Research On Load Identification Method Of Metro Vehicle Frame Based On Vibration Acceleration

As an important tool of urban rail transportation,the subway is facing the opportunity of rapid development in the context of rapid economic development.Based on the perspective of ensuring the safety of vehicle operation,it is very important to use tests to obtain various loads,stresses and wheel-rail contact forces during normal vehicle operation to establish a complete fatigue design system.At present,the widely used strain measurement load identification method has a long preparatory period and very cumbersome steps.Therefore,a load identification method based on vibration acceleration is considered.Through analysis,the transfer relationship between acceleration and load in time,frequency domain and spectrum is established.The reasonable prediction model is obtained,which provides a simpler and faster method for load identification of bogie frame.The main research contents of this paper are as follows:(1)The rigid-flexible coupling dynamics model of a certain type of urban rail transit vehicle was established,and the load and vibration acceleration of the subway vehicle system were obtained by numerical method.The correlation analysis of different statistical parameters of frame load and vibration acceleration obtained by simulation is carried out from the perspective of time and frequency domain,and the correlation between them is established,which lays a theoretical foundation for experimental research The layout scheme of vibration acceleration measuring points of Beijing Metro Line 4 was compiled,and the actual line tests of bogie load vibration acceleration and structural dynamic stress were carried out.The measured data of bogie load and vibration acceleration were obtained and processed.(2)The time-domain correlation analysis of load and vibration acceleration was carried out,and the prediction regression equation of load and acceleration with higher correlation coefficient was given and verified.The results show that the main body load equivalent value has the highest correlation with the corresponding frame acceleration,followed by the air spring acceleration correlation,and the axle box acceleration correlation is the lowest.In the local load,the motor load equivalent value has the highest correlation with its corresponding acceleration,and the gearbox load is second,which is highly correlated.The longitudinal equivalent load is basically irrelevant to the traction rod longitudinal acceleration root mean square.(3)The frequency domain correlation analysis of load and vibration acceleration was carried out.The results show that the vertical load of motor,gearbox load,rolling load and torsional load are similar to their corresponding accelerations in terms of the law of power change.Ignoring the influence of the bogie natural vibration frequency in the low frequency range of 0～5Hz on the load,The predictive regression equations of four types of loads and accelerations in the frequency domain are given,and transfer functions are given for several types of loads and accelerations with low coherence.(4)The measured load spectrum and acceleration spectrum are compiled,the amplitude and frequency analysis method of the load and acceleration under the same spectrum is proposed,and the prediction range of the amplitude and frequency ratio of the two kinds of signals is given and verified.The results show the amplitude ratio between the main load and the vibration acceleration at the end of the side beam of the frame is the best,followed by the frame acceleration at the empty spring position,and the axle box acceleration is the weakest In the local load,the ratio of the motor load and gearbox load to the due vibration acceleration is stable,and the ratio of the longitudinal load to the longitudinal acceleration of the frame fluctuates greatly The results of frequency ratio analysis show that the ratio of the main load to the end acceleration of the frame side beam has a good regularity.For the local load,the ratio of the gearbox load to the acceleration in frequency is the most stable.(5)A method to predict the frequency and amplitude of local load by using the acceleration of axle box and frame is proposed.The results show that it is reasonable to use the frame acceleration to predict the amplitude of the local load.In terms of frequency prediction,the ratio between the acceleration of the frame and the axle box and the load of the gear box is relatively stable.