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Exercise 2: PDA Drop Test - 1 - Exercise 2: PDA Drop Test. In this exercise, we will perform a drop test of a typical personal digital assistant (PDA) electronic device. Mobile electronic devices are becoming increasingly more popular, and the ability of the devices to sustain an impact after being dropped is important. The PDA used in this analysis is illustrated in the figure below. The goal of this analysis is to determine if the case will break or the batteries (C) will be ejected from the device should it suffer a six foot drop onto a rigid surface. A: Glass Touch Screen B: Battery Compartment C: Batteries We will start this exercise with a predefined ANSYS database containing the geometry of the PDA device. This geometry could be imported from any commercial CAD program using a variety of ANSYS translators supporting all major geometry formats.

### Transcript of Tutorial Ansys Exercise2

Exercise 2: PDA Drop Test - 1 -

Exercise 2: PDA Drop Test. In this exercise, we will perform a drop test of a typical personal digital assistant (PDA) electronic device. Mobile electronic devices are becoming increasingly more popular, and the ability of the devices to sustain an impact after being dropped is important. The PDA used in this analysis is illustrated in the figure below. The goal of this analysis is to determine if the case will break or the batteries (C) will be ejected from the device should it suffer a six foot drop onto a rigid surface.

A: Glass Touch Screen B: Battery Compartment C: Batteries

We will start this exercise with a predefined ANSYS database containing the geometry of the PDA device. This geometry could be imported from any commercial CAD program using a variety of ANSYS translators supporting all major geometry formats.

Exercise 2: PDA Drop Test - 2 -

Summary of steps: 1. Launch ANSYS/Multiphysics/LS-DYNA:

2.1. Resume database. 2.2. Plot model 2.3. Plotting Controls 2.4. Set preferences to Structural LS-Dyna

3. Modeling: 3.1. Element Type Definition 3.2. Real Constants

4. Material Properties: 4.1. Case Material Properties 4.2. LCD Material Properties 4.3. Battery Material Properties

5. Model Attributes: 5.1. Case Attributes 5.2. LCD Screen Attributes 5.3. Battery Cover Attributes 5.4. Battery Attributes

6. Meshing: 6.1. Mesh Batteries 6.2. Mesh PDA

7. LS-Dyna Options: 7.1. Contact Definition

8. Drop Test 8.1. Drop Test Input

9. Solution: 9.1. Save Model 9.2. Perform LS-Dyna Solution

Exercise 2: PDA Drop Test - 3 -

10. Post Processing:

10.1. Report Generation 10.2. Von Mises strain animation 10.3. Determine max stress in PDA. 10.4. Determine max stress in LCD display. 10.5. Report Assembly

11. Conclusions: 11.1. Examine Stress and Strain Values 11.2. Exit ANSYS.

Exercise 2: PDA Drop Test - 4 -

1.1.B 1.1.A

1.1.D

1.1.C

Step-by-step Instructions: Before beginning this problem, create a separate folder on your computer for this job and copy the ANSYS database pda.db to this folder. This file is located on CD 1 in a folder called Input Files. 1. Launch ANSYS/LS-Dyna

1.1. Launch ANSYS using your start menu. A. Browse to select the working directory you just created for this job. B. Enter a job name (pda1). All ANSYS files created for this problem will

have a filename of pda1 allowed by a unique extension. C. Change the workspace and database sizes for this job to be 512 and

128 respectively. D. Click RUN to start the ANSYS GUI.

Exercise 2: PDA Drop Test - 5 -

2.1.A

2.1.B

2.1.C

2.1.D

2. Setup

you. This database contains only the geometry of the PDA. In the ANSYS utility menu, pick File

B. Resume from… C. Pick the file pda.db which you should have copied to the working

folder from the CD. D. OK. E. The model will be loaded into ANSYS and plotted in the graphics

window. Note that by default, ANSYS plots only the solid entities or “volumes”. For our model, the batteries are the only solid entities. The PDA device will be modeled with shells or “areas”.

