| With the rapid development of the subway,the safety problems brought about by the continuous lightening of trains and the increasingly complex track conditions have become increasingly prominent,and the subway bogie frame frequently suffers fatigue damage.In order to study the cause of frame crack failure and prolong the service life of the frame,this paper takes a certain line of the Beijing subway as the research object,carries out the dynamic stress and dynamic load test of the frame in the operating environment,and carries out the fatigue strength evaluation.Therefore,the influence of frame resonance,the causes of resonance induction and the resonance transfer characteristics are analyzed.The main research contents are as follows:(1)Complete the dynamic stress and dynamic load test of the framework under the operating environment;the Miner linear accumulation method is used to evaluate the fatigue strength,the result is that it is difficult to meet the fatigue strength requirements of multiple regional measuring points;from the time domain waveform analysis,the stress signals have beat vibration,from the frequency domain waveform analysis stress and load signals have dominant frequencies,so it is judged that the frame may resonate and accelerate fatigue damage during operation.(2)The natural vibration characteristics of the frame are obtained using different methods.Use finite element simulation to solve the natural frequency and mode shape of the frame;use the random decrement method to identify the damping ratio through the test signal,and use the Poly MAX method to identify the natural frequency and damping ratio through the test signal;compare different methods to obtain results,analyze the causes of errors and determine the parameters used.The resonance of the frame during operation is determined by comparing the bandpass phase of the beam with the mode shape.(3)Analyze the influence of frame resonance and the cause of resonance induction.The resonance frequency band is calculated by the half-power method,and the proportion of resonance damage is calculated in different regions.The result is that the second and third order resonance damage accounts for the largest proportion;the proportion of resonance damage between stations is calculated,and the result is that the curve between stations is larger than that between straight stations.By analyzing the dynamic stress characteristics,the reasons for the resonance of the overall structure frame,including rail corrugation,wheel polygons,rail gap impact and motor rotation frequency,and the resonance conditions of the frame caused by various reasons are analyzed.(4)Through the method of combining simulation calculation and analysis of load characteristics,the relationship between frame resonance and vertical load transfer is analyzed.The influence of the vertical load of the frame on its fatigue damage-prone region is analyzed through the harmonic response;the beam deformation of the frame under the measured load is analyzed through the transient dynamics,and the reason for the resonance is analyzed by comparing with the modal mode shape,which may act on the frame through the analysis;By analyzing the influence of line conditions and operating speed on vertical loads,it is further determined which loads act on the frame through the cause of resonance.62 Figures,13 Tables,89 References. |
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