EFFECTS OF FIBER AND INTERFACIAL LAYER MORPHOLOGIES ON THE THERMOPLASTIC RESPONSE OF METAL MATRIX COMPOSITES

This paper examines the effect of fiber and interfacial layer morphologies on thermal stress fields in metal matrix composites (MMCs). A micromechanics model based on an arbitrarily layered concentric cylinder configuration is used to calculate thermal stress fields in MMCs subjected to spatially uniform temperature changes. The fiber is modeled as a layered material with isotropic or orthotropic, elastic layers whereas the surrounding matrix, including interfacial layers, is treated as a strain-hardening, elasto-plastic, von Mises solid with temperature-dependent parameters. The solution to the boundary-value problem of an arbitrarily layered concentric cylinder under the prescribed thermal loading is obtained using the local/global stiffness matrix formulation originally developed for stress analysis of multilayered elastic media. Examples are provided that illustrate how the morphology of the SCS6 silicon carbide fiber and the use of multiple compliant layers at the fiber-matrix interface affect the evolution of residual stresses in SiC-Ti composites during fabrication cool-down.