Effective wave speeds in an SiC-particle-reinforced Al composite

TLDR: In this paper, a SiC particle-reinforced aluminum-alloy composite was modeled as prolate spheroids distributed randomly, both in position and orientation, and wave speeds of plane waves, both longitudinal and shear, were calculated in the longwavelength limit.

Abstract: Plane‐wave propagation in an SiC‐particle‐reinforced aluminum‐alloy composite was studied. Considering the composite to possess orthotropic symmetry (nine independent elastic constants), by a pulse‐echo method, nine independent ultrasonic velocities were measured. Measured elastic stiffnesses departed negatively up to 40% from a rule‐of‐mixture model. Using ensemble‐average, scattered‐plane‐wave methods, the composite was modeled as SiC particles represented as prolate spheroids distributed randomly, both in position and in orientation. Wave speeds of plane waves, both longitudinal and shear, were calculated in the long‐wavelength limit. These wave speeds lead to equations for the effective static bulk and shear moduli of the composite. Further, a nonhomogeneous particle distribution was considered. Wave‐speed equations were derived for the case where the composite contains particle‐free aluminum‐alloy regions that were represented by oblate spheroids. The resulting anisotropic composite behaves transvers...