2012 ANSYS, Inc. March 28, 2013 1 Release 14.5

14.5 Release

Workshop 4B Modal Analysis (Model Airplane Wing)

ANSYS Mechanical Linear and Nonlinear Dynamics

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Workshop 4B - Goals

Our goal is to determine the first 5 natural frequencies and mode shapes for the prestressed model airplane wing shown.

Assume one end of the wing is fully fixed.

The wing is made of Titanium.

Fixed End

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Workshop 4B Project Schematic From the project schematic, insert a

new Static Structural system.

Drop a Modal system onto the Solution cell of the Static Structural.

Import the Geometry file

wing.iges

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Workshop 4B - Preprocessing Edit the Engineering Data cell.

add Titanium Alloy from the General Materials library to Engineering Data

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Workshop 4B - Preprocessing Return to the Project, and Edit the Model cell to open the Mechanical application.

set the wing material assignment to Titanium Alloy

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Workshop 4B Units In Mechanical, set the following units system:

in, lbm, lbf, F, s, V, A Degrees RPM

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Workshop 4B - Environment

Constrain the far end of the wing.

On the >Static Structural branch >Insert>Fixed Supports. Switch to face selection mode as necessary Use LMB to pick the applicable surface. Click Apply in the Details window Use Depth Picking and/or reorient the model as necessary

throughout.

Depth

Picking

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Workshop 4B - Environment

Apply a pressure load to the underside of the wing.

On the >Static Structural branch >Insert>Pressure. Switch to face selection mode as necessary Use LMB to pick the applicable surface. Click Apply in the Details window Set the magnitude to 0.1 psi.

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Workshop 4B Static Solution Solve the Static Structural model.

Review the results.

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Workshop 4B Modal Solution

Check the Details of Modal Analysis Settings

set Max Modes to Find to 5 set Calculate Stress to Yes set Calculate Strain to Yes

Solve the Modal analysis.

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Workshop 4B - Results After the modal solution is completed wed like to review the

modal shapes for each frequency.

Click on the Modal Solution Branch in the Tree. Then LMB on the top of the Frequency Column in the Tabular Data region, and >RMB>Create Mode Shape Results

This will automatically insert Total Deformation objects in the Tree for all modes solved.

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Workshop 4B - Results To get an overall view of the Modal results step thru (LMB) the

Total Deformation result objects for each mode.

Remember to Animate (Play & Stop) the mode from the Timeline window.

You can typically rotate the model during animation too.

Note: Make a note of your highest natural Frequency mode: Max Indicated Freq = _________________Hz.

Experiment with the Vector Graphics and (vector) scale slider. Animation and rotation can also be performed on Vector plots.