Dependence of mixed-mode crack propagation on the variation of σr and τrθ

Abstract

The variation of the direction θ p of crack propagation in mixed mode with the angle β of the inclined crack is shown to fit very well to the variation of θ r , of the bisector of the angle of directions θ r1 and θ r2 of max σ r and sufficiently well to that of θ rθ , bisector of the angle of directions θ rθ1 and θ rθ2 of min τ rθ < 0 and max τ rθ > 0. The variation of σ cr / σ cr I , causing initiation of propagation, with β as predicted by the max σ θ criterion, fits very well to that of a critical loading evaluated by considering the combined “opening” effect of σ and τ rθ along the circumference of a small circle centered at the crack tip. The above results may be used as criteria of mixed-mode fracture based on σ r and τ rθ .