Research On Low Frequency Broadband Flexural Transducer Of Giant Magnetostrictive Material

Vibrating sound sources,including those driven by piezoelectric materials and giant magnetostrictive materials,are not only used in the research of underwater acoustic engineering,such as low-frequency active detection,underwater acoustic communication and ocean sound propagation research,but also widely used Ocean exploration,geological exploration and geoacoustic detection in the oil and gas industry.However,many sound sources currently in use are constrained by frequency,bandwidth,and power,thus limiting their use in ocean exploration.The demand for low-frequency,wide-band,high-power vibrating ocean sound sources has always existed,and low-frequency high-power transducers are also an important direction for underwater acoustic engineering research.The research focuses on how to achieve low-frequency broadband high-power acoustic emission.The transducer uses a double IV type flexure shell structure,instead of the traditional active material PZT crystal stack or rare earth rod as the driving vibrator,so that the resonance frequency of the transducer is effectively reduced;two vibration modes of the same phase and reverse phase of the double shell structure The state realizes the broadband transmission of the transducer in the low frequency band;the two-stage shell displacement amplification structure is used to realize the two-stage amplification of the displacement of the driving vibrator.The active driving material uses the rare earth giant magnetostrictive material Terfenol-D with a large strain coefficient.By setting a reasonable prestressed operating point and bias magnetic field conditions,the rare earth giant magnetostrictive material can be fully utilized to achieve a large sound source.Power acoustic emission.The finite element software COMSOL was used for simulation analysis and structural optimization of the low-frequency broadband transducer,including the optimization of the transducer housing structure,the optimization of the bias magnetic circuit of the rare earth material,and the analysis of the setting of the prestress.According to the optimization results,the structural size of the transducer is determined,the parts are processed,and finally the prototype of the transducer is produced for underwater testing.The actual test results of the transducer prototype show that the in-phase resonance frequency of the transducer is 320 Hz,the anti-phase resonance frequency is 500 Hz,the operating bandwidth is 260 Hz,the maximum transmission current response is 181 d B,and the in-band fluctuation is 10 d B.The final test results show that the transducer driven by giant magnetostrictive materials expands the emission bandwidth in the low frequency band and has the characteristics of highpower emission.