Ductile Mixed-mode Fracture Criterion Development and Crack Growth Simulations Stable tearing crack growth (slow ductile growth of a macroscopic crack in a load-bearing structure) is an important fracture failure process in ductile materials (e.g. metals) and usually precedes the final catastrophic failure of a structure. In recent years, there has been a growing demand for a simulation-based structural design and evaluation methodology that takes into account the stable tearing crack growth process. Within such a methodology, two tools must be available: (1) an efficient computer simulation code that can handle the kinematics of curvilinear crack growth and perform conventional stress analysis, and (2) a practical mixed-mode fracture criterion that can predict both the instant and direction of crack growth. This presentation will describe research efforts at the University of South Carolina aimed at understanding the stable tearing crack growth process and developing a simulation based prediction methodology for the process. Topics include the mixed-mode CTOD criterion, development of the 3D simulation software CRACK3D, effects of stress constraint, modeling of crack tunneling, and experimental validation studies