Study On The Key Technology Of The High-speed Train Carbody

The China high-speed railway has gained rapid development, the four longitudinal and four horizontal passenger special lines have been initially built, and many series of high-speed trains have been researched and developed with the train speed of 200km/h-400km/h. The train body, which is the core bearing component of the high-speed train, faces complex service environment and intense impact loads, which have obvious influence on the running safety, comfortability, environment and economy of the high-speed train. In accordance with enough strength and stiffness, good vibration and fatigue characteristic, the design of the high-speed train body should improve the aerodynamic characteristics of the high-speed train, reduce the weight of the high-speed train, and provide protection for the passengers under severe shock condition. Therefore, the key technology for the aerodynamic design, passive safety design and lightweight design will be studied in the present paper. The main research works are as follows:(1) The numerical computation and reduced scale model test methods for the aerodynamic performance research of the high-speed train were constructed. The influence of each factor for the numerical computation on the computation results of aerodynamic performance of the high-speed train was studied and their influence pattern was obtained. The recommended value of each factor (such as boundary condition, turbulent model, reduced scale, incoming velocity) for the numerical computation of the aerodynamic performance of the high-speed train was proposed. The influence of each factor for the reduced scale model test on the simulation test results of aerodynamic performance of the high-speed train was studied, and the recommended value of each factor (such as reduced scale, Reynolds number, line condition, similarity criterion) for the reduced scale model test of the aerodynamic performance of the high-speed train was proposed.(2) The refinement aerodynamic design method of the high-speed train body was established. To address the problems caused by the increasing of train body height and the change of cross-sectional shape for the uniform cross section of the high-speed train, the influence of the main design variables (such as the train body cross section, slenderness ratio, diversion trench) and the surface smooth schemes of train body roof on the aerodynamic performance of the high-speed train were studied. The three dimensional parametric model for the streamlined head was established based on the free deformation method and sample surface method. The response surface models for the aerodynamic drag force and aeroacoustics of the high-speed train were constructed by the Kriging surrogate model, and the streamlined head scheme of the high-speed train with optimal aerodynamic performance was obtained by the multi-objective adaptive genetic algorithm. As for the three key areas of paragraph, bogie and windshield, the optimal surface smooth design schemes were determined by the structural surface smooth design. The aerodynamic performance for the design schemes of the high-speed train body was optimal, which was verified by the reduced scale model test, whole train aerodynamic computation and full scale line test.(3) Collaborative design method of multi-stage energy-absorbing system for high-speed train was established and an engineering plan was formed. Meanwhile, a rigid-flexible coupling dynamic analysis model was constructed for three-dimensional high-speed train impact and the fast solution for rigid-flexible coupling multi-body system was established. A series of parameters, such as impact force, velocity, deceleration, duration and energy absorption of each car in the impact process were obtained. Different designs were carried out according to the energy distribution plan, including collaborative design of multi-stage energy-absorbing system for full covered high-speed train, optimal design for crashworthiness of main energy-absorbing system, auto-damage design for high-speed train head and overload design for cowcatcher. Also, component tests were conducted to verify these designs. All mentioned designs and tests were combined to form the multi-stage energy-absorbing plan for high-speed train system. Take a high-speed train as an example, a multi-stage energy-absorbing plan for the whole train system was made. Then, elaborate finite element simulation model of the whole train system was constructed for explicit finite element analysis and component tests were conducted to verify scientific and feasibility of the design. Displacement and energy absorption of the crashworthy body satisfied corresponding indicators in EN 15227.(4) The lightweight design method for the high-speed train was established and an engineering plan was formed in this paper. One kind of quick-analysis method for the carbody structure was established, the complex finite element model was simplified and the simple finite model for the carbody profile was obtained by this method, which can improve the calculation efficiency. The carbody lightweight design could be realized by using the structural optimization, which consists of the optimization variable, constraint condition and objective function. The strength theory and analysis program was adopted, with the stiffness matching condition, the relationship between the profile space, dimension and constraint can be make sure for the carbody profile. Based on the EN12663-1:2010, the finite element model of the high-speed train was built and the stress and stiffness of the carbody were analyzed, meanwhile the displacement and stress sensitivity to design variables were obtained. Finally, the optimization design of the structure lightweight was formed. This kind of method was used to the third generation of the high-speed train, and the carbody structure experience the bench test and the operation test.