Alternate Bar Orientations

Transcription

1 APPENDIX N Alternate Bar Orientations Objectives: The effects of alternate bar orientation vector. MSC.Nastran 120 Exercise Workbook N-1

2 N-2 MSC.Nastran 120 Exercise Workbook

3 APPENDIX N Alternate Bar Orientations Model Description: Model an aluminum bar using MSC.Patran. Two different coordinate frames will be used for the analysis of this bar to show that the final results will be equal. You will generate a MSC.Patran input file and examine its contents. Figure N.1 40 in Table N.1 - Bar Properties Material Aluminum Elastic Modulus, E = 10E6 psi Poisson s Ratio, v = 0.3 Area 0.97 in 2 I1 0.2 in 4 I in 4 Torsional Constant in 4 MSC.Nastran 120 Exercise Workbook N-3

4 Suggested Exercise Steps: Define a local coordinate system. Define Geometry for the finite element model. Mesh the Geometry to create finite elements. Define material properties. Define element properties. Generate an MSC.Nastran input file. Inspect the MSC.Nastran input file and determine which coordinate system the Bar Orientation Vector is defined in. Submit the model to MSC.Nastran for analysis. Interpret the results from the.f06 file. Change the Analysis Coordinate Frame from the Basic Rectangular to a local coordinate system. Generate an MSC.Nastran input file. Inspect the MSC.Nastran input file and determine which coordinate system the Bar Orientation Vector is defined in. N-4 MSC.Nastran 120 Exercise Workbook

5 APPENDIX N Alternate Bar Orientations Exercise Procedure: 1. Create a new database called bar.db. File/New... New Database Name: bar In the New Model Preference form set the following: Tolerance: Analysis Code: Analysis Type: Default MSC/NASTRAN Structural NOTE: Whenever possible, toggle off the Auto Execute option by left clicking the check box. 2. Create a user defined Coordinate System. Geometry Object: Coord Method: 3Point Coord ID List: 99 Origin: [ ] Point on Axis 3: [ ] Point on Plane 1-3: [ ] 3. Define geometry for the model. Geometry Object: Curve MSC.Nastran 120 Exercise Workbook N-5

6 Method: XYZ Vector Coordinates List: <40 0 0> Origin Coordinates List: [ ] 4. Mesh the geometry to create finite elements. Finite Elements Object: Mesh Type: Curve Global Edge Length: 10 Curve List: Curve 1 Node Coordinate Frames... Analysis Coordinate Frame: Coord 99 Refer. Coordinate Frame: Coord Define material properties. Materials Object: Isotropic Method: Manual Input Material Name: alum Input Properties... Elastic Modulus = 10E6 Poisson Ratio = 0.3 N-6 MSC.Nastran 120 Exercise Workbook

7 APPENDIX N Alternate Bar Orientations 6. Define element properties. Properties Object: 1D Method: Beam Property Set Name: bar Input Properties... Material Name: m:mat_1 Bar Orientation: <0, 1, 0> (scroll down using scroll bar) Area: 0.97 [Inertia 1,1]: 0.2 [Inertia 2,2]: 2.65 Select Members: Curve 1 Add 7. Define constraints for the model. Loads/BCs Object: Displacement Type: Nodal New Set Name: fixed Input Data... Translations <T1 T2 T3> <0 0 0> Rotations <R1 R2 R3> <0 0 0> Analysis Coordinate Frame: Coord 99 MSC.Nastran 120 Exercise Workbook N-7

8 Select Application Region... Select Geometry Entities: Point 1 Add 8. Create the nodal force. Loads/BCs Object: Force Type: Nodal New Set Name: load Input Data... Force <F1 F2 F3> < > Analysis Coordinate Frame: Coord 99 Select Application Region... Geometry Filter: FEM Select Nodes: Node 5 Add 9. Generate an MSC.Nastran input deck. Analysis Action: Analyze Object: Entire Model Method: Analysis Deck N-8 MSC.Nastran 120 Exercise Workbook

