Modelling techniques for 1-3 composite transducers
A selection of novel modelling techniques are presented for predicting the behaviour of a thickness mode composite piezoelectric transducer comprising an array of ceramic pillars embedded in a polymer matrix. Finite element analysis is employed to establish the vibrational and electromechanical characteristics of an arbitrary composite structure. Thereafter, the equivalent thickness mode transducer parameters are employed in a modified transducer model to establish the impedance, transmission and reception characteristics. A novel algorithm for calculating the acoustic pressure profile, resulting from an arbitrarily excited, rectangular aperture is employed to determine the field structure of the composite transducer. This algorithm is incorporated into an array model capable of predicting the field characteristics of steered and focused arrays. Theoretical and practical results, for composite, sliced and monolithic ceramic arrays are compared. Finally, low frequency, stacked composite structures are considered. A range of novel characteristics are obtained by using, to full advantage, the versatility of composite materials. It is believed that these modelling techniques, which have been verified experimentally, offer considerable insight into composite transducer behaviour and are conducive to effective, computer based, design.