Numerical computation of complex stress intensity factors of interface cracks in bi-materials based on photoelastic theory

This paper presents a new numerical method for obtaining the complex stress intensity factor with an interface crack in bi-materials using photoelastic isochromatic fringe numbers N. The theoretical solution of stress field at the crack tip was deduced from Muskhelishvili's stress function and an undetermined term sigma(0) which is a function of material properties was added to this theoretical solution. A partial differential iterative equation with fast convergence was formed by applying the photoelastic theory. The complex stress intensity factor K=K-1+iK(2) and sigma(0) were obtained by Newton-Raphson iteration method and K domain was discussed. The simulant photoelastic isochromatic fringe pattern could be generated through image processing and numerical calculation according to K and sigma(0). The simulant isochromatic fringe pattern accords with experimental photoelastic isochromatic fringe pattern, so it is practicable for this numerical method of obtaining the complex stress intensity factor.