MIXED-MODE FRACTURE CRITERIA FOR AN INTERFACE CRACK

Fracture tests of aluminum/epoxy dissimilar materials with an interface crack are carried out under comprehensive mixed mode conditions, using circular disk type (brazil-nut-sandwich) specimens under compression or tension loading in various directions. The stress intensity factors for an interface crack are analyzed by the boundary element method, and the fracture criteria for an interface crack are investigated and discussed based on the interfacial fracture mechanics. In the brazil-nut-sandwich compression tests, the crack kinks into the epoxy resin and the fracture angles are well predicted by the sigma(thetamax) criterion proposed by the authors. In the brazil-nut-sandwich tension tests, the crack grows along the interface and the mixed mode fracture criteria are clarified experimentally. A method to evaluate the possible path and the strength of the interface crack is proposed by comparison with both criteria.