Development of PZT piezoelements for simultaneous generation and reception of longitudinal and shear ultrasonic waves

Ultrasonic methods are often used for measurement of various non-electric quantities, for example, pressure or displacements. In this case in order to increase accuracy of measurements longitudinal L and shear SH ultrasonic waves simultaneously propagating in solids along the same path must be used. For simultaneous generation/reception of L and SH waves dual mode PZT transducers may be used, but up to now only theoretical studies are known with a little experimental confirmation. A dual mode piezoelement can be manufactured as a rotated Z-cut element from a large thick PZT block. Objective of our study was investigation of transient processes in dual mode PZT piezoelements, optimization of their geometry and development of manufacturing technology. Vibrations of rotated Z-cut disc and rectangular shape piezoelectric elements in a pulse mode were investigated by a numerical modeling using ANSYS finite elements code. The volume of the disc was meshed using the SOLID5 elements. Modeling results were verified by experiments using steel measurement bodies and a good correspondence has been obtained. At the angle θ=36° L and SH waves of similar amplitudes are excited.