeling of materials is by specifying some sort of material based failure criterion My favorite approach is to use the MAT ADD EROSION card to specify the exact failure criteria that is needed For metals one approach is to set the EFFEPS maximum effective strain at failure to 3x MXEPS maximum principal strain at failure This ensures that the material does not prematurely fails under compressive plastic deformation but still remains true to the mechanical test data Exercise Open LS DYNA manual Vol II R7 0 pdf see Class Reference Notes Keyword Manuals and read the MAT ADD EROSION card section Kepenmi brast Form LS DYNA Analysis for Structural Mechanics Fry Pack MAT ADD BHOGION_ TITLE fan 40 haw ED Mabe Uae Portetieber TITLE i MID Ba MAPRES MNEPS Bu og E MNPIEES HOPI a1GVM MxEPS a 3 DAM IMGTYP LCSOG ECRIT 9 LEAD EPSTHIN 90 Tata tee Seale DO Lage 0 Tate deletes cord amp 00 SIGTH DORIT 2014 saj Accept Delete Detaut Duns Subsys 1 Senny NUMFIP NCS 1D 1a IMPULSE FAILTM EADEXP LOREGD Another way of modeling failure is by CONSTRAINED TIED NODES FAILURE With this formulation bond failure can be modeled in a direct and simple manner by setting the plastic strain required to pull apart the nodes Of course this plastic strain is taken from that elements integration point The setup for this failure mechanism is to take a clean mesh and let LSPP create th
63. e tied connections This is done by breaking apart the elements and then tying together the adjacent nodes Upon failure the elements fly apart but are not deleted An example of this concept is can be found at www dynaexamples com Intro by J Reid Sphere Plate Given all that prefer the simplicity of MAT ADD EROSION Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 55 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 7 9 W ORKSHOP VII MODELING GENERAL FAILURE 2014 Objective Modeling of material failure is not as complex as one might think if a reasonable expectation is taken from the outset It should be noted that All models are wrong but some models are useful and hence when trying to replicate failure in a structure one should strive for upmost simplicity prior to adding complexity This concept segues into another saying elegant simplicity is deceptively difficult to achieve within the MAT 24 card is improved upon by using the MAT ADD EROSION approach Model Introduction A flat bar is held at its end near the hole and the rail is given an initial velocity to impact against the bar and move it upward 9 Workshop Tasks Student Bonus Open up LSPP with your final model file and increase the initial velocity of the bar and note the results Open Flat Bar Bending Start dyn and inspect material law used for t
64. ebsite Blog2 d3view com 00 Eusa impact Shells Mo Buk Viscosity 100 Eso impact Shells Quadratic Linear Bulk Viscosity D p t00 t00 et a Pal ar i i Koll 2 2 Time E 03 Time E 03 Analyst Note Although not necessary it is recommended to add CONTROL BULK VISCOSITY to any transient structural FEA analysis since it tends to slightly damper out crazy oscillations at little numerical cost and with little energy cost Page 79 of 105 gt EAS FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 10 LOADS CONSTRAINTS AND RIGID WALLS 10 1 LOADS 10 1 1 INITIALIZATION LOADS The most common initialization load is INITIAL_VELOCITY_option For example for any type of drop test the structure is given a uniform initial velocity and then allowed to instantaneously hit the target The other common initialization command is INITIAL TEMPERATURE for thermal analysis work 10 1 2 POINT AND PRESSURE LOADS There is nothing complex to these loads Point loads are those loads applied at nodes while pressure loads are applied over element faces In LS PrePost pressure loads are applied onto segments i e faces 10 1 3 BopyLoaps LOAD BO DY_option Body loads are most commonly defined as constant acceleration to capture the effect of gravity Keep in mind that LS DYNA treats body acceleration loads differently and that to obtain the same direction o
65. ed whereas the low frequencies rigid body bodies are not influenced thereby a lot of artificial mass can be added to the system without adulterating the global solution e This method is very effective if it is applied to limited regions with very small critical timesteps SMS is invoked with the IMSCL command over a single part or multiple parts Solution time is 10 seconds for no mass scaling and 5 and 6 seconds for SMS and CMS respectively SMS is more computationally expensive but has large benefits for some models Example Courtesy of www DynaSupport com Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute DEE ARE ik heter di al TET ST EN ket On bag te Mew p Ge frr P eee Ge at BE Petal ahd N in Kinetic Energy E 3 an in Qo e LS DYNA Analysis for Structural Mechanics 2014 Time step ranges from 2 89 to 4 74e 4 No Mass Scaling Contours of Time Step min 0 000289222 at cham 4001 Mmars0 000474061 at comet 4338 To atu Jui Fringe Levels 7414 04 5564 14 37 14 08 1964 04 4 3010 04 12156004 34720 04 1447 ee 3 2524 04 3 6774 04 7970 04 la t or ve reENddeog 0 ko a AE eS e 02 0 8 Page 28 of 105 FINITE ELEMENT ANALYSIS 7 Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 3 4 IMPLICIT MESH VERSUS EXPLICIT MESH CHARACTERISTICS
66. eling of elastomers soft plastics and rubbers C Plastic and foams Plastic materials have very unusual engineering stress strain curve due to necking However once corrected for true stress strain the curve looks very reasonable The curve on the right is for a uniaxial test performed on rubber Experimental uniaxial data can be directly entered into the material card For the modeling of rubbers this is a very common approach Viscoplasticity This concept is fundamental in the ea modeling of plastic rubber or foam fA materials These materials deform via ND the stretching of their long chain hydro JE carbon network As such they are very sensitive to strain rate effects As the strain rate increases their complete P o Figure 27 1 Uniaxial specimen for experimental data Rubber stress strain curve will shift upward plen Bay Analyst s Note Whenever a new material model is simulated a virtual test coupon analysis should be done and the results compared to the mechanical test d d ta change in gauge length _ AL gauge length L Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 49 of 105 AK JA KAZARN FINITE ELEMENT ANALYSIS KJA Tl N AN icti i i LS DYNA Analysis for Structural Mechanics Predictive Engineering LS DYNA Analysis for Structural Mechanic 2014 7 5 MATERIAL MODELS FOR MODELING FOAMS The following table presen
67. ence Notes Damping titled Baseball Ball Material Damping Example dyn along with a movie file of what one can expect to witness fet ta OVE NSR at Vectra Arayan Fergie s ONAN p ee 5 gt Mec Yew Geumetry 004 Apr cetor Seterg tek NIKE BASELINE BAT STUDY Time 0 0017098 Arama Eigen Fee gt hast N he 1 lims DEI TRIS lt 4 Obl 172202 anse DB G GIOA G GSV Ges vaATDADGSH 4 ss gr Hawehall Had Material Damping bammphe DOG mr an ERS ES Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute 2014 i p og JG RAS TOs 6 ha 3 w r LJ amp o Sz a A a COLOR 177 Hoop Page 77 of 105 Finite ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 9 2 INSTRUCTOR STUDENT LED WorkKSHOP VII DAMPING An example is given of a vibration problem run by NX Nastran normal modes analysis and then by undamped and damped transient analysis If the student desires the model is easy to switch to LS DYNA implicit for an Eigenvalue run Script The model is inspected within Femap and and Nastran normal modes analysis is run The first natural frequency is noted The model is then exported out to LS DYNA and directly analyzed A History plot is made of node 1 in the Z direction Using LSPP X Y plot tools under Oper a fft is applied and note the frequency at the first big spike on the FFT graph The model