Exercise 2: PDA Drop Test - 6 -

2.1.E

Only batteries are shown

Exercise 2: PDA Drop Test - 7 -

2.2.A

2.2.B

2.2. Plot Model

A. In order to view the entire model, we must plot areas. In the ANSYS Utility Menu, pick Plot

B. Areas

Exercise 2: PDA Drop Test - 8 -

Exercise 2: PDA Drop Test - 9 -

2.3.A

2.3.B 2.4.C

2.3. Plotting Controls A. Use the Pan/Zoom/Rotate function to scrutinize all parts of the model.

In the utility menu, pick PlotCtrls B. Pan, Zoom, Rotate… A view control window will appear on your

screen. C. You may want to keep this window active at all times.

Exercise 2: PDA Drop Test - 10 -

These buttons will orient yourdisplay to predefined view perspectives. Zoom by picking a center

point and the edge of your window.

Zoom by picking two diagonal corners of your window.

Arrows will pan your model in the direction of the arrow. The distance your model is moved can be controlled using the Rate slider below.

Rotate buttons will incrementally rotate your model about the screen axis and direction shown on the button. The amount of rotation is also controlled by the rate slider.

Activate dynamic mode. With this button checked, you can use dynamic viewing controls. Use the left mouse button to pan the model. With the middle button depressed, move up/down to zoom in/out, and left/right to rotate about the screen Z-axis. With the right button depressed, move up/down to rotate about the screen X-axis, and left/right to rotate about the screen Y-axis.

With dynamic Mode checked, you can use the mouse buttons described at left to move the model or the lights used in light source shading.

The Fit button will scale your model to fit in the window.

Exercise 2: PDA Drop Test - 11 -

Exercise 2: PDA Drop Test - 12 -

2.4.A

2.4.C

2.4.B

2.4. Set preferences to Structural LS-Dyna

A. In the ANSYS main menu, pick Preferences… B. Pick the button that says LS-Dyna Explicit. Note: Your menu may

look slightly different depending on which ANSYS products you have licensed.

C. OK. This filters the menu system to show you commands used for explicit analysis only.

Exercise 2: PDA Drop Test - 13 -

3.1.A 3.1.B

3. Modeling: In this section we will perform all the model definition, which includes defining element types, materials, real constants, meshing and creating contact pairs.

3.1. Element Type Definition For this analysis, we will use two element types. A shell element will be used for the case, LCD screen, and battery cover. The batteries will be meshed with solid brick elements.

Exercise 2: PDA Drop Test - 14 -

3.1.C

3.1.D

3.1.E

3.1.F

C. Add D. Pick Thin Shell 163 E. The Element type reference number is set to 1. F. Apply.

Exercise 2: PDA Drop Test - 15 -

3.1.G

3.1.J

3.1.H

3.1.I

G. Pick 3D Solid 164. H. Element type reference number 2 should be predefined for you. I. OK. J. The two element types you just defined should be listed in the Element

Types dialog. Pick Close.

Exercise 2: PDA Drop Test - 16 -

3.2.A

3.2. Real Constants:

Some element types require additional properties to be defined, which are not inherent in their basic definition such as thicknesses. Real constants are used to define these properties. The shell elements used for the case and LCD screen require a shear factor, number of out-of-plane integration points, and a thickness. We will assign a third real constant for the battery cover even though its properties are identical to the case. The reason for this will be discussed later during parts creation and contact definition.

A. In the Preprocessor menu, pick Real Constants…

Exercise 2: PDA Drop Test - 17 -

3.2.B

3.2.C

3.2.D

B. Add. C. Pick Type 1 SHELL163 as the type of real constant you want to define. D. OK.

Exercise 2: PDA Drop Test - 18 -

3.2.E

3.2.F

3.2.G

3.2.H

E. Enter 5/6 for the shear factor. F. For No. of integration points, enter 3. G. For Thickness at node 1, enter 0.5. This real constant will be used for

the case and battery cover. The remaining thicknesses will default to this value.

H. OK.

Exercise 2: PDA Drop Test - 19 -

3.2.I

3.2.K

3.2.J

I. Set 1 should show up in the Real Constant Set list. Pick Add… to add

another one. J. Pick Type 1 SHELL163 again for the type of real constant to define. K. OK.

Exercise 2: PDA Drop Test - 20 -

3.2.L

3.2.M

3.2.N

3.2.O

L. Enter 5/6 for the shear factor. M. For No. of Integration points, enter 3. N. This real constant will be used for the LCD screen. Enter a thickness of

0.75. O. OK.

Exercise 2: PDA Drop Test - 21 -

3.2.R

3.2.Q

3.2.P

P. Set 2 should show up in the Real Constant Set list. Pick Add… to add

the battery cover real constant.

