Research On Scanning Flexible Array Eddy Current Non-destructive Flaw Detection Of Bogie Frame

In recent years,with the rapid development of China's high-speed railway technology,the working conditions of various parts of the train even worse,the situation is more complex,higher performance requirements.In the course of high-speed train operation,bogie frame inevitably appeared in all kinds of subtle cracks,which will seriously threaten the operation of the vehicle safety.At home and abroad,most of the disintegration of the bogie overhaul,in the routine maintenance inspection of the EMU(first and second level maintenance),the detection method of the bogie is taken by visual observation with strong light flashlight.The method has large detection error and interference.The bogie is under the vehicle body and the detection space is narrow and the surface of the frame remains with paint or dust.Based on the above problem,this paper carries out bogie scanning from the aspects of determination of scanning flexible array nondestructive flaw detection method,detection coil magnetic field modeling and simulation analysis,flexible array eddy current sensor and detection system design and production,Study on Eddy Current Nondestructive Flaw Detector of Flexible Array.Nondestructive testing of eddy current has more advantages than other five non-destructive testing methods.Combined with the characteristics of the crack distribution of the bogie frame,the new flexible eddy current non-destructive testing method is adopted.The design of flexible eddy current sensor is the key of this paper.In this paper,a flexible eddy current array sensor composed of a single large excitation coil and four small detection coils is designed.Based on the electromagnetic field theory,the mathematical model of the flexible eddy current array element is established,the formulas for calculating the magnetic field strength in the radial and axial directions of the coil are derived,the relationship between the magnetic field strength of the coil and the parameters such as current,coil gap,inner diameter and so on was analyzed by simulation analysis.Design of flexible array eddy current nondestructive testing system.The ICL8038 waveform generator module is used as the excitation generation module;To FPA1000 series power amplifier module as a power amplifier circuit;Using 4-way solid-state relay module as a multi-time-sharing scan switch on the eddy current array detection signal time-division multiplexing,both to simplify the follow-up circuit and eliminate the interference between the array coil;The output of the weak detection signal is pre-amplified with OP07;And then through the valid value A / D conversion circuit input to the computer to determine whether the detected signal exists crack.Finally,the computer simulation system is set up as the core platform,the validity of the previous chapter theory,the detection effect of the detection system and the related parameters are studied,the experiment object adopts the simulation frame material and the corner shape steel,the flexible eddy current array sensor is placed on the three-axis gantry mechanical slide,and the gantry mechanical slide is programmed to realize the scanning detection.The experimental results are in good agreement with the simulation results,Which laid a foundation for the future theoretical research and experimental research.