Enhancement of the mode purity of shear horizontal mode of a thickness-shear transducer through design changes
Abstract
In ultrasonic guided waves, arrays of thickness-shear piezoelectric transducers
are often used to generate Lamb waves in plates and longitudinal/torsional
waves in pipes. Although the ultrasonic output of the transducer is well known
both numerically and experimentally, few results are available in the
literature regarding the influence of geometry, electrode layout and materials
on the ultrasonic output of the transducer: in particular, the influence of
those parameters on the mode purity of the generated shear horizontal mode in
plates require further investigation. Numerical simulations with finite element
modelling (Comsol Multiphysics) have been conducted on a thickness-shear
transducer on a plate to understand the influence of these parameters on the
mode purity of the transducer. Experimental validation with a new prototype has
been conducted to confirm the numerical results and compare them with different
configurations. Moreover, the physical behaviour of the transducer is analysed
by understanding the interaction between its surface and the waveguide. The
desired physical behaviour of the transducer is also represented through an
objective function and the various numerical and experimental results are
compared to the objective function.
