Thermoelastic stress fluctuations in random-structure coated particulate composites

In this paper linearly thermoelastic composite media are considered, consisting of a homogeneous matrix containing a statistically homogeneous random set of ellipsoidal uncoated or coated inclusions. This study constitutes an extension of the theory regarding the purely isothermal elastic case and uncoated ellipsoidal inclusions. Effective properties (such as compliance, thermal expansion, stored energy) and both first and second statistical moments of stresses in the components are estimated for the general case of nonhomogeneity of the thermoelastic inclusion properties. The micromechanical approach is based on Green's function techniques and on the generalization of the 'multiparticle effective field' method (MEFM), previously proposed for the estimation of stress field averages in the components. The application of this theory is demonstrated by calculating this overall yield surfaces of composite materials. The influence of the coating is analyzed both by the assumption of homogeneity of the stress field in the inclusion core and the thin-layer hypothesis. (C) Elsevier, Paris.