Generalization of mixed mode crack behavior on the base of nonlinear fracture resistance parameters

Abstract

Nonlinear crack-tip fracture resistance parameters for two types of cruciform specimens and a compact tension–shear specimen subjected to mixed mode loading are studied by using an elastic–plastic finite element (FE) analysis. FE analysis is performed for two types of steel and titanium and aluminum alloys with different elastic–plastic properties. A Ramberg–Osgood stress–strain relation is used to characterize the elastic-plastic properties of considered materials. Different degrees of mode mixity from pure Mode I to pure Mode II are realized in all considered specimens by combinations of the nominal stresses σn, remote biaxial stress ratio η, and the initial crack angle α with respect to the loading direction. For the specified geometry of the specimens considered, the governing parameter of the elastic– plastic crack-tip stress field In-factor, the stress triaxiality, J-integral are determined as a function of mode mixity and elastic–plastic material properties, described by strain hardening exponent. As a result influence of the specimen configuration on all considered nonlinear fracture resistance parameters is evaluated.