68. ered at the end of these course notes Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 50 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 7 6 WoRrRKsHop VI MODELING AN ELASTOMER BALL WITH HEX AND TET ELEMENTS Solid Element Meshing for Soft Materials Hexahedral versus Tetrahedral Whenever possible a hex mesh should be used for the modeling of soft materials The recommended element formulation is ELFORM 1 hex or 13 tet Both are one point Guassian integration formulations and can handle large deformations without element aspect failure problems not negative volume Another recommendation is to use ELFORM 1 for non perfect hex s Please take a read within Review of Solid Element Formulations Erhart pdf Class Reference Notes Solid Elements and it has an excellent section on Hourglass Control Element Quality and Negative Volumes Large deformation behavior in soft materials is highly sensitive to mesh characteristics In an ideal situation brick elements are always preferred due to their regularity of formation shape and distribution Even with a high quality mesh under high compression loading brick elements can generate negative volumes The best solution is to refine the load application and or improve the mesh quality Prior to embracing any one path it is recommended to consult references i e www DY
69. essary to change this factor for shock loading or for increased contact stability with soft materials Cwavespeed Based on this conditions the time step can be increased to provide faster solution times by artificially increasing the density of the material e g mass scaling lowering the modulus or by increasing the element size of the mesh Dreanriat sy radictiva Enoinaaringan Plaaca Nn Nat Canu nr Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 21 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 3 3 Mass SCALING EVERYBODY DOES IT BUT Nosopy REALLY LIKES IT Explicit Time Step Mass Scaling Control_Timestep e Mass scaling is very useful and directly increases the timestep The concept is simple Larger Timestep Lower Solution Time e One can also just simply increase the global density of the material for non dynamic simulations i e where inertia effects can be considered small e CONTROL TIMESTEP Conventional mass scaling CMS negative value of DT2MS The mass of small or stiff elements is increased to prevent a very small timestep Thus artificial inertia forces are added which influence all eigenfrequencies including rigid body modes This means this additional mass must be used very carefully so that the resulting non physical inertia effects do not dominate the global solution This is the standard default m
70. ethod that is widely used e With CMS a recommended target is not to exceed 5 of the mass of the system or 10 of the mass of any one part Added mass can be tracked with DATABASE options of GLSTAT for entire model and MATSUM for individual parts Note All general recommendations and tips are given in Explicit Model Check Out and Recommendations Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute L eng theiement E p Mass Scaling 70 1 02 2 71x1076 ATimstepcr TSSFAC 5 384 mm ms CAtuminum 0 0 9 0 0371 0 0334 5 384 0 9 0 037 0 0334 ms e LS DYNA time step is different between Femap and LS DYNA due to TSSFAC 0 9 default e Mesh quality affects Time Step just tweak it ATimestep 0 9 Clean Mesh Mesh Toolbox Tweaked Page 22 of 105 FINITE ELEMENT ANALYSIS Predictive Enainesring LS DYNA Analysis for Structural Mechanics 2014 3 3 1 WORKSHOP FEMAP TO LS DYNA WITH MASS SCALING BASICS What You Will Learn Units kN mm ms kg How to build your first LS DYNA model from the ground up Linear elastic material model of aluminum and how to improve the run times using mass scaling Tasks Open Femap model Femap to LS DYNA with Mass Scaling Basics Start modfem and create LS DYNA Contoe Data From Isotropic Material and then plate property with thickness SENSE 1 0 investigate Formulation for plates and just note mn
71. f gravity in Nastran one must switch the sign of the acceleration load Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 80 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 10 2 WORKSHOP APPLYING MOVING BOUNDARY CONDITIONS 2014 This workshop is quite simple and just demonstrates how one can create a variety of boundary conditions using some of the LS DYNA commands Objective Interrogate the Femap model and notice how the load condition is defined with a 5 Hz function with gravity We are going to bounce the cube down this shaker but the model needs some work Tasks Setup contact between the cube and the shaker pan within Femap with a static friction of 0 3 Define the two Regions using Properties and then setup the Connector MC eee ke ve kn Ame me DT cay etree Lemery Ot Following this procedure define glued contact eee TIED between the shaker table springs the lats coll ro and the bed supports Keep it simple and use us an OFFSET To bridge the gap between the components set the slave master thickness to 2 For ease create Regions using Properties Set up Analysis Manager for a run time of 5 0 seconds with a results frequency of 0 05 Run model Please note estimated run time and time step e Assume we don t need to have the shaker table bed supports as deformable switch the material mode
72. f the structure s tip This done by creating another curve with the following four points 0 0 5e 4 O 6e 4 1000 1e 2 1000 and SIDR 0 Then under LOAD NODE POINT pick the node at the far end of the beam it ll be 6352 with DOF 2 and LCID 2 with any luck and hit Accept t o2 OF Time 6 03 EEE LEDE e Run analysis Student Extra Take the prior model and add mass scaling to model Remember to set the DT2MS value to a negative number Forgot why Please read the manual since structured organic learning sticks the best Analyst s Note After completing Workshop XIV come back to this example and switch to implicit Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 87 of 105 FINITE ELEMENT ANALYSIS LS DYNA Analysis for Structural Mechanics 2014 Predictive Engineering 13 IMPLICIT EXPLICIT SWITCHING FOR BURST CONTAINMENT An application for implicit startup is the initialization of the steady state stress field for rotating equipment For systems with high speed rotating components the model can be initialized to its steady state spinning condition using an implicit analysis To model any downstream event that may be highly nonlinear and dynamic the model can then be switched over to an explicit analysis The trick is performing this type of analysis is to remember that LS DYNA lets you apply boundary conditions and manage contact beh
73. fying what DOF s are to be released Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 57 of 105 Finite ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 7 10 2 INSTRUCTOR LED WorRKSHOP V RBE2 TO CNRB A Y direction load is applied to the independent node of a RBE2 element around a hole in a plate model The corners of the plate model are pinned This example will be used to demonstrate how a RBE2 element is translated into LS DYNA and its behavior The process is self discovery and no walk through video is provided The instructor will walk through the steps and then the student is left to explore e i ia r k a s m k Goals Open Femap model and inspect Rigid Link Export to LS DYNA model and review d within LSPP R del Th Stress results from the default run cat ND Lo OE Er EIES Given the model setup what stress CNRB in Y Direction and re run model units are we seeing Define MCD Element Enter Nodes ar Select vilt a x ee oe tt et el et RE Ta CNet Kap JOAR wee STL 1 Tew Cet Feste IT MP Do 777 Tete bakst ov A Check out the DRFLAG and RRFLAGS Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 58 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 7 10 3 WorksHop VIII USING RIGID BO
74. gps Led Workshop Vi Contact Negative je Shing Energy Contact Ids ten ren g _A Standard SOFT2 _B Refined Mesh SOFT 2 A Iniggnal Ene Hourglass Energy _ Sliding Energy 1 2 3 4 Time E 03 ans mie wa a e Pot ee it o te ine oa j Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 66 of 105 AKA II I CASRN RN 3 TN NE ee LS DYNA Analysis for Structural Mechanics 2014 Predictive Engineering LS DYNA Analysis for Structural Mechanics 0 8 5 INTERMEDIATE CONTACT ANALYSIS 8 5 1 BEAM AND EDGE TO EDGE CONTACT MODELING Where Regular AUTOMATIC Contact Fails CONTACT_AUTOMATIC_GENERAL Beam and direct edge to edge contact creates special challenges since contact is based on a line between two nodes For beam elements the contact surface is enforced as a cylinder regardless of the beam s cross section The algorithm checks contact along the length of the beam and at its end With this capability all of the more complex interactions shown on the right are found and prevented These are other features to this contact such as AUTOMATIC GENERAL is a single surface contact and the user only defines the slave set for contact 8 5 2 SPECIAL CONTACT OPTIONS CONTACT AUTOMATIC End Contact Occurs for all Automatic To handle contact at the end of plates a semi circular projection is made Contacts via Projection as shown on the graphic on t
