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为了实现对钢绞线的主动健康监测,采用安装在结构外表面上的磁致伸缩传感器激励和接收高阶纵向超声导波,优化各种参数以用于缺陷的识别和评估。实验选取经Hanning窗调制的正弦脉冲信号在7芯钢绞线中激励中心频率0.86MHz的高阶纵向超声导波L(0,2)模态,用于在两根钢绞线外围钢丝和中心钢丝中人工缺陷的检测。实验分析了L(0,2)模态对不同钢丝中的缺陷敏感程度,并进一步研究了缺陷深度和激励信号周期数对接收到的导波信号幅度的影响。实验结果表明,利用磁致伸缩传感器激励频率0.86MHz的L(0,2)模态可以用于钢绞线中的缺陷检测,对钢绞线外围钢丝的检测能力优于中心钢丝,并且缺陷回波的幅度可实现对缺陷大小的表征。同时,激励信号周期数的优化对高阶纵向超声导波用于钢绞线的缺陷检测显得十分重要。
In order to achieve the active health monitoring of the strand, a magnetostrictive sensor installed on the outer surface of the structure is used to excite and receive the high-order longitudinal ultrasonic guided waves and optimize various parameters for defect identification and assessment. The sine wave pulse signal modulated by Hanning window is selected as the experiment. The L (0,2) mode of high-order longitudinal ultrasonic guided wave of center frequency of 0.86MHz is excited in a 7-core steel strand, Detection of artificial defects in steel wire. The sensitivity of L (0,2) mode to different defects in different steel wires was analyzed experimentally, and the effect of defect depth and the number of excitation signal cycles on the received guided-wave signal amplitude was further studied. The experimental results show that L (0,2) modal with magnetostrictive sensor excitation frequency of 0.86MHz can be used for defect detection in strand, the detection ability of the strand around the strand is better than that of the center wire, and the defect back The magnitude of the wave enables the characterization of the size of the defect. At the same time, the optimization of the number of excitation signals is very important for the detection of high-order longitudinal ultrasonic guided waves for the detection of strand defects.