Load Spectrum Study On Intercity EMU Bogie Frame

During the last decade,the development of high-speed EMU in China is remarkable.Although four vertical and four horizontal frames have been basically formed,the design and test of the domestic bogie frame still rely on international standards,and the load spectrum of the bogie frame for operation conditions in our country has not been established.With high-speed EMU technology to flourish,there is an urgent need for the bogie frame load spectrum research.In the field of domestic and foreign research load spectrum,the guidance of the bogie frame bench load spectrum is very rare.The reason is mainly due to the complexity of loading condition of bogie frame.With respect to the cantilever structure on the plane six-component systems and critical components of the wing,the bogie frame is a large frame parts,and complex stress state lead after a rain-flow statistics lost the timing relationship between load and stress.Then it is difficult to obtain consistent load spectrum based on damage.Aiming intercity EMU bogie frame,load spectra were studied to establish a line measured load and dynamic stress load spectrum based model.For intercity EMU Bogie Frame which is frame structure member,theory about its load spectrum methods is studied.Based on direct independent load testing technology,its discrete load spectrum is established.The main contents and innovation are described as follows:(1)For intercity EMU bogie frame such a complex structural elements,a test methodology supporting damage consistent load spectrum including critical loads and damage information is establish firstly in the world.The test methodology comprises two parts.One is for all load structure bear were established based on calibration direct Measurement method decoupled.The other is the development of injury consistent load spectrum necessary load-stress(damage)transfer coefficient calibration method.(2)On the basis of comparing different typical time-domain load identification methods,the applicability of the method to the load identification of bogie frame is studied.A load-stress transfer and the actual relationship between the stress responses are obtained using this study.The research confirmed that the bogie frame time-domain load identification problem identification using improved load truncated singular value decomposition(ITSVD)obtained the results obtained more closely than other methods Found load value.At the same time applicable conditions of the method is analysized from the load-stress transfer coefficient point of view.(3)For the establishment of damage consistent load spectrum needed for solving optimization problems,based on the Monte Carlo method,through comparative analysis system,it is confirmed that the use of Latin Hypercube Sampling Quasi Monte Carlo method in computational efficiency and adaptability of obvious advantages.To establish a damage consistent load spectrum applicable effective optimization algorithm is determined.(4)For the establishment of this complex problem bogie frame structure load spectrum to the measured load,measured stress test and calibration of load-stress transfer relationship-based,by analyzing the phase relationship between the measured load,respectively amplitude and varying phase constant amplitude varying phase strategy,by using of Latin Hypercube sampling Quasi Monte Carlo optimization solutions,based on consistency injury criteria,the methodology for the preparation of the bogie frame damage consistent load spectrum is established.The verification results of the measured data of the bogie frame of the inter city EMU show that the established load spectrum can be secured to the frame fatigue critical to achieve full coverage,so that the use of the fatigue test the load spectrum can be sure that the framework has sufficient under operating conditions the fatigue reliability.Aiming the establishment of intercity EMU Bogie Frame load spectrum,the load calibration method and the time domain independent load decoupling method is established.The morbid based transfer matrix inversion domain load calculation method is studied.Finally,the complete load spectrum mathematical model is presented.This systematic approach has a strong engineering application value and theoretical significance.