Calculating the frequency response of a mechanical system using the FMI-Standard

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Hi,

 

I'm currently trying to use the FMI-Standard in order to calculate the frequency response of a mechanical System in Matlab/Simulink.

This is my current approach:

1. Import a stp-file in Hypermesh, do the meshing and define a material and property (OptiStruct-Solver)

2. Export the Hypermesh-Session as fem-file

3. Create a flexible body in MotionView using FlexPrep and the fem-file from step 2

- Synthesis Type: Craig-Bampton

- Cutoff type/value: 15 highest Modes

- perform stress and strain recovery

4. Define a torque as input and an angular displacement at the same point as the output, by using SolverVariables and SolverArrays

5. Export the MotionSolve-Model as FMU

 

After defining the necessary environmental variables and importing the FMU in Simulink the simulation works fine, but the frequency response isn't plausible and it seems to be independent of the chosen material in step 1.

Can you imagine a possible reason for that?

 

Thank you in advance!

 

The problem seems to be, that the rotational stiffness is infinite, no matter which material I choose, even though the translational stiffness is not infinite.
Has anyone of you experienced the same problem so far?

 

Thank you in advance!

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