Learning Forum

[Chris Quan]

Erosion controls is only used with Lagrange, shell, and beam parts. The erosion is only used to remove the elements that are distorted or degenerated so these elements won't cause small time step that prevents the model running in excessively long time. 

 

Erosion is not a failure model so it is not used to replace material failure model. Furthermore, the same material could have different erosion strain in different simulations or different materials could have the same erosion strain in the same simulations.

 

The formulation we used to calculate erosion strain is independent of material strength and failure models. The rule of thumb on determining the value of erosion strain is to have material elements fail first and then is eroded away. This will make sure that the material strength will not get under-predicted.

 

Because of the reasons above, it is very difficult to give you an exact number of the erosion strain for your specific material without knowing your simulations and models. Erosion controls are defined under Analysis Settings.

 

A material element can be eroded (removed) when its geometric strain limit is reached (default 1.5), or when the material in the element fails (default no), or when the time step controled by the element reaches a given minimum value (default no). Thus, if you want to include the post-failure behavior in your simulations, erosion strain (geometric strain) should be large enough to have material failed first and then eroded. If you do not want to include post-failure behavior in your simulations, you can use erosion with material failure. If you have time step issues due to element distorsion, you can use erosion by time step.