A coupled mixed-mode cohesive zone model: An extension to three-dimensional contact problems

In this study a phenomenological three-dimensional coupled (3DC) mixed-mode cohesive zone model (CZM) is proposed. This is done by extending an improved version of the well established exponential CZM of Xu and Needleman (XN) to 3D contact problems. Coupled traction-separation relationships are individually presented for normal and transverse directions. The proposed model preserves all the essential features of the XN model and yet correctly describes mixed-mode separation and in particular mixed-mode closure conditions. Moreover, it provides the possibility to explicitly account for all three components of the gap function, i.e. separations in different directions. The 3DC model has some independent parameters, i.e. interface properties, similar to the XN model. All the cohesive zone parameters can be determined using mode-I and mode-II experiments.