Q. Pick Type 1 SHELL163 again for the type of real constant to define. R. OK.

Exercise 2: PDA Drop Test - 22 -

3.2.S

3.2.T

3.2.U

3.2.V

S. Enter 5/6 for the shear factor. T. For No. of integration points, enter 3. U. For Thickness at node 1, enter 0.5. This real constant will be used for

the case and battery cover. The remaining thicknesses will default to this value.

V. OK.

Exercise 2: PDA Drop Test - 23 -

3.2.W

W. Close the Real Constants dialog.

Exercise 2: PDA Drop Test - 24 -

4.1.A 4.1.B

4. Material Properties: We will define three material models for our PDA. Material 1 will be a bilinear kinematic hardening model for the Polyurethane case. Material 2 will be a bilinear kinematic hardening model for the liquid crystal display. The third material will be a linear elastic model for the batteries.

4.1. Case Material Model. A. In the Preprocessor menu, pick Material Props. B. Define MAT Model…

Exercise 2: PDA Drop Test - 25 -

4.1.C

4.1.F

4.1.E

4.1.D

4.1.G

C. Pick Add. D. The material ID number defaults to 1. E. Pick Plasticity. F. Bilinear Kinemat. G. OK.

Exercise 2: PDA Drop Test - 26 -

4.1.H

4.1.I

4.1.J

4.1.J

4.1.K

4.1.M

H. A dialog will appear for you to enter the material properties. The units

for our model are mm-Kg-Mpa. Enter 1.71e-9 for the density. I. Enter 17200 for Young’s Modulus. J. Enter 0.35 for the Poisson’s Ratio. K. Enter 228 for the Yield Stress. L. Enter 5000 for the Tangent Modulus. M. OK.

Exercise 2: PDA Drop Test - 27 -

4.2.A

4.2.D

4.2.C

4.2.B

4.2.E

4.2. LCD Material Model:

A. Material 1 should appear in the Material Model list. Pick Add… to add the LCD material model.

B. Material ID number 2 should be predefined for this model. C. Pick Plasticity. D. Bilinear Kinemat. E. OK.

Exercise 2: PDA Drop Test - 28 -

4.2.F

4.2.G

4.2.H

4.2.I

4.2.J

4.2.K

F. A dialog will appear for you to enter the material properties. The units

for our model are mm-Kg-Mpa. Enter 1.64e-9 for the density G. Enter 10500 for Young’s Modulus. H. Enter 0.30 for the Poisson’s Ratio. I. Enter 125 for the Yield Stress. J. Enter 1000 for the Tangent Modulus. K. OK.

Exercise 2: PDA Drop Test - 29 -

4.3.A

4.3.C

4.3.D

4.3.B

4.3. Battery Material Properties

A. Pick Add… again to add the battery material model. B. Material ID number 3 should be predefined for you. C. Pick Linear Elastic. D. OK.

Exercise 2: PDA Drop Test - 30 -

4.3.E

4.3.F

4.3.G

4.3.H

E. Enter 6.1e-9 for density. F. Enter 70000 for Young’s Modulus. G. Enter 0.29 for Poisson’s Ratio. H. OK.

Exercise 2: PDA Drop Test - 31 -

4.3.I

I. We have completed the material definition. Pick Close.

Exercise 2: PDA Drop Test - 32 -

5. Model Attributes Before we mesh our model, we will assign material, real constant, and element type attributes to the geometry. These attributes will then be assigned to the elements as the geometric entities are meshed. We will use the assignments listed in the table below:

Part Material ID Real Constant Element Type Case 1 1 1 Screen 2 2 1 Battery Cover 1 3 1 Batteries 3 1 2

5.1. Case Attributes:

Since the case is the largest part of this model, the easiest way to do this will be to assign the case attributes to all areas in the model, then to individually assign attributes to the screen and battery cover. The batteries are the only volumes (solids) in the model, so we can easily assign attributes to them.

