Reply To: Lsdyna rolling process,negative volume

[Pedram Samadian]

Hi,

A negative volume message in LS-DYNA during forming simulation typically indicates that an element has become so distorted due to extremely large deformations that its calculated volume is negative. You can try the following ways to address this issue:

1- Ensure the mesh is well-structured, with elements having good aspect ratios (ideally close to 1 for quadrilaterals). Use a finer mesh in areas with high deformation (e.g., near punch corners, die entry radii). Overly coarse elements can lead to distortion.

2- Check your input hardening curve cover the expected range of strains.

3- Use a proper contact card with reasonable values for different parameters. The choice of imporper values for contact parameters can result in unrealistic penetrations or excessive forces.You can check the LS-DYNA user’s manual Vol.1 (LSDYNA Manuals) to learn about different contact cards in LS-DYNA. 

4- Reduce the loading step size to allow the simulation to handle large deformations more accurately. Ramp up the input load or velocity profile gradually.

5- Use appropriate control cards including control shell/solid/hourglass. You check the LS-DYNA user’s manual Vol.1 (LSDYNA Manuals) for more information. 

6- Use appropriate element formulations to better handle large deformations (Avoid fully integration elements, which is more vulnerable to negative volume element error). 

7- Reduce the mass or time scaling in the simulation.

8 - Ensure the units of the parameters input to your model are consistent (https://www.dynasupport.com/howtos/general/consistent-units).

I hope these tips are helpful.

Thanks,

Pedram