On the Interface Debonding Models

Abstract

Interface debonding models offer the possibility to simulate numerically the interface crack growth, and the eventual contact friction behaviour on the cracked area. The paper considers models in the framework of an Interface Damage Mechanics, relating displacement discontinuities across the interface to the corresponding tractions, through various constitutive and damage equations. The approach is based on the initial works by Needleman (1987) and Tvergaard (1990a, 1990b). After a brief review of the existing models, two new versions are proposed and discussed in detail, with the purpose of simulating mixed mode progressive decohesion, followed by a contact/friction behaviour after complete separation, and to guarantee the continuity between the two phases. The first modified model considers coupling terms in the elastic behaviour with damage. The second one introduces the possibility for sliding effects, obeying the Coulomb criterion, during the decohesion phase. The initial Tvergaard model and the second modified model are shown to be derivable from a state potential. Moreover, the thermodynamic framework is used to choose some characteristics of the Model II under a compressive behaviour. Under tension, the models reduce to the classical one. A three-dimensional generalization is given in the Appendix. In addition, the numerical simulation capabilities of the interface debonding models are illustrated by two examples: the fibre-matrix-interface decohesion in a Metal Matrix composite with a bridged matrix crack and the delamination of a DCB (Double Cantilever Beam) specimen.