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Introduction to MSC.visualNastran 4D

October 2002

VND101 EXERCISE WORKBOOKMSC.visualNastran 4D

DISCLAIMER

MSC.Software Corporation reserves the right to make changes in specifications and other information contained in this document without prior notice.

The concepts, methods, and examples presented in this text are for illustrative and educational purposes only, and are not intended to be exhaustive or to apply to any particular engineering problem or design. MSC.Software Corporation assumes no liability or responsibility to any person or company for direct or indirect damages resulting from the use of any information contained herein.

User Documentation: Copyright 2001 MSC.Software Corporation. Printed in U.S.A. All Rights Reserved.

This notice shall be marked on any reproduction of this documentation, in whole or in part. Any reproduction or distribution of this document, in whole or in part, without the prior written consent of MSC.Software Corporation is prohibited.

MSC and MSC. are registered trademarks and service marks of MSC.Software Corporation. NASTRAN is a registered trademark of the National Aeronautics and Space Administration. MSC.Nastran is an enhanced proprietary version developed and maintained by MSC.Software Corporation. MSC.Patran is a trademark of MSC.Software Corporation.

All other trademarks are the property of their respective owners.

MSC.visualNastran Desktop

Exercise Workbook

Swinging Blocks

WS01-4VND101, Workshop 01

Exercise OverviewCreate and Position the BlocksAdd the ConstraintsSpecify Collisions between the BlocksAdd a Ball and SpringInclude one block in FEAAdd two MetersModify the existing ConstraintsInsert a Slider Control


I - Setup

1) Go to the World menu and pick Display Settings. Or, hit the Display Settings button on the toolbar.

2) Go to the Display Settings tab.

3) Uncheck “Automatic Size” in the “Constraint and Coord Appearance” area. (Figure 1)

4) Go to the Grid tab under the Display Settings Tree.

5) Uncheck “Automatic Sizes” in the Grid area and make sure “Snap to Grid” is checked.

The Grid dialog box should look like Figure 2.

6) Press the “Close” button to close the “Settings” dialog box.

Figure 1 Display Settings

Figure 2 Settings – Grid Tab


II - Create and Position the Blocks

7) Pick the Box tool from the Toolbar.

As soon as you pick a Box tool, the “Edit Grid” appears in the drawing window.

8) Starting anywhere on the grid, create the base of a new block by beginning with your cursor right at a grid intersection, click the mouse to start the base of the rectangle.

9) Move the mouse away (dragging a rectangle as you go) “.32” in the Y-direction and “.02” on the X direction, and click a second time to establish the base of the block.

The numerical size of the block is located in the Status Line at the bottom of the screen. Refer to Figure 3.

Starting at a blue intersection, you will go ½ a grid square in “X” and 8 squares in the “Y”.

10) Move the mouse upwards “.08” in the Z (four grid snaps) and click the mouse a third time to establish the height of the block.

The block should look like the one in Figure 3. Figure 3 MSC.visualNastran Simulation Window

Block Dimensions



11) Start a new block by picking the Box tool again.

12) From the right end of the existing block, place the first click one grid square behind (in the negative X direction) and one grid square right (in the positive Y direction).

13) Move the cursor (and form a rectangle as you move) 2 squares “.08” left in the –Y, and 8 squares “.32” forward in the +X and place the second click there.

Figure 4 is provided as a reference, but your second block should look like that in Figure 5.

Figure 5 Draw Second Block

Figure 4 Start and Finish of Second Block

First Click

Second Click



14) And finally, move the mouse down one snap increment below the grid in the –Z “.02” and place the third click there, completing the second block.

The simulation window should now look like Figure 6.

15) Pick the Rotate Around tool and rotate the view around to see what the two blocks look like from different viewing angles. (Figure 7)

16) Hit the “H” key to return to the original, or “Home” view.

Figure 6 Finished Second Block

Figure 7 Rotate Around


Now we’ll move the first block upwards into position.

17) Using the Arrow Tool, select the first block created to make it active.

Notice that the block displays a gray bounding box to indicate that it is selected.

18) Pick the Drag Z tool and drag the first block upwards along the positive Z until the Z field in the Status Line at the bottom of the screen reads “.24”.

19) Hit the Green Play button in the Playback controls.

The blocks proceed to drop out of the viewing area.

20) After a couple of seconds, hit the Stop and Reset button to bring the Blocks back to their original position.

It is important to reset the simulation each time to be sure that changes take effect at the initial state of the system, not some state farther along in time.

Figure 8 Move First Block


Figure 9 Playback Controls

PlayStopReset


III - Add the Constraints

The next phase is to define the motion of the blocks by applying Constraints.

21) In the toolbar, click on the arrow next to Create Constraint.

22) In the pull-down menu, select Revolute Joint. (Figure 10)

The Edit Grid appears in the drawing window, and the curser has a black “Revolute Joint” icon next to it.

