| Bogie is an important part of train operation,and its reliability directly affects the safety of train operation.Traditional damage detection methods of bogie frame usually use magnetic particle inspection,only static cracks can be detected.As a dynamic detection technology,acoustic emission can monitor the damage evolution process in real time.However,the use of acoustic emission technology to detect the damage of bogie frame is still blank in the field detection of railway,and the use of acoustic emission technology to detect the damage of bogie frame lacks theoretical research.This paper focuses on the acoustic emission technology of bogie frame,including the propagation characteristics of acoustic emission wave,the influence of shape structure on acoustic emission characteristics,the acoustic emission characteristics of frame materials,the influence of paint coating on acoustic emission positioning and the method of acoustic emission positioning.Through the above research,the feasibility of structural damage acoustic emission detection is analyzed,so as to provide acoustic emission technology in the framework.The research on damage detection provides basic theoretical support.The main contents are as follows:(1)The propagation characteristics of AE waves in plate structures were researched,including: the generation and propagation of AE waves in plate structures under lead-breaking excitation were analyzed by ABAQUS finite element simulation,and then the wave velocities and waveforms were compared and verified by simulation and lead-breaking experiments.The main conclusions are as follows: the velocity and acceleration parameters in X and Z directions of nodes can better characterize the propagation characteristics of AE waves,and the velocity values of AE spreading wave and bending wave were calculated by Z direction velocity parameters of nodes;the simulation and experiment verify that the velocity and waveform were basically the same,and the ABAQUS finite element software can be used to analyze the generation,communication and visualization process of AE waves in complex structures.(2)In order to grasp the acoustic emission characteristics of the frame S355J2 steel under tension,the acoustic emission characteristics of three typical shape structures were studied by selecting the appropriate section for the acoustic emission tensile test.Three models with different cross-section shapes were simulated by ABAQUS finite element software.The trajectory distribution,energy and wave velocity of acoustic emission wave were compared and analyzed.The structure with chamfer transition was found to be suitable for acquisition and detection of acoustic emission signal in unidirectional tension test.(3)In order to study the acoustic emission characteristics of frame S355J2 steel compared with ordinary Q235 steel,unidirectional tension tests were carried out for two kinds of materials,using acoustic emission parameter analysis method and waveform analysis method.The main conclusions are as follows: the acoustic emission characteristics of frame S355J2 steel under tension are mastered;the early warning and red warning of damage location can be realized by acoustic emission damage detection of structure.The peak frequency of S355J2 steel is similar to that of Q235 steel,and the difference of spectrum characteristics is small.The uniformity and compactness of Q355J2 material are better than that of Q235 material.(4)Sound source localization of CRH380 B frame was studied.The influence of coating on localization accuracy was analyzed by time-frequency analysis,wavelet analysis and modal identification.The main conclusions are as follows: the coating on material surface affects the localization accuracy of acoustic emission to a great extent;it is found that single-mode S1 wave is most suitable for acoustic source localization of coated frame,in which the frequency distribution of S1 wave is 250-350.MHz and wave velocity are 4 500 m/s. |
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