WS13-1 VND101, Workshop 13 MSC.visualNastran 4D Exercise Workbook Pin and Bracket Assembly

WS13-1VND101, Workshop 13

MSC.visualNastran 4D

Exercise Workbook

Pin and Bracket Assembly



ObjectivesThis exercise is design to introduce stress analysis in vN4D.

You will determine the contours and deformation of the part caused by stress.

Exercise OverviewIntroduction to visualNastran Desktop 4D stress analysis.

Import/Open a model from various CAD applications.

Simulation and Display Settings.

Create a material.

Apply a pressure load.

Apply restraints.

Mesh the model.

Solve model.

Evaluate result.


I - Open Assembly / Connect Part

1) Open the associated Bracket_Pin.* file using the CAD package you are working with. If no CAD package is available, import Bracket_pin.SAT or Bracket_Pin.x_t.

If ACIS (choose override units and select inches) or Parasolid file is imported, skip sub-step 2, 3 and 4. Go directly to Creating Rigid Joint.

2) Connect the assembly or drawing over from Native CAD to MSC.visualNastran 4D

Connecting the part over from Solidworks, MDT, Pro-e, Inventor, and SolidEdge utilize Automatic Constraint mapping which transfer mates into physical joints.

3) Once the assembly is brought in from CAD, you will notice that the bracket and the Pin is connected with a revolute joint.

4) Skip to “3 - Constraint Navigator”.

Figure 1 Open file


No Feature Detected

Arc Detected

Vertex Detected

II - Creating a Rigid Joint

5) When bodies are imported, you have to manually create the constraint to simulate desired motion. For this assembly, a rigid joint is need to hold the two parts together.

6) Hide the “Pin” and rotate the “Bracket” so the hole on the back face is visible. (Figure 2)

This can be done first by right-clicking on the pin and picking Hide. Then you can rotate the Bracket around to view the back face using the Rotate Around and Pan tools.

7) Pick the Coord tool from the toolbar and hover the mouse over the body.

You will notice that vN4D allows arc detection for easy placement in the center of the hole.

8) Move the mouse to the hi-lighted circular edge until you find a cross-hair that allows you to place the coord in the center of the hole. (Figure 3)

9) Left mouse click when the Arc is detected. (Figure 4)

Figure 2 Back face surface detection

Figure 4 Coord Placement

Figure 3 Cross-hair



10) Turn the visibility of the pin back on and hide the bracket by right clicking in the Object List or the bodies.

11) Place a coord on one of the faces of the “Pin”. (Figure 6)

Pick the circular edge second to the back face. If you would like to see the coord placed, right-click on the “Pin” and choose Visibility>Translucent.

12) Right-click on the hidden bracket in the Object List and pick Show.

Hidden objects will have a be lighter icon to symbolize it is hidden.

13) Go to the Object List and expand on the two bodies so you can select the two Coords that we created.

Expand the two bodies by clicking on the plus sign to the left of the body. If there is a minus sign, then the body is already expanded and clicking the minus sign will hide the coords and constraints attached to the body in the Object Browser.

Hold down the “Control” key to multi-select. (Figure 7)

Figure 5 Hiding and showing bodies

Figure 6 Coord Placement

Figure 7 Selecting both Coords



14) With the two coords highlighted, pick the Create Constraint tool.

15) Pick “Rigid Joint” when the Create Constraint dialog box appears.

16) Accept the default joint type and Click “Create”.

The default join type is Face-to-face, where the coord on the pin flips and joins the “Bracket”.

The rigid joint will appear as in Figure 9.

Figure 8 Selecting both Coords

Figure 9 Rigid Joint


III - Constraint Navigator 17) Right-click on the “Pin” and pick Constraint Navigator to open the navigator.

Constraint Navigator allows you to examine relationships among bodies, subassemblies, and constraints so that you can verify and modify your simulation model. Clicking on the Constraint Navigator will lighten the assembly.

18) Navigate through the constraints within the assembly by clicking Next on the toolbar beneath the green constraint icon and use the Move tool to see its motion. (Figure 11)

Start by clicking Next once to focus on a constraint. Pick the Move tool, click on the body of the constraint, and drag the body around to view the type of constraint is highlighted.

Since there is only one constraint at this time, the Next tool becomes inactive after the first click. If there were 5 constraints, the Next tool will navigate through all 5 constraints.

19) Click Done after moving the assembly and observing the type of connection. (Figure 11)

The colors of the bodies revert back to being bold.

20) Change the “Revolute Joint” to a “Rigid Joint” if it is not already so by double-clicking on the constraint either in the Connection Window or the Object List Window.

If the pin rotated inside the Bracket instead of moving with it, then the constraint is a Revolute Joint. when changing a Revolute Joint to a Rigid Joint, you can either make the rigid joint measurable or optimized. In this case we will want to Optimized the rigid joint for faster simulation.

21) Click “Close” to close the Properties dialog box.

Figure 10 Constraint Navigator

Figure 11 Navigating through constraints


IV - Display and Simulation Setting

22) From the World menu select Display Settings or click the Display Settings tool.

