Multifrequency piezoelectric composites: one-dimensional modeling

It has been proposed that multifrequency piezoelectric composites increase the bandwidth of the standard piezocomposite configurations. The geometrica l approach consists of the use of piezoelectric elements with different wid th-to-thickness ratios in the same polymer matrix. A one-dimensional modeli ng of these new structures can be made, performing an homogenization of the overall composite parameters by linking Onoe's coupling mode theory with s tandard one-dimensional composite models. A strong approximation must be in troduced to define a 'virtual' c(13) elastic constant. The model accurately predicts the transducer behaviour of 2-2 standard piezocomposites with pie zoceramic elements having a width-to-thickness ratio w:t between 0 and 0.8. In the case of double composites, the coupling between the different reson ators, explained by a physical model, is made empirically introducing a mut ual induction coefficient between the inductances of their respective equiv alent circuits. The computed and experimental results show the usefulness o f the double design. (C) 1999 Elsevier Science B.V. All rights reserved.