75. he default simulation Understand unit system since it is not completely uncommon in the world of LS DYNA Run Model and inspect failure mode Note Rigid material modeling technique In the following workshop a basic failure mechanism Delete failure criterion from material card Er Et iE A post with a hole te hit by a beem and ia supposed to s at the bota Open LS DYNA Material Manual and read up on the sess ea MAT ADD EROSION card Then within LSPP add a tensile strain failure criterion MXEPS 0 25 to the existing material law Rerun model t ove vier ga sr we leer pee Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute mr c s F By p e lji Page 56 of 105 FINITE ELEMENT ANALYSIS o o Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 7 10 MODELING RIGID BODIES 7 10 1 RIGID MATERIALS MAT 020 or MAT RIGID This is one of the most powerful modeling techniques within LS DYNA By setting bodies i e parts to use MAT RIGID where deformation and As y stresses are not of interest significant CPU savings can be realized In the v background LS DYNA retains the surface mesh of the part for contact x 7 behavior and calculates an inertia matrix to simulate the dynamic A behavior of the body What is useful with this approach is that the body i still retains its inertia and physical characteristics as it interacts with other
76. he dynamic and the static problem For dynamic problems this means that we are solving the following equation ma cv kd f where n time step A common terminology is to call the kd part the internal force in the structure The basic problem is to determine the displacement at some future time or d at time 7 1 In conceptual terms the difference between Explicit and Implicit dynamic solutions can be written as Explicit a fav NN All these terms are known at time state n and thus can be solved directly For implicit the solution depends on nodal velocities and accelerations at state n 1 quantities which are unknown Implicit oe Ge a tt d va Given these unknowns an iterative solution at each time step is required Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 17 of 105 Pp MI AK 7 HN SN FINITE ELEMENT ANALYSIS PAZ Ti TAA DY ALA A nalvs sc fap Chr Tadi r AA m al m sn apm 20 14 2D IINA AlldiV5IS TOF DU UCUU Aa IVICUGIIUSs Predictive Engineering 2 2 EXPLICIT DYNAMIC Internal and external forces are summed at each node point and a nodal acceleration is computed by dividing by nodal mass The solution is advanced by integrating this acceleration in time The maximum time step size is limited by the Courant condition producing an algorithm which typically requires many relatively inexpensive time steps Using this criterion
77. he right for all AUTOMATIC contacts The radius of the projection is the plate thickness and the option SHLEDG lets the user chose between round or square edge ISYM This option controls how the contact algorithm handles symmetry edges If your model has a symmetry plane enforced by SPC constraints you ll want to set ISYM 1 CONTROL CONTACT This end contact option is the gotcha when constructing the perfect mesh Allows one stop shopping to set your contact options Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 67 of 105 FINITE ELEMENT NALYSIS H e Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 8 6 WOorksHop X EDGE TO EDGE CONTACT Problem Statement A thin 0 002 m corrugated plate is slammed into two other plates using a recommended default contact algorithm of AUTOMATIC SINGLE SURFACE Upon inspection it doesn t work How would you fix it Script e Run model and look at contact behavior e Change contact to AUTOMATIC GENERAL e Re analyze model and check contact Analyst s Note One may note that LS DYNA is warning you that the time step should not exceed 1 4e 5 while the model s running time step is 2 1e 4 e Reduce timestep via TSSFAC to 0 5 add CONTROL_TIMESTEP card e Re analyze and then lastly remove the interpenetration by translation STFS TT Gee Ge wt angs Der _ le a gar I pms
78. i structure Dislocations move up to the speed of sound aid EGNET within the metal e The graph on the right provides a rough order of 1800 PEER magnitude idea of how strain rate affects the true _ stress in steels and aluminum The strain rate is in aa te seconds 1400 e An example of strain rate effects might be that for Sa rotor burst The rotor an a pmnlet a spins at 55 000 rom The E i _ Amnealed 3 tip velocity of the turbine ne blade at burst is 575 m s Gi As the blade impacts the 2 EE containment ring one 600 i 1 4462 could expect to see l significant strain rate ak ea effects 200 __ Duplex 2 e For example given a 10 mm tall carbon steel cylinder that is compressed 10 at 575 m s This would give a 0 ee strain rate of 575 s or log 2 8 From the chart on 0 00 050 100 150 200 250 3 00 the right one could expect an increase in the yield log T Alby stress of gt 50 e Strain rate effects can be evaluated by numerical testing i e exploratory work looking at maximums Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 48 of 105 FINITE ELEMENT NALYSIS H e Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 7 4 PART 2 ELASTOMERS AND FOAMS 7 4 1 MODELING ELASTOMERS VS Foams VISCOPLASTICITY The Material section of the LS DYNA keyword manual provides a wealth of practical information on the mod
79. ictive Engineering Please Do Not Copy or Distribute LS DYNA Analysis for Structural Mechanics 2014 Analyst s Note Tied contacts are not really contacts but a constraint relationship that uses the CONTACT card entry format For an explicit analysis the constraint option ties the adjacent nodal velocities together while for implicit the displacements are tied This explains why the nodes must be on the same plane or adjacent and also why this formulation can t be used with rigid bodies or have SPCs attached to any node that is tied Additionally it is only generally applicable for just translational DOF TX TY amp TZ With the OFFSET formulation the penalty method is used If the BEAM option is employed all six DOF s are tied together by essentially using little springs between the nodes This is the most computationally expensive tied contact but the most robust Since the tied contact is enforced by springs the nodes can be offset rigid bodies can be tied together and even SPCs can be applied to the tied nodes The reason that we like constraint Tied Contact is that it is stable whereas penalty Tied Contact Offset is penalty based and has all the standard pathologies of regular contact such as the possibility of creating negative sliding interface energy Page 69 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering 8 8 CONTACT_TIED_ SURFACE TO SURFACE _NODES TO SURFACE SHELL EDGE TO SURFACE
80. ift Key and the left right and middle mouse button Class Referenced Note s Section The detailed usage of LS PrePost in its own rights is a two day class see Class Reference Notes LS PrePost Introduction Manual LS PrePost Introduction pdf Workshop Goal To Get Comfortable with LSPP Post Processing e Open PDF file and review contents Take 10 minutes e Walk through PDF until arriving at Workshop 7 q Mode Ssecton e Perform exercises as listed as Bookmarks M Post Processing Load Results input File and Make a Movie Cit a Secton Pane Create a Frege Contour Piot derSfy Nodes and Elements by ID Piot Time Hestory Dats Plot ASC8 Data Plot Measured Value Plot Sinout Data Format a Plot and Save Curve Data Workshop 8 Post Processing Advanced El View Multiple Modets F Create Cross Put Pi Modly Range Semngs E View Velocity Vectors E Cokes Groups and Views mm p 15 18 1 8 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 43 of 105 FINITE ELEMENT ANALYSIS E aS N Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 7 MATERIAL MODELING 7 1 PART 1 METALS 7 1 1 ENGINEERING STRESS STRAIN VS TRUE STRESS STRAIN The constitutive large strain modeling of all materials is based on the true stress strain response of the material Starting with a simple tensile test the engineering stress strain is just the force over the original cross
