Workshop 4.2 2D Structural Analysis - ttu.eeinnomet.ttu.ee/martin/MER0070/WB/WS8/AxisymmetricPressure/WB-M… · WS4.2: 2D Structural Analysis WS4.2-2 ANSYS, Inc. Proprietary © 2009

WS4.2-1ANSYS, Inc. Proprietary

© 2009 ANSYS, Inc. All rights reserved.May 5, 2009

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Workbench - Mechanical Introduction 12.0

Workshop 4.2

2D Structural Analysis

WS4.2: 2D Structural Analysis



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Workshop SupplementWorkshop 4.2 - Goals

• Workshop 4.2 consists of a 2 part assembly representing a pressure

cap and retaining flange (full model shown below).

• We will solve it as a 2D axisymmetric model (shown on next page).

Pressure Cap

Retaining Ring

Full Model




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Workshop SupplementWorkshop 4.2 – Assumptions

• 2D axisymmetric model assumptions:

• The retaining ring is fixed at its mounting holes.

• The contact region between the parts is frictionless.

• The base of the pressure cap is constrained using a compression only

support.

– Note: due to the presence of the bolt holes the structure is not truly axisymmetric.

Pressure Cap

Retaining Ring




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Workshop Supplement. . . Workshop 4.2 – Project Schematic

• Open the Project page.

• From the Units menu verify:– Project units are set to “Metric (kg, mm, s, C, mA, mV).

– “Display Values in Project Units” is checked (on).




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Workshop SupplementWorkshop 4.2 – Project Schematic

1. Double click “Static

Structural” analysis type to

add a new system.

2. RMB the Geometry cell and

request “Properties”. 2

1




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Workshop SupplementWorkshop 4.2 - Project Schematic

3. In the “Analysis Type” field specify “2D”.

• Once this setting is made the properties window may be closed if desired.

• Note this setting indicates the model to be analyzed is not a full 3D model but represents a symmetry section. It is important that this is set prior to importinggeometry as this setting cannot be changed after the import.

3




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Workshop SupplementWorkshop 4.2 - Project Schematic

4. Double click the “Engineering Data” cell

to add material properties.

5. With the “General Materials” library

highlighted choose the „+‟ next to

“Stainless Steel” to add the material to

the project.

6. “Return to Project”.

6

5

4




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Workshop SupplementWorkshop 4.2 – Geometry Setup

7. From the “Geometry” cell, RMB >

“Import Geometry” and browse to:

“Axisym_pressure_2D_12.x_t”.

8. Double click the “Model” cell to

start Mechanical.

7

8




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Workshop SupplementWorkshop 4.2 – Preprocessing

9. Set the working unit system:

• “Units > Metric (mm, kg, N, s, mV, mA)”.

10. Change part behavior to “Axisymmetric”:

a. Highlight the “Geometry” branch

b. Change the “2D Behavior” under the “Details of

Geometry” to “Axisymmetric”

• Rename the Parts:

• Part1: RMB > Rename to “Retaining Ring”.

• Part2: RMB > Rename to “Pressure Cap”.

9

a.

b.




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Workshop Supplement…Workshop 4.2 – Preprocessing

11. Change the material assigned to the

“Pressure Cap”:

a. Highlight “Pressure Cap”

b. Under the “Details of “Pressure Cap”

Choose Material > Assignment =

“Stainless Steel”.

12. Modify contact behavior:

a. In the “Details of Contact Region”,

change the “Type” to “Frictionless”

11a.

11b.

12a.




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Workshop Supplement…Workshop 4.2 – Contact

13. Generate the Mesh:

a. RMB the “Mesh” branch and choose “Generate

Mesh”.

a.




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Workshop SupplementWorkshop 4.2 – Environment

14. Apply Loads on the model (make sure the Static Structural branch is highlighted):

a. Select the 4 inside edges (shown in dashed black lines) of the Pressure Cap .• Hint : select one of the edges and use “extend to limits”

b. “RMB > Insert > Pressure”.

c. Set the pressure magnitude = 0.1 MPa.

a.b.

c.




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Workshop Supplement…Workshop 4.2 – Environment

15. Apply Supports to the model:

a. Highlight the bottom edge of the pressure cap

(shown in black dashed lines).

b.“RMB > Insert > Compression Only Support”.

a.

b.




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Workshop Supplement…Workshop 4.2 – Environment

c. Select the middle line on the top of the retaining ring (shown in black

dashed lines).

d. “RMB > Insert > Fixed Support”.

• Note : Remember, the axisymmetric assumption here is that the retaining ring is a continuous solid.

Actually there are bolt holes around its circumference. For this reason, when the model was created

in DesignModeler this separate line was intentionally created to provide a location to add our

support.

c.

d.




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Workshop SupplementWorkshop 4.2 – Solution

• Solve the model.• Notes on axisymmetry :

• Notice that the model lies completely in +X space with the Y axis as the axis of revolution. This is required for axisymmetry.

• Axisymmetry assumes that the model is a complete 360 degree model. For this reason no constraints in the X direction are required. The portion of the pressure load acting in the +X direction is assumed to be offset by an equal portion in the –X direction.

• View any warning messages/errors : a. Errors/warning messages are displayed in the “Messages” tab at the bottom of the graphics

screen.

b. Double click on the message to view it. Click “OK” to close the warning window.• Note : Note: due to the fact that the pressure cap is constrained using frictionless contact and a

compression only support, weak springs are added to prevent rigid body motion




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Workshop SupplementWorkshop 4.2 – Postprocessing

• Insert Results into the “Solution” branch:

• Highlight the Solution branch, RMB and insert Stress > Equivalent (von-

Mises)

• Highlight the Solution branch, RMB and Insert> Deformation > Total

• Switch to body select mode, select the pressure cap and repeat steps

(a.) and (b.)• Note : the last two results are now scoped to the pressure cap. This will allow us to isolate its

response.

• Solve




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Workshop Supplement…Workshop 4.2 – Postprocessing

• Highlight each of the result objects to inspect the result.

Equivalent Stress on all bodies Total Deformation on Pressure Cap




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Workshop Supplement…Workshop 4.2 – Postprocessing

View Solution time by highlighting the “Solution Information” branch:

– The graphics window will change to the Worksheet view. Scroll to the

bottom of the solution information and note the Elapsed Time (this will

vary by machine).• Note, CP time represents the sum for all processors used. In multiprocessor machines it will

generally exceed elapsed time.




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Workshop Supplement. . . Workshop 4.2 – Comparison

• Solution time comparison using refined 3D symmetry mesh:

– 2D Elapsed Time = 9.0 seconds.

– 3D Elapsed Time = 41.0 seconds.

Documents

Workshop 4.2 2D Structural Analysis - ttu.eeinnomet.ttu.ee/martin/MER0070/WB/WS8/AxisymmetricPressure/WB-M… · WS4.2: 2D Structural Analysis WS4.2-2 ANSYS, Inc. Proprietary © 2009