23) Click the Units tab. (Figure 12)

24) Set the “Unit System” to “English (pounds)” by scrolling down the pull-down menu and highlighting English (pounds). (Figure 12)

All the dimensions in this simulation is now converted to the English (pounds) unit system. The different units are displayed underneath Unit System. For example, “Pressure” is measured in “psi”.

25) Click “Close”.

Figure 12 Display Settings - Units


IV - Display and Simulation Setting

26) From the World menu, pick Simulation Settings or click on the Simulation Settings tool in the toolbar.

Notice that the Simulation Settings menu is the same as the Display Settings menu. You can move from one tab to another, all under the Settings menu.

27) Click on the FEA tab and pick “Stress” for “Analysis Type”. (Figure 13)

28) Make sure the “Desired Outputs” are “Displacement”, “Stress”, and “Strain”. (Figure 13)

29) Click “Apply” and “Close”. Figure 13 Simulation Settings - FEA


V - Specify Material30) Double-click on the “Bracket” in the simulation window.

The Properties dialog box appears.

31) Pick the Material tab and click “Change” to change the material.

The “Material Properties” window appears.

32) Pick Aluminum 2024-T3 as the type of material and click “OK”. (Figure 15)

33) Click the Appearance tab.

34) If not already assigned, assign the name “bracket_assy_piece-1”.

35) Leave everything else default and click “Apply” and “Close”.

36) Repeat steps 30 thru 35 for the pin and assign the name “pin_assy_piece-1”. Choose Steel-ANSI 304 for the pin material.

Figure15 Material PropertiesFigure 14 Material


VI - Apply Pressure

Now we will assign a pressure force to the back face of the pin.

37) Pick the Structural Load tool.

Picking this tool will change the mouse curser from an arrow to two arrows and a question mark.

38) Pick the back face of the pin. (Figure 16)

You may need to use the “Rotate Around” tool. The face will be highlighted black and the curser changes to display two arrows and a sheet of paper once the curser is hovering over the face. (Figure 16)

39) Double-click the constraint (green arrows) just created to open the Properties dialog box.

40) Under the Structural Load tab, pick “Pressure” as the load “Type”. (Figure 17)

41) Type in “100 psi” as the amount of pressure normal to the wall.

42) Click “Apply” and “Close”.

Figure 16 Simulation Settings - FEA

Figure 17 Simulation Settings - FEA


VII - Apply Restraints

Figure 18 Restraint placement

43) Rotate the assembly to get a better view of the holes.

The faces of the holes will be selected for the restraint.

44) To apply restraints, go to Insert>Restraint or click the Restraint tool.

Two arrow tips with a question mark takes place of the arrow curser once Restraint is picked.

45) Select half the face of one of the holes as shown in Figure 18.

Once half of the face is selected, blue restraint crosses appear on that half.

46) Repeat steps *** and *** for the other half of the hole.

You may need to use the Rotate Around tool to see the other half of the hole.

47) Repeat steps 43 though 46 for the next hole.

The model with restraints applied is displayed in Figure 19.

Figure 19 Restraints


VIII - Meshing the Geometry48) Double-click on the bracket in the simulation window.

The Properties dialog box of body appears.

49) Pick the FEA tab and check “Include in FEA”.

Once “Include in FEA” is checked, the rest of the dialog box becomes active.

50) Check “Show mesh” and enter “0.3” for the “Default Mesh Size”. Accept all other defaults. (Figure 20)

51) Click the Mesh button to mesh the model.

A separate window appears as the model is meshed. Once the window disappears, the bracket is meshed .

52) Close the Properties dialog box.

53) Now double-click the pin.

54) Select the FEA tab in the Properties of body window that appears.

55) Check Include in FEA.

56) Check Show mesh and enter “0.2” for the Default Mesh Size. Accept all other defaults.

57) Click the Mesh button to mesh the model.

The pin is now meshed.

58) Close the Properties window.

Solid elements are set by default. The simulation window now shows the bracket and pin with mesh elements. (Figure 21)

Figure 20 Properties of body - Mesh

Figure 21 Meshed assembly


IX - FEA Analysis

59) Click the “Solve FEA” button in the playback controls.

60) The MSC.Nastran analysis window appears to display analysis is in progress. (Figure 22)

The analysis may take a few minutes.

After results are completed, visualNastran Desktop will display the result in the simulation window.

61) If not already shown, results such as Mesh, Contours, Deformation and Forces can be displayed by right-clicking on the model in the simulation window. (Figure 23)

62) Another way would be to click on FEA display in the Properties List and the Properties dialog box of body will appear.

63) Pick the FEA Display tab and check on the respective result to display. (Figure 24)

Figure 23 Show Contours

Figure 22 MSC.Nastran analysis in progress

Figure 24 Display results


X - Results Animation

Figure 25 Animate result

64) The simulation window displays the result as shown in Figure 25.

65) To animate the result click the arrow next to the “Run” button in the Playback Controls.

66) Pick Animate FEA from the pull-down menu, and hit that button.

67) View other modes of vibration by changing the mode in the Display Settings.


Review

You learned how to apply stress analysis in visualNastran Desktop 4D.

You learned how to display the different results of the analysis.

You also learned how to animate the stress application.


Documents

WS13-1 VND101, Workshop 13 MSC.visualNastran 4D Exercise Workbook Pin and Bracket Assembly