FEA Dynamic Analysis

[MRiva]

Hi, I'm working on a project that entails calculating the frequency response on a steel structure made with 2D elements.

Does anybody knows a rule of thumb to define the minimum size of elements in order to be able to obtain reasonable results for a certain frequency?

Say for example that I would like to calculate the frequency response on a 10 mm thick plate at 300 Hz.

Thank you!

 

[FEA way]

There’s no general rule like that, it all depends on specific case. But you can perform sort of mesh study - run several analyses, each with finer mesh and compare the results to check % difference in results.

 

[MRiva]

Ok, Thanks.That's what I'm doing, but I wanted to have a rough number on what is the minimum number of elements you need in order to represent a certain frequency due to the wavelenght in, for example, steel.

 

[FEA way]

In case of acoustics you need at least 6 second-order elements per wavelength so you can calculate maximum element size from this formula:

h_max = λ/6 = c/6f

But I haven’t heard about such requirement/recommendation for structural dynamics.