Abstract
Magnetic flux leakage (MFL) detection is a common nondestructive detection method which is usually used to detect the surface defects of steel pipes and rails. To suppress the interference of lift-off on the detection signal of the defects in rail head surfaces, a filtering method is proposed according to the distribution characteristics of the defect leakage magnetic field (LMF) in different directions. The sensor array is used to confirm the reference signal according to the difference between the signals in x and z directions. The installation mode of the sensors is deduced according to the distribution of the defect LMF. The experimental results show that this method can effectively suppress the lift-off interference in the MFL signal of the defects in the rail head surfaces.
Highlights
Railway is an important mode of public transportation in contemporary society
Ultrasonic detection is a widely used and mature rail detection technology [3,4]. It is a convenient method for detection of the internal defects of a rail, but due to the need for a coupling agent, ultrasonic detection cannot complete noncontact detection, so the detection speed cannot be further improved, and it is difficult to detect the surface defects by ultrasound
With the development of Magnetic flux leakage (MFL) detection [8,9,10], various requirements are proposed for railway detection equipment, such as high speed, high efficiency, and high resolution, so interferences such as lift-off interference must be suppressed
Summary
Railway is an important mode of public transportation in contemporary society. With the increase in railway running mileage and speed, the risk of the rail defects affected by repeated extrusion, friction, and impact of train wheel sets becomes higher [1]. The advantages of MFL are high sensitivity, high speed, and simple operation It can detect the surface or subsurface defects [7], but the detection signal is affected by the lift-off change, the magnetic field excitation, and others. With the development of MFL detection [8,9,10], various requirements are proposed for railway detection equipment, such as high speed, high efficiency, and high resolution, so interferences such as lift-off interference must be suppressed. The interference can be suppressed by hardware such as differential circuit [11], but as the interference is affected by detection speed, the state of the rail surface, and other factors, a circuit is difficult to apply to various situations. This paper presents a method to suppress the lift-off interference in MFL detection
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