81. igher frequencies Since they are dissipative their energy loss should be tracked This can be done with the CONTROL_ENERGY option of RYLEN 2 Energy loss is then reported in the glstat and matsum files 9 1 2 DAMPING_FREQUENCY_RANGE This is a more elegant approach to damping and allows the user to specify the critical damping coefficient and the frequency range to damp Itis effective when used with low amounts of damping e g 1 or 2 and when the frequency range is no more than a factor of 30x e g 100 to 3 000 Analyst s Notes I know of no shortcut to producing good agreement with the observed loss in a test I can only suggest good judgment and a trial and error approach in order to tune the numerical damping Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 76 of 105 j FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 9 1 3 MATERIAL DAMPING E G ELASTOMERS AND FOAMS Elastomers e g MAT_181 Simplified Rubber and foams e g MAT_053 Fu Chang foam have the ability to add damping directly within the material card Recommended values are between 0 05 and 0 5 However there is no true recommended value since each material application is a bit different and requires some observation by the analyst to determine the appropriate value 9 1 4 Student Example on Material Damping An example of material damping is provided in the Class Refer
82. ine stinnted clock time to complete sec hro Apply mass scaling to obtain similar Max Displacements Keep in a pera Frauen Z peroontege increase SBB3E O mind that the higher the time step the faster your analysis will aa 11 t 3 3790E 01 dt 3 E o run and in practice it can take a 120 minute run and allow it to run in 80 minutes with no adverse effects It is a huge productivity boost Moder Time Step eass ed by Mass sealing Won Displacement C serer oosams oo 078i mm Class Bonus What happens when the CFL Criterion is not met e g set TSSFAC 2 0 Page 27 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering 3 3 2 INSTRUCTOR LED WORKSHOP I MASS SCALING ADVANCED Explicit Time Step Mass Scaling CONTROL_TIMESTEP e Mass scaling is no free lunch For dynamic systems added mass can affect the response of the system e It is just something to monitor and make an engineering judgment about its effectiveness time savings versus potential detrimental effects Mass scaling is my universal modeling condiment and the aim is typically no more than 5 additional mass Analyst Note Would this make your dynamic F ma analysis more conservative or less e Conventional mass scaling CMS has morphed to using the negative JDT2MS option as the recommended default e Selective mass scaling SMS Using selective mass scaling only the high frequencies are affect
83. ines should be orthogonal or parallel to the stress wave front and thus orthogonal Note The stress wave front is that induced by the dominant load Workshop lll Mesh for Explicit Success The student meshes the geometry to obtain the best quality results possible with the minimum element count and CPU cost Tasks e Mesh geometry using a mesh sizing of 5 mm e Setup Analysis Manager with a termination time of 10 milliseconds with data output at 50 us 0 050 ms intervals e Review results and plot resultant displacement at the top corner node where the load was applied Y e Investigate the following by recording the effects of i Plate NIP ii Mesh Density iii ELFORM amp iv Mass Scaling on the displacement at the end of the beam Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Resultant ad 2014 Page 39 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 5 3 SCALAR ELEMENTS NASTRAN CBUSH EQUIVALENTS The CBUSH element is of such general utility that it merits its own special section on how to obtain equivalent behavior within LS DYNA One of the concepts that merit attention is that an explicit analysis always requires mass whereas a static implicit analysis only requires stiffness Hence in a static analysis one can have elements with zero length i e zero mass whereas in an explicit analysis mass must be p
84. ks through the setup and debugging process A comparison is also provided between the Nastran and LS DYNA model Script Review contact setup within Femap Run NX Nastran Analysis Set Analysis Manager to LS DYNA model and export Run LS DYNA model and interrogate results Change contact to BEAM OFFSET Verify Tied Status and correct accordingly Re analyze model and interrogate results Analyst s Note The Tied option considers a node tied if it is within 5 of the element s thickness This applies to all _ TIED formulations As mentioned the constraint option moves the slave node to be adjacent to the master surface while the offset option accounts for the gap but whether or not it is tied depends upon the separation of the nodes To override the default setting one can set the SST and MST to a negative number that reflects the absolute distance to search for a tie relationship between the slave and master nodes Required Reading Class Reference Notes Keyword Manuals LS DYNA_manual_Vol_I_R7 0 pdf General Remarks on CONTACT on page 549 to 555 os frege Leven Syv LECA LAS ieot gt PE zp Vi 198 se a 2 7 STVET TTT e Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 74 of 105 FINITE ELEMENT ANALYSIS PT NY z Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 8 10 1 INSTRUCTOR LED BONUS WORKSHOP BAD ENERGY WITH TIED
85. l to rigid and note the speed up Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 81 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 10 3 WorksHop XII DROP TEST OF PRESSURE VESSEL This exercise is geared toward increasing your confidence in using LS DYNA We are going to do a standard drop test where the body is given an initial velocity and a rigid wall is placed directly beneath the vessel At the end of this exercise we ll fill the vessel with a fluid The objective is to get familiar with manipulating a model within LS PrePost LSPP The workshop starts by exporting the model from Femap where one has defined the materials aluminum and rubber and the mesh with a few predefined LS DYNA options within the Femap Analysis Set Manager Workshop Script e A thin walled 0 05 aluminum vessel that is 24 in diameter and 36 tall is impacted at a speed of 100 MPH 1 760 in s against a rigid wall The first task is to set the initial velocity for the vessel followed by creating the rigid wall e Use INITIAL VELOCITY GENERATION to get the vessel going One will need to create a part set to define what you want to initialize see SET PART Set initial velocity to Vy 1 760 and all other options default e Define rigid wall with RIGIDWALL_PLANAR We are placing this wall perpendicular to the bottom of the vessel The bottom
86. l to full SPH analysis o CONTROL SPH IDIM 3 o SECTION SPH o PART o CONTACT AUTOMATIC NODES o TERMINATION 0 025 s e View results e Atthe end of this workshop see Class Reference Notes SPH LSTC SPH Short Course Notes pdf D rn A A 4 tae hai a A Pe A D Cor iy Ar an Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute 2014 SPH Generation Create Modify Box E Del Ole Sphere Cone Solid Center a Solid Nodes Shell Volume Circle 4 Point quad area Shell Center SP Pa shell Nodes Num pa Beam Area Pitx 05 SphName Filling Property Ratio 100 Dirx Dir 0 0 0 0 1 0 Create Sph Part for Unfilled part PID Dern Clearance Density 1000 T same Para Start NID Start FID Apply Accept Reject Page 94 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 14 3 SPH WorksHop II FLUID MODELING In this example courtesy of Kirk Fraser the plate is made _ rigid and the ball is turned into water by using two cards Renee m ang MAT NULL and EOS GRUNEISEN 4 MD a x Mu TES ERDO m j wo mvo T 3 00 10808 T T T Learning Objective e Material modeling of fluids is not that difficult It is equivalent to modeling an isotropic solid material with E and v For a fluid at its simplest form there is speed of sound c density and viscosity e The Cwater is
