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.