Hi ENG-TIPS community,

I'm working on layer delamination in fibre-reinforced-plastics due to low-velocity-impacts.

The stacking sequence of the laminate I want to model is [0,90,90,90,90,0] and experiments have shown that the shape of the delamination is "peanut-like" and debonding occurs only in the plane-of-changing-direction opposite to the 2000N impact.
I'm trying to model the debonding via a cohesive zone using contact and target elements.

The initial results of the simulation look quite promising. Contact gap and slinding distance are significantly greater in the plane where debonding occurs in real life.

The problem is that I can't find a way for the two surfaces to actually debond!

When I'm setting the maximum contact stresses as well as the critical fracture energy to very low values (assuming this'd lead to quick debonding) the solution doesn't converge.

I don't know what is wrong with my code and would greatly appreciate if someone with more experience could give me some hints what might me the problem.

I attached my code. Mesh density and CHZ data are set to random values that ensure a quick solution. (Though - as explained - no true debonding.)

I hope you can help me.

Your's sincerely,
Alex