87. merical validity of your contacts If friction is zero than the GLSTAT value should be 1 or less of the internal energy Interrogate local sliding energy by plotting all of the SLEOUT values If they are negative greater than 5 of the peak internal energy be worried and start digging 15 5 MATERIAL MODELING ERRORS Although much ado is made about strain rate sensitivity for most engineering applications the only really strain rate sensitive materials are carbon based materials rubbers elastomers plastics and foams and to obtain such data is not Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 102 of 105 I gt KAR AXA TTA NW FINITE ELEMENT ANALYSIS KNAL Tl VA Predictive Engineerin ern is fc te hanic 2014 that difficult from any good material testing laboratory What is more common is just plain screwing up the material model Thus it is almost mandatory to demonstrate with a virtual coupon test model that one can match test data with the LS DYNA model Such correlation should be within every engineering report Never underestimate the power of KISS and always attend to the basics before making your life more difficult 15 6 CONTACT OPTIONS WITH RECOMMENDATIONS SOFT 2 Soft 2 is really a quite good standard contact option IGNORE 1 For handling small penetrations that are not worth the time to fix this option is very useful Please don t expect it to do wonders or
88. of the vessel is at 0 0 0 To avoid initial contact with the rigid wall it is placed below the outer skin of the vessel at 0 0 025 0 and the head of the vector at 0 1 0 to define its position e Run model and notice that the pressure vessel skin folds in upon itself e Add CONTACT AUTOMATIC SINGLE SURFACE use prior part set for your single surface and set SOFT 2 for improved contact behavior Run model and it should look better This model has Finish I appended e The next step is to apply a pressure load Pressure loads are typically applied to segments which is LS DYNA terminology for element faces This operation could be done in Femap but we ll proceed with LSPP One will need to Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 82 of 105 FINITE ELEMENT ANALYSIS nl LS DYNA Analysis for Structural Me 1ICS Predictive Engineering LS DYNA Anal VSIS TOF tructura Mechanics 2014 create a segment set define a load curve and then create the pressure load e To create your segment set use the Create Entity option within LSPP This option is located within the Model and Part toolbar below the Keyword Manager button Within the Create Entity screen expand the Set Data option and select SET SEGM option Another pane will appear Within this pane you ll want to Create Cre the new segment set would recommend picking the segments using the ByPart option After picking
89. ontact Handles all six DOF and offsets Typically very numerically stable with little negative sliding interface energy Also may glue deformable bodies onto rigid bodies Cons None except that it is penalty based Page 70 of 105 FINITE ELEMENT ANALYSIS Predictive in LS DYNA Analysis for Structural Mechanics 2014 8 9 WOorksHop XI A TIED CONTACT FOR HEX TO TET MESH TRANSITIONS TIED SURFACE TO SURFACE Background for TIED Contact Analysis The advantages of using a hex mesh for explicit work centers on better shape control during large deformation and the ability to maintain a larger time step The last items is often pivotal in keeping your solution running fast without having the program add excessive mass if automatic mass scaling is invoked CONTROL TIMESTEP DTMS negative timestep value In the implicit world the use of hex elements are desired for the ability to provide equivalent stress mapping using far less nodes eight node brick versus the use of five 10 node tetrahedrals to fill the same space or 8 26 nodes and often times cleaner stress contours This workshop shows how to setup the mesh transition and run the analysis using the implicit solution Tapp i Sr sner r reka K G mu Workshop Script A small endoscopic surgical stapling anvil is given a 40 Ibf QC proof load The yield stress of the powder metallurgy SS is 110 ksi Is this device safe for surgical use e One starts with the
90. ops and explores in a bit greater detail the CONTROL_SPH control card options ISHOW Lara ae IEROD and ICONT to make the simulation more efficient Lastly the student is encouraged to set the fan blade failure criterion using MAT ADD EROSION MXEPS 0 05 while enforcing contact between the parts SPH Workshop IV Sante Siri Siba simen rem ran AA pt EN at r 13 ae eg t tt pet Hands On Script The procedure is to open the starting file Workshops SPH SPH Workshop IV Bird Strike Default SPH Workshiop IV Default Start dyn inspect the model and then use this baseline model to create the other two simulations This is an interactive instructor student Workshop and questions should be asked if any of the operations don t feel right Please note that file folders exist with the completed final dyn model within the folder Lastly if one is bored or has time change the failure criterion for the bird Defaults ISHOW 1 IEROD 1 amp ICONT 1 BLADE FAILURE e 18 ser Re wer ee ees o v tee n r owes La Leben ont vo ke st bn MTT nE i 7 dd p gt y th gee pro m i S M Woreshap fv Bast Med Stree Detaut ti Tree GOCE Fringe Laver Comans of EZ FTA EE e agi Ledechee Ges e T 8 T a n aill Kam m e dom i am See SG gt Se pr omy sm ow 99 N di H f f I i i 2 Ter 0ta Prge Laver Cormman of Etectve brenn feet ipi 2 and opt 82
91. or Distribute LS DYNA Analysis for Structural Mechanics 2014 LS DYNA KEYWORD USER S MANUAL VOLUME I Required Commands KEYWORD CONTROL TERMINATION NODE ELEMENT SECTION MAT PART DATABASE BINARY D3PLOT END Page 30 of 105 Ga ger SS A Ar AN IJ FINITE ELEMENT ANALYSIS kX Ne Predictive Engineering 2014 4 3 UNITS Many a fine analysis model has been brought down by bad units Although one may wonder why in this modern age one still has to twiddle with units and not have it addressed by the interface is philosophical like engineering debate between the ability to hand edit the deck or be hand cuffed to a gui pronounced gooey interface Moving past this discussion to use LS DYNA effectively one should have a rock solid and un shakable conviction in your chosen system of units Since the majority of LS DYNA work is dynamic the analyst will often be looking at the energies of the system or velocities in addition to displacements and stresses Hence a consistent set of units that are easy to follow can provide significant relief in the debugging of an errant analysis A general guide to units can be viewed within the Class Reference Notes Units see Consistent units LS DYNA Support pdf Saying all that here are the four unit systems that I have standardized on for analysis work It doesn t mean they are the best but at least they are generally accepted Consistent Unit Sets for LS DYNA Anal
92. or can be separated into a hydrostatic stress tensor pd and a deviatoric stress tensor 0 jj Ojj Oy PO The deviatoric stress is calculated by the material model constitutive law The pressure term p must then come from an equation of state EOS The EOS provides a relationship between pressure and the volume can also be a relation of temperature and or energy Depending on the compressibility of the material different types of EOS s are possible A very popular EOS is the Gruneisen equation of state The full version of this EOS compression is a po Cult 1 28 Ge p u2 u3 z Yo au E L i Du Se 57 S inn The equation appears rather complicated at first glance if we focus on a weakly compressible fluid many engineering fluids can be considered this way the equation of state can be reduced to p py C Where p is the initial reference density for the material C is the speed of sound in the material and u 1 All the 0 other parameters are curve found by curve fitting to a set of compression experiments These parameters are typically only needed when the pressure loading is very high as in shock waves In the figure shown on the next page we can see a comparison between an EOS specified with only the speed of sound linear dependency of pressure on volume and an EOS to give a cubic dependency of pressure on volume In the subsequent workshops the units are p Pa po kg m specified as RO on MAT NULL
