Study On The Lightweight Of Metro Car Body Using Superelement Technology

With the continuous progress of urbanization, the problem of urban traffic jams has become particularly prominent, and the demand for urban rail transit is also greatly improved. Under the background of such research, the lightweight scheme meets the requirement for the strength and stiffness of the car body is put forward. By reducing the weight of the vehicle body, the manufacturing cost is reduced, the vibration and noise are reduced, and the service life of the vehicle and the line is effectively prolonged.First, introducing the advanced analysis of finite element-the theory of super element method, which is also known as static condensation. And comparing the calculations between super element method and the conventional method by two examples from both the theory resolution and the finite element solution. Coming to the conclusion that the results are reliable and credibility in both two aspects. The way of the establishment, invocation and extension of the super element in the ANSYS platform and the notices in the process of use are introduced in the paper. Then, a finite element model of the car body is established and divided into 9 super elements. According to the relevant standard, the paper analyses the strength and stiffness of the car body in 5 representative static strength conditions and the free vibration under curb weight. Extending the super element results to the overall car body and choose 9 nodes arbitrarily as the test points from the super elements. Comparing the super element method and conventional method of the test points stress to verify the reliability of the calculation results.In consideration of the existing commonly used optimization software, OptiStruct cannot be used in both static strength and modal at the same time. So, the paper introduces static stiffness and analyses the stiffness contribution of each super element from the perspective of the static stiffness sensitivity. Through the analysis of the contribution rate of each part by the 5 static strength conditions, it can be known that the traction beam and end beam have the greatest influence on the stiffness of the car body. The conclusion can provide reference for the choice of design variables during the optimization and choose the logical optimization model. Finally, checking the car body for both static strength and modal,which are meeting standard requirements. Optimization results show that the weight of the steel structure reduces to 6395kg from 7389kg,which is reduced by 13.45% and the lightweight effect is obvious.In this paper, the super element method is introduced into the lightweight analysis of the car body, and the static stiffness sensitivity of the element is analyzed according to the characteristics of the independence of each component in the complete car body. It is effectively to lighten the car body on the basis of choosing the reasonable optimization variable by sensitivity analysis.