A new integral equation method for calculating interacting stress intensity factor of multiple crack-hole problem

In this paper, a new integral equation method is proposed based on elementary solutions and superposition principle to study multiple crack-hole problem under both remote and surface stresses. Several typical crack-hole problems are solved in order to compare the calculation results of interacting stress intensity factors (SIFs) obtained by the newly proposed method with those obtained by Green's function method, dislocation density method, finite element method and digital photo-elasticity method, and further to investigate the effect of loading conditions and crack-hole geometric parameters on SIFs. Research results show that there exists a neutral inclination angle alpha(0) of the crack (with x-axis) for eliminating the crack-hole interaction when sigma(infinity )(x)>= sigma(infinity)(y). Increase of sigma(infinity)(x) is helpful for cracking arrest and the compressive stresses on crack and hole surfaces are helpful for crack propagation. In addition, the normal stress (p) on the crack surface only affects K-I and alpha(0) of K-I, while the normal stress (n) on the hole surface affects both K-I and alpha(0) of K-I, and K-II and alpha(0) of K-II. The hole radius (R) and the crack-hole spacing distance (t) have little effect on alpha(0) of K-I and K-II. The new integral equation method not only has almost the same calculation results of SIFs as the Green's function, dislocation density and finite element methods, but also has advantage of simplicity and wide applicability over Green's function and dislocation density methods in calculating the interacting SIFs of the cracks under both remote and surface stresses.