Cohesive zone modeling of dynamic failure in homogeneous and functionally graded materials

This work investigates dynamic failure processes in homogeneous and functionally graded materials (FGMs). The failure criterion is incorporated in the cohesive zone model (CZM) using both a finite cohesive strength and work to fracture in the material description. A novel CZM for FGMs is explored and incorporated into a finite element framework. The material gradation is approximated at the element level using a graded element formulation. Examples are provided to verify the numerical approach, and to investigate the influence of material gradation on crack initiation and propagation in Mode-I as well as in mixed-mode fracture problems. The examples include spontaneous rapid crack growth in homogeneous and FGM strips, dynamic crack propagation in actual monolithic and epoxy/glass FGM beams (three-point bending) under impact loading, and mixed-mode crack propagation in pre-cracked steel and graded plates.