Finite Element Model of Stress Wave Topology in Unidirectional Graphite/Epoxy: Wave Velocities and Flux Deviations

Until recently, the use of a finite element model (FEM) to simulate stress wave propagation has been limited to solutions where the number of degrees of freedom are kept to a minimum, because of hardware limitations on computer memory and computational speed. With the advent of a number of new supercomputers, numerical simulation becomes a reasonable approach to some simpler problems. Recently, Ludwig, et. at [1,2] have demonstrated the feasibility of such an approach for problems where materials are either isotropic or only slightly anisotropic. We extend this effort to unidirectional graphite/epoxy which has large variations in elastic properties. For this material the effect of elastic anisotropy on stress wave propagation has been studied both experimentally and analytically [3,4] and several interesting properties have been predicted and measured: mode transitions, sensitivity of flux deviations to small changes in anisotropy, and shear wave speeds exceeding longitudinal waves. With a FEM we can simulate and study some of these properties most effectively.