摘要
针对钢管非接触式扭转导波检测的需求,基于Wiedemann效应设计了一种新型导波传感器,该传感器由永磁铁、回折线圈和屏蔽层组成.首先,采用ANSYS仿真软件研究了钢管中静态偏置磁场分布,并分析了传感器的工作原理,通过实验验证了传感器在钢管中激励和接收扭转导波的可行性.然后,分析了检测信号中噪声信号的产生原因,利用铜皮作为屏蔽层对回折线圈轴向段激励产生的周向动态磁场进行屏蔽,提高了检测信号的信噪比.接着,通过实验研究了传感器的频率特性,结果表明传感器的最佳激励频率与回折线圈的设计频率一致.最后,将传感器应用于钢管缺陷检测,结果表明该传感器能够识别出横截面积损失3%的周向刻槽缺陷.
Based on Wiedemann effect, a guided wave sensor was designed to meet the requirement of the non-contact torsional guided wave detection for steel pipes.The sensor consisted of permanent magnets,meander coils and shielding layers.First,the static bias magnetic field in the steel pipe was studied by ANSYS,and the working principle of the sensor was presented.The torsional guided wave excited and received by the sensor was verified through experiments. Then, the causes of the noise signal were analyzed, and some copper strips were used to shield the circumferential dynamic magnetic field generated by the axial part of meander coils to improve the signal-to-noise ratio of the detection signal.The frequency characteristics of the sensor were studied by experiments,and the optimal excitation frequency was consistent with the design frequency of the meander coil.Finally,the sensor was used to detect defects of steel pipes.Experimental results show that the sensor can detect the circumferential notch defect with a cross-sectional area loss of 3%.
引文
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