Verifying results when using contact controls stabilization

[boek]

I am running a static analysis of a structure with multiple load steps. There are multiple contact definitions. In one of the load step, the structure deforms in a way such that a gap occurs between a contact pair. One of these surfaces is latter loaded, but since there is an initial gap the solution fails to converge.

Initially, I tried use weak springs to stabilize the model but this method is very inconsistent. Contact fails to establish and surfaces move past each other. Instead, I use contact controls with stabilization to close the gap. This works, but I need to verify my results. I have read that one should compare ALLSD against ALLIE. Here, the recommendation is to keep ALLSD to less than 5% of ALLIE. However, I have multiple load steps before the contact stabilization is active, and as a results ALLIE is very large compared to ALLSD. However, if I instead where to compare ALLSD to the ALLIE generated in the contact stabilization step, i.e. comparing it to the difference between the ALLSD in the stabilization step and a previous step, the ratio becomes large.

How am I supposed to verify my results? I am also wondering if there are any other variables that I could look at? If I am not misunderstood contact controls stabilization does not apply any viscous forces that I can plot?

 

[FEA way]

You could also use contact damping stress (CDSTRESS) output and compare it with true contact stresses CSTRESS. But such a comparison should be done after contact is established. Before that those contact damping stresses can be rather high.