An Analytical and Numerical Investigation of Rayleigh Wave Scattering by a Surface Defect in Orthotropic Media

This study presents a reciprocity-based analytical model for Rayleigh wave scattering by localized surface defects in orthotropic elastic half-spaces. Closed-form expressions for forward and backward scattering amplitudes are derived directly from the elastodynamic reciprocity theorem, linking the scattered field to defect geometry and excitation frequency without numerical discretization. Finite-element comparisons confirmed the accuracy and robustness of the proposed approach across a wide parameter range. The results show that scattering is primarily governed by the defect’s width-to-depth ratio: broader and shallower cavities yield smoother and more stable responses, whereas deeper defects cause slightly stronger discrepancies. The proposed compact formulation offers a clear physical interpretation of wave–defect interaction and practical guidance for Nondestructive Evaluation (NDE) and Structural Health Monitoring (SHM) in anisotropic and orthotropic media.