Research on a kind of Longitudinal Transducer Driven by Ni-Mn-Ga Alloys

Ni-Mn-Ga alloys, a kind of magnetic shape memory alloys (MSMAs), can exhibit maximum expansion strains of 6% when an external magnetic field applied, and have a fast response time, high power density, which making MSMAbased actuators kHz capable. For this reason, we presented a kind of low-frequency, small-sized longitudinal transducer driven by Ni-Mn-Ga in this paper and fabricated a prototype. The finite element method was used to design and analyze the magnetic induction intensity distribution in the drive magnetic circuit. Meanwhile, the displacement of the radiating surface in the air and the sound source level in the water of the transducer were measured. According to the results, the radiating surface displacement of the transducer can reach up to 0.12 mm in the air, and the sound source level in the water exceeded 130 dB. The strain test result of the Ni-Mn-Ga transducer is much higher than that of piezoelectric ceramics or Terfenol-D with the same dimensions. Therefore, it can be realized by using Ni-Mn-Ga alloys to design a low-frequency transducer with a small size.