Optimization of SAW-type Surface Wave Ultrasonic Sensors for Ultrasonic SHM
Résumé
Surface acoustic waves (SAW) are particularly suited for effectively monitoring and characterizing a structure’s surfaces (condition of the surface, coating, thin layer, micro-cracks, etc.), and in some cases it is necessary to permanently keep the sensors on the structures to enable continuous monitoring. This article focuses on the optimization of SAW-type interdigital sensors (or IDT sensors for InterDigital Transducer) because they can largely address this issue. Initially, the ability of piezoelectric materials (lead zirconate titanate [PZT] and Niobate de lithium) to generate SAW is studied by modeling. Then a design of an IDT sensor is defined and optimized for the generation of SAW on a substrate. Parameters such as electrode’s periodicity, thickness of piezoelectric plate, and type of contact between the plate and the substrate, are studied. Finally, experimental results are compared with those obtained by modeling.