Crack-tip opening angle-based numerical implementation for fully plastic crack growth analyses

This study introduces implementation of a nodal release technique into a FEM/continuum model to enable simulation of fully plastic crack growth. The nodal release technique is implemented in the user-defined element form on the symmetry line of a deeply single-edge cracked specimen so that the force at the crack-tip node on the symmetry line is made zero after several steps upon the satisfaction of a chosen fracture criterion, and an incremental crack extension is achieved. The fracture criterion adopts the crack-tip opening angle (CTOA) which is determined from the specimen’s loading geometry [1]. For evaluation of the present model, the crack growth simulation results from the present FEM model were compared to those from the line-spring model of Lee and Parks [2].