Optimization Design On Welded Frame For Intercity Multiple Units

As an important component of the vehicle,the bogie has made important contributions in improving running speed,curve passing capacity,dynamic performance and comfortableness,and the difference of its specific structure has great influence on vehicle operation.Frame as a support frame of the bogie,its role is not only to support the body in the running process of the vehicle,it also transfers all kinds of longitudinal force,transverse force and vertical force between wheel and vehicle body,thus,the safety operation of the railway vehicledirectly affected by the reliability of the bogie frame.Therefore,it is necessary to carry out finite element analysis and structural optimization design for bogie frame.In this paper,the welded frame of intercity EMU bogie is taken as the research object.First of all,the actual operating conditions is applied to the frame,and analysis of intercity EMU bogie is performed to evaluate the strength and stiffness by using the ANSYS software.Then,the fatigue strength of the bogie frame was evaluated based on the master S-N curve method.The fatigue load of the whole frame includes vertical dynamic load,vertical quasi static load,transverse quasi-static load and torsional load,and is loaded according to the standard of UIC515-4 in three stages.According to the key welding seam of the frame,the FE-weld software is used to calculate the equivalent structural stress and to evaluate the weld life with the master S-N curve method.According to the analysis results of the static strength and fatigue life of the bogie frame,topology optimization and anti-fatigue size optimization design of the frame longeron are performed by OptiStruct software.First,3D solid grid is used to fill internal longeron,and the minimum volume of the frame longeron is taken as the objective,and the density of the elements in the design area is taken as the design variable,a topology optimization model which is constrained by static strength and stiffness is established.The optimization model is solved and the new structure of the longeron is obtained.On the basis of the new topology structure,using Isight software,the minimum total mass of the longeron is taken as the objective and the thickness of the longeron as the design variable,a size optimization model,with static strength,stiffness and fatigue damage constraints is constructed and solved by combining the Kriging surrogate model with MIGA.After the topology optimization and size optimization design,the mass is reduced finally by 20.6%.According to the analysis results of the static strength and fatigue life of the bogie frame,topology optimization design of internal stiffened panel of side frame is performed by OptiStruct software,and anti-fatigue size optimization design for the side frame structure is carrird out.On the basis of the original stiffened panel structure 3 piece of stiffener plate is added on each side,and the minimum strain energy of the stiffener plate is taken as the objective,and the density of the elements in the design area is taken as the design variable,a topology optimization model which is constrained by static strength and volume is established,and solving the new structure of stiffened panel.For new side frame structure,considering the frame fatigue load,braking load,anti roll load and shock load,using Isight software,an anti-fatigue lightweight model with static strength and fatigue cumulative damage constraints is constructed and solved by combining the Kriging surrogate model with MIGA.the mass is reduced finally by 16%.Through topology optimization and size optimization,the mass of longeron and side frame is reduced in the case of strength,stiffness and fatigue strength meet the requirments,realize the effective lightweight design of welding structure.