93. or if CID 0 then the beam follows the global coordinate system just like Nastran The mass of the element is calculated the field VOL and INER if torque is present and the mass density of the material A basic element is given below for a zero length CBUSH element in a unique coordinate system Nastran CBUSH Property Card Equivalent LS DYNA Keywords SECTION BEAM TITLE CBUSH Equivalent Element Title CBUSM v S secid elform shrf ar irid cst scoor nsm 1 6 1 000000 2 2 3 000000 0 000 S vol iner cid ca offset rrcon srcon trcon Other NASTRAN CROD CVISC 1 000000 1 000000 1 0 000 0 000 0 000 0 000 0 000 ELEMENT BEAM S eid pid ni n2 n3 rtl rri rt2 rr2 local 1 1 400 401 0 0 0 0 0 2 Sen DEFINE COORDINATE SYSTEM DOF Stiffness Damping 4 488 999 28 99994 414 4192 105 6686 180 7164 227 1846 670 4222 17 28623 199 297 irak tl nests MAT LINEAR ELASTIC DISCRETE BEAM TITLE Stress Cost Strain Coat Spring Stiffnesses Trans o 0 S mid ro tkr tks tkt rkr rks rkt Rot 0 0 1 0 001000 0 000 1 0000E 6 1 0000E 6 0 000 0 000 0 000 S tdr tds tdt rdr rds rdt ox cance 0 000 0 000 0 000 0 000 0 000 0 000 Define Property SPRING DAMPER Color 110 Palette Layer 1 Spring Damp Loc Origentabon CSys 4 Actuetor X St for fos fot mor mos mot 0 000 0 000 0 000 0 000 0 000 0 000 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 41 of 105 Finite ELEMENT ANALYSIS 7 i
94. particle hydrodynamics a meshfree particle method Hackensack New Jersey World Scientific 2003 4 D Voileau Fluid Mechanics and the SPH Method Theory and Applications Oxford UK Oxford University Press 2012 5 W G Hoover Smooth Particle Applied Mechanics The State of the Art Advanced Series in Nonlinear Dynamics Singapore World Scientific Publishing 2006 6 LSTC LS DYNA Keywords User Manual Volume 1 no Version 971 July 12 2012 2012 7 LSTC LS DYNA Materials User Manual Volume 2 no Version 971 July 12 2012 2012 8 S Marrone A Colagrossi D Le Touz et al Fast free surface detection and level set function definition in SPH solvers Journal of Computational Physics vol 229 no 10 pp 3652 3663 2010 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 100 of 105 FINITE ELEMENT ANALYSIS Predictive Enginesring LS DYNA Analysis for Structural Mechanics 2014 15 EXPLICIT MODEL CHECK OUT AND RECOMMENDATIONS If you think you might have a simulation that is working here s a short list of things to check for and review Here s an order of checking Units Mesh d3hsp File History Plots Material Modeling Contact Behavior Etc 15 1 UNITS It is recommended to settle on one unit system for as much of your LS DYNA work as possible to avoid unit problems when one is unfamiliar with a specific system A commonly recommend system
95. r rotate through space Interesting enough the INN 2 option is default for implicit calculations Both of these options will slow the simulation down by as much as 10 Proprietary Information to Predictive Engineering Please Do Not Copy or r Distribute Page 88 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 13 1 1 WORKSHOP XIV IMPLICIT EXPLICIT TURBINE SPIN UP This workshop will show the student how to setup a turbine simulation from implicit ramp up to steady state rotating movement The model has been mostly prepared and the student is required to finish the setup using the following Keywords CONTROL ACCURACY OSU 1 INN 2 CONTROL IMPLICIT GENERAL IMFLAG 1 DTO 0 25 CONTROL IMPLICIT SOLVER LSOLVR 6 INITIAL VELOCITY GENERATION PHASE 1 INITIAL VELOCITY GENERATION START TIME STIME 1 00001 INITIAL VELOCITY RIGID BODY VZR 225 LOAD BODY PARTS PSID 1 LOAD BODY RZ LCID 2 SF 225 BOUNDARY SPC SET BIRTH DEATH NSID 1 DOFX 1 DEATH 1 0 For any implicit analysis it is recommended to use the double precision solver jamne o This is activated within the LS D YNA Program Manager under Solver Select LSDYNA Solver When completed one should see the graphic on the right a small d within the solver name re ov grim ER be EEG Sy ee nee t r tee p p po poy e pmr pae Workshop XIV Implicit Explicit Turbine Spin Up
96. resent and likewise a finite length Although LS DYNA has several methodologies to arrive at simulation the behavior of Nastran CBUSH element e g ELEMENT_DISCRETE we will present the most basic method and the one recommended by LSTC In Nastran the CBUSH property card specifies orientation and stiffness In LS DYNA these capabilities are handled by two cards i ELEMENT SECTION ELFORM 6 orientation and ii MAT_LINEAR_ELASTIC_BEAM stiffness values Nastran CBUSH LS DYNA Equivalent SECTION_BEAM amp MAT_66 Type coun Property Wehees Ne NN en mr t nemo nt I vater i j on ww Pace i spnsgD ise one Drem Pa ah d d men Drier Dei Doe tday i a 7 Orgrtatan Coe O Seer Ari AST LASAR DANE CORSE BA TINE th Stee Street Recovery Stress Chef Shen Coe ELILE trass a a hers Ole OEP De 81 ft a t JE mem gt 9 29 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 40 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 If the connection has zero length then the SECTION BEAM ELFORM 6 field SCOOR should be set to a value corresponding to the requirements of the analysis In other words take a look at the manual and www dynasupport com under discrete beams since the choice of SCOOR is not obvious Our general default is SCOOR 3 Importantly a CID must be defined
97. s for Structural Mechanics 2014 COURSE OUTLINE MA DET 9 LL ATT IN Me Ur tenets cae ames onttsntsecod adam a enaasoeaeinsaiecae saunas anctntacacae T 9 VENN 9 LNM 9 ENN 10 1 5 SPECIFIC APPLICATIONS COURTESY OF PREDICTIVE ENGINEERING wcaiv vcssavauseniwnaivestdupannindasvenssuncaasanionaeye siniuasawaiasnanspunsedeabieassvaskdunsamabaaneueasaseianbewaba aneds 11 Ze WALID VER VS Ee CIT ANANA atest penis E cena teranens os EE E ATA 17 LVS 17 2 PUTIN 18 NNN 18 gt PINSEN ANNES LUT NNN 19 L ENN 19 L FUNN VNR 20 3 2 TIME STEP SIGNIFICANCE COURANT FRIEDRICHS LEWY CFL CHARACTERISTIC LENGTH scccesscccessssccnscscesssecenscsceecseeeeceseeuessteuecsseensseeeueceseueceseuaees 21 3 3 IWIASS SCALING EVERYBODY DOES IT BUT NOBODY REALLY LIKES T issciccitasniscasaniacastanasinssaniinnibantaieieaasiaaedensaantieanananibiadiasaaaatncdibadeiandadaiaatibesssiauaaeias 22 3 3 1 WOrksnop Femap to LS DYNA with Mass Scaling BASICS siiccicssidtavasasscssaeicdentiennennanapibanansanaeasareddaatainnmuandgaddesniannessasdiacataestansadatieasnes 23 3 3 2 Instructor Led Workshop l Mass Scaling AdVANnCed cccsssccccssececesecccesececesececsececsuuceeseneceseueceseueesseeceseuecessuscesseeeesenecetsuecessenees 28 2A IMPLICIT MESH YERSUS PTE NNN 29 3 4 1 Instructor Led Workshop II Implicit versus Explicit Mesh Differences rrrrnnrrrnnanrrnnnnrrnnnnnrnnnnnsrnnnnevnnnnnennnnnennnnnsvnnnnesnnnnnsnnnnnsennnnee 29 4 FIRST LS DYNA MODEL GETTI
98. seeressrresresssreessrreseressrerssreeserreseeresrersseeesseress 89 14 SMOOTHED PARTICLE HYDRODYNAMICS SPH eererunrnnrnnnnnnnnnvnnnnvnnnnvnnnnnnnnnnnnnnnvnnnnnnnnnvnnnnnnnnnnnnnnnnnnnnvennnnnnnunnnnusnnnnnuennn 90 14 1 MON 90 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 6 of 105 FINITE ELEMENT NALYSIS I e Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 14 1 1 A Little Bit of Theory skip this if you don t NNN 90 14 1 2 Lagtr ngian NNN 92 fF AG Ws TN NN 93 VIL Common keywords Nav 93 14 2 FA TENNE 94 14 3 PAWO POPI FEOT MO 2 NE NE NE EE NE 95 14 4 PAVEN NN 96 TL NNN NNN 97 14 5 Sa K GE OR ER Tee EEE EEE ER EE SE RE EER 98 NNN 99 14 6 REREPEN E EE NR EE EE EE EE EN 100 15 EXPLICIT MODEL CHECK OUT AND RECOMMENDATIONS ccccceccsecscceccecsecsecsecseeseesececceccuceecesseeseeseeeeeseeecees 101 15 1 MN 101 1 2 ME EE NE EN ENE EE NE EE ENER 101 15 3 D3HsP FILE LS DYNA EQUIVALENT TO THE NASTRAN FOG FILE iaissscvsstsccasdncanenencssseasstossnennsasancducasaanbeassianaslopsnanacesuandhmeasanabaandeauutarsaanansrubaci aas 101 15 4 POL RE TREN EEE A TE EE EE RE KER EN 102 15 5 VNR 102 15 6 CONTACT OPTIONS ENN Ge 103 15 7 EMNENE en 104 15 8 PEER ES EN DO EE EN EE EE EEE TE 105 15 9 EEE EEE E E ETE T EEE E E E E A EE EE ENE 106 16 IMPLICIT CHECK OUT AND FE NENNE 107 16 1 INNEN 108 17 PRE ETNMENN T A A E N S 109 18 FLUID STRUCTURE INTERACTION AND MUL
99. stant gravity These static stress state conditions can be simulated in LS DYNA using two techniques Explicit Dynamic Relaxation or Implicit Static Analysis Dynamic Relaxation DR CONTROL DYNAMIC RELAXATION DR is a heavily damped explicit analysis that is initiated prior to the main transient analysis It has all the characteristics of a standard explicit run but it is assumed that stresses are relatively elastic and that displacements are small The solution is heavily damped and unexpected results may be generated Nevertheless with some models it does a great job with bolt preload tire inflation or application of a shrink fit In the DR process the load is applied e g bolt preload as a transient load with a sharp ramp up and then a steady state application The model dynamically responds to this load application with all the characteristics of a standard explicit transient analysis As the model is solved the nodal velocities are reduced at each timestep by the dynamic relaxation factor default 0 995 The kinetic energy KE is calculated at prescribed steps and when this energy has decreased sufficiently against the initial KE the solution is considered converged and the DR process shuts down and the solution is handed over to the regular normal explicit transient analysis sequence There are lots of options to manage this process and the student is referred to the Class Reference Notes for more information Analyst s Note ha
