Hello Peter

I have a doubt regarding the input data. I saw that, in Abaqus, the compressive yield stress has to be greater than the tensile yield stress, otherwise an error message occours. This is because the cast iron model is implemented with the cast iron flow potential (like specified here

My material is a bit difficult to inteprete, but the compressive behaviour suggests a compressive yield stress that is lower than tensile yield stress. This doesn't create an error in Ansys. Is this still correct though, can I use the cast iron model this way? It is the only way I have to model a materiale that have different behaviour in tension and compression. 

Do you also know how to find the plastic poisson's ratio? I have a polimeric material, but on the internet I cannot find any data, even through all my academic and university resources. 

Many thanks