FINITE-ELEMENT ANALYSIS OF PERIODIC AND RANDOM 2-2-PIEZOCOMPOSITE TRANSDUCERS WITH FINITE DIMENSIONS

A finite size periodic 2-2 composite transducer has been studied using finite element method, and the numerical results are verified by expe riments. The focus of this study is on the mode coupling between the t hickness resonance and pitch resonance. Such coupling effectively limi ts the pitch size of the composites preventing them being used in high frequencies. The effects of randomness is also being investigated usi ng finite element analysis. The pitch. resonance can be effectively su ppressed by introducing 50 to 80% randomness in the structure. Numeric al results also show that the decoupling of the thickness resonance an d pitch resonance can increase the electromechanical coupling coeffici ent k(t) for the thickness mode and shifts the thickness resonance fre quency.