The interaction of two parallel semi-elliptical surface cracks under tension and bending

Multiple cracks are often observed in engineering structures; and their int eraction and coalescence may significantly affect their life. Knowledge of the behavior of interacting cracks is very limited A major component of any linear fracture mechanics model for fatigue crack growth is the calculatio n of the crack-tip stress intensity factor, SIF. In this paper a parametric study is presented for two parallel surface cracks in an infinite plate su bjected to remote tension or to pure bending loads. The stress intensity fa ctors for these cracks as a function of the crack-front position, depth, sh ape, and plate thickness are calculated using three-dimensional (3-D) finit e element, (FE) analysis. The ratios of crack depth to plate thickness, a/t , and to crack length, a/c, range from 0.1 to 0.62 and 0.1 to 1.0, respecti vely. Where possible, a comparison of 3-D with 2-D results is also consider ed.