Fatigue Life Analysis And Evaluation Of A-type Subway Aluminum Alloy Car Body

Due to the rapid development of China's rail transit,the frequency of subway use is increasing,and subway safety is becoming more and more important.With the increase of subway running speed,subway driving conditions become more and more complicated,road conditions are getting worse,and the probability of fatigue damage of the car body is greatly increased.Therefore,in the process of subway car body design,the problem of structural fatigue life has become the first problem to be solved.This article takes the A-type subway aluminum alloy car body as the research object,and analyzes the fatigue life of key parts of the car body.Firstly,the research on the massive meshing strategy and technology of the vehicle body is carried out.The applicability of the three-dimensional meshing method and the shell meshing method to the complex vehicle body structure is compared,and a finite element model of the vehicle body is established.Then,according to the standard EN12663: 2010 "Railway Application-Structural Requirements for Rail Car Body",the static strength check of the car body under various working conditions was performed,and a modal analysis was performed to obtain the natural frequency and mode shape of each step of the car body.Secondly,based on SIMPACK software,a multi-rigid body dynamic model of the subway system was established,and the triaxial acceleration-time history of the vehicle body under the fatigue sample line was obtained.At the same time,the vertical displacement data at the vehicle body pillow beam were measured and obtained through data processing.The vertical acceleration-time history of the vehicle body;the triaxial simulation load spectrum of the vehicle body and the vertical measured load spectrum of the vehicle body were obtained by the rain current counting method,respectively.Then,based on the IIW standard,the fatigue strength of the subway car body was initially evaluated.The fatigue life comparison results calculated from the vertical simulated load spectrum and the vertical measured load spectrum were used to verify the accuracy of the vehicle body simulated load spectrum.The fatigue life of key parts of the vehicle body is obtained more accurately by simulation of load spectrum;the influence of different influencing factors on the fatigue life of dangerous parts is analyzed.Finally,the key parts fatigue life prediction models based on BP neural network model and stepwise regression model were obtained,and the advantages and disadvantages of the two proxy models were compared.