Reserach On Multi-flexible Body Modeling And Dynamic Characteristics Of High-speed Pantograph-catenary System Based On The Absolute Nodal Coordinate Formulation

With the continuous improvement of train operation speed,the problem of large deformation in high-speed pantograph and catenary system gradually becomes prominent.The traditional modeling and analysis method of multi-flexible body system based on the assumption of small deformation cannot accurately describe the large deformation and large rotation phenomenon in high-speed pantograph and catenary system,which reflects the disadvantages of the traditional modeling method of pantograph and catenary system.Absolute Nodal Coordinate Formulation(ANCF)uses the absolute gradient vector of the node to describe the rotation of the element,so that it is not limited by the deformation amplitude.In addition,the mass matrix derived from the dynamic equation is a constant matrix,and there are not additional terms such as Coriolis acceleration and centrifugal acceleration in the equation.Therefore,the modeling method and dynamic characteristics of high-speed pantograph and catenary system are studied in this thesis based on the ANCF.Firstly,considering the computation problem of large-scale model,this thesis improves the traditional ANCF cable element,and proposes a new type of low degree of freedom cable element based on ANCF.The position vector of any point on the central line of the new element is obtained by integrating the gradient vector on the central line of the new cable element along the central line.For the interpolation of the gradient vector,the linear interpolation function is adopted as the shape function.The generalized coordinates of the new element are composed of the gradient vector and the position vector of the first node,which reduces the degree of freedom of the new element by nearly half that of the traditional element.In this thesis,the accuracy of the new cable element is verified by classical static and dynamic numerical examples.Then,before modeling catenary system using the new ANCF cable element,for the form-finding problem of catenary,the degradation dynamics model is established by using the equilibrium condition and the independent equations are added to solve the initial length and generalized coordinates of element according to the tension conditions.Therefore,a new form-finding method of tensioning element is proposed and applied to the form-finding analysis of the catenary in this thesis.The equilibrium configuration of catenary is verified by using the dynamic models and comparing the results of literature.Finally,the catenary is modeled by using the new ANCF cable element and the three-mass model is used to simplify the pantograph model,so the pantograph and catenary coupling system is established.The modeling method is verified by the European standard EN50318 and vertical dynamics of the pantograph and catenary system is studied by using this model.Moreover,the simulation model of Beijing-Tianjin intercity high-speed railway pantograph and catenary system is established by using the new ANCF cable element,the dynamic characteristics of the pantograph and catenary system under different speed levels and stochastic cross wind environment are studied in this thesis.The results show that the Absolute Nodal Coordinate Formulation is suitable for the multi-flexible body dynamic modeling of catenary;and the coupling model based on the new cable element can capture the dynamic characteristics of the pantograph and catenary system;in addition,after considering the influence of stochastic cross wind,pantograph and catenary system has a great influence on the current collection performance.