Exercise 2: PDA Drop Test - 33 -

5.1.A

5.1.B

A. In the Preprocessor menu, under –Attributes- pick Define. B. All Areas.

Exercise 2: PDA Drop Test - 34 -

5.1.F

5.1.E

5.1.D

5.1.C

5.2.A

C. Set the case material number to 1. D. Set Real constant set number to 1. E. Set Element type number to 1 SHELL163. F. OK.

5.2. Screen Attributes:

A. Next we will do the screen. In the Define attributes dialog, pick Picked Areas.

Exercise 2: PDA Drop Test - 35 -

5.2.C

5.2.B

B. A dialog will appear for you to select the

screen area. You may need to use the pan/zoom/rotate function to orient your model to the front. Pick the LCD screen area as shown below.

C. OK.

Exercise 2: PDA Drop Test - 36 -

5.2.G

5.2.F

5.2.E

5.2.D

D. Set the case material number to 2. E. Set Real constant set number to 2. F. Set Element type number to 1 SHELL163. G. Apply.

Exercise 2: PDA Drop Test - 37 -

5.3.A

5.3.B

5.3.C

5.3. Battery Cover Attributes:

The Area Attributes picker dialog should still be active since you picked Apply instead of OK above. Use the pan/zoom/rotate function to orient the model so you can see the bottom side of the PDA.

A. In the picker dialog, change the method of picking from single to loop. With this method, you can pick one area of the battery cover, and all additional areas connected to it will also be selected.

B. Pick one area on the battery cover. When you release the mouse button, the three tabs on the top and bottom edges of the cover should also be selected.

C. In the picker dialog, you should have a total of 4 areas selected. Pick OK.

Make sure these tabs are selected also.

Exercise 2: PDA Drop Test - 38 -

5.3.G

5.3.F

5.3.E

5.3.D

D. Set the case material number to 1. E. Set Real constant set number to 3. F. Set Element type number to 1 SHELL163. G. OK.

Exercise 2: PDA Drop Test - 39 -

5.3.D

5.4.B

5.4. Battery Attributes:

A. Before we assign attributes to the batteries, let’s plot them. In the Utilities menu, pick Plot.

B. Volumes.

Exercise 2: PDA Drop Test - 40 -

5.4.C

5.4.D

C. The batteries should be plotted as shown below:

D. In the define attributes dialog, pick All Volumes.

Exercise 2: PDA Drop Test - 41 -

5.4.H

5.4.G

5.4.F

5.4.E

E. Set the case material number to 3. F. Set Real constant set number to 1. G. Set Element type number to 2 SOLID164. H. OK.

Exercise 2: PDA Drop Test - 42 -

6.1.A

6.1.B

6. Meshing:

6.1. Mesh Batteries: A. In the Preprocessor menu, activate the MeshTool. B. Next, we will set the global element size. Pick the Set button under

Size Controls: Global

Exercise 2: PDA Drop Test - 43 -

6.1.C

6.1.D

C. We will use an element size of 5 mm. Enter 5 for Element edge length. D. OK.

Exercise 2: PDA Drop Test - 44 -

6.1.H

6.1.F

6.1.E

6.1.G

E. The Meshtool should already set to mesh Volumes. F. For element shape, pick Hex. G. Mesh. H. Pick All.

Exercise 2: PDA Drop Test - 45 -

6.1.I

I. ANSYS will mesh the volumes and plot them as shown below.

6.2. Mesh PDA:

Next, we will mesh the case, LDC display, and battery cover all at once. In order to do this, we must select all the areas in the model except for those that make up the batteries. This can be done easily using the powerful select logic within ANSYS. We will do this by selecting all areas that are attached to the batteries (volumes), then selecting the inverse of this set.

Exercise 2: PDA Drop Test - 46 -

6.2.A

6.2.C

6.2.B

A. In the Utilities Menu, pick Select. B. Everything below. C. Selected Volumes.

Exercise 2: PDA Drop Test - 47 -

6.2.D

6.2.E

D. In the Utility menu, pick Plot. E. Areas.

Exercise 2: PDA Drop Test - 48 -

6.2.F

F. You should only see the areas that encompass the batteries.

Exercise 2: PDA Drop Test - 49 -

6.2.G

6.2.H

6.2.J

6.2.I

6.2.K 6.2.L

G. In the Utilities menu, pick Select. H. Entities.

I. Areas. J. Invert. K. Pick the Replot button. L. Pres the Cancel button to close the Select Entities dialog.

Exercise 2: PDA Drop Test - 50 -

6.2.M

M. The PDA areas should now be plotted in the graphics window.

Exercise 2: PDA Drop Test - 51 -

6.2.N

6.2.Q

6.2.P

6.2.O

N. We are now ready to mesh the PDA. In the Preprocessor, activate the

MeshTool again. O. Change Volumes to Areas. P. For Shape, pick Free. Q. Mesh.

