Design, fabrication and finite element modeling of a new wagon wheel flextensional transducer

Cymbal and moonie transducers exhibit greatly improved performance characteristics compared to a simple piezoelectric disk. This behavior is mainly due to the amplifying nature of the endcaps employed in these devices. Although these endcaps improve the displacement by amplifying the small lateral displacement associated with the d 31 coefficient to a large axial displacement, this mechanism generates a very high tangential stress in the caps, which leads to a reduction in the efficiency of this transformation. In this paper, we report on a new end cap design, called the wagon wheel flextensional transducer, in which some of the clamping boundary conditions are eased by removing the metal in areas of high stress concentration. In the wagon wheel design, the tangential stresses are further reduced, thereby improving the efficiency of the transformation of the lateral to axial displacement, and consequently increasing the displacement response of the devices. Structural and impedance analyses of the devices were carried out using the commercially available software codes, ABAQUS and ATILA, respectively. Results reported for finite element modeling and experimental characterization suggest that these devices exhibit improved displacement characteristics compared to cymbal devices with similar dimensions.