Analysis of magnetic interferences in ultrasonic magnetostrictive patch transducers

Magnetostrictive patch transducers are operated by the magnetostrictive principle, the coupling phenomenon between magnetic and elastic fields. When multiple magnetostrictive patch transducers are used in close proximity as for ultrasonic imaging of a damaged plate, the magnetic fields used to drive transducers can interfere with each other, resulting in distortion in the ultrasonic waves transmitted and measured by the transducers. While a number of recent papers have investigated the development and applications of the transducers, no study has been reported on the analysis of the effects of the magnetic interference. In this paper, we analyze the effects of both the dynamic actuating and the static biasing magnetic fields of a magnetostrictive patch transducer on the occurrence of undesired cross-talk signals in a receiving transducer and also on the radiation pattern of an adjacent transmitting transducer. The analysis is performed both experimentally and semi-analytically and a guideline is suggested to minimize the undesirable interference. While the specific transducer used in this study is an omni-directional Lamb wave magnetostrictive patch transducer, the findings from this study can be utilized for any type of magnetostrictive patch transducers.