Crack growth resistance curves in strain-softening materials

Abstract A theoretical model has been developed for the crack growth resistance ( K R ) curves in strain-softening materials with power law softening stress (σ)-crack opening displacement (δ) relationships. Both exact and approximate solution methods have been used to calculate K R curves for a fibre cement composite in a double-cantilever-beam (DCB) geometry. There is good agreement between these two solutions. When the crack growth is normalized with respect to the saturated softening (or fibre bridging) zone there is an almost unique K R curve which is independent of specimen geometry and initial crack length. The effects of the softening index ( n ) of the power law σ-δ relationship on the shapes, saturated softening zone lengths and plateau values of the K R curves are also studied.