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TUTORIAL 1 IMPORTING, MODIFYING, & EXPORTING NASTRAN DECKS

TUTORIAL 1 IMPORTING, MODIFYING, & EXPORTING NASTRAN DECKS.

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TUTORIAL 1 IMPORTING, MODIFYING, & EXPORTING NASTRAN DECKS

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  1. TUTORIAL 1 IMPORTING, MODIFYING, & EXPORTING NASTRAN DECKS

  2. As in the other tutorials, all menu items that need to be selected will be preceded by a maroon right arrow: >User action. Mouse buttons are indicated as follows: -- 1B = First (left) button -- used for selecting items-- 2B = Second (middle) button -- used for "OK"-- 3B = Third (right) button -- used for View Manipulation & pop-up menusNormally 1B is used, unless otherwise . Table Of Contents SectionPage Step1. Import Nastran Deck. 3 Step2. Use Statistics Panel . 5 Step3. Create & Modify Parts, Material properties and BC Sets. 6 Step4. Add Forces & SPC's To Model. 9 Step5. Clean Up Model. 13 Step6 . Change Units. 16 Step7 . Set Output Options & Export Nastran Deck. 16 Step8 . Convert Nastran File To Ls-Dyna Format. 17

  3. Step1. Import Nastran Deck. Let's Start: • Launch MSC.SOFY according to your local configuration. • Select >NASTRAN mode from entry screen. • Before importing an existing model, it is good practice to first set the I/O options to insure proper importing of entities. • Top menu bar >Select >Options>I/O Options >NASTRAN Opts >Input Options. • In the dialog box, set your input options to match the example below. • Notice there are many options for offsetting entity ID's. • In most cases these boxes should be checked (selected) to avoid duplicate ID numbers, particularly if you are adding parts into an existing model. • Also, if the NASTRAN deck was created in Hypermesh, you should check the box >Import HM Cards to retain names of parts, boundary conditions, etc. d e

  4. Step1. Import Nastran Deck. k • Now set the units to match the file being imported: Select >Options menu >Units Mgr. • In the Units Manager dialog box Select >Standard Units button, which brings up another pop-up with several choices of units. • Choose >NASTRAN (without WTMASS card) >OK. • Check that the derived units are appropriate, as well. • For example, Choose >N-mm for torque to maintain a consistent set of units. • When finished >Exit the dialog box. • Now to import the NASTRAN deck Select >File menu >Import >NASTRAN. • In the dialog box "Select Nastran file to merge“ navigate to the file …/SOFY3.0/SOFY_MASTER2/DEMOS/Tutorials_NASTRAN/Tut_N-1_floor.nas q. Click. >Open. r. Watch the message area at the bottom for any error messages. • When complete, you should have the following model on the canvas p s

  5. Step2. Use Statistics Panel. d • Looking at the title bar of your MSC.SOFY window, note that your model has been given a temporary MSC.SOFY database file name, same as your imported deck, except with extension "sof." • This file is only temporary, unless you perform a Save operation. • Find out some statistics about the model by selecting Statistics icon from tool bar. • An information panel comes up with the statistics about the current scene, such as number of parts, number of CQUAD4 elements, and so on. (Note that only entities currently displayed are included in the Statistics.) c

  6. Step3. Create & Modify Parts, Material properties and BC Sets. • Let's examine and modify some of the parts in the model. 1. From Collection block> Type >Part should already be displayed. 2. Click with >3B over the part name:>PNL_RR_FLR 3. From the pop-up> select >Modify. 4. Changethickness to 0.75 5. Click >Modify 6. Select >Exit the panel. b. To create a new material: 1. In Collection block>Type >Material. 2. Click the >Create button 3. Select >MAT1 type. (Note that MAT2, 3, 4, 5, 8, 9, and MAT10 material cards are also supported.) 4. Name the material >Alum and give values of E= 70000, and Nu= 2.7e-9. 5. Click >Create button 6. Select >Exit. a-4 a-4 a-5

  7. Step3. Create & Modify Parts, Material properties and BC Sets. (Cont’d) c. Assign a different material property to an existing part: 1. In Collection block, change Type >Part. 2. Click with >3B over the part name >loadplate3. 3. Select >Modify 4. Double-click in the field for MID (material ID) and choose >Select from the pop-up.(Note: you can also Create materials from this panel. ) 5. An entity selection box pops up with a list of available materials in the model. 6. Choose >Alum 7. Click Ok. 8. Now click >Modify in the Modify part panel>Exit. c-3 c-6 c-4

  8. Step3. Create & Modify Parts, Material properties and BC Sets. (Cont’d) d-3 d. Let's examine the BC (Boundary Condition) Sets. 1. From Collection block>Type >BC Sets. 2. Click >Details icon in toolbar to add labels.3. Collection Block >turn off various BC Sets to get familiar with them, ending with >All On. 4. Note there are many BC Sets that are the same color. 5. To make it easier to tell the BC sets apart, let's change their colors. 6. Click with >3B in the list area, and choose >Auto-color. 7. MSC.SOFY automatically assigns colors to the BC sets. e. Create a new BC Set 1. Click >3B in list area of Collection Block (Type=BC Sets). 2. Select >Create from the pop-up list. 3. Type in the name: Rr_edge 4. Click >Create 5. Select >Exit. d-6 e-3 e-4

