Multiaxial crack growth rate under variable T-stress

•Fatigue crack growth rate are studied through experiments and computations.•Different biaxial and mixed-mode loading conditions are considered.•A method is suggested for calculating the mixed mode plastic stress intensity factor.•It is demonstrated that the plastic SIF can characterize the crack growth rate.

Fatigue crack growth rate are studied through experiments and numerical computations under different biaxial and mixed-mode loading conditions. Cruciform specimens under biaxial loading and compact tension–shear specimens are considered. The different degrees of mode mixity from pure mode I to pure mode II are given by the combinations of the far-field stress level, load biaxiality and inclined crack angle. For the particular specimen geometries considered, the T-stress and the numerical constant of the plastic stress field distributions In are obtained as a function of the dimensionless crack length, load biaxiality and mode mixity. A method is also suggested for calculating the plastic stress intensity factor for any mixed-mode I/II loading based on the T-stress and power law solutions. It is further demonstrated that the plastic stress intensity factor accounting for the in-plane and out-of-plane constraint effect can be used to characterize the multiaxial crack growth rate for a variety of specimen geometries.