Dynamic Modeling And Analysis Of Pantograph-catenary System Based On Absolute Nodal Coordinate Formulation

High-speed trains are most electrically powered,the electricity is collected from a railway catenary using a pantograph installed on the train roof,and the quality of current-collection of the train directly affects the stability and safety of its operation.Pantograph-catenary system is the key component for the train to obtain current,when the pantograph runs at higher speed,the vibration of catenary will be more intense,and the geometric nonlinear influence of large displacement and large deformation of each cable will be more significant.Absolute nodal coordinate formulation(ANCF)describes the motion and deformation of a flexible body through the absolute position vectors and the gradient vectors of element nodes,without the assumption of small deformation,and has great advantages in dealing with large displacements,large deformations of cables and various complex constraints.In this thesis,dynamic modeling and analysis of pantograph-catenary system were carried out based on absolute nodal coordinate formulation,and the following study contents were mainly completed:Firstly,based on the basic theory of continuum mechanics,the mass matrix,viscoelastic force vector and external force vector of three-dimensional two-nodes ANCF gradient deficient cable/beam element were derived,based on D’Alembert principle,the kinetic equation of cable/beam system was established,and the corresponding numerical algorithm was given,and the model was verified by numerical simulation,it provided a theoretical basis for establishing a catenary multi-flexible-body kinetic model.Considering the geometric nonlinearity of catenary cables with large displacements and large deformations as well as the variations of initial lengths of cables,a time-varying finite element model of catenary was established based on ANCF gradient deficient cable/beam elements with variable-lengths and constant-lengths,and a form-finding method for catenary was proposed.In this method,the catenary was tensioned from any simple initial configuration to an equilibrium configuration that met the design requirements through a simplified simulation of the installation process.The effectiveness and accuracy of the proposed method were verified by three form-finding examples,the results show that the proposed method is insensitive to initial conditions and has high computational accuracy,it does not need to split and recombine the model and can be easily extended to the form-finding computations of other catenaries with complex configurations.Then,in order to consider the nonlinear geometric relations of each member in pantograph frame structure,a multi-rigid-body model of pantograph was established based on the absolute coordinates,the kinetic equation of the model was obtained by the Lagrange multiplier method,and the validity and correctness of the model were verified by two sets of working conditions.Then by the penalty function method,the simulation of pantograph slide sliding contact with the contact wire was achieved,the coupling kinetic model of multi-rigidbody pantograph and multi-flexible-body catenary was established,and based on the model,the dynamics simulation of pantograph-catenary system of Wuhan-Guangzhou high-speed railway was carried out,the effectiveness and correctness of the proposed model was verified by relevant technical standards.Finally,three fault models of pantograph-catenary system were further established,including falling off of catenary dropper,settlement of catenary mast foundation and stuck lag of pantograph lower arm bearing,and the corresponding dynamics simulations were carried out,and the kinetic characteristics of pantograph-catenary system with the three faults were analyzed.The results show that the established ANCF-based coupling kinetic model of multirigid-body pantograph and multi-flexible-body catenary can accurately simulate the motion posture of pantograph and the geometric nonlinearity of large displacements and large deformations of catenary cables during the train running,can be applied to complex dynamics simulations of pantograph-catenary system,and can consider more actual situations,it has certain value for practical engineering applications.