Simultaneous generation of longitudinal and shear bulk ultrasonic waves in solids

The ability to generate acoustic longitudinal and shear bulk waves in solid materials using a single transducer is a suitable feature required in several devices and systems involving ultrasonic waves. The problem addressed here is that of the, possibly wideband, multimode buffer delay line, usable, for example, in non-destructive evaluation applications. The solution considered for this purpose is to use rotated, Y -cut, single-layer or two-layer transducers. The theory pertinent to this kind of transducer is briefly recalled and the results of the numerical analysis using two different delay line materials and three different piezoelectric materials are reported in detail. One experimental realization is also described.