Exercise 2: PDA Drop Test - 52 -

6.2.R

6.2.S

R. Pick All. S. It may take a few minutes to mesh the PDA.

ANSYS will plot the mesh in the graphics window when finished.

Exercise 2: PDA Drop Test - 53 -

6.2.U

6.2.T

T. Let’s verify that the attributes were set for the case, LCD display, and

battery cover as we desire. In the Utilities menu, pick PlotCtrls. U. Numbering.

Exercise 2: PDA Drop Test - 54 -

6.2.X

6.2.W

6.2.V

V. For Elem / Attrib numbering, pick Real Const num. W. Select Colors only for Numbering shown with. X. OK.

Y. Use the pan/zoom/rotate function to view all sides of the model. The LCD display and battery cover should be a different color from the case.

As a separate exercise on your own, change the plot numbering to Material ID and replot the mesh. Use the select function to select the batteries and verify their attributes.

Exercise 2: PDA Drop Test - 55 -

6.2.Y

Exercise 2: PDA Drop Test - 56 -

7.1.A

7.1.B

7.1.C

7.1.D

7. LS-Dyna Options:

7.1. Contact Definition. A. Before we proceed, let’s make sure all entities are selected. In the

Utilities menu, pick Select. B. Everything.

C. In LS-Dyna “Parts” are used to define contact

between different components of a model. We will need to define parts in order to simulate contact between the batteries, case and battery cover. .In the Preprocessor menu, pick LS-DYNA Options.

D. Parts Options.

Exercise 2: PDA Drop Test - 57 -

7.1.E

7.1.F

E. Create Parts should be highlighted. Pick OK. F. ANSYS will create a part for each unique combination of material ID,

real constant, and element type, and list these for you. Recall earlier that we used a separate real constant for the battery cover even though it was the same as case. This was done to ensure that the battery cover would be it’s own part. Otherwise, we could not define contact between the battery cover and the case.

Exercise 2: PDA Drop Test - 58 -

7.1.H

7.1.I

G. Before you close the parts list window, make a note of the part ID

numbers and identify which component they refer to based on the attributes we defined earlier. It may be helpful to update the table in section 5 of this demo and add a column for part ID. Create and print out a table like the one below:

Part Part ID Material ID Real Constant Element Type Case 3 1 1 1 Screen 4 2 2 1 Battery Cover 2 1 3 1 Batteries 1 3 1 2

We are now ready to define contact between the various parts. We will define three contact pairs:

• Contact between the case (3) and batteries (1).

• Contact between the case (3) and battery cover (2).

• Contact between the battery cover (2) and batteries (1).

H. In the LS-Dyna Options menu, pick Contact. I. Define Contact.

Exercise 2: PDA Drop Test - 59 -

7.1.J

7.1.K

7.1.L

7.1.M

7.1.N

7.1.O

J. In the Contact Parameter Definitions dialog, pick Nodes to Surface. K. General (NTS). L. For Static Friction Coefficient, enter 0.2. M. For Dynamic Friction Coefficient, enter 0.1. N. For Viscous Damping Coefficient, enter 0.1. O. Apply.

Exercise 2: PDA Drop Test - 60 -

7.1.P

7.1.Q

7.1.R

P. Pick 3 (case) for the Contact Part no. Q. Pick 1 (batteries) for the Target Part no. R. Apply.

Exercise 2: PDA Drop Test - 61 -

7.1.S

S. We will use the same contact options for the next pair also. Pick Apply

in the Contact Parameters Definition dialog.

Exercise 2: PDA Drop Test - 62 -

7.1.T

7.1.U

7.1.V

T. Pick 3 (case) for the Contact Part no. U. Pick 2 (battery cover) for the Target Part no. V. Apply.

Exercise 2: PDA Drop Test - 63 -

7.1.W

W. We will use the same contact options for the last pair. Pick OK in the

Contact Parameters Definition dialog.

