Element size and stress state dependent failure criterion implementation to LS-DYNA

Material behaviour is implemented to subroutine umat47v. It is a vectorized subroutine for x64 bit computers. For reference see: Kõrgesaar, M., Romanoff, J., 2014. Influence of mesh size, stress triaxiality and damage induced softening on ductile fracture of large-scale shell structures. Mar. Struct. 38, 1–17. doi:10.1016/j.marstruc.2014.05.001