涡流引起的钢棒磁化滞后时间理论计算

发布时间：2018-05-02 05:12

本文选题：涡流效应 + 磁化　；参考：《机械工程学报》2015年22期

【摘要】：在漏磁检测中,当检测速度增大时,漏磁场随之减小。针对这一现象,对钢棒在瞬变磁场下的磁化模型进行分析,在线圈中通入方波电流激励模拟外磁场瞬间变化的情况。通过求解谐波形式的Maxwell方程组得到单频电流激励下钢棒内磁矢量及磁场强度分布;对方波激励情形,通过Fourier变换将方波分解成谐波的叠加,计算得到各频率下的响应函数,再通过逆变换得到磁场的时域响应;计算电导率、磁导率对磁场达到稳定所需时间的影响。结果表明,在外磁场瞬间变化时,钢棒表面处的磁场几乎随外磁场同步变化,而中心处的磁场明显滞后于外磁场的变化,这一滞后效应导致了高速检测时钢棒内磁化不足,从而进一步影响了漏磁场的大小。
[Abstract]:In magnetic flux leakage detection, the magnetic flux leakage decreases when the detection speed increases. In view of this phenomenon, the magnetization model of steel bar under transient magnetic field is analyzed, and the instantaneous change of external magnetic field is simulated by the square wave current excitation in the on-line loop. By solving the Maxwell equations in harmonic form, the magnetic vector and magnetic field intensity distribution in the steel rod excited by single frequency current are obtained, and the square wave is decomposed into harmonic superposition by Fourier transform, and the response function at each frequency is calculated. The time domain response of the magnetic field is obtained by inverse transformation, and the effect of conductivity and permeability on the time required for the stability of the magnetic field is calculated. The results show that the magnetic field on the surface of the steel bar changes almost synchronously with the external magnetic field when the external magnetic field changes instantly, while the magnetic field at the center obviously lags behind the change of the external magnetic field. This hysteresis effect leads to the lack of magnetization in the steel bar at high speed detection. This further affects the magnitude of magnetic leakage.
【作者单位】：华中科技大学数字制造装备与技术国家重点实验室;
【基金】：国家自然科学基金资助项目(51275193)
【分类号】：TG115.28

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