Effect of the nonlinear displacement-dependent characteristics of a hydraulic damper on high-speed rail pantograph dynamics

Abstract

A new simplified-parametric model is proposed to describe the nonlinear displacementdependent damping characteristics of a railway pantograph hydraulic damper and validated by the experimental results in this study. Then, a full mathematical model of the pantograph-catenary system, which incorporates the new pantograph damper model, is established to simulate the effect of the damping characteristics on the pantograph dynamics. The simulation results show that large Fconst and C0 in the pantograph damper model can improve both the raising performance and contact quality of the pantograph, whereas a large C0 has no obvious effect on the lowering time of the pantograph; the nonlinear damping characteristics described by the second item in the new damper model have dominating effects on the total lowering time, maximum acceleration and maximum impact acceleration of the pantograph. Thus, within the constraint of total lowering time, increasing the second item damping characteristics of the damper will obviously improve the lowering performance of the pantograph and reduce excessive impact between the pantograph and its base frame. The proposed concise pantograph hydraulic damper model appears to be more complete and accurate than the previous single-parameter model, so it is more useful in the context of pantograph-catenary dynamics simulation and further parameter optimizations. The obtained simulation results are also valuable and instructive for further optimal specification of railway pantograph hydraulic dampers.

Experimental research into the low-temperature characteristics of a hydraulic damper and the effect on the dynamics of the pantograph of a high-speed train running in extreme cold weather conditions

“…In order to study the influence of low-temperature damping characteristics of the damper on the pantograph dynamics, a simplified-parametric damper model proposed and experimentally validated in Wang et al. 16 is adapted for the theoretical presentation of the above experimental results, and the nonlinear model is determined as where F d is the output damping force by the hydraulic damper, C 0 is the initial damping coefficient of the damper during extension, x ( t ) is the instantaneous displacement of the damper, s a is the displacement amplitude of the damper, s 1 is the distance from the first orifice in the rod to the point (0, s a /2), A f is the cross-section area of orifice in the rod for fluid exiting, A n is the changeable cross-section area of orifice in the rod for fluid entering, k 11 is a constant, and F const is the damping force of the damper during compression.…”

“…Equation (7) describes the fluctuating stiffness of the catenary in terms of the pantograph moving speed and time; it is a law fitted 21 from the finite element model of the common Chinese catenary, and pertinent parameter specifications can be found in Wang et al. 16 and Guo. 21…”

“…A detailed MATALB/Simulink model is developed 16 using the above mathematical model of the pantograph–catenary system, with which the simplified-parametric pantograph damper model described by equation (1) is coupled. In the pantograph dynamics simulation, theoretical presentations of the experimentally obtained damping characteristics of the pantograph damper, as shown in Figure 2, at 20 ℃, −10 ℃, −30 ℃ and −50 ℃ in the second section are respectively used.…”

“…Because the currently used simple linear damper model is inadequate and less adaptive to the working conditions of the pantograph, Wang et al. 16 continued to propose a simplified-parametric model to summarize the nonlinear displacement-dependent characteristics of a pantograph hydraulic damper. The simplified-parametric damper model was then validated and incorporated into a thorough pantograph–catenary dynamics simulation, and valuable results of damper parameter effects on pantograph dynamics were obtained.…”

“…Thus, to explore how damping characteristics of the pantograph damper vary in an extremely cold environment and how they affect pantograph dynamics, an experimental research on the low-temperature characteristics of a pantograph hydraulic damper is carried out in this study; the experimental results are analysed and key parameters are identified to obtain the theoretical description of low-temperature damping characteristics of the damper by using a simplified-parametric damper model. 16 A mathematical model of the pantograph–catenary system incorporating the pantograph damper model was then established to simulate the effect of low-temperature characteristics of the damper on the pantograph dynamics and valuable results are obtained. The results obtained in this study are valuable in understanding the low-temperature characteristics of a hydraulic damper, and instructive in the optimal specification of the pantograph damper for high-speed trains running in cold environments.…”