23) Click on the middle of the face of the top block, about one grid square in from the right end. (Figure 11)

The face will turn black, a red coord is placed in that spot, and a line connects that coord to your curser when you move it around.

24) Hit “Enter” on the keyboard. (Figure 11)

Hitting “Enter” will constrain the block to the background.

25) Hit the Green Play button to run the simulation.

The upper block begins to swing about the revolute constraint, and the lower block drops out of the screen, both due to gravity.

26) After a couple of seconds, hit the Stop and then the Reset button to bring the blocks back.

Figure 10 Revolute Joint

Figure 11 Place Coord on First Block


III - Add the Constraints

We need to set a similar Constraint for the other block.

27) Click on the arrow next to Create Constraint and select Revolute Joint.

28) Click on the middle of the face of the second block, about one grid square back from the front end of the block. (Figure 12)

29) Hit “Enter” on the keyboard.

Again, this attaches the constraint to the background.

30) Hit the Play button to run the simulation.

The upper block begins swinging again, and the lower block doesn’t move. The upper block swings right THROUGH the lower block. Clearly we need to specify some Contact.

31) Hit Stop and then Reset to bring the blocks back to their starting position.

Figure 12 Revolute Constraint on Second Block

Figure 13 Run Simulation


IV - Specify Collisions between the Blocks

Now, we’ll tell the two clocks to collide with each other.

32) With the Arrow tool, select both blocks to make them both active.

To do this, click on one block, and then Control-Click on the other one to select them both.

33) Right-Click on either block.

A pop-up menu will appear.

34) Move down the menu and pick Collide. (Figure 14)

No apparent change occurs to the blocks. If you were to right-click on one of the blocks again, you’d see that the “Collide” options is highlighted to indicated that this mode is on for these two selected blocks.

35) Hit the Play button to see how the blocks behave.

The two blocks swing around on their pivots. (Figure 15)

36) Hit the Stop and Reset button.

Figure 15 Blocks Rotate Around Pivots

Figure 14 Collide


V - Add Ball and Spring

Now we’ll add a ball that’s hanging from a spring from the lower block.

37) Pick the Sphere tool.

38) Create a small sphere by first, clicking behind the far end of the lower block.

39) Move away one grid snap (.02 radius) and click a second time to complete the sphere. (Figure 16)

The exact placement of this sphere won’t be critical. Just get it very near the end of the block. Even if it ends up inside the lower block when you draw it, it won’t matter.

40) With the Sphere still selected, pick the “Drag Z” tool and move the Sphere down below the grid about 0.10.

You can observe how far you’ve dragged the sphere by looking at the “Z” value in the Status Line.

Figure 16 Add Sphere



41) Click on the arrow next to the Create Constraint tool and select Linear Spring/Damper from the pull-down menu.

42) Click anywhere on the sphere.

43) Move over to the top face of the lower block and select the middle of the back end. (Figure 18)

The spring constraint now connects the sphere and the lower block.

Figure 18 Add Spring/Damper Constraint

Figure 17 Create Constraint Pull-down Menu



Now we’ll run the simulation again to see how the system behaves Before we do so adjust your view so that the whole motion will be visible when it plays.

44) Use the Zoom In/Out tool and the Rotate around tool (if necessary) to adjust your view to something like what you see in Figure 19.

45) Hit the Green Play button to run the simulation.

The two blocks swing around and the ball-and-spring has a significant effect on the motion of the lower block.

Because the exact placement of the “Revolute Joints” and “Spring/Damper” was not specified, no two simulations will be exactly the same.

If the blocks get caught on each other, you can modify the simulation by changing the mass of the ball. To do this, 1) Double-click on the Ball. This brings up it’s Properties dialog box. 2) Click on the “Material” tab. 3) Change the mass by doubling it or cutting it in half. Either change should make enough of a difference in the simulation. 4) Hit the “Close” button.

46) Stop and Reset the simulation.

Figure 19 Simulation Window


VI - Include One Block in FEA

Next we will look at a simple FEA on the lower block that results from the spring applying varying loads to the block through time.

47) Right-click on the lower block, and in the resulting pop-up menu pick Include in FEA. (Figure 8)

A series of “load arrows” appear on the block to indicate that the stresses will be calculated as a result of the loads being distributed along this top face.

48) Click on the “Solve FEA” button in the “Play Controls” area.

It’s the rainbow-colored gyroscope at the bottom of the screen. The stresses on the lower block are calculated and displayed as color banding on the block itself. A legend for the values also is created.

Figure 20 Include in FEA

Figure 21 Second Block Included in FEA


VI - Include One Block in FEA

49) Select the arrow button next to Play in the Playback Controls.

50) In the Pull-down menu, select Motion with FEA. (Figure 22)

51) Click on the new “Run with FEA” button. (Figure 23)

Now as your new animation plays, the FEA color-banding will update with every frame to show you how the stresses behave throughout the simulation

52) Click the Stop and Reset button.

53) Right-click the lower block, and in the resulting pop-up menu, select Include in FEA again to uncheck it.

