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Introduction to ANSYS Introduction to ANSYSMechanical

Transcript of Introduction to ANSYS Mechanical (2D)

Workshop 4.2 2D Structural Analysis y

WS4.2-1

Release 12.1 January 2010

WS4.2: 2D Structural Analysis

Workshop 4.2 - Goals

Workshop Supplement

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 p

Retaining Ri R t i i Ring

Full Model

WS4.2-2

Release 12.1 January 2010

WS4.2: 2D Structural Analysis

Workshop 4.2 Assumptions 2D axisymmetric model assumptions:

Workshop Supplement

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

WS4.2-3

Release 12.1 January 2010

WS4.2: 2D Structural Analysis

. . . 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). Metric Display Values in Project Units is checked (on).

Workshop Supplement

WS4.2-4

Release 12.1 January 2010

WS4.2: 2D Structural Analysis

Workshop 4.2 Project Schematic1. Double click Static Structural analysis type to add a new system. 1

Workshop Supplement

2. RMB the Geometry cell and request Properties.

2

WS4.2-5

Release 12.1 January 2010

WS4.2: 2D Structural Analysis

Workshop 4.2 - Project Schematic3. In the Analysis Type field specify 2D. Once this setting is made the properties window may be closed if desired.

Workshop Supplement

Note this setting indicates the y model to be analyzed is not a full 3D model but represents a symmetry section. It is important that this is set prior to importing geometry as this setting cannot be changed after the import.WS4.2-6

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Release 12.1 January 2010

WS4.2: 2D Structural Analysis

Workshop 4.2 - Project Schematic4. Double click the Engineering Data cell to add material properties. 4

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5. With the General Materials library highlighted choose the + next to Stainless Steel to add the material to Stainless Steel the project. 6. 6 Return to Project. Project 6 5ANSYS, Inc. Proprietary 2010 ANSYS, Inc. All rights reserved.

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Release 12.1 January 2010

WS4.2: 2D Structural Analysis

Workshop 4.2 Geometry Setup7. From the Geometry cell, RMB > Import Geometry and browse to: Axisym_pressure_2D_12.stp. 7

Workshop Supplement

8. Double click the Model cell to start Mechanical. 8

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Release 12.1 January 2010

WS4.2: 2D Structural Analysis

Workshop 4.2 Preprocessing9. Set the working unit system: Units > Metric (mm, kg, N, s, mV, mA).

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10. Change part behavior to Axisymmetric:a. Highlight the Geometry branch b. Change the 2D Behavior under the Details of b Ch h B h i d h D il f Geometry to Axisymmetric

a.

Rename the Parts: Part 1: RMB > Rename to Retaining Ring. Part 2: RMB > Rename to Pressure Cap. p

b.

WS4.2-9

Release 12.1 January 2010

WS4.2: 2D Structural Analysis

Workshop 4.2 Preprocessing11. Change the material assigned to the Pressure Cap:a. Highlight Pressure Cap b. Under the D t il f P b U d th Details of Pressure Cap C Choose Material > Assignment = Stainless Steel.

Workshop Supplement

11a.

11b.

12. Modify contact behavior:a. In the Details of Contact Region, change the Type to Frictionless g yp

WS4.2-10

Release 12.1 January 2010

WS4.2: 2D Structural Analysis

Workshop 4.2 Contact13. Generate the Mesh:a. RMB the Mesh branch and choose Generate Mesh.

Workshop Supplement

a.

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Release 12.1 January 2010

WS4.2: 2D Structural Analysis

Workshop 4.2 Environment14. 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

Workshop Supplement

b. RMB > Insert > Pressure. c. Set the pressure magnitude = 0.1 MPa.

a.

b.

WS4.2-12

Release 12.1 January 2010

WS4.2: 2D Structural Analysis

Workshop 4.2 Environment15. Apply Supports to the model:a. Highlight the bottom edge of the pressure cap g g g p p (shown in black dashed lines). b. RMB > Insert > Compression Only Support.

Workshop Supplement

b.

WS4.2-13

WS4.2: 2D Structural Analysis

Workshop 4.2 Environment

Workshop Supplement

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.

d. c.

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WS4.2: 2D Structural Analysis

Workshop 4.2 Solution Solve the model. Notes on axisymmetry :

Workshop Supplement

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 required. 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. b Double click on the message to view it Click OK to close the warning window it. 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

WS4.2-15

Release 12.1 January 2010

WS4.2: 2D Structural Analysis

Workshop 4.2 Postprocessing Insert Results into the Solution branch:

Workshop Supplement

Highlight the Solution branch, RMB and insert Stress > Equivalent (vonMises) 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 l t t N t : th last two results are now scoped to the pressure cap. This will allow us t i l t it lt d t th Thi ill ll to isolate its response.

Solve

WS4.2-16

Release 12.1 January 2010

WS4.2: 2D Structural Analysis

Workshop 4.2 Postprocessing

Workshop Supplement

Highlight each of the result objects to inspect the results.

Equivalent Stress on all bodies

Total Deformation on Pressure Cap

WS4.2-17

Release 12.1 January 2010

WS4.2: 2D Structural Analysis

Workshop 4.2 Postprocessing

Workshop Supplement

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 b machine). by hi ) Note, CP time represents the sum for all processors used. In multiprocessor machines it will sometimes exceed elapsed time.

WS4.2-18

Release 12.1 January 2010

WS4.2: 2D Structural Analysis

. . . Workshop 4.2 Comparison 2D Elapsed Time = 9.0 seconds. 3D Elapsed Time = 41.0 seconds.

Workshop Supplement

Solution time comparison using refined 3D symmetry mesh: