Study On Dynamic Stress Tracking And Load Spectrum Testing Scheme Of EMU Bogie On The Beijing-guangzhou Railway Line

With the increase of train load and running speed,the frequency range of the train on the operating line is widening.And the weight of welding bogie frame is lighter,its natural frequency will also be reduced,therefore,the low order elastic vibration may be in the range of disturbance,so that some parts of the frame produce large deformation.In addition,the stress concentration caused by the geometric mutation appears in the part of the welded joint,where is often the weak part of fatigue strength.When the bogie is running on the line for a long time,the damage of parts with higher stress and strain will accumulate gradually,and the fatigue failure will occur when the value reaches a certain value,which seriously endangers the safe operation of trains.The fatigue failure of high speed train structure is always concerned by people,In order to predict the service life of the structure,it is necessary to combine the measured load time history and the theoretical analysis of the train to compile a representative load spectrum,which can be used as the basis of structural fatigue analysis.Therefore,it is very important to obtain the true and reliable load spectrum for fatigue research of bogie frame.This paper was based on the structural strength Laboratory of Beijing JiaoTong University "the dynamic stress testing project of CRH380BL EMU' bogie",taking the CRH380BL type EMU as the research object and aiming at realizing the long-term tracking test of load spectrum,the stress measurement points on the bogie were optimized and used to calculate the load reasonably.Based on the above research objectives,the main research work and conclusions are as follows:(1)The finite element model of the bogie frame for EMU was established before the test.We use the fourth strength theory to check the static strength of the frame,and using Goodman fatigue limit diagram to check fatigue strength of frame.The results showed that the structure of the bogie frame for EMU met the requirements of static strength and fatigue strength.At the same time,we also obtained the large stress positions of frame,which were the basis for measuring fatigue dangerous position of frame.(2)Completed the layout of the stress measurement points,equipment installation and commissioning work.In the testing process,processing and analyzing data of the equipment regular collection,through the process of rain flow counting,the 16 stress spectrum of the corresponding measuring points is obtained.(3)Based on the measured data,by using the measured stress spectrum,the cumulative fatigue damage and fatigue life of the frame are calculated.According to the whole life cycle of the frame,the equivalent stress amplitude of each measuring point is calculated to check whether it meets the operational requirements,and provides the basis for the maintenance period of the EMU.It also analyzes the influence of equivalent stress of the measuring points around turning round.The results show that bogie frame for multiple units meet the operational requirements of 12 million km.One or two parts of antenna beam do not meet the operational requirements of 2 million 400 thousand km,replacing it in three repairing according to its actual life.(4)According to the loads,such as under up and down load,lateral load,longitudinal load on the bogie frame for multiple units,based on the measured stress on the line,through the simulation calibration,three kinds of load identification points are obtained,the load spectrum of three kinds of loads is established,and the correlation analysis is carried out.(5)The identification scheme of other loads on the frame is proposed,the load identification points are optimized,and the corresponding load transfer coefficient matrix is obtained,and the decoupling matrix is analyzed.The results show that the load test scheme is feasible.