An experimentally verified finite element study of the stress-strain response of crack geometries experiencing large-scale yieding

摘要

Large-strain, three-dimensional finite element analyses with incremental plasticity were performed for a variety of crack geometries to study local crack-tip stress-strain fields and associated global fracture parameters under conditiolns of large-scale yielding. The geometries analyzed include thin, single-edge crack tension, single-edge crack bending, and centr-crack tesion fracture speciments with varying crack depth (a/W) ratios. Two materials were investigated: a high-ardening, low strength steel and a moderate-hardening, high-strength steel. Mesh refinement studies were performed to ensure convergence of the finite element predictions. The studies eamine the effects of in-plane crack-tip element size, intial crack-tip radius size, and number of through-thickness layers on predicted distributions of crack-tip stress and plastic strain and predicted values of the J-integral and CTOD. In addition, the finite element predictions of specimen behavior were verifed experimentally by direct measurements, namely load displacement, load longitudinal strain, and load CTOD, made during and following testing of the fracture specimens.