CHARACTERIZATION OF ANISOTROPIC ELASTIC-CONSTANTS OF SILICON-CARBIDE PARTICULATE-REINFORCED ALUMINUM METAL-MATRIX COMPOSITES .2. THEORY

The effective elastic constants of composite materials contain arbitrarily oriented ellipsoidal fibers were derived using the concept of orientation-dependent average fields and the strain concentration factor tensors. Under the prescribed boundary condition, the concentration factor was evaluated by the Mori-Tanaka method and the Eshelby's equivalent inclusion principle. The fourth-rank tensor expression for the elastic stiffnesses was recast into matrix form for easier numerical computations. The theoretical model developed was applied to the computation of the anisotropic elastic constants of the extruded Al/SiC(p) composites considered in Part I of this series. Good agreement was found between the model predictions and the ultrasonic measurement results. Comparisons with the Hashin-Shtrikman (H-S) bounds for isotropic composites were also presented. It was found that while the H-S lower bound predicted the out-of-plane properties, it generally gave a poor estimate for the in-plane properties of these composites.