Finite Element Solutions for Magnetic Field Problems in Terfenol-D Transducers

Abstract

An appropriate magnetic design helps ensure that the Terfenol-D (Terbium- Dysprosium-Iron alloy) rods in giant magnetostrictive transducers have the perfect magnetostriction ability. To determine the optimum Terfenol-D rod state, a segmented stack configuration comprised by the Terfenol-D rods and NdFeB (neodymium-iron-boron) permanent magnets is presented. The bias magnetic field distributions simulated through the finite element method indicate that the segmented stack configuration is one effective way to produce the desired bias magnetic field. Particularly for long stacks, establishing a majority of domain to satisfy the desired bias magnetic field range is feasible. On the other hand, the eddy current losses of Terfenol-D rods are also the crucial to their magnetostriction ability. To reduce eddy current losses, the configuration with digital slots in the Terfenol-D rods is presented. The induced eddy currents and the losses are estimated. The simulations reveal that the digital slots configuration decreases the eddy current losses by 78.5% compared to the same size Terfenol-D rod with only a hole. A Terfenol-D transducer prototype has been manufactured using a Terfenol-D rod with a mechanical prestress of about 10 MPa and a bias magnetic field of about 42 kA/m. Its maximum transmitting current response of 185.4 dB at 3.75 kHz indicates its practicability for application as an underwater projector.

An All-Fiber Optical Sensor Combined with FBG and CFBG-FP for Attitude Estimation

“…As a result, the pulling force of the mass ball on the FBG is constantly under axial extension to avoid excessive pulling power, which prevents the FBG from being fatigued. Terfenol-D [ 23 ] is the magnetostrictive material, which possesses superior magnetic characteristics and energy conversion efficiency than pure nickel (Ni) and piezoelectric ceramics (PZT).…”

Thermal Analysis of Terfenol-D Rods with Different Structures

“…He [ 15 ] proposed a method to calculate the number of radial slits of the Terfenol-D rod, which reduces the eddy current loss and saves on cost. Teng et al [ 16 ] developed a Terfenol-D transducer; digital slots were set on the Terfenol-D rod to reduce the eddy current loss. Huang et al [ 17 ] cut Terfenol-D into different square rings, studied the changes in its magnetic energy losses under different frequencies and magnetic flux density amplitudes, and analyzed the influence of material anisotropy on the losses.…”

Study on high frequency magnetic energy loss of Terfenol-D rods with different structures

“…Tao et al (2012) investigated the influence of the eddy current loss on material vibration output characteristics and impedance characteristics between the laminated structure and the monolithic structure, and the results showed that the Terfenol-D rod with laminated structure had smaller eddy current loss and higher eddy current cut-off frequency. Teng and Li (2020) presented digital slots on a Terfenol-D rod to reduce eddy current loss, the simulations reveal that the configuration of the slots decreases the eddy current losses by 78.5% compared to the untreated rod. At present, there are many studies on eddy current loss and eddy current distribution of rods, few studies on the hysteresis loss and its distribution of the rods.…”