LEFM crack path models evaluation under proportional and non-proportional load in low carbon steels using digital image correlation data

Abstract

Crack path models were evaluated with experimentally obtained SIF for proportional and non-proportional loading for plane and tubular ductile steel samples. For non-proportional loading, most of the models had trouble matching experimental results, but the strain energy density criterion (SED). The difference may be attributed to the origin of the SIF ranges, which account for accumulated plasticity and shielding by crack roughness, and to the non-proportionality of the mixed-mode applied load. The matching in the SED is attributed to the inclusion of mode III and the way it is evaluated. A comparison of computational cost for the models is made, suggesting that the type of load and the computing time may need to be included in the CP model selection.