A multiscale peridynamic model for surface acoustic wave-defect interactions

Surface acoustic wave (SAW)-based ultrasonic inspection has emerged as a promising technique for non-destructive evaluation (NDE) of machined surfaces of hard and brittle materials. However, accurately simulating SAW propagation and its interaction with crack remains challenging. In this study, an efficient multiscale ultrasound peridynamic (PD) modeling framework is developed to address these limitations. A strategy for developing a low-scattering model with smooth SAW transmission is introduced by introducing a transition PD horizon and combining with a convergence analysis of the wavelength-to-particle-spacing ratio. Furthermore, a customizable local damage matrix mapping method is implemented, significantly enhancing modeling flexibility and computational efficiency. The proposed approach is applied to simulate SAW propagation in polysilicon, investigating the influence of transverse cracks, longitudinal cracks, and cracks with different growth stages. Numerical results clearly capture the SAW evolution under varying damage scenarios. Moreover, by extracting the Rayleigh ellipse characteristics from the surface receiving point trajectories, the influence of different types of damage on wave behavior is intuitively revealed. This work presents an accurate SAW-based tool for NDE with broad applicability to damage assessment of material surfaces.