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Modal Analysis of a Model Airplane Wing

• Problem Specification
• Problem Description
• Build Geometry Steps
• Define Material Steps
• Generate Mesh Steps
• Apply Loads Steps
• Obtain Solution Steps
• Review Results Steps

Problem Specification

• Applicable ANSYS Products:   ANSYS/Multiphysics, ANSYS/Mechanical, ANSYS/Structural, ANSYS/LinearPlus, ANSYS/ED
• Level of Difficulty:  easy
• Interactive Time Required:   30 to 45 minutes
• Discipline:  structural
• Analysis Type:  modal
• Element Types Used:  PLANE42 and SOLID45
• ANSYS Features Demonstrated:   bottom-up solid modeling, splines with slope vectors, extrusion with a mesh, selecting, eigenvalue modal analysis, animation

Problem Description

This is a simple modal analysis of a wing of a model airplane.  The wing is of uniform configuration along its length and its cross-sectional area is defined to be a straight line and a spline as shown.  It is held fixed to the body of the airplane on one end and hangs freely at the other.  The objective of the problem is to find the wing's natural frequencies and mode shapes.

Given

The dimensions of the wing are as shown above.  The wing is made of low density polyethylene with a Young's modulus of 38x10³ psi, Poisson's ration of 0.3, and a density of 1.033E-3 slugs/in³.

Approach and Assumptions

Assume the side of the wing connected to the plane is completely fixed in all degrees of freedom.  The wing is solid and material properties are constant and isotropic.

Use solid modeling to generate a 2-D model of the cross-section of the wing, create a reasonable mesh and then extrude the cross-section into a 3-D solid model which will automatically be meshed.

To minimize the solid modeling time, simplify the creation of the 2-D airfoil profile.   To accurately follow the contour of this airfoil would require making more data points.

Additionally, the mesh used in this example will be fairly coarse for the element types used.  This coarse mesh is used here so that this tutorial can be used with the ANSYS/ED product.

Summary of Steps

Use the information in this description and the steps below as a guideline in solving the problem on your own.  Or, use the detailed interactive step-by-step solution by choosing the link for step 1.

Build Geometry

1. Create keypoints at given locations.
2. Create lines and splines between keypoints.
3. Create cross-sectional area.

Define Materials

4. Define constant material properties.

Generate Mesh

5. Set preferences.
6. Define element type.
7. Mesh the area.
8. Extrude the meshed area into a meshed volume.

Apply Loads

9. Unselect 2-D elements.
10. Apply constraints to the model.

Obtain Solution

11. Specify analysis types and options.
12. Solve.

Review Results

13. List the natural frequencies.
14. Animate the five mode shapes.
15. Exit the ANSYS program.

 ANA SAYFAYA DÖNMEK İÇİN TIKLAYINIZ.