INTERFACE FRACTURE-ANALYSIS OF JOINTS WITH A DUCTILE INTERLAYER

Plane strain problem of an interface crack with two interface shear yield zones and one crack-face contact zone is studied. The plastic yielding of the interlayer is stimulated by the interface shear yield zones and contact zone is included near one tip of the interface crack. An interesting and important phenomenon found in this analysis is that for such an interface crack the applied compressive normal stress can increase the stress intensity factor K(I) at one of the two crack tips, the size of the crack-face contact zone, and the maximum value of the crack opening, in a combined normal and shear stress field. Examples are given for two pairs of materials used in ceramic-metal brazed joints. Si3N4/Ni and Si3N4/Incoloy 909.