基于Halbach阵列电磁超声纵波换能器优化设计

Optimum Design of Electromagnetic Acoustic Longitudinal Wave Transducer Based on Halbach Array

传统电磁超声纵波换能器换能效率低,水平偏置磁场弱且无法被充分利用,导致回波信号幅值小,影响检测结果的准确性。该文应用一种新型纵波换能器,其永磁体磁极方向按照Halbach阵列排布,能够显著增强水平磁场。为提高其回波幅值,利用有限元软件进行建模,分别采用正交试验和均匀试验方法,在考虑线圈匝数的前提下,对换能器参数进行优化。仿真结果表明,降低导线间距、导线宽度和导线高度,将永磁体提离距离固定在合适范围内,均可以增强回波信号;设置合适的激励电流频率,能够使得声衰减和回波幅值处于适中水平,有利于检测。实验结果表明,优化后的换能器相较于优化前回波幅值提高了83%。

The traditional electromagnetic acoustic longitudinal wave transducers possess low energy conversion efficiency as well as weak horizontal bias magnetic field which cannot be fully utilized, resulting in a modest echo signal and affecting the accuracy of the detection. In this paper, a new type of longitudinal wave transducer is applied, whose permanent magnet poles are arranged according to the Halbach array, which can significantly intensify the horizontal magnetic field. Aiming to improve the echo signal, the finite element software was used, and the orthogonal test and uniform test methods were operated respectively. The parameters of the transducer were optimized with considering the number of coil turns. The simulation results illustrate that reducing the spacing, width,and height of the wire can enhance the echo signal, maintaining the lift-off distance of the permanent magnet within a proper range can also be so. Make the sound attenuation and voltage amplitude at a appropriate level is conducive to detection by setting a proper excitation frequency. The experimental results demonstrate that the echo amplitude of the optimized transducer is 83 % higher than that of the previous transducer.