Application Of Brake Disc Defects Inspection Of High-speed Train By Using Electromagnetic Tomography

With the rapid development of high-speed railway,the mileage and speed of high-speed railway have been greatly improved.In order to ensure the safety and reliable operation of trains,higher standards have been put forward for various performance indicators,especially for the stability of the braking system As the core component of the braking system,the brake disc is inevitably defective in production process,and long-term extrusion and friction are more likely to lead to potential safety hazards,which seriously threaten the safety of human life and property.In view of the disadvantages of complex operation and low detection accuracy of the current brake disc defect detection technology,the electromagnetic tomography(EMT)used in this paper is a new nondestructive testing technology based on the principle of electromagnetic induction.The measured object field is stimulated and detected by multiple coils,and the detected data can be reconstructed by the algorithm,and then the location,shape,size and other distribution information of defects can be displayed visually,which is of great significance to the detection of brake disc defects.Here are the main content:(1)Based on the research of the structure characteristics of high-speed train brake discs,the common defect types and crack propagation modes of brake discs are analyzed.Combined with the basic principle of EMT,this paper innovatively designed the sensor coil array structure suitable for high-speed train brake disc defect detection.The three-dimensional model and sensor structure model of the brake disc defect were established by the electromagnetic field simulation software Maxwell.(2)The EMT model of brake disc defect is simulated and analyzed,the specific contents are as follows:analyze the influence of different excitation currents and different excitation frequencies on the internal magnetic induction intensity of the brake disc,determine the appropriate number of finite element splitting units,and analyze the sensitive field data obtained by the automatic simulation program.In-depth study of the imaging principles of various image reconstruction algorithms,including linear back projection algorithm,Tikhonov regularization algorithm,Landweber iterative algorithm and Split Bregman algorithm,compared and analyzed the effects of different algorithms on the reconstructed images.The simulation verified the feasibility of electromagnetic tomography in the detection of brake disc defects in high-speed trains,and the Split Bregman algorithm has better reconstruction quality for brake disc defects.(3)On the basis of simulation and verification,designed the excitation generation and recovery detection module,signal conditioning module,sensor module,image reconstruction module,etc.,and built the EMT hardware system for brake disc defect detection.Combined the upper computer and the lower computer software system to complete the functions of Ethernet communication,document loading,data storage and view display.Through data acquisition and imaging reconstruction experiments on brake disc defects,compared the quality of reconstructed image in different algorithms by different evaluation indexes.The experimental results show that the electromagnetic tomography method is suitable for the detection of the brake disc defects.