analytical and numerical study of pre-stress effect in piezoelectric sandwich type ultrasonic transducer

In this paper, the effect of pre-stress condition on the resonance frequency of the transducer is studied by using numerical and analytical methods. to compare the obtained results, two sandwich-type transducers with nominal frequency of 25 khz and 30 khz are considered. experimental determination of pre-stress value in transducer is described and measured. then resonance frequency of transducers in the presence of pre-stress is determined by impedance analyser. numerical analysis is conducted by modelling three-dimensional transducer in details at abaqus software. the resonance frequency is determined with and without pre-stress. the fe results show that by applying pre-stress on the transducers, the resonance frequency of transducers decreased. furthermore, the fe results are very close to experimental results. furthermore, a systematic analytical solution is presented based on one-dimensional wave propagation. the resultant displacement for each sub-section of the transducer is calculated and then all of them are assembled and solved by considering the continuity conditions of displacement and force components. it is found that pre-load condition that is produced by central bolt reduces resonance frequency of the transducer. the obtained analytical results provide fast and reliable model for predicting resonance frequency of transducer.