strain softening behaviour

Hello Everyone,

I am a beginner in FEA of composites under impact in commercial explicit code Pam Crash.I want to know why the behaviour of composite plies with CDM approach show mesh dependency?Or a more general question for me is that what makes the FE simulation of a material with strain softening behavior mesh dependence(If this conclusion is right)? Does it make any difference with regard to mesh dependency if one uses implicit codes??

Thanks

Setareh