Elastoplastic constitutive model for particle-dispersed composites accounting for interfacial damage

For establishing the constitutive law, the property of a composite material is generally described by focusing on the relation between the average stress and the average strain in multiple phases. While the interface between matrix and inclusions undergoes damage, this relation should be modified accordingly. The effects of damaged interface on the strain field in composite are considered in two ways. First, the degradation of matrix-inclusion interface makes the strain field inside inclusions no longer uniform as that of inclusions with perfectly bonded interface. Secondly, it contributes to the average strain in composite by an additional strain, which is yielded from an integration of relative displacement between matrix and inclusion over their interface. In present paper, the first part is considered by using a modified Eshelby's S-tensor. After deriving the local relative displacement distributions between matrix and inclusion at the interface, the second effect of damaged interface on the average strain can be expressed in terms of the corresponding eigenstrain, by introducing a damage-relevant tensor D, which is a fourth order tensor, and tends to zero when the interface is perfect. Both the tangential and normal discontinuities at the interface are independently modeled. The numerical results are also shown. It is found that the interface conditions of debonding and/or sliding give detrimental effects on the overall properties of composites. Thus, the establishment of the most appropriate model describing properly the meso-local phenomena. (C) 2002 Elsevier Science B.V. All rights reserved.