54) In the pop-up dialog box, hit “Yes” to erase the FEA results.

Figure 22 Play Pull-down Menu

Figure 23 Motion with FEA


VII - Add Two Meters55) With the Arrow tool, click on the lower block to

select it.

The Connections list displays a list of the objects connected to this body.

56) Go to the Insert menu and pick Meter>Angular Velocity.

A blank graph for the meter data appears, along with a Tiling Options dialog box, as shown in Figure 25.

57) In the Tiling Options dialog box, accept the default setting and click OK.

The result is shown in Figure 26.

Figure 24 Angular Velocity Meter

Figure 26 Angular Velocity Meter for Second Sphere

Figure 25 Tiling Options


VII - Add Two Meters

Figure 27 Add Position Meter

58) With the Arrow tool, click on the ball to select it.

59) Go to the Insert menu and pick Meter >Position.

60) In the dialog box that appears (the same one as before), confirm the “Tile Vertically” option and hit the “OK” button.

The Simulation window should look like Figure 27.

61) Hit the Play button to run the simulation with the meters.

Now you’ll see at time-progression of measured data for the parameters of the simulation that you’ve asked for. (Figure 28)



VIII - Modify the Existing Constraints

62) Hit the Reset button to bring the simulation back to its starting position.

63) Maximize the drawing window by hitting it’s maximize button. (Figure 29)

This will cause the drawing window to enlarge and cover-over the two graph windows. They are still there, they’re just underneath the main window now.

64) Hit the “H” key to take the view back to the “Home” view.

Of course, if the view that results for you isn’t useful as a “Home View” then use the Pan and Zoom tool to arrange an new one, and then hit the “S” key to make the current view be the Home view.

65) Using the Arrow tool, right-click on the upper “Revolute Joint” and in the resulting pop-up menu pick Properties. (Figure 30)

Figure 29 Maximize

Figure 30 Pull-Down Menu of Revolute Joint



66) Pick the Constraint tab in the “Properties” dialog box.

67) Scroll down in the list of constraints and pick “Revolute Motor”. (Figure 31)

68) Go to the Motor tab (Figure 32), enter “180” in the data field for “Value”, and hit the “Close” button.

You will see that the symbol of the Constraint has changed. It now looks like Figure 33.

Figure 31 Constraint Page

Figure 32 Motor Page

Figure 33 Revolute Motor



69) Hit the green Play button.

The upper Block begins rotating around at a constant velocity.

70) Hit the Reset button to bring the simulation back to its starting position.

71) Using the Arrow tool, double-click on the “Revolute Joint” on the lower block.

This immediately brings up the Properties dialog box for that object.

72) Scroll down in the list of constraints and pick “Revolute Spring/Damper”.

73) Hit the “Close” button. Figure 34 Constraint Tab



With this new set-up, the sphere certainly will hit the two blocks. Now we have to collide the Sphere with the two blocks.

74) With the Arrow tool, select all three bodies by clicking on each one while holding down the “Control” key.

75) Right-click on any of the three bodies and in the resulting pop-up menu, pick Collide.


The upper block begins rotating around at a constant velocity, AND the lower block springs back and forth accordingly.

Figure 35 Collide



IX - Insert a Slider Control

Now, we will add a slider control to the revolute motor which will allow us to interactively control the direction and speed of the motor, thereby changing the way the upper block behaves.

77) With the Arrow tool, select the green “Motor” constraint on the upper block to make it active.

Its green bounding box will be displayed to indicate that it has been selected.

78) Go to the Insert menu and go down to Control>Rotational Velocity. (Figure 37)

79) Pick the “Slider” option and hit the “OK” button.

Now you will see a new Slider window as shown in Figure 39. You can move this slider around the screen by dragging its Title Bar.

Figure 37 Rotational Velocity Slider

Figure 38 Input Type

Figure 39 Slider



80) Double-click in the gray area of the slider to bring up its “Properties” dialog box.

81) Set the “Min” value to “-360”, and the “Max” value to “360”.

This will allow the upper block to move one direction or the other at a maximum speed of 360 degrees per second.

You can now drag the slider back and forth, causing the upper block to rotate at different speeds and different directions.

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


At first, since the rotational velocity of the block is set to zero, nothing moves except that the ball begins bouncing up and down.

84) Grab the slider and slowly move it one way or the other. Keep moving it to different positions as the simulation runs and observe the effect.

The slider has been moved over to the left in Figure 41.

Figure 40 Input Tab

Figure 41 Simulation with Slider



IMPORTANT NOTE:

Once you run the simulation once and move the slider around causing the block to rotate in various ways, then when you stop the simulation and reset it and immediately play it again, it will only replay the simulation you just created. You find that you can’t move the slider because it’s replaying the movements you made previously.

To start over with a new simulation in which you can move the slider again in a different way, you must first Erase the Motion History. That is; 1) Reset the simulation to the beginning, and 2) Go to the “World” menu and pick “Erase Motion History”.

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