Keywords: catenary, contact wire, fatigue, fracture, numerical simulation, extended finite elements method, fatigue test.

The role of a catenary system is to transmit the electrical energy from the energy supply point to trains. To ensure a good energy capture during the passage of a train, the pantograph applies a vertical force to the contact wire. This upward force causes a periodic bending stress which can lead to a fatigue fracture.

To predict the propagation of this fatigue fracture, different approaches could be considered. In this paper, the extended finite elements method (XFEM) is used, implemented in the software Cas3M developed by the Commissariat à l'Energie Atomique (CEA), to simulate the fatigue crack growth of the contact wire.

The material characteristics and parameters of the Paris law were identified using experimental tests performed in a laboratory of the Société Nationale des Chemins de Fer Français (SNCF). Specimens were cut directly from the contact wire. Two mean-stress levels were considered. The stress intensity factors were calculated using the finite element method.

Two geometries of fracture were studied. The numerical results show a good agreement with the observation in terms of the evolution of the crack shape and its growth rate. These preliminary results show that this numerical strategy can be used to predict the critical size and the residual life of fatigue cracks detected during maintenance operations.

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