Selection Of Dynamic Stress Measuring Points For Establishment Of Load Spectrum

With the rapid development of China's high-speed railway,safe and comfortable ride environment has become a general concern of the community.As the most important sub-system of high-speed trains,the fatigue strength of the bogie is critical to the safety of high-speed rail.Therefore,the analysis of fatigue strength of the bogie to extend the service life of high-speed trains,expand the scale of train production,improve passenger comfort and economic benefits have a great impact.In order to be able to analyze the fatigue strength of the bogie,we need to effectively simulate the loading conditions of the load-bearing structures of the high-speed trains under the actual line running conditions,and the load time history that characterizes the load conditions can well reflect the The load time course is the load spectrum.And the load spectrum in line with the actual operating conditions of the line can be used as the theoretical basis for the design of the fatigue strength of the high-speed train,so its authenticity is very important.The establishment of a load spectrum conforming to the actual line operation requires a lot of stress information,but due to the space constraints of the equipment compartment,it is necessary to optimize the long-term tracking of the bogie stress points.Based on the structural strength laboratory of China Jiaotong University,this paper takes the Chinese standard EMU as the research object,and establishes the long-term service tracking and load spectrum,and optimizes the stress measurement points.Based on this,the main research work and related conclusions are as follows:(1)The calibration of the bogie is carried out.The relationship between the load and the stress is obtained.The calibration error leads to the nonuniformity before and after loading.Finally,the load stress transfer coefficient is obtained by linear fitting.(2)The stress information is obtained by the line,and the combination of the measuring points for long-term tracking is selected based on the equivalent stress and the second equivalent stress in the symmetrical region and the stress concentration region.(3)According to the load information,twelve discrete load spectra are established.Due to the loss of time correlation,the load spectrum is required to check the damage consistency.The calibration of the load spectrum by genetic algorithm shows that the calibration of the load spectrum is in accordance with the actual requirements.(4)The stress transfer coefficient of the load can be obtained by the calibration test.The sensitivity of the stress measurement point to the twelve kinds of loads can be obtained.According to the sensitivity degree and the secondary equivalent stress value of the subregion,the stress measurement points are established to meet the long service planning and the load spectrum combination.According to the combination of measuring points,we find out the twelve kinds of loads,but the existence of the disequilibrium matrix leads to the difference between the load and the actual load.Finally,the accurate twelve kinds of discrete loads are obtained by the regularization method.Through the damage consistency and correlation verification,it shows that the selected measuring points meet the long service planning and the establishment of load spectrum.The research results of this paper provide the basis for the long-term tracking and the load spectrum of the Chinese standard EMU bogie,and provide the data support for the long-term fatigue strength tracking test of the bogie.