9 APPENDIX N Alternate Bar Orientations An MSC.Nastran input file called bar.bdf will be generated. This process of translating the model into an input file is called the Forward Translation. The Forward Translation is complete when the Heartbeat turns green. 10. Examine the MSC.Nastran input file (bar.bdf) that was just created. Figure N.2 BEGIN BULK PARAM POST -1 PARAM PATVER 3. PARAM AUTOSPC YES PARAM INREL 0 PARAM ALTRED NO PARAM COUPMASS -1 PARAM K6ROT 0. PARAM WTMASS 1. PARAM,NOCOMPS,-1 PARAM PRTMAXIM YES $ Direct Text Input for Bulk Data $ Elements and Element Properties for region : bar PBAR CBAR CBAR CBAR CBAR $ Referenced Material Records $ Material Record : alum $ Description of Material : Date: 26-Feb-98 Time: 15:26:39 MAT $ Nodes of the Entire Model GRID GRID GRID GRID GRID $ Loads for Load Case : Default SPCADD 2 1 LOAD $ Displacement Constraints of Load Set : fixed SPC $ Nodal Forces of Load Set : load FORCE $ Referenced Coordinate Frames CORD2R A + A ENDDATA 75cf4224 MSC.Nastran 120 Exercise Workbook N-9

10 Note: Regardless of the user specification, MSC.Patran will convert the orientation to reference the displacement coordinate system of the grid. 11. Submit the job for analysis and review the results. To submit the MSC.Patran.bdf file for analysis, find an available UNIX shell window. At the command prompt enter: nastran plate.bdf scr=yes. Monitor the run using the UNIX ps command. Figure N.3 D I S P L A C E M E N T V E C T O R POINT ID. TYPE T1 T2 T3 R1 R2 R3 1 G G E E G E E G E E G E E Is the result consistent with the loading? Is it consistent with the displacement coordinate system? 12. Modify the displacement coordinate system from Coord 99 to Coord 0. Finite Elements Action: Modify Object: Node Type: Edit Nodal Attributes: Analysis Coordinate Frame: Coord 0 Node List Node 1:5 Analysis Coordinate Frame 13. Generate an MSC.Nastran input deck and inspect the.bdf file. Analysis Action: Analyze N-10 MSC.Nastran 120 Exercise Workbook

11 APPENDIX N Alternate Bar Orientations Object: Entire Model Method: Analysis Deck MSC.Nastran 120 Exercise Workbook N-11

12 Figure N.4 CEND SEALL = ALL SUPER = ALL TITLE = MSC.Nastran job created on 26-Feb-98 at 15:43:49 ECHO = NONE MAXLINES = $ Direct Text Input for Global Case Control Data SUBCASE 1 $ Subcase name : Default SUBTITLE=Default SPC = 2 LOAD = 2 DISPLACEMENT(SORT1,REAL)=ALL SPCFORCES(SORT1,REAL)=ALL STRESS(SORT1,REAL,VONMISES,BILIN)=ALL BEGIN BULK PARAM POST -1 PARAM PATVER 3. PARAM AUTOSPC YES PARAM INREL 0 PARAM ALTRED NO PARAM COUPMASS -1 PARAM K6ROT 0. PARAM WTMASS 1. PARAM,NOCOMPS,-1 PARAM PRTMAXIM YES $ Direct Text Input for Bulk Data $ Elements and Element Properties for region : bar PBAR CBAR CBAR CBAR CBAR $ Referenced Material Records $ Material Record : alum $ Description of Material : Date: 26-Feb-98 Time: 15:26:39 MAT $ Nodes of the Entire Model GRID GRID GRID GRID GRID $ Loads for Load Case : Default SPCADD 2 1 LOAD $ Displacement Constraints of Load Set : fixed SPC $ Nodal Forces of Load Set : load FORCE $ Referenced Coordinate Frames CORD2R A ENDDATA b9820b92 Quit MSC.Patran after finishing this exercise. N-12 MSC.Nastran 120 Exercise Workbook