Toward a damage-based finite element fracture theory and application to ductile metals

In this work, the simulation of monotonic fracture in ductile metals was studied and a method of predicting damage-based fracture propagation was introduced. Traditional methodologies for predicting stable crack growth were investigated, and an error analysis was performed to show the suitability of the fracture simulation method chosen for this study. J2 plasticity was investigated for its applicability in predicting crack advance direction for mode-I and mixed-mode simulations. A two parameter crack advance criterion was introduced, and crack propagation simulations were performed to show the suitability of the new fracture criterion that is dependent on damage. J2 plasticity was modified in an attempt to capture the damage mechanisms occurring in front of the crack tip. The end result of this research is a computational tool that is capable of predicting the crack propagation path based on physical and measurable material parameters without knowledge of the crack trajectory a priori while also allowing the constitutive model for the material response to be readily changed. An error analysis was also performed on the existing equations of crack surface displacements for symmetric cracks emanating from a circular hole in an infinite plate subjected to remote stress and stress applied to a segment of the crack surface. New equations were developed for crack surface displacements for symmetric cracks emanating from the circular hole in an infinite plate subjected to a remote stress