Abstract
An analytical and numerical study of the overall behaviour of metal-matrix composites reinforced by particles or short fibres is presented. The particles are elastic and the matrix is elastic-plastic with isotropic hardening. Cell calculations are performed under the assumption of continuity of displacements and tractions across the interfaces and are compared with theoretical predictions for the overall stress-strain curves of the composites derived from a bounding procedure for non-linear materials. Experimental evidence of the influence of the interface on the overall characteristics of the composite has been given in the literature. To get some insight into this problem, a model of interfacial degradation is proposed. The influence of the interface properties on the overall ductility, through its effect on the deformation of the matrix surrounding the reinforcements, is discussed. Finally, the effects of ductile damage due to void growth in the matrix and to cracking of the particles are respectively examined.

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