Trouble understanding allowable elastic slip Abaqus - clarifying question

[tugni925]

"In reality the elastic slip is assumed to correspond to the elastic displacement in the surface roughness. To find the correct elastic slip value for the analysis is difficult. However, the elastic slip value can be adjusted to real material parameters to capture the real behaviour of the slip. In Abaqus the elastic slip can be specified either as a fraction of the element length or as an absolute distance. By default the elastic slip is defined as 0.5% of the average length of all contact surface elements in the model. However, when using the absolute distance the elastic slip is independent of the element size."

So as I understand it elastic slip does have a physical meaning and its not just "numerical junk". But why can we then set an absolute distance for elastic slip, should this not be a default value for specific materials? I do not understand how it makes sense to be able to choose an elastic slip.

 

[FEA way]

It corresponds to real-life behavior but without proper setting it’s unrealistic. And in most cases, you can’t set this up correctly because you would need some very detailed experimental data. Thus, users are encouraged to use the formulation without elastic slip or adjust the value for elastic slip using trial and error method.

 

[tugni925]

When I am adjusting via trial and error, how would I know I have the right elastic slip?

 

[FEA way]

You would have to compare results (contact force/stress) from the analysis with those obtained experimentally.

 

[tugni925]

The trial and error method is to adjust the penalty stiffness? - Which is what controls the elastic slip?