What is XFEM?

XFEM, Extended Finite Element Method, is a method used to model discontinuity within a continuum with the aid of additional degrees of freedom, it is specifically used to model crack propagation throughout the model. It connects LEFM to finite element by adding 8 additional DOFs to the nodes of the element containing the crack tip, and the jump in displacement across the cracked surface is modeled by adding heaviside function to the nodes of the elements containing the crack. 

There are a few free XFEM codes such as XFEM++, getfem++ and openxfem++.

It is also implemented in Abaqus. 

It is also possible to connect EPFM with FE by using J integral, but this is only valid for local plasticity.

Isotropic Hardening, von Mises plasticity, UMAT

UMAT by