Introduction to MSC.Patran
Contents
1. Read Results Now we are ready to submit our finite element model for analysis Under Analysis we will set up the job for the analysis and submit it directly from MSC Patran to MSC Nastran Analysis Object Entire Model Method Full Run Job Name box_beam_loadcase_1 Translation Parameters If you have time you may Solution T want to look at the subordi OR pe nate forms for these options Direct Text Input The defaults for these options are fine for our Subcase Create model load_case_1 Subcase Select Apply o After pressing Apply the heartbeat on the main form will turn blue and you should see a number of messages scroll by in the Command Line The heartbeat will then turn to green which means you can continue executing operations in MSC Patran while the analysis is running To see if MSC Nastran has completed with no errors open another window and search the contents of the file box beam loadcase 1 f04 in the directory where you started up MSC Patran for the string EXIT MSC Patran 301 Exercise Workbook Release 9 0 Exercise 1 Geometry Model of Space Satellite For UNIX enter more box_beam_loadcase1 f04 grep EXIT For Windows NT enter type box beam loadcasel f04 find EXIT If MSC Nastran completed with no errors you should see the following line 16 23 52 0 20 20 2 0 0 11 4 0 0 SESTATIC 145 EXIT BEGN Once the analysis has successfully completed it will produce a b2. Create a New Group Create a Before we go on and mesh our box beam model we want to keep our New Group soon to be finite element mesh in a group that is separate from our geometry model To do this we will created a new empty group called fem_model and make fem_model our current group Group Create New Group Name 7 Make Current Group Contents Add Entity Selection Apply Cancel Note fem model has replaced default group at the top of our viewport which means fem_model is our new current group MSC Patran301 Exercise Workbook Release9 0 1 11 Define Mesh Seeds 1 12 9 Define Mesh Seeds on one end of the Solid Before we mesh the outer surfaces of our solids we want to take advantage of a feature called Mesh Seeds Mesh Seeds allow you to define exactly how many elements and even what node spacing you want on selected curves or edges of a surface or a solid For our box beam model we want to define mesh seeds of five elements in the Y and Z directions and 15 elements in the X direction To do this we do the following Finite Elements Action Create Object Mesh Seed Type Uniform Q Number of Elements Number Curve List Mi Because mesh seeds can only be associated with curves or with edges of surfaces or solids the select menu only has one icon This means MSC Patran will only look for any curves or edges that you select Since we want to select the edg
3. Force Load Apply Load Now we want to finsh our Loads BCs by applying our 100 pound downward force on the right corner of the solid The force will be defined by a vector in the global rectangular coordinate frame where we will have zero pounds in the X direction 100 pounds in the Y direction and zero pounds in the Z direction Again we don t need to create the finite element mesh before applying our force We can associated the force with the solid Q Loads BCs New Set Name Force F1 F2 F3 Analysis Coordinate Frame MSC Patran301 Exercise Workbook Release9 0 1 9 Select Application Region Geometry Select Geometry Entities Since we want to apply our force to a point on the solid switch the select menu icon to the Point or Vertex icon a Cursor select the corner point of the right end of the solid as shown Click on this corner of the solid with the left mouse button MSC Patran will highlight the point in red You should see Point 7 entered in the Select Geometry Entities databox If you cursor selected another point by mistake press the right mouse button to deselect it Finish creating the force by pressing the following menu buttons Add OK Apply 1 10 MSC Patran 301 Exercise Workbook Release 9 0 Exercise 1 Geometry Model of Space Satellite Now you should see a yellow arrow drawn on the selected corner point of the solid which is our 100 pound force 100 0 8
4. not be an option depend ga o 23 lt c R 2 e lt un L un 3 d 2 c c 2 e oO Input Properties Material Name Thickness 0 05 Select Members 1 MSC Patran 301 Exercise Workbook Release 9 0 Exercise 1 Geometry Model of Space Satellite Since we want to associate our element properties with the outside surfaces faces of our solid make sure the Surface or Face icon is highlighted in the select menu X Now cursor select the entire model remember our solid is still in the group default_group which is still posted displayed to the viewport Click on the Iso 1 View icon at the top to see the whole model Select the entire model using the rectangular selection box You should see Solid 1 1 1 2 1 3 1 4 1 5 1 6 appear in the databox which are the solid face ID s Apply 15 Create a Load Case Create a Load Case Now we want to create a load case which groups selected loads and boundary conditions into a single set which can be referenced for the analysis Q Load Cases Load Case Name load case description 7 Make Current Load Case Type Static MSC Patran301 Exercise Workbook Release9 0 1 19 Analyze Job Status Results 1 20 Description load_case_1 Now click on the Assign Prioritize Loads BCs button Select Loads BCs to add to Disp_fixed spreadsheet Force_100 pound_down OK Apply 16 Perform the Analysis Check Status of Job
