New definition of stress intensity factors for an interface crack with physical meaning
Xu Jin Quan; Mutoh Yoshiharu
Abstract:It is well known that the stress becomes oscillatory singular near an interface crack tip. Due to the oscillation, the definition of the stress intensity factor for an interface crack would be different from that for a crack in a homogeneous media. Several definitions for an interface crack have been reported. However, in application of interfacial fracture mechanics, there is still lack of the definition with physical meanings so that researchers may use different definitions. In the present paper, natures of the existing definitions have been discussed in detail. Then, based on the similarity principle for an interface crack in which a relative distance is accepted instead of an absolute distance, a new definition with physical meanings has been proposed. In the new definition, K1 and K2 approximately correspond the remote tensile and shear stresses, respectively. The tensile and shear stresses in the domain of stress intensity factors are also dominantly expressed by K1 and K2, respectively. These two properties make the new definition more convenient for the strength evaluation of dissimilar joints than the existing definitions. It is also noted that the stress intensity factors for interface cracks based on the existing definitions can be easily reduced to those based on the new definition. Key Words:interface crack, stress intensity factor, definition, oscillation singularity, similarity principle