Dynamic Modeling Based On Vibration Testing And Nonlinear Stochastic Dynamic Analyzing Of Pantograph System

In the process of train running, the pantograph on the roof gets current and supplies electric power to the train through contacting the catenary by uplift force. Pantograph is one of the key parts in the high speed train and its dynamic performance has a directly effect upon current-receiving quality. In this thesis, the nonlinear dynamic model of DSA200pantograph was established based on the vibration testing of the key components, and the nonlinear stochastic dynamics of the carbon strip suspension was studied analytically.For an actual pantograph system, the most critical component is the pan-head suspension subsystem. The modal testing of the pantograph (especially the pan-head subsystem) was carried out firstly, and their natural frequency and vibration modal were identified experimentally. As train speed is low, the nonlinear of pantograph itself can be ignored for the small vertical displacement. However, with the increasing of train speed, the effects of the nonlinearities of the pantograph become unneglected. The nonlinear dynamic model of the pantograph system was then established based on vibration testing of the key components. The nonlinear stiffness characteristic of the pan-head suspension system was calculated straightly according to the geometric structure of pantograph. The equivalent mass of the frame of the pantograph and the relationship with the operational height were obtained by free vibration periodic method. The dynamic characteristics of the damper in the base of the pantograph were tested, which shows strong nonlinearity, asymmetry and hysteretic characteristic. The corresponding Besinger dynamic model was established. A dynamic model of the carbon-strip suspension possessing nonlinear stiffness was developed. The contact force between the pantograph and catenary is represented as a combination of harmonic and random excitations. Using stochastic averaging, a diffusion or Fokker-Planck-Kolmogorov equation governing the stationary response of the carbon-strip suspension is derived. In order to solve the nonlinear stochastic dynamic problem analytically, the stochastic averaging method based on generalized harmonic functions is applied. Based on the stationary response, the stochastic jump of carbon strip motion and its bifurcation as the nonlinear stiffnesses parameters change are examined.