Dynamic Characteristics And Applications Of Rare Earth Gaint Magnetostrictive Transducer

Rare earth gaint magnetostrictive transducer is a device which changes electromagnetic energy into mechanical energy or sound energy. It has high mechanical and electrical conversion efficient. As a sound source in nondestructive testing, gaint magnetostrictive transducer has advantages on repetition and easy to multiple signal acquisition comparing with the hammer source. Compared with piezoelectric transducer, higher energy is excitated, so it is suitable for acoustic nondestructive testing massive components quality in large projects. The drive capacity, response character and energy conversion efficiency are affected by the dynamic performances of gaint magnetostrictive transducer.In this paper, acoustic nondestructive testing, acoustic source, magnetostrictive materials, and gaint magnetostrictive transducer were reviewed firstly. Then the magnetic field characteristics and strain distribution of gaint magnetostrictive transducer were analyzed. The transfer function dynamic model of transducer was created, and the structural parameters over the dynamic characteristics of gaint magnetostrictive transducer were studied. Finally, the transducer developed was used in the CT detection of acoustic waves, and the quality of concrete was evaluated. The main contents and results contained in the following:(1) The magnetic field and strain distribution of giant magnetostrictive rods were studied about different AC drive frequency by using ANSYS electromagnetic field element method. The results showed when the input AC frequency increased, the uniformity of axial magnetic field was increased, while the uniformity of radial magnetic field was reduced, and geometric distribution of the magnetostrictive strain was changed significantly.(2) The axial direction transfer function dynamic model of gaint magnetostrictive transducer was established using Kirchhoff law, energy conservation and so on. Structural parameters on the dynamic performance impact of gaint magnetostrictive transducer were studied by using Matlab. The results showed that a single increase such as rod radius r, length l, plate spring stiffness Kl, the load quality MF, would improve the dynamic characteristics of gaint magnetostrictive transducer. To achieve excellent dynamic performance of gaint magnetostrictive transducer, the value of structural parameters must be taken into account. (3) The transducer developed was used in the CT detection of acoustic waves, and the quality of concrete was evaluated. The results showed when the gaint magnetostrictive transducer was used as vibration source, the distance of wave acoustic was propagated farther, it had better data repeatability and high efficiency. it is suitable for acoustic nondestructive testing of massive components in large projects.Through the research, the magnetic field characteristics, strain distribution and structure parameters to the dynamic behavior of gaint magnetostrictive transducer were obtained. It had advantages in CT detection of acoustic engineering. The results may serve as useful guidelines for the gaint magnetostrictive transducer design and project utilization.