Stress Analysis and Fatigue Life Prediction of Contact Wire Located at Steady Arms in High-Speed Railway Catenary System

In an electrified railway system, the pantograph on the train roof is used to collect the electric current through a sliding contact with the contact wire (CW) of the catenary. The CW is mounted laterally in a zigzag relative to the track centerline with the help of a steady arm to ensure symmetrical wear on the pantograph’s strip, which is beneficial to slow the wear process and extend the service life. Under the pantograph’s impact, the CW around the steady arm forms a stress concentration and has been recognized as a vulnerable point in the catenary system. This article performed a uniaxial tensile test and high-cycle fatigue test to measure the mechanical properties and fatigue characteristics of Cu–Mg alloy that is used for manufacturing high-speed CW. A stress analysis method is proposed based on the combination of the pantograph–catenary interaction model and the solid CW specimen model. In the pantograph–catenary interaction simulation, the catenary is modeled using the Euler–Bernoulli beam element. The 3-D solid element is used to model the CW segment. The nodal displacements of the CW segment obtained from the pantograph–catenary interaction simulation are transferred to the CW specimen model. The stress distribution on the CW section and the entire multiaxial transient stress field are analyzed. Based on fatigue test results and stress time history data obtained by simulation, using the nominal stress method, the uniaxial fatigue and multiaxial fatigue analyses are performed to reveal the fatigue characteristics with different speed classes. The results indicate that the weakest points appear at both the wing point and the top point on a CW section. The CW’s fatigue life reduces by over 50% when the speed class is upgraded from 350 to 400 km/h.

I. Introduction

The pantograph–catenary is widely used in modern electrified railway systems to power the electric train. The pantograph mounted on the train roof collects the electric current from the contact wire (CW) of the catenary through a sliding contact. To slow the wear process of the pantograph’s strip and extend the service life, symmetrical and uniform wear on the pantograph strip is desirable. The practical solution is to arrange CW laterally in a zigzag relative to the track centerline, as shown in Fig. 1(a), which ensures that the wear does not only happen at one point of the pantograph strip. This special arrangement is normally realized by the steady arm mounted on the pole, as shown in Fig. 1(b). Due to the bending of the CW located around the steady arm, stress and mass concentrations are likely to form under the impact of pantographs. In particular, large stress in the lateral direction may occur at the place where the CW is clamped by the steady arm clip. The CW located at the steady arm is more likely to be subjected to mechanical fatigue failure. These factors make the CW around steady arms the weakest points along the whole catenary, where the breakages are mostly observed at these positions [1]. Fig. 1.

(a) Zigzag in catenary. (b) Zigzag realized by the steady arm.