Research On High Power And Low Frequency Class Ⅳ Giant Magnetostrictive Transducer

In recent years,driven by the needs of marine national defense security,resource detection and long-distance communication,the core equipment in marine engineering research and application-high-power low-frequency transducer has become a research hotspot.Giant magnetostrictive material has the advantages of high energy density,large strain amount,small sound speed and low Young’s modulus.As a transducer driving material,it can better achieve high-power and low-frequency performance indicators.The flextensional shell has the characteristics of displacement amplification and low operating frequency.Therefore,giant magnetostrictive Ⅳflextensional transducers have unique advantages in low frequency,high power,and small size.This paper focuses on the design and development of high-power and low-frequency type Ⅳ giant magnetostrictive transducers,and mainly solves three aspects: the linear working range of giant magnetostrictive rods,the structure design of transducers,and the development of transducer reliability.,the main work of the paper is as follows:(1)Focusing on the linear working range of giant magnetostrictive bars,a platform for measuring the working characteristics of giant magnetostrictive bars was designed and built,and the output of different numbers of giant magnetostrictive bars under different bias magnetic fields and prestresses was tested and analyzed.characteristic.The measurement results show that under the bias of 10 mm permanent magnet and the prestress range of 16～24MPa,the giant magnetostrictive bar has the best working properties.(2)According to the structural design requirements of giant magnetostrictive transducers,the analysis and design methods of magnetic circuit structure and mechanical structure are studied in this paper.In the design of the magnetic circuit structure,an improved radial slitting method combining long and short slits is proposed,which can effectively reduce the eddy current loss.When the input current is 15 A and the frequency of 500 Hz,compared with the uncut method,the eddy current loss is reduced proportionally.It reaches 79.7%;in terms of mechanical structure design,the finite element design method is used to optimize the shell structure parameters,and the piezoelectric-piezomagnetic comparison method is used to analyze the electrical and acoustic characteristic parameters of the designed transducer.The simulation results show that the resonant frequency of the transducer is 420 Hz,and the transmit current response is 189.5 d B.(3)A prototype of a high-power,low-frequency Ⅳ giant magnetostrictive transducer was developed.In view of the reliability and high-efficiency transduction of the transducer under strong hydrostatic pressure,a solution for mechanical decoupling and watertight potting of the transducer was proposed.Laboratory tests and lake tests of the transducer have been carried out,and the test results show that the fabricated type Ⅳ giant magnetostrictive transducer meets the design expectations and verifies the correctness of the proposed development method and process.The high-power and low-frequency type Ⅳ giant magnetostrictive transducer developed in this paper has a resonance frequency of 420 Hz and a sound source level of 204.1d B when the driving current is 15 A at 30 m underwater.