Research On Evaluation Method Of Rail Welded Joint Irregularity Based On Vehicle Axle Box Acceleration

The track regularity has an important influence on the running quality of the train.With the Big Speed Increase of China's Trains and the development of high-speed railway,The raising speed railway has much more stringent requirements of track regularity.Through welding,the structural diseases such as seam and staggering of common joints are eliminated,and the ride comfort has been greatly improved.However,affected by the welding process,material defects,uneven wear and other factors,the weld may be uneven.According to the current "maintenance regulation",the surface quality and straightness of the on-site welding joints of the main line rail shall be inspected not less than once a year;for the welded joints with low collapse and slight injury,the inspection shall not be less than once a quarter.How to find out the defects such as weld collapse in time plays an important role in line maintenance.The comprehensive inspection train checks the line once every 10-15 days,and the detection frequency is much higher than that of manual inspection.If the rail inspection system data can be used to judge the weld irregularity,it means that there is a more rapid method to detect weld defects,which is of great significance to improve the quality of line equipment and promote the railway infrastructure maintenance from "periodic maintenance" to "condition based maintenance".At present,the space sampling frequency of track inspection system is0.25m/point,and the range of weld irregularity is only ten to tens of millimeters.The current track inspection system can not directly identify the weld irregularity.In this paper,through the statistical analysis of the types,mechanism and treatment measures of welding joint defects,and collecting the dynamic data of the defective parts of the welded joints,the time-frequency characteristics of the vehicle dynamic response data at welded joints is obtained by using the time-frequency analysis to analyze the vehicle dynamic response data under different working conditions.Based on the measured weld straightness data,the finite element simulation model of welded joint is established.Using the verified model,the influence of fastener stiffness,driving speed,joint wavelength,joint wave depth and other factors are simulated,and the influencing factors and rules of welded joint are studied.Based on the results of time-frequency analysis and finite element simulation,the resonance demodulation method is used toanalyze and calculate the vehicle dynamic response data,and the method to evaluate the welded joints state is obtained.According to the evaluation results,the effectiveness of the evaluation method to evaluate the welded joints state is verified.