Comparison of Mesoscale Crack Advance and Process Zone Element Approaches for Simulating Ductile Crack Trajectories in Steel

Abstract

Rigorous application of continuum damage mechanics (CDM) models coupled with crack propagation schemes can predict crack branching or zigzag trajectories near the crack tip, even when the macroscopic crack growth is straight. This arises from oscillations in the local damage field and is consistent with experimental observations of ductile tearing; however, it complicates finite element simulations. This study investigates this behavior through two crack propagation strategies in finite element simulations. The first, termed the Mesoscale Crack Advance (MCA) approach, explicitly tracks changes in crack trajectory based on the evolving local damage field. The second, termed the Process Zone Element (PZE) approach, represents damage and crack advance in an averaged sense over a material's characteristic length. Both approaches produce similar results. Despite its simplified formulation, the PZE approach captures the essential features of ductile crack propagation and provides a computationally efficient, practical alternative for simulating ductile crack growth and brittle fracture.