5. specified group to which all newly created entities will belong You can only specify one group at a time to be the current group for each viewport MSC Patran301 Exercise Workbook Release9 0 1 5 Create a Solid Change the Viewing Angle Change the Viewing Angle 1 6 3 Create a Solid Though the box beam we will be creating is hollow we will create a solid of the box beam and later mesh the outside surfaces of the solid Keep in mind the dimensions of the beam are 5 inches long with a 1 inch cross section We will create the solid with the long direction in the X direction Q Geometry Vector Coordinates List Origin Coordinates List Apply For fun rotate the model by placing the cursor in the viewport and holding down the middle mouse button and dragging the mouse around Notice that when you release the button a View Fit View is automatically performed You can switch from the rotate function to translate or zoom by entering Preferences Mouse 4 Change the View Angle Instead of using the middle mouse button to change the view of the model you can use the Viewing menu by doing the following Viewing Angles Q Model Absolute Angles 20 10 0 Apply 5 Reset the Number of Display Lines All surfaces and faces of solids are shown with additional lines called Display Lines These are not actual geometric boundaries but they are visualization lines to help you see the interior curvature of
6. ATRAN_FEA Analysis Type Note If the analysis code MSC PATRAN_FEA is not available to you choose another structural analysis code for which you have licenses If the part of the screen which was covered by the New Model Preferences form is not redrawn press the refresh button 2 A Short Word on Viewports and Groups After pressing OK on the New Model Preferences form you should see a large graphics window called the MSC Patran Viewport see below A viewport is a window in which you view your model You can display more than one viewport but to keep it simple we will be working with only one MSC Patran 301 Exercise Workbook Release 9 0 Exercise 1 Geometry Model of Space Satellite 7777 Viewport Name Current Group Name default viewport default group Database Name box beam Soo ae Entity or En Mode box beamdb default viewport default group Entit This is the Origin Marker 4 This is the Global Axes Y x coordinate frame symbol x The Current Viewport has a bright red border The top of the viewport lists the name of database you are working on the name of the viewport the name of the current group you are working with and the mode of operation for displaying the model Entity or Group mode A Group is a defined collection of geometry and or finite element entities Entities such as a surface or an element can belong to more than one group The Current Group is a
7. C Patran 301 Exercise Workbook Release 9 0 Exercise 1 Geometry Model of Space Satellite Next let s create a color fringe plot of our von Mises stresses Invariant stresses such as von Mises stresses are a good choice for a fringe plot since they are scalar quantities and they are a good predictor of the yield stress in metals like aluminum Results Select Result Case s ies Select Fringe Result Quant Apply 20 Create a Combined Fringe Deformed Plot Let s create a contour plot of our membrane stresses on top of a deformed shape plot by doing the following Results Apply Now you should see the contour plot on top of the deformed shape plot 21 Modify the Finite Element Mode Optional Note the high stress regions are bending stresses in the opposing corners at the box beam s open end opposite of the welded end But they are well below aluminum s 30 ksi yield stress Being the good engineer that you are you realize the design could be greatly improved by welding a cap on the open end of the beam Try posting the geometry model default group and mesh the solid face on the open end You can then quickly equivalence and optimize the model and assign the existing element properties to this new area MSC Patran301 Exercise Workbook Release9 0 1 23 Close the Database and Quit MSC Patran 1 24 Run the model through MSC Nastran again and see if the stress levels improve Good luck 22 Clo
8. Exercise 1 Introduction to C Patran MS MSC PATRAN Version 9 0 19 Dec 99 16 33 42 A irj 2 m S a I z o a z 2 E wu S ET foe o S Ea a d a o 3 vi U i vi A A 02 Nd 96 default Deformation Max 1 93 Objectives E Create geometry for a Beam BI Add Loads and Boundary Conditions M Review analysis results 1 1 MSC Patran 301 Exercise Workbook Release 9 0 1 2 MSC Patran 301 Exercise Workbook Release 9 0 Exercise 1 Geometry Model of Space Satellite Model Description This exercise will take you through the steps of modeling an open ended aluminum box beam that is welded to a rigid surface It has dimensions that are shown in the diagram below A downward 100 pound force will be applied as shown You will determine how much the box beam will deflect as well as the maximum von Mises stress Welded Base Wilaterial Aluminum Suggested Exercise Steps Create a new database and name it as box_beam db Create geometry Apply boundary conditions and loads Analyze model and view results MSC Patran301 Exercise Workbook Release9 0 1 3 Open a New Database 1 4 Exercise Procedure Note In most MSC Patran forms the default setting for the Auto Execute button is on thus you do not need to press Apply 1 Create a new database and name it box beam db File New New Model Preferences Tolerance Default Analysis Code MSC P
