Mesh Dependence in Menetrey-Willam
I am trying to model the cracking behaviour of unreinforced concrete or screed. I am using the Menetrey-Willam-Model and according to the underlying crack-band model, I need to define a tension softening behavior via the yield function Omega_t (curve of tensile relative stress over plastic strain kappa) without losing the objectivity of the model. I can either use exponential softening or linear softening. In the case of exponential softening the parameters fracture energy G_ft and residual relative stress Omega_tr have to be defined. In linear softening, the parameters are again the residual relative stress Omega_t and the plastic strain limit kappa_tr.
Now my question concerns the mesh dependency: In the Menetrey-Willam documentation in the Ansys Help there is a parameter "effective element length" to "overcome mesh-depenedent softening behavior". If I use exponential softening, the effective element length influences the model obviously through the yield function (equation 4-47 in the documentation). But in linear softening I have to define the yield function directly through the parameter of the plastic strain limit kappa_tr.
So the effective element length doesn't influence the material model in case of linear softening, does it? So the linear softening behavior is fully mesh-dependent, isn't it?
Or is there another way, in which the effective element length influences the material behavior in the case of linear softening?
Thank you in adavance for your help!