Research On Underwater Acoustic Transducer Based On Giant Magnetostrictive Material

With the development of national military and ocean strategy, underwater acousticcommunication technology has entered into a new era. As an important part ofelectroacoustic converting system, the performance of underwater acoustic transducerdirectly determine the merits of underwater acoustic communication system. GiantMagnetostrictive Material (GMM) is a new type of intelligent material, it has theadvantages of large magnetostriction, high energy density, high electromechanicalcoupling coefficient, high energy conversion efficiency and fast response, and it is verysuitable for low frequency, broadband and high power underwater acoustic transducer.This paper focus on the performance requirements of transducer, a double excitationtransducer was designed based on giant magnetostrictive material, and the structureoptimization of transducer was studied. The specific research contents of this paperinclude the following points.(1) This paper expounds the background and significance of giant magnetostrictivetransducer, the performance index and the bandwidth requirement of underwateracoustic transducer were introduced in detail, the factor which affects the performanceof transducer and the methods to realize low frequency and broadband characteristics oftransducer were analyzed, the current research status of relevant study in our countryand abroad was summarized from transducer structure and material, and thedevelopment trend of underwater acoustic transducer was also summarized.(2) The mathematical basis of using finite element method to analysis giantmagnetostrictive transducer was introduced, the piezoelectric-piezomagnetic analogymethod was used to solve electromechanical coupling of giant magnetostrictivetransduce, and the principle of piezoelectric-piezomagnetic analogy method wasdeducted in detail, the general process of finite element analysis of transducer byANSYS software was introduced briefly.(3) This paper has detail introduced the ideal and method of designing a lowfrequency and broadband transducer; the performance of cylinder giant magnetostrictiverod with different size was analyzed, and the dimensions of the giant magnetostrictiverod was finally determined; different structure of front mass was designed, modelanalysis was carried out on the respective transducer, the line chart of the first and second model frequency of each transducer was obtained and compared, the structure ofhead mass was determined, then according to the simulation, different size of headmass’s influences on the properties of transducer was compared, optimization of thestructure of head mass was taken; the structure of dish-type middle mass was designedbased on the system’s lumped parameter model, simulation analysis was taken ondifferent materials of middle mass; the preload device and the bias magnetic field wasdesigned through briefly comparing and analysis, and the overall structure of thedouble-excitation longitudinal vibration transducer based on giant magnetostrictivematerial was finally established.(4) The finite element models of double-excitation longitudinal vibrationtransducer both in the air and under water were established, and their harmonic responseanalysis was taken, impedance curve and transmitting current response both in the airand under water were obtained, so were the radiating sound field and directivity curveof transducer under water, The simulation results indicates that the transducer workingwith the characteristics of low frequency and bandwidth, and also good directivity.