9. can be erased by either pressing the Reset Graphics button or by exiting the Finite Elements Application and continuing on to the next step 13 Define the Material Properties Define Since the box beam is made of aluminum we can assume the material Material is isotropic and it will behave in the linear elastic region To create the Properties material property Q Materials Action Create Object Isotropic Method Manual Input Material Name Constitutive Model Linear Elastic Elastic Modulus 10 0e6 Poisson Ratio Density 0 000259 Je Thermal Expand Coeff Apply MSC Patran301 Exercise Workbook Release9 0 1 17 Define Element Properties 14 Define the Element Properties Now we will define the element properties for our Quad4 elements The elements have a thickness of 0 05 inches and should reference the aluminum material property that we have just created We will associate the element properties with the geometry model and not the finite elements This will allow MSC Patran to reassociate the properties to the elements if we later decide to remesh the model First let s reset the view to make it easier to cursor select our elements Press Iso 1 View icon from the toolbar Y hx Now let s create our element property and reference it to our geometry model Q Properties Action Create Dimension D Type Shell Property Set Name box_beam_shell Option s Homogenous Standard Formulation May
10. es of the solid that are in the Y and Z directions use the rectangular cursor select box and cursor select the edges on the left end or the right end of the solid the illustration below shows the solid s right end edges being selected Use the rectangular cursor selection box and select the edges on the left or right end of the solid Apply MSC Patran 301 Exercise Workbook Release 9 0 Exercise 1 Geometry Model of Space Satellite Now we want to create our second mesh seed for 15 elements in the X direction Number of Elements Number 15 Curve List Select one of the 4 edges in the middle area of the solid The selected edge of the solid will be red Apply 10 Mesh the Outside Faces of the Solid with Quad4s Meshing Now we re ready to create our finite element mesh Though we have a solid we want to create a surface mesh made of 4 noded quadrilateral elements Quad4s MSC Patran allows you to create a surface mesh on the faces of our solid To do this do the following Q Finite Elements Global Edge Length Element Topology Q IsoMesh Surface List IEEE Notice the select menu will only allow you to select surfaces or solid faces because the Type option on the Finite Elements form is set to Surface Again either individually select the outside solid faces not including the two ends using shift click or MSC Patran301 Exercise Workbook Release9 0 1 13 SESS Equivalence 1 14 you may n
11. ies At the left of the menu you should see a select menu By default the Geometric Entity icon is highlighted which means MSC Patran will look for all geometry entities when you cursor select entities in the viewport But we want to cursor select only the edges of the solid for our fixed boundary conditions Thus click on the Curve or Edge icon Cursor select the left end edges of our solid by using a rectangular cursor selection Se With the cursor at point A hold down the left mouse button and drag the cursor to point B so that you have drawn a rectangular box around the left end edges of the solid as shown Then release the mouse button Note MSC Patran highlights the selected edges in red and the Select Geometry Entities databox will list the solid edge IDs i e Solid 1 1 1 1 1 2 1 1 3 etc If you are not happy with what you have selected you can deselect the edges by using the right mouse button Finish creating the boundary condition by pressing the following menu buttons Add OK Apply MSC Patran 301 Exercise Workbook Release 9 0 Exercise 1 Geometry Model of Space Satellite You should see light blue cones being drawn on the end of the solid at the Display Lines point locations shown below These represent the three fixed translational and the three fixed rotational boundary conditions Remember these have been applied to the geometry 7 Apply the 100 pound
12. ow cursor select the faces in the middle area of the solid using the rectangular cursor selection box Use the rectangular cursor selection box and select the edges in the middle of the solid Use Preferences Picking and select Enclose any portion of entity The selected edges of the solid will be red The Surface List databox should list solid 1 3 1 4 1 5 1 6 Apply The model should now look like the following 11 Equivalence the Coincident Nodes You may not realize it but duplicate or coincident nodes were created along the edges between the neighboring solid faces You will need to equivalence the nodes to remove each on of the two coincident nodes Q Finite Elements Action Equivalence Object All Type Tolerance Cube MSC Patran 301 Exercise Workbook Release 9 0 Exercise 1 Geometry Model of Space Satellite Equivalencing Tolerance 0 005 Apply Purple circles will appear which tell you where the coincident nodes were found and removed 12 Align the Element Normals Element Why bother you may ask You may not realize it but 2 D shell Normals elements like the Quad4s used in this box beam model have a defined top and bottom surface for results output By default the Quads4s we created have their positive surface normals which are the elements top surfaces pointing in the positive global coordinate directions But for postprocessing the results we want the normals to be pointing outward f
