| In order to meet better the operational needs of Chinese high-speed railway,to unify the model of the rail vehicle and for the purpose of catering to the "go-out"strategy of Chinese railway as well as the foundation of the self-owned brand,China Railway Corporation has developed the Chinese standardized EMU.The bogie frame has been tracked and tested during a long period for the highly reliable assessment of the bogie frame and the upgrade of the fatigue design standard of the bogie frame.The testing equipment was placed in the equipment compartment and due to the limit of space,the number of testing channels available for the dynamic stress measurement is about 40 except for the channels occupied by the load and line identification.The aim of this study is to select the combination of dynamic stress measuring points which could meet the reliability evaluation and the establishment of load spectrum under the condition of high limits.In this paper,the Chinese standard EMU model was studied.First,the calibration test was carried out in the laboratory,obtaining the transmission relationship between the loads and the stresses at dynamic stress measuring points.The line test was carried out in Daxi Passenger Dedicated Line,obtaining the actual load signals based on the calibration factors and the associated data processing method.By studying the load characteristics through the combination of the GPS velocity signal and the gyro signal,the acceleration/deceleration,braking,straight curve,entry and exit conditions can be identified according to the characteristics of the relevant load signal.The effects of empty/overload and different velocity classes on the load were studied taking the equivalent load as parameter.It turns out that the effect of empty/overload on the equivalent load is limited while and the effect of velocity is large.When the velocity is within 300km/h?350km/h,and the equivalent load increases with the increase of velocity.So the load signal under 350km/h speed level was used to establish the damage consistent load spectrum.By studying the damage contribution of each load to the dynamic stress measuring point,the measuring points were divided into two group,one of which were the measurement points with high correlation of single loads.The correlation between these stress measuring points and their corresponding load signals was analyzed,based on which the measurement points with high correlation coefficient were selected to solve the single loads.The other part were the measuring points with a high correlation with multiple loads.The stress measuring points contributing to only two or three kinds of load coupling damage were selected.The corresponding loads could thus be obtained by inverse decoupling calculation.According to the linear regression relationship,the reverse load amplitudes were corrected so that it could replace the measured load signals.The bogie was divided into 10 typical regions,the representative fatigue reliability measuring points were selected in each region after comparing the equivalent stresses at each points.The measuring points for damage consistency calibration were selected by comparing the damage caused by the actual tested load spectrum,the actual damage and the damage caused by the calibrated load spectrum.Through the above research,under the condition of long-term service tracking test,the dynamic stress measurement points which are suitable for the establishment of load spectrum and reliability evaluation are selected,this paper also provide the basis and reference for establishing the fatigue design standard and long-term tracking test scheme which accords with the application conditions of the high-speed railway in our country. |
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