Patran - Normal Modes Analysis

[Renegard]

Hi everybody!

I have a question concerning Patran normal modes analysis (sol 103):

When performing a normal modes analysis it is possible to request the element stresses as output as well. Do these element stresses have a real physical meaning or are they meaningless?

Cheers R.

 

[izax1]

The value of the stresses will be meaningless unless you apply a dynamic load and some damping, but the relative value could be of help.

 

[BlasMolero]

Hello!,
Both Stress & Displacements are useless values in a Normal Modes/Eigenvalue analysis (SOL103), but Displacements are an easy way to see deformed shape of every mode in the screen.

But one insteresting value could be the Strain Energy Output, a result that you can request when solving a Normal Modes/Eigenvalue analysis (SOL103) analysis. Frequently you are faced with the decision of modifying your structure in order to meet stringent design criteria. In most instances, your objective is to maximize the benefits with minimal changes. The element strain energy output is an excellent tool for identifying areas of modification that will reap the most benefits for design changes.

The only additional input needed is the “ESE” request in the Case Control Section. And the modern postprocessors packages support plotting strain energy output. For plate and solid elements, these strain energy plots look similar to stress contour plots.

Best regards,
Blas.

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Blas Molero Hidalgo
Ingeniero Industrial
Director

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