Effect of a Graded Interface on a Crack Approaching at an Oblique Angle

Abstract

A model problem is considered in which a crack propagates under ductile conditions through an edge-notched plane-strain tension strip. The strip consists of two monolithic material regions joined transversely by a thin graded layer. The material regions are elastically identical but dissimilar in their plastic and fracture-toughness properties. A range of initial crack configurations is studied, including cracks at various angles to the graded layer and with various initial positions in relation to it. A finite-element-based computational procedure containing a number of novel features is used to study the curvilinear crack growth that occurs in this problem. For the problem parameters under consideration, net-section yielding is induced in the more ductile of the two materials, even when the crack trajectory lies well inside the more brittle material. In general, it is found that the brittle material strongly attracts the crack trajectory, and that the presence of the lower-flow-stress material in conjun...