Resistance curves for mixed mode interface crack growth between dissimilar elastic-plastic solids

For crack growth along an interface joining two elastic–plastic solids resistance curves are analysed numerically, under conditions of small scale yielding. As mismatch of elastic properties is accounted for, the corresponding oscillating stress singularity fields are applied as boundary conditions on the outer edge of the region analysed.

The fracture process is represented in terms of a cohesive zone model, for which the work of separation per unit area and the peak stress required for separation are basic parameters. Effects of different kinds of mismatch between the two materials are analysed, including cases where the substrate remains elastic as well as cases where both materials yield plastically.

For all the cases studied it is shown that plastic flow near the crack tip results in much larger resistance to crack growth when mode II conditions dominate at the crack tip than when mode I conditions dominate.