MIXED-MODE FRACTURE CRITERIA FOR AN INTERFACE CRACK

Fracture tests of aluminum/epoxy dissimilar materials with an interfac e crack are carried out under comprehensive mixed mode conditions, usi ng circular disk type (brazil-nut-sandwich) specimens under compressio n or tension loading in various directions. The stress intensity facto rs 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 a nd the fracture angles are well predicted by the sigma(thetamax) crite rion proposed by the authors. In the brazil-nut-sandwich tension tests , the crack grows along the interface and the mixed mode fracture crit eria are clarified experimentally. A method to evaluate the possible p ath and the strength of the interface crack is proposed by comparison with both criteria.