Fatigue crack growth analysis of biaxially loaded hole-edge cracks using boundary cracklet method (BCM)

Fatigue crack growth (FCG) behavior of two symmetric cracks originating at different orientations from the outer periphery of a hole in an infinite plate under biaxial tension-tension loading is presented using two-dimensional boundary cracklet method. Symmetric precracks of known length and orientation are modelled as initial cracks, and biaxial traction is applied as a far-field loading. The rate of FCG is computed using Walker's equation, whereas the direction of propagation of crack tip is predicted using the minimum strain energy density criterion. The parametric study is performed with various orientations of initial precracks, biaxiality stress ratios (λ), and stress ratios (R) to show their effects on FCG behavior. Results suggest that for equiaxial loading, the crack propagation direction depends upon the position and initial angle of the crack. Cracks tend to grow perpendicular to that stress which is dominant of the two applied stresses when the biaxiality ratio is not unity.