Research On Lightweight Structure Of 160 Km/h Electric EMU

Along with the continuous development and rapid progress of Chinese social economy,the development opportunities of the rail transit industry have also increased.Energy-saving and emission-reducing design of rail vehicles has become a highly regarded direction.Through lightweight research,the car body structure can reduce costs,decrease material usage,and lessen environmental pollution on the basis of meeting performance requirements such as static strength,stiffness and fatigue strength.Therefore,the research on train lightweight is of great significance.This paper investigates the EMU body capable of reaching 160 km/h,and focuses on several key aspects of its structural performance.Firstly,a finite element model of the car body is established based on its geometric characteristics.The working condition and loading of the car body are then determined in accordance with the TB/T3550.1-2019 standard,and its static strength,equivalent torsional stiffness,and bending stiffness are subsequently calculated.To further understand the modal vibration features of the vehicle body,the modes of empty vehicle and reconditioning are analyzed.Lastly,the fatigue strength of the vehicle body is evaluated using the BS7608 standard.Building upon the static strength,stiffness,modal analysis,and fatigue strength calculations of the car body,this study delves into the research of lightweight car body structures.Given the high number of degrees of freedom in the finite element model of the vehicle body structure,optimizing its structure poses a significant challenge.To overcome this,a block local optimization technology is proposed in this paper.Firstly,the variable group is selected as the thickness of the partial plate and beam structure of the chassis,and each variable’s relative stress,displacement,and mass sensitivity are comprehensively analyzed to identify the effective design variables.With strength and stiffness as constraints and minimum mass as the optimization objective,the size of the frame variables is optimized,and the optimized results are applied to the original car body.Following the local optimization of the bottom frame,the beam-column structure of the side wall is optimized similarly,and finally,the thickness of the beam-column of the end wall and the roof part is optimized to arrive at the vehicle size optimization scheme.On the basis of size optimization,topological optimization is carried out on the longitudinal compression condition and vertical static load condition for the main bearing structure such as the car body beam and column.Due to the existence of weight reduction holes in other beam and column structures of the vehicle body,the optimization space is limited.Therefore,this paper selects the plate structure near the underframe pillow beam and traction beam as optimization variables,adopts the variable density method for topology optimization,and obtains the density distribution diagram of topological units in the underframe position.Based on the density distribution map,the shape optimization scheme is proposed,and the vehicle body mass is further reduced by adding local weight reduction holes.The optimization scheme of each step is summarized to form the final lightweight scheme of the car body and applied to the 160 km/h EMU body.The weight of the car body is reduced by 1106.02 kg,6.89% compared with the original body.The static strength,stiffness,mode and fatigue strength of the lightweight car body are checked and verified that the above indexes meet the standard requirements.In order to investigate the vibration fatigue life of the vehicle body structure under the running condition of the line,the modal structure stress method is used to predict the running fatigue life of the lightweight vehicle body.Through verification,the lightweight vehicle body meets the requirements of the relevant standards for the safe service mileage.The lightweight scheme is feasible and effective.