Numerical Characterization of Overhead Conductor Local Loading Conditions at Wire Contact Points in the Vicinity of Suspension Clamps

Wind-induced vibration is one of the main causes of overhead conductor fatigue, especially at the suspension points. These critical locations involve several inter-wire contact points prone to fretting damage due to conductor cyclic bending. Assessing the severity of these local loading conditions is therefore essential to better understand, predict, and prevent conductor failures. Available numerical models allow full 3D representations of conductor-clamp systems under cyclic bending, while considering all local contact interactions. Exploiting a recent finite element model based on an efficient beam-to-beam contact modelling strategy, this paper proposes a complete numerical characterization of conductor local loading conditions in the vicinity of suspension clamp. The study considers an ACSR Bersfort conductor installed in a short-radius metallic suspension clamp and subjected to cyclic bending loads associated to Aeolian vibrations. Using a factorial design of experiments (DOE), the characterization considers two key factors: the bending amplitude (Yb) and the conductor axial tension (T), each at three levels. From the DOE simulation results, the analyses highlight the parameter interactions with respect to the local loading conditions: wire mean (σm) and alternating (σa) bulk stresses, normal (P) and tangential (Q) inter-wire contact forces and the contact slip (δ). Results from the DOE thus provide a global and detailed description of the relationships between the external loads and local loading conditions being at the origin of conductor fretting fatigue damage. Under given Yb and T conditions, the proposed characterization therefore allows the identification of the critical contact points and their associated local solicitation for further in-depth and targeted investigations.