Nonlinear resonance interaction of ultrasonic waves under applied stress

The stress effect on the nonlinear resonance interaction T+T→L is experimentally investigated using an Al 5083 specimen. Compressive stress applied at the localized region where two noncollinear transverse waves intersect each other is shown to vary, up to ±8.5%, of the amplitude of the longitudinal wave generated through the resonance interaction. The amplitude variation with stress is explained by relating the stress induced change of elastic wave velocities (acoustoelastic effect) to the change in the resonance angle, and then to the directional characteristics of the two incoming transverse beams. The weak anisotropy of the material is taken into account.