Fatigue Analysis And Structural Optimization Of Subway Carbody

Aluminum alloy materials are widely used in subway carbody due to their advantages of light weight,corrosion resistance and high strength.As an important bearing part of the rail vehicle structure,the carbody must bear not only static loads but also dynamic alternating loads during operation,so the safety of the carbody structure should be paid attention to.In this paper,a certain type of aluminum alloy subway carbody is taken as the research object,the static and fatigue strength of the carbody are analyzed,and the structure optimization is carried out on this basis.The main research contents are as follows:(1)Hyper Mesh software is used to model the carbody with finite element,and 8 static working conditions are imposed on the model according to the BS EN12663-2010 standard,and the calculation is carried out in combination with ANSYS software.On this basis,the modal,stiffness and static strength are checked according to relevant standards,and the results meet the requirements of the standard.(2)According to the BS EN12663-2010 standard,the carbody is subjected to fatigue conditions,and the fatigue life of the dangerous welds are predicted based on the structural stress method of the ASME-2015 standard and the nominal stress method of the IIW-2008 standard,and the cumulative damage ratio is calculated.Comparing and analyzing the calculation results of the two methods,it is found that the fatigue strength of the carbody meets the standard requirements,and the prediction results of the structural stress method are more accurate and conservative.(3)Local improvements are made to parts that are problematic in static strength and fatigue strength analysis.For the parts with safety margins in the static strength analysis,size optimization is carried out based on continuous variables and discrete variables with different iteration steps,and the most suitable size optimization scheme is selected by comparing the size optimization results.Topological optimization is carried out on the position where the stress concentration still exists after the size optimization,and the key parts are thickened according to the density nephogram.After the optimization,the stress value is obviously reduced.Finally,the modal,stiffness and static strength of the optimized carbody are re-checked to judge the feasibility of structural optimization.