The mixed mode crack growth rate in cruciform specimens subject to biaxial loading

•Cruciform specimens with an inclined crack subject to biaxial loads are used to study the fatigue crack growth rate.•A method for infiltrating the mixed mode displacement of cracks in the deformed state is suggested.•The combined effect of load biaxiality and crack orientation on the crack growth rate is made explicit.

Cruciform specimens of two configurations with an inclined crack subject to a system of biaxial loads are used to study the fatigue crack growth rate. A method for infiltrating the mixed mode displacement of cracks in the deformed state is suggested. For the particular specimen geometries considered, the T-stress and the geometry dependent correction factors, as well as the numerical constant of the plastic stress distributions In, are obtained as a function of the dimensionless crack length, load biaxiality and mode mixity. The combined effect of load biaxiality and crack orientation on the crack growth rate for low-strength and high-strength steels is made explicit. Additionally, a comparative study of a cruciform specimen with a working area thinned with respect to a flat cruciform specimen is performed through experiments and numerical computations under various mixed mode biaxial loading conditions.