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Hi,
Good morning,
why we see the frequency difference (Modal Analysis) while comparing between different solvers, for example optistruct Vs Lsdyna or Optistruct Vs Ansys.
there might be several reasons for that. A few comments below:
- each solver is different and their formulations differ as well. It is normal to have some difference.
- but assuming the model assumptions are close enough, you shouldn't see too much of difference.
- frequency could be related to a spring natural frequency, where f=sqrt(k/m) >> so, both stiffness and mass affect the results
- if the mesh is not the same, so stiffness is not exactly the same, thus frequency will be affected.
- connections and contacts for the bodies of your model >> this could influence overall stiffness
- check the mass of each model, making sure it is close enough
- boundary conditions should be the same in both models
- check for strain energy >> compare to check if both models present the same regions with higher strain energy
Apart from that, you should give more details on your models.
I completely agree with @Adriano A. Koga, Also you can check if damping is considered it should be equal, the implementation of damping models can vary between solvers, affecting the natural frequencies.