Teng Duo, Li Yatian
School of Marine Science and Technology, Northwestern Polytechnical University, Xi'an 710072, China.
National Key Laboratory for Underwater Information Processing and Control, Xi'an 710072, China.
Sensors (Basel). 2020 May 15;20(10):2808. doi: 10.3390/s20102808.
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.
合适的磁路设计有助于确保超磁致伸缩换能器中的Terfenol-D（铽-镝-铁合金）棒具有理想的磁致伸缩能力。为了确定最佳的Terfenol-D棒状态，提出了一种由Terfenol-D棒和钕铁硼（钕-铁-硼）永磁体组成的分段堆叠结构。通过有限元方法模拟的偏置磁场分布表明，分段堆叠结构是产生所需偏置磁场的一种有效方法。特别是对于长堆叠，建立大部分磁畴以满足所需的偏置磁场范围是可行的。另一方面，Terfenol-D棒的涡流损耗对其磁致伸缩能力也至关重要。为了降低涡流损耗，提出了在Terfenol-D棒中设置数字槽的结构。估算了感应涡流和损耗。模拟结果表明，与仅带有一个孔的相同尺寸的Terfenol-D棒相比，数字槽结构可使涡流损耗降低78.5%。已经制造了一个Terfenol-D换能器原型，该原型使用了具有约10 MPa机械预应力和约42 kA/m偏置磁场的Terfenol-D棒。其在3.75 kHz时的最大发射电流响应为185.4 dB，表明其作为水下发射器应用的实用性。
