Viscoelastic wave propagation in anisotropic media with application for composite cure monitoring

This paper addresses some of the theoretical and experimental aspects of utilizing ultrasonic sensors for monitoring composite curing. A material model is first presented which predicts the variation of the viscoelastic stiffness matrix components as a function of cure time. Using these predicted properties, the time-dependent behavior of the longitudinal reflection factor, R_ll, due to an obliquely incident longitudinal wave is determined for two specific cases. The first case involves the determination of the reflection factor from the interface between an elastic isotropic media and a viscoelastic anisotropic media. The second boundary value problem presented extends this analysis to the case of a viscoelastic anisotropic layer bounded by two identical elastic isotropic half-spaces. Finally, results of this modeling are compared with experimental results.