Exercise 2: PDA Drop Test - 64 -

7.1.X

7.1.Y

7.1.Z

X. Pick 2 (battery cover) for the Contact Part no. Y. Pick 1 (batteries) for the Target Part no. Z. Apply.

Exercise 2: PDA Drop Test - 65 -

8.1.A

8.1.B

8.1.C

8. Drop Test: The ANSYS drop test module can greatly simplify the set up of a drop test analysis. We will use it to perform the following functions:

• Orient the model to its impact position.

• Define G.

• Define a drop height.

• Automatically define a rigid impact surface and contact definition between it and your model.

8.1. Drop Test Input: A. First, we must enter the drop test module. In the ANSYS Main Menu,

pick Drop Test Module. B. Initialize. C. OK.

Exercise 2: PDA Drop Test - 66 -

8.1.D

8.1.E 8.1.F

D. When the initialization procedure completes, your model will be plotted

in the graphics window, with the default orientation for G shown in the upper left.

E. Pick the Orient Model button. F. Several methods of orienting your model are available. We will use an

input vector method. Pick Input Vector.

Exercise 2: PDA Drop Test - 67 -

8.1.G

8.1.H

8.1.I

G. A dialog will appear for you to enter the x,y,z vector defining the vertical

direction. Enter 3, 10, 5 as the vector components as shown below. H. OK.

I. ANSYS will create a rigid target surface oriented using this vector, and position it so that it is just about to impact the lowest portion of the model. The graphics view will be oriented normal to drop direction. Note that your model hasn’t been moved, only the view direction.

Exercise 2: PDA Drop Test - 68 -

8.1.J

8.1.K

J. Use the pan/zoom/rotate function to view how the model is oriented.

Rotate the model –90 degrees about the screen Y-axis.

K. Next, we will define the units of gravity. In the Drop Test Module menu, pick Define g.

Exercise 2: PDA Drop Test - 69 -

8.1.L

8.1.M

8.1.N

L. Since our model is built in units of millimeters, pick 9810 mm/s^2. M. OK.

N. In the Drop Test Menu, pick Drop Height.

Exercise 2: PDA Drop Test - 70 -

8.1.O

8.1.P

8.1.Q

O. Enter a value of 1829 mm, which is approximately 6-feet. We will use

the default height reference point, which is the lowest point or impact point on the model.

P. OK. ANSYS will use the drop height and acceleration of gravity to determine an initial velocity for the model. This way, the analysis can begin at a point just prior to impact in order to save computation time. Analyzing the free fall would be costly and unnecessary.

Q. Next, pick Solution Ctrls in the Drop Test Module menu.

Exercise 2: PDA Drop Test - 71 -

8.1.T

8.1.S

8.1.R

8.1.U

R. Enter a value of 0.06 for the time. S. We will use the default setting of 100 for Result file output interval. T. Change the Time-History output interval to 100. U. OK.

Exercise 2: PDA Drop Test - 72 -

8.1.V

8.1.W

V. ANSYS will give you the option of calculating the node nearest to the

center of gravity and saving time history data for this node. This may be beneficial for post processing some problems. Close this Note.

W. Pick OK to calculate this node. This may take a few minutes.

Exercise 2: PDA Drop Test - 73 -

9.1.A

9.2.A

9.2.B

9. Solution: We are ready to solve the problem.

9.1. Save model: A. In the Toolbar menu, pick SAVE_DB.

9.2. Perform LS_Dyna Solution:

A. In the Drop Test Module menu, pick Solve. B. ANSYS will display the drop test information.

Pick Close when you have finished reviewing this note.

Exercise 2: PDA Drop Test - 74 -

9.2.C

C. Pick OK to solve the analysis. The solution may take several hours.

Exercise 2: PDA Drop Test - 75 -

10.1.C

10.1.B

10.1.A

10. Post Processing: For this model, we will generate animations of the impact event over time, and also plot the von mises stress in the PDA components. We will generate an HTML report during the process.

10.1. Report Generation. A. In the ANSYS Main Menu, pick General PostProc. B. In the Utility menu, pick File. C. Report Generator.

