Single-sided non-collinear shear wave mixing for material characterization

This Letter develops a single-sided non-collinear shear wave mixing technique for material characterization based on the phase-matching interface condition. Analytical modeling reveals that the interference between incident and reflected waves produces standing wave patterns whose interaction significantly enhances the mixed wave energy. Finite element simulations and experimental measurements demonstrate that the generated mixed longitudinal wave reaches its maximum amplitude when the mixing occurs at the traction-free surface. Additional simulations confirm the analytical prediction that the amplitude of the mixed longitudinal wave scales proportionally with the Murnaghan third-order elastic constant m. These findings confirm the feasibility of the proposed approach, highlighting its potential as a single-sided ultrasonic nondestructive evaluation technique to characterize the nonlinear elastic properties of a material.