Strength Analysis Of Heavy-duty Rail Car Body And Structural Optimization Design Of Underframe

The car body is the main bearing parts of the vehicle system.In the course of operation,it is necessary not only to bear its own gravity,various equipment loads,longitudinal force,but also to bear the impact load between different vehicles.Therefore,in order to meet the requirements of relevant national technical standards,it is necessary to analysis the strength of Car body structure,to ensure the safe and reliable operation of the vehicle.The optimization design of the structure of the railway locomotive is mainly focused on the design of strength,stiffness and so on.For the underframe of the car body,the structure and the load is complicated,the large number of finite element units,and at the same times,there are many uncertain factors that can influence the structural strength.For example,the material’s own characteristics,manufacturing tolerances and environmental factors and so on.Therefore,in order to make the underframe with sufficient strength,and the optimization program has sufficient robustness,it’s need to consider the uncertainty of the combination of optimization design,so that the design more reliable.In this paper,the strength and modal analysis of the car body structure of the heavy-duty rail vehicle are carried out.On this basis,the underframe part of the vehicle body is optimized,and in combination of the strength of the underframe structure and the robustness of the optimization scheme to optimize the design of the underframe.The work done in this paper is as follows:(1)According to the characteristics of the structure of the heavy-duty rail car body,the finite element model of the car body is established.According to the relevant standard of the locomotive vehicle,eight kinds of working conditions and modal simulation are carried out.According to TB/T1335-1996 "Railway vehicle strength design and test identification specification",TB/T2541-2010 "internal combustion engine,electric locomotive body static strength test method",EN12663 "structure requirements of railway vehicle bodies" and TB/T25334.1-2010 " Part one:diesel locomotive body "and other related design standards on the body structure to analysis the strength of the vehicle.(2)According to the structural strength analysis results of the vehicle body,ANSYS is used to optimize the design of the underframe structure of the car body by using Isight optimization platform.In order to improve the optimization efficiency and reduce the computational cost,the mathematical model of the undercarriage is established by using the experimental design method instead of the finite element model.Taking the maximum stress level on the body frame as the objective function,under the constraint condition of the strength requirement of other working conditions,the optimization design of the undercarriage structure is carried out and the optimization scheme of the underframe is obtained.(3)The reliability analysis of the optimized underframe design scheme is carried out.From the point of view of the robustness of the optimization scheme,the Sigma level analysis method is used to calculate the Sigma level of the design of variables are idealized.The results show that it’s not meet the requirements of engineering manufacturing,it’s need to do the reliability optimization design.Therefore,a combinatorial optimization design is proposed to improve the underframe structure strength and the robustness of the optimization scheme.(4)In the process of combinatorial optimization,a reasonable combination optimization strategy is formulated.Different types of optimization algorithms and evaluation methods were selected in different optimization stages.The three different types of algorithms of The adaptive simulated annealing method,Hooke-Jeeves,NLPQL and Second Order Reliability Method were used together.So as to get the heavy-duty rail car body’s underframe optimization design of take the manufacturing tolerances and other uncertain factors into account.The results of the proposed scheme are verified by simulation and the results are analyzed.In this paper,the combination of optimization design method take the uncertainties like the manufacturing process of manufacturing tolerances,the use of the environment,the material and so on into account.It provides a basis for the design and manufacture of the locomotive body,and provides a new idea for the design and analysis of the body structure of the internal combustion locomotive body structure and even all the rail vehicles,and improves the efficiency of the body design.