Fiber-matrix interfacial constitutive relations for metal matrix composites

This article presents a three dimensional fiber-matrix debonding model for weakly bonded composites based on a modified Needleman type cohesive zone model. In this model the fiber-matrix interface is fully described by its strength and ductility under normal and shear loading. Debonding initiates when a quadratic interaction of the interfacial tractions attains a critical value (the interfacial strength). Coulombic frictional forces resist sliding after debonding initiates. Complete interfacial separation occurs when the magnitude of the resultant interfacial displacement exceeds the ductility of the interface. The debonding model is implemented, along with the Bodner-Partom viscoplastic model, in the method of cells micromechanical model of Aboudi to take advantage of the model's computational efficiency. Model predictions for cyclic loading are observed to agree well with the experimentally obtained transverse tensile and axial shear responses of silicon carbide/titanium.