Ebrahim Saib, Z. M., Croxford, A. J., & Drinkwater, B. W. (2024). Numerical model of nonlinear elastic bulk wave propagation in solids for non-destructive evaluation. Ultrasonics, 137, 107188.
https://doi.org/10.1016/j.ultras.2023.107188
Abstract
The energy transfer between frequency bands is shown and the amplitude trend of the harmonics are validated against available theories. It is then used to simulate the nonlinear ultrasonic field generated by a finite-size element of an array in a solid to better understand its behaviour. An array-element directivity at the second harmonic frequency is shown. Since the FDTD model does not account for attenuation, a correction using a ray-based approach is applied to the simulated result for direct comparison against experimental measurements. The field obtained from a typical array used in non-destructive testing is then simulated to characterise its behaviour. Experimental comparison of the nonlinear displacement fields for different focal positions showed good agreement, further validating the FDTD model. This FDTD model opens opportunities to virtually experiment and design appropriate nonlinear ultrasonic array inspections whilst isolating and understanding contribution from material nonlinearity.
Bruce Drinkwater 