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.
Highlights
Transducers are devices that convert electrical energy into acoustical energy or vice versa [1].The energy conversion, known as transduction, can be accomplished through various physical processes, e.g., electrostatic, magnetostatic, electrostriction, magnetostriction, piezoelectricity, etc. [2].Transducers utilize special physical effects, appropriate vibration systems, and indispensable accessory components to achieve the transduction
Piezoelectric transducers and magnetostrictive transducers have the advantages of outstanding mechanoacoustical performance, reliable configurations, and convenient operation [3,4,5,6]
We focus on the Terfenol-D rods, comprise the magnetic circuit
Summary
Transducers are devices that convert electrical energy into acoustical energy or vice versa [1]. Piezoelectric transducers and magnetostrictive transducers have the advantages of outstanding mechanoacoustical performance, reliable configurations, and convenient operation [3,4,5,6] These types of transducers are widely used in detection, prospecting, medical, and underwater acoustic applications [7]. Many studies have discussed design and analysis methods, focusing on the electroacoustic characteristics of Terfenol-D transducers. Such implementations presuppose that the properties of Terfenol-D are unchangeable. In 2020, Huang et al developed the magnetoelastic dynamic strain model for Terfenol-D transducers, which considered eddy current losses [24] These previous studies provide insight into the design or analysis of Terfenol-D transducers from mechanical, magnetic, electrical, and thermal perspectives, respectively. This paper discusses the magnetic field problem in a Terfenol-D transducer, addressing both the effective configuration to produce the appropriate bias magnetic field within the Terfenol-D rods, and the feasible to reduce the eddy current losses of Terfenol-D rods
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