Abstract:
Backed transducers are widely used in acoustics and ultrasonic imaging. The finite element method (FEM) has been employed to characterize these transducers. But generally, the backing has not been considered. In fact, to model backed transducers by the FEM, the main drawback is generally the large size of the numerical problem. The aim of this paper is to show how the backing mesh can be quite limited. As will be shown in this paper, this is possible by reducing the thickness of backing T[inf B] and by scaling up the tangent of the phase angle (tan (delta)) keeping the product T[inf B] tan (delta) constant. Experimental results concerning a lithium niobate transducer bar are compared to the numerical one obtained by the FEM. Moreover, it will be shown that when an additional layer is placed between the backing and the piezoelectric material, the transducer bandwidth decreases.