Couple effects of mixed mode biaxial loading and crack tip configuration on plastic stress intensity factor behavior at small and large scale yielding

Abstract

In this paper the plastic stress intensity factor (SIF) approach is used to study the coupling effects of loading biaxiality, material properties and crack tip configuration in both the small- and large-scale yielding ranges. For comparison between small-scale and large-scale yielding solutions, a rectangular plate with a centered line crack subjected to biaxial loading and three types of test specimens under mixed mode loading were analysed by using a finite element method. Numerical analysis was performed for two types of steel and titanium and aluminum alloys with different elastic–plastic properties. Both the mathematical notch type crack tip and the crack tip with finite radius of curvature were considered. The governing parameter of the elastic–plastic crack-tip stress field In-integral, J-integral, and the plastic SIF were calculated as functions of loading biaxiality and applied stress levels. Special emphasis was put on an ambivalent J-integral and the plastic SIF behavior for specified the crack tip geometries. Contrary trends of biaxiality effects on J-integral behavior were established depending on crack tip configuration. Nonlinear fracture resistance parameters in the form of J-integral, In-integral and the plastic SIF were calculated as a function of the material properties and mode mixity for specified test specimen geometries. Finally, the applicability of the plastic stress intensity factor approach to large-scale yielding analysis of mixed mode crack tip stress fields was demonstrated.