Impedance analysis of acoustic vibration element using giant magnetorestrictive material

Giant magnetoresistive material offers great magnetostriction over 1000 p.p.m., making it well-suited to acoustic transducers for acoustic ocean tomography systems. The acoustic vibration element using giant magnetostrictive material (AVEG) is a transducer is a drive unit developed for this purpose. The authors discuss the following three points through measurement of AVEG impedance: measurement of mechanical resonance frequency based on electrical impedance characteristics; calculation of equivalent circuit constraints based on analysis of motional impedance characteristics; and comparison between calculated and measured values for the displacement-current sensitivity of the vibrating terminal. Around the resonance frequency, the displacement-current sensitivity values measured with a laser Doppler vibrometer almost exactly matched the values calculated by using the equivalent circuit constants. This indicates that mechanical vibration can be estimated from the impedance characteristics.<>