Experimental and numerical analysis of a transducer for the generation of guided waves

Dry-coupled thickness-shear transducers represent one of the most common ways to excite guided waves for the inspection of tubular and plate-like structures. Although already established in industry, some features of these transducers need to be studied, i.e. the uniformity of vibration, the modes excitability and the transmission of ultrasonic energy into the inspected structure. In particular, due to the dispersive behaviour of guided waves and the mode coupling these transducers require a precise characterization to guarantee a uniform in-plane vibration. A numerical and experimental characterization of the assembly has been carried out to assess the influence of the elements of the assembly into the uniformity of vibration. The outcome of the results in terms of mode-shape, displacement pattern and resonance frequencies is discussed to predict useful design changes to enhance the ultrasonic performance of these transducers.