Finite Element Modelling of the Thermo-Mechanical Properties of Metal-Matrix Composites

Particle-reinforced metal-matrix composites (MMC) show great potential as light weight materials for a variety of automotive applications. The high specific modulus and strength of these materials make them suitable for disk brake rotors, connecting rods, cylinder liners, and other high temperature components. Typically, MMC’s consist of an aluminum matrix reinforced by particles of SiC or TiC. Models that accurately describe the properties of MMC’s have been developed. The inputs to the models are the properties of the constituents (e.g., moduli, yield strength, coefficient of thermal expansion, creep rate, thermal conductivity), the volume fraction of particles, and information regarding the phase geometry (particle shape and distribution). Some linear properties (for example modulus) can be estimated with sufficient accuracy by applying rigorous bounds, either Hashin-Shtrikman or the third-order bounds of Milton, Torquato, and others. However, for non-linear properties such as yield strength, finite element analysis (FEA) has proven to be extremely useful. FEA modeling has included: (1) residual stresses induced by thermal mismatch between the matrix and the reinforcing particles, (2) stress-strain relation under uniaxial loading, (3) creep, and (4) thermal conductivity of MMC’s. In most cases, the FEA results agree well with experiments done by Allison and coworkers. One possible exception is creep, where the agreement is not as good, possibly demonstrating the significance of changes in matrix microstructure in the composite relative to the unreinforced material.