A Finite Element Study On Frictional Self-Excited Vibration Of A Pantograph/Catenary System

With the development of the railway system, the electric railway is playing a more and more important role in the railway network. Nowadays the majority of the high speed railway system is electric railway. When running at a high speed, the electric railway locomotive acquires energy from the catenary system through a pantograph. The contact between the pantograph and catenary is the most important sliding friction pair in the electric railway system. Unfortunately, the pantograph/catenary system works in an unfavorable condition, so the contact loss always happens and the quality of current collection is unsatisfactory. When the contact loss happens, arc discharge will occur, which increases wear of the catenary and the strip and therefore reduces the service life of the components. As the speed of the train increases, the quality of the current collection will get worse. Unstable vibration of the catenary/pantograph system has been a challenging issue for many engineers and researchers due to its immense complexity. One of vital problems to the high speed railway system is to ensure constant and stable current collection.Because there is continuous arc discharge, the contact loss between the catenary and the pantograph may be induced by friction. The experimental data show that the friction coefficient of the catenary/pantograph system can reach up to0.3or0.4and in this case, the catenary/pantograph system has a strong propensity of unstable vibration occurrence induced by friction, In this paper, the three-dimensional finite element model of the catenary/pantograph system is established, which includes a pantograph, a support line and a contact line, the steady arms and the droppers. Meanwhile, the sensitivity of parameters, including the friction coefficient, lift force, the stiffness of the dropper, the tension applied on the ends of the support line and contact line and the velocity of the train, is performed. The following conclusions are obtained:(1) The friction coefficient has a heavy influence on the occurrence of the friction induced vibration of the catenary/pantograph system. As the friction coefficient increases, the real part of the complex eigenvalue becomes larger and the number of the unstable mode increases, which suggest the instability propensity of the catenary/pantograph system increases with increasing friction coefficient.(2) There is a critical friction coefficient for each unstable mode. Mode coupling appears when friction coefficient is larger than the critical value. Mode coupling maybe is the cause of the unstable vibration of the catenary/pantograph system.(3) Lift force has a significant influence on the propensity of the unstable vibration of the catenary/pantograph system. As the lift force increases, the real part of the complex eigenvalue increases, and therefore the propensity of the unstable vibration becomes stronger.(4) The tension applied on the ends of the support line and contact line has a slight effect on the motion instability of the catenary/pantograph system. The real part of the complex value increases slightly with increasing tension. The tension applied on the ends of the support line and contact line can be decreased properly to suppress the propensity of the self-excited vibration of the catenary/pantograph system.(5) The stiffness of the dropper has less influence on the real part of the complex eigenvalue, and hence less influence on the motion instability of the catenary/pantograph system. In the construction of the catenary, the stiffness of the dropper can be increased properly to enhance the overall stiffness of the catenary.(6) The velocity of the train has less influence on the propensity of the unstable vibration. The simulation results show that there are small differences between the real parts of the complex value for different velocities.