钢绞线中激励纵向模态的磁致伸缩型激励及接收器的选型

Development of Magnetostrictive Transmitter and Receiver for Exciting Ultrasonic Longitudinal Guided Waves in Steel Strands

为在钢绞线中有效激励和接收纵向模态超声导波,对磁致伸缩型传感器的敏感元件螺线管的结构进行了优化,并进行了试验验证。首先,对利用磁致伸缩效应在钢绞线中激励及接收纵向模态超声导波的方法进行了分析,选用频率160kHz的L(0,1)纵向模态作为用于公称直径17.8mm的7芯钢绞线检测的导波。设计制作了激励该模态专用磁致伸缩型传感器。经过对结构和绕向不同的螺线管进行比较后,选取3段式螺线管作为磁致伸缩型传感器的敏感元件。为证实其检测能力,利用该传感器对钢绞线外围钢丝上的人工缺陷进行了检测,通过得到的实验信号可以很好确定缺陷位置。本文的研究为今后进一步检测钢绞线的健康状况奠定了基础。

For the excitation and reception of ultrasonic longitudinal guided waves in steel strands efficiently, the configuration of spiral tube as the sensing element of magnetostrictive transducer is optimized, Furthermore, the experiments are achieved to verify the optimization of the transducers. Excitation and reception method of the longitudinal modes in the steel strands based on magnetostrictive effect is analyzed theoretically. L(0,1) mode at 160kHz is chosen for the inspection of seven-wire steel strands with a 17.80mm nominal diameter. Magnetostrictive transducer is designed and implemented for excitation and reception of this guided wave mode. By comparison with others’ different lengths and winding directions, three-section spiral tube with reverse normal winding directions is suitable for being the sensing element of developed magnetostrictive transducer. For validating the inspection ability of this type of transducers, they are used for artificial defect detection in one of helical wires of steel strand. Received experimental signals show that the defect can be detected and located well, which provides a basis for health monitoring of steel strands by ultrasonic guided wave technique.