Exercise 2: PDA Drop Test - 76 -

10.1.D

10.1.E

D. ANSYS will prompt you for a directory name to store the report files and whether to append or overwrite an existing report. Accept the defaults by picking OK.

E. ANSYS will prompt you to create a new directory. Pick Yes.

ANSYS will resize your graphics window so that subsequent screen captures that are done for the report will properly sized for an HTML report. Also, a report creation wizard will appear as shown below.

Capture the current screen plot for the report.

Generate an animation.

Capture a listing

Capture a table.

Modify settings

Assemble items into a report.

Exercise 2: PDA Drop Test - 77 -

10.1.F

10.1.G

10.1.H

F. We will begin creating our report by generating animations of the

deformed results. First, let’s set the deformed model scaling to true scaling. By default, ANSYS scales the deformed shape to equal 5% of the model length. This is appropriate for small deflection analyses, but for a drop test, we wish to see the true scaling. In the Utilities menu, pick PlotCtrls.

G. Style. H. Displacement Scaling.

Exercise 2: PDA Drop Test - 78 -

10.1.I

10.1.J

I. Change t he Displacement scale factor to 1.0 (true Scale). J. OK.

Exercise 2: PDA Drop Test - 79 -

10.1.K

10.1.L

K. In the General Postproc menu, pick Last Set to load the final results

dataset into memory.

L. In the ANSYS Report Generation wizard, pick the video camera icon to

generate an animation.

Exercise 2: PDA Drop Test - 80 -

10.1.M

10.1.N

10.1.O

10.1.P

10.1.Q

10.1.R

M. In the Animation Capture dialog, select Over Time. N. OK.

O. For Number of animation frames, enter 50. P. For display type, pick Stress. Q. Von Mises SEQV. R. OK. The animation generation may take several minutes to complete.

Exercise 2: PDA Drop Test - 81 -

10.2.A

10.1.S

S. When the animation is complete, the displaced results from the final time point will remain displayed in the graphics window. Note that the battery cover has popped out and ejected the batteries.

10.2. Von Mises strain animation:

A. Next, pick the video camera again to generate another animation.

Exercise 2: PDA Drop Test - 82 -

10.2.B

10.2.C

B. We will use the same settings. Pick OK.

C. In the graphics window, use the pan/zoom rotate function to rotate the model 90 degrees in the Y- direction. The view should look like the one below.

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10.2.F

10.2.E

10.2.D

D. This time we will animate the plastic strain. For display type, pick

Strain-plastic. E. vonMises EPPLEQV. F. OK.

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10.2.G

G. A plot of the final time point will remain in the graphics window when

the animation generation is complete.

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10.3.A

10.3.B

10.3.C

10.3. Determine Max Stress in PDA:

Next, we wish to determine the maximum stress in the PDA. This most likely occurs at or soon after the moment of impact. We will plot the Von Mises stress at the first few time points, to locate the worst condition.

A. In the General Postproc menu under –Read Results- pick First Set. This will load the results of the first time point into memory.

B. Pick Plot Results. C. Nodal Solution.

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10.3.F

10.3.E

10.3.D

D. Pick Stress. E. Von Mises. F. OK.

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10.3.G

G. The von Mises stress from the first time point will be plotted in the

graphics window. This is the moment just before impact, so it should have zero stress.

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10.3.G 10.3.H

H. Use the pan/zoom/rotate function to view the PDA from the front again.

You will have to rotate 90 degrees about the +Y axis.

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10.3.I

10.3.J

10.3.K

Results-, pick Next Set. Thjs will load results from the next time point into memory.

J. In the Utilities menu, pick Plot. K. Replot.

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10.3.L

L. The Von Mises stress will be plotted. Note the maximum value should

be around 186 PSI.

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10.3.M

M. Repeat this procedure until the stress level starts to decrease, then

pick the Previous Set button in the General Postproc menu to return to the maximum condition. In the example below, the maximum occurs at the fourth time point with a stress level of 322 PSI.

Recall when we defined material properties that the yield stress for the case material is 128 PSI. The case clearly has yielded or broken.

Exercise 2: PDA Drop Test - 92 -

10.3.O

10.3.N

10.3.R

10.3.Q

10.3.P

N. Let’s capture this image so that we can add it to our HTML report later.

In the Utilities menu, pick File. O. Report Generator.

