Simulation and measurement of structural scattering in shear wave angle beam transducers

Structural scattering, a key acoustic feature of shear wave angle beam transducers, generates echoes when elastic waves propagate and reflect within the transducer’s wedge structure. This study adopted structural scattering to analyze the transducer’s structural parameters and established a numerical model via COMSOL to characterize its dynamic acoustic field. Primary structural scattering is defined as Longitudinal wave Structure Scattering I (LSSI), while secondary scattering covers L-wave Structure Scattering II (LSSII) and S-wave Structure Scattering I (SSSI). The effects of critical parameters including wedge back angle, front angle, front wedge surface shape, and matching backing layer on structural scattering were systematically explored. Results reveal the primary scattering echo amplitude peaks at the wedge back angle of the first critical angle, with two weak-scattering intervals (29°–34° and 38°–41°) at larger angles. The maximum primary scattering amplitude occurs at a 50° front angle, followed by two weak-scattering ranges (60°–80° and 100°–115°). Optimal low scattering is achieved with 3/4λ-deep sawtooth grooves and uniform backing layers. Prototyped transducer reduces structural scattering by over 90% versus commercial counterparts, delivering a 9.5 dB signal-to-noise ratio for Φ1 weld defects. This work provides a foundation for optimized shear wave angle beam transducer design.