Fatigue properties of the pantograph–insulator system of metro trains: Experiments and the design for improvement

The power of a metro vehicle is supplied by the pantograph on the vehicle roof. During pantograph lifting, the insulator set of the pantograph is prone to fracture caused by the impact load. In this work, a Single-arm pantograph–insulator system (SPIS) of metro vehicles was studied for the fatigue fracture of the insulator set induced by impact load. The basic structure of the SPIS was first introduced. The dynamic axial force test and fatigue and fracture damage experiments was then conducted on SPIS for both simulation experiment platform and real vehicles to analyze the causes of the insulator fracture. A method to improve the design structure of the back-end insulator set was proposed to resolve the problems of both the impact failure of the insulator steel core and the stress concentration on the interface between a steel core and an epoxy resin. The finite element analysis results indicated that the improved insulator set shows a much smaller stress concentration. Therefore, the improved insulator set has a greatly reduced fatigue damage subjected to shear effect, which validated the feasibility of the improved structure design.