Ductile crack growth based on damage criterion: Experimental and numerical studies

The continuum mechanical simulation of the microstructural damage process is important in the study of ductile fracture mechanics. In this paper, the continuum damage mechanics framework for ductile materials developed by Lemaitre has been validated experimentally and numerically for A533-B1 alloy steel under triaxial stress conditions. An experimental procedure to identify the damage parameters was established and the experimental calibrated damage parameters were then used in a finite element model. A fully coupled constitutive elastic–plastic-damage model has been developed and implemented inside the ABAQUS implicit FEA code. The model is based on a simplified Lemaitre ductile damage model whose return mapping stage requires the solution of only one scalar non-linear equation. A local crack growth criterion based on the critical damage parameter was proposed; the validity of this criterion was examined by comparing the simulation with the experimental results on standard three point bending (3PB) test. The critical load at crack growth initiation and the fracture toughness, JIc, has also been predicted from the simulation. These numerically predicted values compared favourably with those obtained from experiments.