While much nonlinear ultrasonics research has been conducted on higher harmonic
generation, wave mixing provides the potential for sensitive measurements of incipient
damage unencumbered by instrumentation nonlinearity. Studies of nonlinear ultrasonic
wave mixing, both collinear and noncollinear, for bulk waves have shown the robust
capability of wave mixing for early damage detection. One merit of bulk wave mixing lies in
their non-dispersive nature, but guided waves enable inspection of otherwise inaccessible …