The Direct Superposition Method to Predict Wood Anomalies in Acoustic Diffraction Spectra

摘要

Scholte - Stoneley waves (SSTW) exist at the interface between a solid and a liquid and are important for NDT of near surface defects over long ranges. The frequencies at which SSTW can be generated on a grating through diffraction using normally incident plane waves are calculated using a new direct superposition method (DSM) that superposes evanescent plane waves directly on the corrugations. The calculated frequencies agree very well with miniature scale experiments reported by Claeys et al, measuring reflection spectra when a corrugated stainless steel/water interface is struck by longitudinal ultrasound in the liquid, as well as with large scale experiments on the sea bottom reported by Chamuel and Brooke, measuring Bragg frequencies. The results are better than those obtained from the mode conversion theory (MCT).