13. ox beam loadcase l op2 results file This file must be read into the MSC Patran database before you can begin to postprocess the results Q Analysis Available Jobs Available Files OK Apply You should see messages appear in the Command Line stating which results are being read into the database Now we are ready to postprocess the results Unpost 17 Unpost Erase the Geometry Group Geometry Group MSC Patran301 Exercise Workbook Release9 0 1 21 Create a Deformation Plot Create a Fringe Plot 1 22 Since we are done using the geometry let s erase or unpost the group default group which contains the geometry part of our model Group Post Select Groups to Post Apply Cancel Notice the Loads BCs symbols go away because they are associated with the geometry that is part of default group which is now unposted 18 Create a Deformed Shape Plot Let s create a deformed shape plot based on the displacement results This is an excellent way to view the response of our structure Note The numbering of the result cases may vary Q Results Select Result Case s re Select Result 1 1 DISPLACEMENTS TRANSLATIONAL Apply Although there are other ways to reset the graphics display of our model back to the default wireframe the easiest way is to press Reset Graphics icon at the top before creating another postprocessing results plot 19 Create a Fringe Plot of the von Mises Stresses MS
14. rom the box regardless of their orientation in global XYZ space To show you what we mean let s first plot the existing normal vectors by doing the following First reset the view by looking down on the end of the box beam Click on the Right Side View icon Y z xl Now let s plot the element normal vectors Q Finite Elements object Method Display Control Q Draw Normal Vectors MSC Patran301 Exercise Workbook Release9 0 1 15 Make sure the Test Control icon looks like this It should state Display Only on ET the side Apply You should see red arrows being plotted that look like this A A AAA We want to reverse the element normal directions on these two sides of the box so they point outward ZA AKT Notice the normals are aligned with the Y and Z global coordinate directions Now let s reverse the normal directions of the two sides indicated above First press the Display Only icon under Test Control so that it changes to the Reverse Elements icon Changes to EE Use the left mouse button and pick one element from the top surface which is pointing in the correct or outward direction Apply 1 16 MSC Patran 301 Exercise Workbook Release 9 0 Exercise 1 Geometry Model of Space Satellite You should see the element normals all pointing outward AMAA YYYY vVVY YYYYY The normal vectors red arrows
15. se the Database and Exit MSC Patran File Quit Changes to your model will be automatically saved when you close your database or exit MSC Patran Congratulations and give yourself a big pat on the back You have just had a glimpse of the future the way productive people will be doing finite element analyses from now on And there s much more Try accessing a CAD model creating varying loads and element or material properties through the use of Fields interpolating results from one analysis onto another model as loads and using the Finite Element Sweep mesh creation Examples of these and other features of MSC Patran can be found in Part 10 Example Problems in the MSC Patran User s Manual MSC Patran 301 Exercise Workbook Release 9 0
16. the surfaces and faces MSC Patran 301 Exercise Workbook Release 9 0 Exercise 1 Geometry Model of Space Satellite Sometimes you may need to simplify the display of your model by lowering the number of Display Lines and this is done as follows Display Geometry Number of Display Lines Apply 6 Create the Displacement Boundary Conditions Create MSC Patran has this wonderful ability to associate the loads and Boundary boundary conditions Loads BCs either with the geometry or with the Conditions finite element model The Loads BCs associated with the geometry will be applied automatically to the nodes and elements when they are created If you decide later to remesh the model the Loads BCs will be automatically revised This means you can remesh your model as many times as you wish and you won t have to worry about reassigning the Loads BCs to the mesh MSC Patran will take care of it for you For our box beam model we want to fix the welded end of the beam by defining no movement in all six degrees of freedom which is represented by six zeroes A null or blank value instead of a zero means the specific degree of freedom is free to move To apply the fixed boundary condition Q Loads BCs New Set Name Translations lt T1 T2 T3 gt Rotations RI R2 R3 Analysis Coordinate Frame MSC Patran301 Exercise Workbook Release9 0 1 7 1 8 Select Application Region Q Geometry Select Geometry Entit
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