磁致伸缩纵向导波传感器中偏置磁场的优化设计

摘要

Bias magnetic field is one of the key factors of longitudinal modes guided wave sensor based on magnetostriction. The optimal bias magnetic field is based on the material and excition condition. In order to keep the bias magnet performed in the optmized region, the magnetic field should be adjustable, and the detection signal should be of high SNR and little interference by the bias magnetic field. The usual bias magnetic providers are solenoid and permenant magnet. However,solenoid introduces electromagnetic interference, permennant magnet lacks flexibility. Then an adjustable bias magnetic equipment is promoted and designed. Finite element analysis is introduced to analyze the adjusting effects of the equipment, and result is welcomed. The equipment is used in longitudinal modes guided wave sensor. Results show that it is effective to adjust detection signal, and have the character of high SNR, easy use. This equipment is suitable in longitudinal modes guided wave sensor based on magnetostrictive effection.%偏置磁场大小是磁致伸缩纵向导波传感器设计的关键参数之一,最佳偏置磁场的选择受到材料和激励条件的影响,故要求导波检测系统中偏置磁场可调节性好.目前使用的偏置磁场有两种,其中螺线管线圈产生的磁场信号干扰大,信噪比低,永磁体提供的磁场可调节性不佳.为此,提出一种偏置磁场可以调节的结构方案,并通过该方案研制了一种可以调节的偏置磁场结构.基于建立的数学模型,利用有限元方法验证该结构可以有效调节偏置磁场,应用该结构到纵向磁致伸缩传感器中,结果显示该结构可以有效调节检测信号的幅值,同时,该结构具有信噪比高、使用方便的特点,适合应用于磁致伸缩纵向导波的无损检测.