偏置磁场对磁致伸缩纵向导波换能器效能的影响研究

为提高磁致伸缩导波换能器的激励效能，本文研究了磁场结构参数对偏置磁场空间分布的影响。基于COMSOL有限元仿真平台，对磁致伸缩换能器磁场分布特性进行了数值计算，研究了磁路结构形式、磁路和永磁铁数量等对偏置磁场分布的影响，最后优化出适合纵向导波激励的磁场结构参数。检测实验结果表明，随着偏置磁场磁路数量的增加，偏置磁场强度增大，磁场径向均匀性更好，磁致伸缩换能器的效能也相应提高;在相同磁路数量的条件下，永磁体数量的改变对换能器效能影响较小，四磁路偏置磁场最优;轭铁中部增加永磁铁后的磁路结构的偏置磁场的轴向均匀性更高，其激励效能更好。

Study of the Effect of Bias Magnetic Field on the Efficiency of Magnetostrictive-based Longitudinal Guided Wave Transducer

To improve the excitation efficiency of magnetostrictive guided wave transducer, the influence of magnetic field structure parameters on the spatial distribution of bias magnetic field was studied. Based on the finite element COMSOL simulation platform, the magnetic field distribution characteristics of magnetostrictive transducer were numerically calculated; the effect of the magnetic circuit structure and the number of permanent magnet and magnetic circuit on the distribution of bias magnetic field was investigated. Finally, the optimal magnetic field structure parameters suitable for longitudinal guided wave excitation were obtained. Experimental results show that the static magnetic field intensity increases with the increasing of number of magnetic circuits, and the magnetic field uniformity along radical direction is improved. Therefore the excitation efficiency of magnetostrictive transducer is improved. Under the condition of same number of magnetic circuit, the number of permanent magnet has a little influence on the performance of magnetostrictive transducer. When the number of magnetic circuit is four, the magnetic field performance is optimal. By adding permanent magnet in the middle of yoke iron, the uniformity of magnetic field along the axial direction is improved, which can improve the excitation efficiency of magnetostrictive transducer.