Magnetic flux leakage (MFL) detection is widely used for non-destructive testing of rails, pipelines and storage tanks. The leakage magnetic field (LMF) of a defect, especially a small defect, is usually weak. To find small defects on the rail surface, here a ferrite is added in an LMF sensor to reduce the reluctance to increase the magnetic intensity above the defects. The effects of the cross-sectional shape and size of a ferrite are studied by simulation and experiments, and the suitable dimensions for signal enhancement are found. To suppress the interference caused by the variation of the lift-off distance, two Hall sensors are introduced and a differential circuit is designed for signal post-processing. From the finite element simulation and experiments, it is shown that the MFL signals with a ferrite are significantly increased.

中文翻译：

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用于磁道表面缺陷检测的漏磁信号增强方法

磁通量泄漏（MFL）检测被广泛用于铁路，管道和储罐的无损检测。缺陷，特别是小的缺陷的漏磁场（LMF）通常较弱。为了在轨道表面上发现小的缺陷，这里在LMF传感器中添加了铁氧体，以减少磁阻，以增加缺陷上方的磁强度。通过仿真和实验研究了铁氧体截面形状和尺寸的影响，并找到了适合信号增强的尺寸。为了抑制由提离距离的变化引起的干扰，引入了两个霍尔传感器，并设计了一个差分电路用于信号后处理。从有限元模拟和实验中可以看出，带有铁氧体的MFL信号显着增加。