Effect of surface scratches on the characteristics of nonlinear Rayleigh surface waves in glass

Using nonlinear Rayleigh waves, the effect of surface scratches on the propagation of nonlinear ultrasonic waves in a glass plate was investigated. The results showed that the amplitudes of the fundamental and second harmonics of the nonlinear Rayleigh waves decreased with increasing average width of surface scratches due to the interaction between scratch-induced cracks and wave propagation. The increase of the nonlinearity with the average scratch width suggests that the surface scratches caused the decrease of apparent Young's modulus near the glass surface. Nonlinear Rayleigh surface waves could be a potential method for the quantitative and rapid measurement of surface and subsurface damage in brittle materials.