  9. Step4. Add Forces & SPC's To Model. a-1 a. Create some Forces in the new BC set you just created. 1. Top bar>BC menu>Create BC >Force. 2. In the pop-up menu, you are asked for the magnitude and vector components of the force, (relative to the coordinate system that you will choose in the next step.) 3. Complete the entries as shown . 4. Click >Store 5. Select >Exit. b. In the Pick block, there is a choice of Local or Global Coordinates. c. Select >Local. d. Now notice in the Messages area, you are being prompted to "Create a LCS" (Local Coordinate System). e. Zoom into rear of the floor panel, as shown. f. Choose 3 points on the angled surface near the rear: 2points along the top feature line, and 1 point near the bottom feature line. c f

  10. Step4. Add Forces & SPC's To Model. (Cont’d) h • After selecting 3 points, the LCS is created. • Now select a group of about 10 points in a horizontal line along the angled surface. • Confirm with >2B in the canvas (or >Done in Pick block) and the forces are created. • Because of the vector components, defined in step a, the forces are normal to the angled surface, as can be seen in the side view. • Perhaps the line of forces is not exactly straight. • You can use Align node command to correct it. • From >Node menu (select) >Align. • The first thing you must do is define a vector. • Pick the >first and last points where the forces are applied, • Confirm with >2B • Now pick all the >points in between • Confirm with >2B. • Your line should now be straight. i

  11. Step4. Add Forces & SPC's To Model. (Cont’d) b Create some SPC’s in the new BC set you just created. • Create another BC set, as was done in (Step3-e) • This time giving it the name, SPC_side. • To create SPC's (Single Point Constraints) Select >BC menu >Create BC >SPC. • In the dialog box, de-select the 4, 5, and 6degrees of freedom • Click >Store. • Now you select the nodes for the SPC's. • Open the Extended Pick Dialog (EPD)>Click on >D along left side of Pick menu. • Choose >Shortest path under Pick by Ref. side of dialog. d g h

  12. Step4. Add Forces & SPC's To Model. (Cont’d) • Select the start and end >points of the constraints, the straight portion of the side edge, on the rear half of the part. • As soon as the second point is selected, all points in between are also selected. • Confirm with >2B and now SPC's are placed at all the selected nodes. Repeat on the other side. • Zoom into the group of forces in the left front quadrant of the floor. • Let's say these four forces should be in the same BC set. • List BC Sets in order of ID number by checking the box >ID's in Collection block. • Make the set #3: LFTFRT the "current" BC set, by clicking on its name with the >2B. • Move the forces shown into the current BC Set Select >BC menu bar >Move to Current Set. • Now select the four forces mentioned • Confirm with >2B. (or click >Done) • The color change indicates all forces now belong to the same BC set. j o l p

  13. Step5. Clean Up Model. • To clean up the model before exporting: 1. Select >Utilities menu>ModelCleanup>DeleteUnref. 2. Click >Reverse button to place checks in all boxes 3. Select >Apply. • Watch message area for confirmation of which empty and unreferenced entities have been deleted. • Now to merge duplicate materials & properties Select >Utilities menu >Model Cleanup>Merge Duplicate. • Check the box for >Materials, as there are likely duplicate materials in this model. • Click >Apply and watch Message area for confirmation messages. • This command will merge duplicates only if all fields on the material cards are identical. a b c

  14. If you wish to exclude certain nodes or elements from being renumbered, use the command TopBar >Utilities >ID Mgmt >Lock Entitiy ID's. Also found on >Node menu.) Step5. Clean Up Model. (Cont’d) g • Renumber entities in the model 1. Select >Utilities >ID Mgmt >Model ID Manager. 2. Enter the starting and offset ID numbers, as applicable, for Parts, Grids, Elements, etc. 3. Any entity types that are disabled can be turned to active by checking the box on right side of menu. 4. When ready, click >OK and all selectedentities will be renumbered.

  15. Step6. Change Units. b Now suppose you were going to share this model with someone who uses different units. • You can change the units before exporting to be compatible with the recipient's preferences. • From >File menu >Units Mgr. • Click >Standard Units button • From the pop-up> select >Crash units • Click >OK. • Now >Exit the Units Manager. d

  16. Step7. Set Output Options & Export Nastran Deck. Almost ready to export the NASTRAN deck... • But first, let's check the export options: Options >I/O Options >NASTRAN Opts >Output Options. • Similar to the input options panel, you can select / suppress certain cards and entities from being exported, and you can select single/ double precision cards to be written. • To write a Nastran deck: Select >File menu >Export>Nastran Model. • In the dialog box, give a file name, perhaps "nast_export_crash.nas" • Click >Save. • You may wish to export only a portion of the model: 1. Use >Organize command >Keep the floor panel >PNL-RR-FLR 2. Click >Done>Select >Exit. 3. Go to >File menu >Export >Nastran Scene. 4. Enter a file name, such as "scene_export.nas" 5. Click >Save. • Open each of the files created in steps d and f-4 in Notepad, or similar text editing software to check the contents and units. • Exit MSC.SOFY: File >Quit. (Don't save.)

  17. Step8. Convert Nastran File To Ls-Dyna Format. • Let's convert a NASTRAN file to LS-DYNA format. 1. Re-open MSC.SOFY >choose >LS-DYNA mode from entry screen. 2. From >File menu >Units Manager >Crash std units are selected. 3. Now import the NASTRAN file you just created in Step “d”. File >Import >Nastran. 4. In the dialog box, navigate to the file: "nast_export_crash.nas" 5. Click >Open. • When completed, you should see the same floor pan model on the screen, with all NASTRAN entities converted to LS-DYNA entities. • Now create a Dyna deck: File >Export >Dyna. • In the dialog box, provide a file name, such as "dyn_export_crash.dyn“ • Click >Save. • Check the file contents using a text editor to see how the NASTRAN entities were converted to LS-DYNA. Congratulations!!! You have just completed Nastran Tutorial 1.

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