On the identification of the elastic properties of composites by ultrasonic guided waves and optimization algorithm

This paper examines the potential of ultrasonic guided waves to identify the elastic properties of fiber-reinforced composite laminates widely used in light-weight structures. Due to variability in manufacturing processes, complexities involved in the constituent materials, or degradation in service, a non-destructive tool for the characterization of the composite's properties can be extremely useful. A common assumption is the necessity for multiple wave propagation directions to fully characterize the properties. This paper examines the potential for property characterization by a single wave propagation direction. It proposes a property inversion scheme based on matching phase velocity dispersion curves of relevant guided modes by means of a Simulated Annealing optimization algorithm and a Semi-Analytical Finite Element method to solve the forward problem. Proof-of-principle numerical studies are presented to demonstrate the potential of each selected wave mode to provide identification of several properties, including the lamina elastic constants and the laminate effective constants. It is shown that the complex stress and strain profiles generated by the waves, aided by the anisotropy of the composite, create interesting "coupling" effects that ultimately enable accurate identification of several elastic properties away from the wave propagation direction.