P. Pick Capture Image.

Q. Enter a caption of PDA Maximum Stress.

R. OK.

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10.4.B

10.4.A

10.4.C

10.4.D

10.4.F

10.4.G

10.4.E

10.4. Determine max stress in LCD display:

Next we will select the elements of the LCD display only, and repeat the stress plotting procedure in order to determine the maximum stress in this component.

A. Recall that the LCD display referenced material ID number 2. We can select the elements by that attribute. In the Utilities menu, pick Select.

B. Entities.

C. Elements. D. By Attributes. E. Material num. F. Enter 2 for Min,Max, Inc. G. OK.

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10.4.H

10.4.I

10.4.J

H. In the General Postproc menu under –Read Results- pick First Set.

This will load the results of the first time point into memory. I. Pick Plot Results. J. Nodal Solution.

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10.4.M

10.4.L

10.4.K

K. Pick Stress. L. Von Mises. M. OK.

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10.4.N

N. Like before, the stress at the first time point should be zero.

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10.4.O

O. Repeat the procedure used for the entire model. Pick Next Set and

Plot >Replot until you find the maximum condition. For our example, a maximum stress of 32 PSI occurred during the third time point. Recall that the LCD material yield stress was 125 PSI, so the LCD display should survive this impact.

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10.4.Q

10.4.P

10.4.T

10.4.S

10.4.R

P. Let’s capture this image so that we can add it to our HTML report later.

In the Utilities menu, pick File. Q. Report Generator.

R. Pick Capture Image.

S. Enter a caption of LCD Maximum Stress.

T. OK.

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10.5.A

10.5. Report Assembly:

A. We are now ready to assembly these items into a simple HTML report. Pick the HTML Report Assembler button in the report generator wizard.

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10.5.C

B. A new wizard will appear with options for assembling the HTML report.

Delete item from the report.

Move item up or down in report.

Allows you to insert any image file from your hard drive.

Adds dynamic items to the report.

Adds pre-existing HTML code from a file.

Previously captured images, tables, and lists that are available for assembly.

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10.5.F

10.5.G

10.5.E

10.5.D

C. Lets begin by changing the report heading. Click the Report Heading

button in the HTML Report Assembler wizard shown on the previous page.

D. A dialog will appear for you to enter a Title, Author Name, and Subtitle. Enter anything you wish here. See below for an example.

E. OK.

F. The header will appear in the work area of the Wizard. G. Next, pick the first animation in the Report Images list.

Exercise 2: PDA Drop Test - 102 -

10.5.H

10.5.J

10.5.I

H. This image will be added to the report underneath the heading. I. The icon in the image list will gray out indicating that it has been added

to the report. J. Pick the second animation to add it to the report.

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10.5.K

10.5.L

K. The second animation will be added to the report. L. Pick the next image in the list. This is the PDA Maximum stress image.

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10.5.M

10.5.N

10.5.O

M. The maximum stress image will be added to the report. N. Pick the Text button to add a description of this plot. O. Enter some relevant text in the box that appears.

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10.5.P

10.5.Q

10.5.R

P. Pick the last image in the list to add it to the report. Q. Pick the Text button to add some relevant text. R. Enter a description of the LCD display plot.

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10.5.S

S. We have completed the report definition. Pick the eyeglasses in the

Report assembler window to view your report.

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10.5.U

T. Your report should look like the one below. Pick the image below for a

sample report.

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10.5.U

U. You can add more items to this report, at a later date if you wish. Let’s

quit for now. Pick File >Save and close.

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11. Conclusions:

11.1. Lessons Leaned. The analysis we performed shows that the PDA case has failed and that the batteries popped out. The LCD display survived the impact though. What could we do to improve the design? Increasing the thickness of the case would add strength and stiffness, but would also add weight and increase the cost. What other analyses would be necessary to verify this design. We only analyzed one orientation. As a separate exercise, repeat this analysis using a different orientation vector. What orientations might result in worse stresses on the case? What orientation might be worse for the LCD screen? We dropped this PDA from an initially static condition. What if we applied an initial rotation or additional velocity to the PDA?

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11.2.A

11.2.C

11.2.B

11.2. Exit ANSYS:

A. In the ANSYS toolbar, pick Quit. B. Highlight Quit – No Save? C. OK.