Carbody Load Inversion And Fatigue Prediction Of Monorail Vehicle

In recent years,the development of rail transit has diversified,and monorail vehicles have become a new mode of urban rail transit.After the vehicle operation mileage reaches the advanced repair,the performance status of the vehicle components,such as fatigue failure,needs to be further considered.Therefore,the analysis of the residual life span of vehicle body vibration is the focus of research in the field of rail transit.Based on the actual test data of a single track vehicle,the acceleration and strain data are extracted from the main bearing position of the car body,a method of load inversion based on vehicle system dynamics is proposed.The linear model is used in the air spring,the load of the center pin and the car hook is used to influence factors,and the measured acceleration and dynamic stress data of the line are calculated respectively,and the load of the air spring,the center pin and the car hook are respectively reversed.The load time history process on the vehicle body is obtained respectively.In this paper,the dynamic model of monorail vehicle was established in UM Simulation software,and the load data was obtained by simulation,and the accuracy of the inversion process was verified by comparing with the model inversion results.In ANSYS,the finite element model of vehicle body was established,and the unconstrained modal analysis was conducted to obtain the first 40 mode vibration frequency and vibration mode.By applying the unit sinusoidal load excitation,sweep the frequency in 0-50 hz and obtain the observation point harmonic response under the external load,namely the frequency domain correction coefficient.The Fourier transform is used to transform the load signal into frequency domain,and the frequency domain correction based on harmonic response is carried out.By means of quasi-static analysis,the time domain correction coefficient is obtained,and the time domain correction of the load signal in the inverse transform time domain is obtained,and the load time course of the final correction is obtained,It provides important support for vibration fatigue analysis of vehicle body.The dynamic stress of each observation point is obtained by the fatigue analysis of the vehicle.On the basis of FKM welding structure evaluation criteria,to stress the rain flow count and obtain the average stress,according to the standard for fatigue analysis,obtains each observation point fatigue damage calculation value,through the use of degrees and damage transformation relations,according to the maximum damage prediction residual life vehicle.In this paper,the evaluation of fatigue life is carried out through the combination of time domain and frequency domain,and more accurate simulation is made to analyze the vibration fatigue of vehicle body,and provides theoretical support for vehicle application maintenance.