The sensitivity of ultrasonic wave interactions to material and geometric nonlinearities
makes them very useful for nondestructive characterization. The ability of guided waves to
interrogate inaccessible material domains, be emitted and received from a single surface,
and penetrate long distances provides capabilities that bulk waves do not. Furthermore,
mutual interactions between waves propagating in collinear or non-collinear directions
provide excellent flexibility as to which types of waves are used, as well as their frequencies …