A computational micromechanics study of the effect of interface decohesion on the mechanical behavior of composites

The influence of the interface properties (interface strength and toughness) on the tensile deformation was studied in a model composite made of a random distribution of stiff spherical particles embedded in a ductile matrix. The composite behavior was simulated through the finite element analysis of a three-dimensional representative volume element of the composite microstructure, and interface decohesion was included by means of interface elements whose behavior was governed by a cohesive crack model. The patterns of interface decohesion were in excellent agreement with experimental observations, and the independent effect of both interface strength and toughness on the composite tensile properties (yield strength, tensile strength and ductility) was assessed by a parametrical study in composites with homogeneous and clustered particle distributions. In addition, the ability to use the changes in elastic stiffness or in volumetric strain to monitor damage during deformation was determined. However, simple models of continuum damage mechanics based on these parameters failed to predict the composite flow stress in the presence of interface decohesion.