100. t SPC force plot by summing the SPC s see ASCII button CONTROL IMPLICIT GENERAL IMFLAG 1 CONTACT TIED SURFACE TO SURFACE DATABASE ASCII SPCFORC 1 gt lantarmatinan tr Dra cl rn Crainaarinag D ACA VA Alat Cananu ar Verrikiita i JE i a E U I amp J r I amp U IG L i vV L i gt I c i I 15 p r ic a te Cc D U A J Kees LS UV te J UW LI i L E J LA L T Page 72 of 105 FINITE ELEMENT ANALYSIS aS A e o Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 8 9 1 STUDENT BONUS If this is working for you change the DTO field to 0 1 within the CONTROL IMPLICIT GENERAL card and watch what happens Then change the TIED contact to that of CONTACT TIED SHELL EDGE TO SURFACE BEAM OFFSET If you are wondering what is what read the manual Another avenue is to investigate how plasticity affects the analysis Implement material plasticity using a yield stress of 100 000 psi with a tangent modulus of 100 000 psi If this is too boring change the yield stress to 30 000 psi with a tangent modulus of 10 000 psi Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 73 of 105 FINITE ELEMENT ANALYSIS Predictive Enginesring LS DYNA Analysis for Structural Mechanics 2014 8 10 WorksHop XI B TIED CONTACT FOR GLUING THINGS TOGETHER BEAM OFFSET This workshop takes a typical example of where to use Tied Contact and wal
101. t time step and mass scaling As part of this process you ll get comfortable working with Femap LS DYNA Program Manager and LSPP Our test metric is going to be the maximum displacement from a node at the end of the bar bye sp ert I Lt mi te t Tere er a sore lt lt a is i eee selected and then hit Plot H within the History dialog box When finished something like this should appear as shown on the right Precy TINE JILYII Het SLT DYNALI DYNA Ces MENER Atas EEG Barr tlpar iss i Tasks Ve Ge 1 ben Jer Om me _ LS DYNA Wave Propagation Example RE e Within existing LSPP model open History select Node Y Time 2 2065 j Finga Levels MEER i Contours of Effective Stress v am 1 964e 04 Frang Curve Displacement and then pick a node at the very top of the bar max IP value o min 0 at elem 4544 1 7000 04 istmey Sur near the center any ol node near the center and then max 0 000196431 at elemi 5424 157000 oe i 1 375e 4 be y likewise at the bottom near i porn E 2 EE gt lnr a the center When done you no SPSYaA Yves Prepayanen Bangas s ones Danei ess should have two nodes Sen Kamana fio ved i ri vr 1 2 i erivicirier 2 s g Titlene e Note that the maximum displacement at the top is 0 00781 mm with an explicit timestep 0 0334 ms Proprietary Information to Predictive Engineering Please Do
102. the Courant condition is met Sos mo AE fhe Deana ER UG EA Carnegie tar napa Be Me Mew Geary FEY Mony sensy fer File Open LS DYNA Binary Plot This mother on bece tee 1 9648 04 a me max IP value file will then load its subsequent children files i e min 9 at elem 4544 eee su max 0 000196431 at elem 5424 1 57 10 04 d3plot01 d3plot02 etc automatically To make it 1 3750 04 a easier the first time around go to View Toolbar and 1 1790 04 sg 9 8220 05 i set the toolbars to Text and Icon z7 AN pon Then we will contour the von Mises Stress Toolbar meg pe ry 3 9290 05 EwTol D SEn Bi lew 1 9640 05 0 000e 00 Post FrinComp von Mises Stress Then hit the play button on the Animate dialog box Sit back and enjoy the stress wave colors y Md ee Fare U SF 1 0 PComo Fr are ey ae ea asc liad mout Fato T Partido Q Od hl Cait w AD Outen b Setting tv Vector O llat 241 Inc 1Time OState 1 ms lt B gt 0 gt VI Loop ES 30 Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 24 of 105 FINITE ELEMENT ANALYSIS Predictive Engineering Femap to LS DYNA with Mass Scaling Basics continued LS DYNA Analysis for Structural Mechanics 2014 With the model working let s harvest some data We are going to make several runs of this model to investigate the relationship between mesh explici
103. the solution is unconditionally stable Since the solution is solving for displacements at nodal points the time step must allow the calculation to progress across the element without skipping nodes Hence the explicit solution is limited in time step by the element size and the speed sound in the material under study Even worse the smallest element in the mesh can dictate the time step for the whole solution and likewise combined with the stiffest material fastest speed of sound 2 3 IMPLICIT DYNAMIC A global stiffness matrix is computed decomposed and applied to the nodal out of balance force to obtain a displacement increment Equilibrium iterations are then required to arrive at an acceptable force balance The advantage of this approach is that time step size may be selected by the user The disadvantage is the large numerical effort required to form store and factorize the stiffness matrix Implicit simulations therefore typically involve a relatively small number of expensive time steps The key point of this discussion is that the stiffness matrix i e internal forces has to be decomposed or inverted each time step whereas in the explicit method it is a running analysis where the stiffness terms are re computed each time step but no inversion is required tary Information to Predictive Engineering Please Do Not Copy or Distribute Page 18 of 105 FINITE ELEMENT ANALYSIS AG Predictive Engineering LS DYNA
104. the structure whenever possible uf r ikke Analyst s Note Mass scaling is great but it needs to be combined with a reasonable mesh gradient f fetminhrlvinininiele HE El ak ERE re PG9GD 000 e Ju vanADeS 4 8s OG ge eres Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 29 of 105 IND FINITE ELEMENT ANALYSIS I Predictive Engin ering 4 FIRST LS DYNA MODEL GETTING STARTED 4 1 LS DYNA KEYWoRD MANUAL LS DYNA has perhaps one of the most basic learning methods It is organic One simply has to dig in and learn the basics and there is no substitute for doing it yourself The Keyword Manual also provides recommended usage guidelines and examples on how to use the commands It is your first and best resource 4 2 KEYWORD SYNTAX e Commands are strings of words separated by an underscore e g BOUNDARY PRESCRIBED MOTION RIGID e Text can be uppercase or lowercase e Commands are arranged alphabetically in User s Manual e Order of commands in input deck is unimportant except KEYWORD and DEFINE_TABLE e Keyword command must be left justified starting with an asterisk e A S inthe first column indicates a comment e Input values can be in fixed fields or comma delimited e A blank or zero parameter indicates that the default value of parameter will be used or taken from CONTROL_option Proprietary Information to Predictive Engineering Please Do Not Copy
105. ts the currently available foam material models in use within LS DYNA One recommended foam model is that of MAT 083 or fMAT FU CHANG FOAM Foams are perhaps the most challenging material to model due to their extreme nonlinear behavior upon loading and unloading plus their tendency to become crushed or damaged during loading and then upon unloading present a completely different stress strain response 5 MATSOILAND FOAM 142 MAT TRANSVERSELY ANISOTROPIC CRUSHABLE FOAM 14 MAT SOIL AND FOAM FAILURE 144 MAT PITZER CRUSHABLE FOAM 26 MATHONEYCOMB 154 MAT_DESHPANDE_FLECKFOAM 126 MAT MODIFIED HONEYCOMB 163 MAT MODIFIED CRUSHABLE FOAM 53 MAT CLOSED CELL FOAM 477 MATHILLFOM _ _ S 62 MAT_viscous FOM 179 MAT LOW DENSIN SYNTHETIC FOM 63 MATCRUSHABLE FOAM 180 MAT LOW DENSIY SYNTHETIC FOAM ORTHO _ 73 MAT LOW DENSIIY VISCOUS FOAM y O 75 MAT BILKHU DUBOIS FOM pf O 83 MATFUCHANG FOM Analyst s Note Since foams are modeled using solid elements it is not uncommon to have numerical problems as the foam becomes highly compressed and crushed since the elements used to idealized this behavior likewise become highly distorted or crushed Typically the workarounds are to use highly structured meshes with large element sizes Another technique that is gaining utility is to use SPH Smooth Particle Hydrodynamics to model the foam material This mesh free technique will be cov
