Reply To: spg question

[Chris Quan]

Does your model contain a soft material? Were the elements with negative volume coming from a soft material? If yes, it is true that for low modulus materials such as rubbers, you may encounter error message about "negative volume". You may also observe high hourglass energy as well in these elements. Thus check the hourglass energy in GLSTAT and MATSUM to see if the soft material has large hourglass energy comparing with its internal energy. If yes, you need to refine the mesh of the soft material.

 

More explanations and instructions on negative volume can be found from LSDYNA Negative volume in soft materials (ansys.com)

 

If your model doesn't contain a soft material, you can try the following method to prevent negative volume error:

1. Set ERODE = 1 in *Control_TimeStep to erode elements by small time step. The small time step limit can be specified in *Control_Termination.
2. Reduce time step safety factor. The default is 0.9. You can try smaller time step safety factor such as 0.45, 0.33, etc.
3. Use different hourglass controls such as IHQ = 6 to 9.
4. Use different contact keyword such as *Contact_Interior.

More instructions and discussions about negative volume error can be found in LSDYNA Negative volumes in brick elements (ansys.com)