Why might a Modal analysis performed on unconstrained assembly not produce six rigid body modes with zero frequency?

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Why might a Modal analysis performed on unconstrained assembly not produce six rigid body modes with zero frequency?

Why might a Modal analysis performed on unconstrained assembly not produce six rigid body modes with zero frequency?

Tagged: 18.2, mechanical, Modal/Harmonic Response, structural-dynamics, structural-mechanics

- January 25, 2023 at 7:34 am
  
  FAQ
  Participant
  
  If penalty based contacts are used to tie the parts together, this could introduce artificial stiffness that can affect the free modes. In particular this could affect the three rotational modes. To avoid this try changing the contact formulation to MPC. This should result in six rigid body modes with zero frequency

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Structural Dynamics

Why might a Modal analysis performed on unconstrained assembly not produce six rigid body modes with zero frequency?

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