106. us materials often have high energy absorption characteristics prior to failure That is to say metallic materials generally tend to tear while brittle materials tend to snap Image from article A finite element model for impact simulation with laminated P lass Timmel Kolling Osterrieder DuBois IJIE 2006 Experimental Correlation g The development of a material model often starts with 200 ee stress strain data from a standard mechanical test This SE HE data can then be converted into true stress strain and a very simplified approach used to extend this curve to ae HE a failure i f Puss ts In the high strength steel shown on the right see Class Reference Notes MMPDS AerMet 100 Steel Bar the stress strain curve drops as necking occurs The presented data is all that is needed to generate a useful true stress strain curve for the material EEE Lg PERE LER bitse een preset SASLELES SETTET TELTE ELLES pt 000 om 004 006 O88 Ow 012 08 086 ET Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 46 of 105 FINITE ELEMENT ANALYSIS Predictive Enoinesring LS DYNA Analysis for Structural Mechanics 2014 7 2 WorksHop V ELASTIC PLASTIC MATERIAL FAILURE Objective To approximately model the material AerMet 100 True Stress Strain deformation and failure of the AerMet 100 steel 350 A simplified approach is presented using the piecewise seas linear pl
107. ve often struggled to get DR to work correctly It seems finicky since the process is uses a heavily damped response and it just ain t natural As such whenever possible I strive to use the implicit approach Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 86 of 105 FF f FINITE ELEMENT ANALYSIS fp i Predictive in LS DYNA Analysis for Structural Mechanics 2014 12 2 WorksHop XIII DYNAMIC RELAXATION i As modal frequency response analysis is known as the poor man s anope eS ER transient dynamics Dynamic Relaxation might also be known as the poor man s implicit Nevertheless in many cases it gets the job done a lot faster than straight up implicit and is easier to setup et co s T VE gt ST k T j Script e Using the Start model create bolt loading curve DEFINE CURVE with the following three points 0 0 1e 4 5000 1e 2 5000 Set the SIDR 1 please see Manual about details on this option ESILI TITT e Apply bolt preload load to the four beam elements This is done by INITIAL AXIAL FORCE BEAM please see Manual about details on this Keyword However one will first need to create a beam set This has already been done for you thus proceed gently forward using this predefined beam set Please note unique Material Law required for the use of this Keyword e Apply load of 1 000 units at the far end o
108. will then be given 10 critical damping between 250 and 350 Hz Save and plot results Bs BA ts on dreie ber eigenvalues at time 5 00000E 0 3 ics 8 S KATO Ce le GAR NN SOG 72 H G TDH G V Ges vTNAV S gor gt gt Tr Subtam Haugar Student Bonus One can switch it to an Eigenvalue analysis by adding these two CONTROL cards IMPLICIT EIGENVALUE NEIG 5 and IMPLICIT GENERAL IMFLG 1 Once analyzed you ll want to view the d3eigv Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 78 of 105 SJ AXAN bo DANS FINITE ELEMENT ANALYSIS I Predictive Engineering Although the use of bulk viscosity as a form of damping is not exactly classical since it was developed for the treatment of shock waves through the FEA mesh it has grown into a recommended procedure for general dynamic structural FEA work even when shock waves are not present The CONTROL BULK VISCOSITY card has several options and the default are recommended If shell elements are present in the analysis one should set TYPE 2 to activate this calculation for Shells The reason it is not default is that shock waves are more of a solid element behavior In the case of shells we are more interested in the linear bulk viscosity mechanism see LS DYNA Theory Manual for more details Example of the effects of bulk viscosity on an impact analysis is shown below courtesy of Suri Bali and his excellent w
109. y 0 2 to 0 4 Implicit time integration a possibility in the future in LS DYNA but for now only explicit is available For the truly die hard SPH gear heads I recommend the book by Damien Violeau 4 you gotta really love math to enjoy this book or for a less math intensive approach see the book by William G Hoover 5 Lastly for modeling constitutive relationships in SPH one can use many of the same material cards i e laws as a regular Lagrangian analysis Page 91 of 105 ky N FINITE ELEMENT ANALYSIS WZ PA Predictive SA LS DYNA Analysis for Structural Mechanics 2014 14 1 2 LAGRANGIAN VS EULERIAN The two most common frames of reference for numerical simulations is Lagrangian or Eulerian You can think of Lagrangian reference like you are Eulerian Lagrangian sitting on a plane and Eulerian like you are on the ground not moving and watching the plane go Wow look at by Lagrangian makes following the history of each material point very easy compared with the Eulerian description CFD codes finite difference finite volume and finite element are written from an Eulerian formulation The Lagrangian nature of SPH makes it a very powerful numerical method this opens many doors that Eulerian method closes or makes it difficult to open the door Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 92 of 105 FINITE ELEMENT ANALYSIS H gt Predictive Engineering L
110. y in soft materials To counter these problems the contact option SOFT 2 is recommended This switches the contact search routine to segment to segment and locally calculates the stiffness for the penalty approach It should be considered the default Proprietary Information to Predictive Engineering Please Do Not Copy or Distribute Page 61 of 105 FINITE ELEMENT ANALYSIS N o o Predictive Engineering LS DYNA Analysis for Structural Mechanics 2014 8 2 2 CONTACT WHEN THINGS ERODE For numerical efficiency the contact algorithm only looks at free edges and faces If element erosion occurs i e element failure the standard contact algorithm is not prepared to look for contact on these newly generated faces If one knows ahead of time then the contact can be switched to ERODING with EROSOP 1 The EROSOP option is required to allocate memory storage for the newly created element surfaces This option should not be evoked for most element erosion situations since it is not very numerically efficient For example plate models are typically just fine without using element erosion but as shown below it is critical AUTOMATIC SINGLE SURFACE ERODING SINGLE SURFACE M LPF 4 Beta POATEN IONAD DONNI DYNA Cuntisrestanoesionmeben IE Dodrstaralget LS Preovt 4 Met ITOE HL AOOHHER FNAVS DYNA Cuan W tadopriNortahap OK Croce svete lpect ke fe be Few Geometry IM Spree Sette thee te ne gaw Gerety IM ippies ettnge tiv
111. ysis Mass Length Time Force Stress Energy Density Steel Young s Gravity ee elem o 7m sores sm om me fn rates romanen rie wm n e ven nan sare sao Page 31 of 105 FINITE ELEMENT ANALYSIS Predictive Enginesring 4 4 REFERENCE MATERIALS AND PROGRAM DOWNLOAD The first site to visit www Isdynasupport com Another great site www dynasupport com LS DYNA Examples www DYNAExamples com LS DYNA Conference Papers www dynalook com Newsletter www FEAlnformation com Yahoo Discussion Group LS DYNAOyahoogroups com Aerospace Working Group awg Istc com 4 5 SUBMITTING LS DYNA ANALYSIS JOBS AND SENSE SWITCHES LS DYNA Analysis for Structural Mechanics 2014 LSTC Program Download Site ftp user computer ftp stc com SMP Version Is dyna MPP Version mpp dyna SMP Windows pc dyna Analysis jobs can be submitted directly with command line syntax or using the Windows manger shown on the right Bi 15 0174 Program Manager EILL VALG pek NINI While LS DYNA is running the user can interrupt the analysis and request En S r Pen er nn de ae ne run Mager ann Dee Diil He 3 Sais M Ol Alalila 9 mid analysis information This interrupt is initiated by typing ctrl c on keyboard and thena sense switch can be activated by typing the following sw1 sw2 sw3 sw4 swa stop A restart file is written and LS DYNA terminates LS DYNA responds with current job statistics A

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