Research On Impact Dynamics Of Collector/Third Rail Ends

The curved end section of the third rail is a crucial part of the third-rail electrification system that mainly serves the purpose of guaranteeing the smooth passing of collector shoes over breakpoints in the third rail. Momentary impacts may occur between the third rail end and the collector shoe passing at high speed, which may easily cause detachments and arching. Meanwhile, excessive impact forces may accelerate the fatigue of the collector, reducing its service life, or even immediately damage the collector and cause accidents. An investigation of such impact processes is thus necessary in order to find ways to facilitate a smooth transition of the collector shoe onto the contact surface of the third rail. This paper proposes a dynamics model based on the continuous contact force impact theory as well as a simulation model in ADAMS for collector shoe-third rail end impact, and validated the model with results from track tests with actual vehicles of Wuxi Metro Line 2. Main contents of this paper’s research include:(1) The paper analyzes two commonly used contact-impact modelling methods, namely the discrete contact force model and the continuous contact force model. Since the collector shoe-third rail end impact is a consistent and finite process and involves friction, the discrete model, which cannot solve for the contact force and assumes the process to be instantaneous, is eliminated and the continuous model, which can accurately solve for the contact force from displacement and acceleration is chosen for the impact analysis.(2) Considering the elastic deformation of the swing arm of the current collector and ignoring that of other structures including contact rail (regarded as rigid bodies), the third rail collision model is established in ADAMS. This model is integrated into a metro vehicle dynamics model to simultaneously consider the influence from the stochastic irregularities of the running rails and the third rail. Validation of the model is done with the actual train test data on Wuxi Metro Line 2.(3) Using the above-mentioned collision model, the paper investigates the dynamic response for the collector and the effects of dynamic parameters of collector and design parameters of the third rail ends section on the dynamics of the collector shoe. In particular, the vertical acceleration and displacement of the collector shoe are in depth analyzed.(4) Based on the NURBS curve with continuous second-order derivatives, this paper proposes parametrical designs of three new third rail end section geometries referred to as S1,S2, and S3. A comparison between impact dynamics of the three newly proposed geometries with those of the P1 geometry currently used on the third rails of Wuxi Metro Line 2 show that the S1,S2 and S3 geometries produce improved dynamics than the P1 geometry during the collector shoe’s transition from the end section to the straight section of the third rail. Furthermore, with the increase of the weighting factor ω1 that changes the local curve geometry of the third rail end, a greater decrease in the dynamic forces of the collector can be achieved, resulting in better current collecting qualities.