Application of Power Amplifier in High-speed Railway Track Detection

With the rapid increase of railway speed and the development of high-speed railway, the continuous increase of traffic density, load and speed has accelerated the damage of rails. During the use of rails, due to natural factors and train loads, various damages and defects are prone to occur on the surface and inside of the rails. In severe cases, it may even cause major accidents such as rail breakage and train derailment. Because regular inspection of railway rails is very important, the following two inspection methods are introduced:

Nondestructive testing technology is applied to high-speed railway rail inspection:

When using ultrasonic guided waves for non-destructive testing of rails, an excitation signal can be generated by a signal generator, and after being amplified by a power amplifier, the ultrasonic guided wave is excited at one end of the rail by a waveguide sensor. If the guided wave propagates along the undamaged rail head, rail waist and rail bottom, the group velocity and phase velocity of the guided wave are basically consistent; if the guided wave encounters an interface discontinuity during propagation, reflection, scattering and mode conversion may occur, which will produce an echo carrying local defect characteristics. By analyzing the echo signal, the location of the defect can be determined, and the echo amplitude can also be used to assess the degree of rail damage.

Electromagnetic testing is used in high-speed railway rail testing:

A relationship model is established between various factors such as cracks, stress and microstructure changes on the rail surface and at a certain depth in the sub-surface under high-speed AC excitation, and the current magnetic field and signal response, and information such as crack characteristics and stress distribution of the tested rail is obtained.

Experimental platform: sensor part, signal amplification and conditioning part power amplifier, data acquisition part, signal excitation part, signal acquisition and computer processing, and rail samples, etc.

In terms of the excitation magnetic field signal, it is planned to use excitation sources with different frequencies and waveforms according to different moving speeds, and different excitation sources are used for simulated excitation according to different moving speeds.

By detecting the distribution of the magnetic field on the straight line under pulse excitation, while identifying the defect position and characteristics, it is intended to compensate for the speed influence during high-speed inspection based on the phase and coupling relationship between the outputs of each sensor to improve the inspection rate. After signal conditioning, the output signal of the sensor array and the response signal of the induction coil are subjected to multi-channel synchronous high-speed data acquisition and transmitted to the computer for processing, so as to analyze the output signal of each sensor unit in the sensor array and the response signal of the induction coil, calculate the moving speed of the current detection system, and compensate for the moving speed and lift-off effect, finally forming an image of the defect situation and stress distribution situation of the tested rail at different depths, so as to judge and locate the defect crack.