Friction Properties at the Contact Interfaces of Overhead Line Aluminium Conductors

Overhead conductors may undergo fretting fatigue failures at contact interfaces located at or near the suspension clamps. Some recent experimental studies were carried out on individual wires to understand the fretting fatigue phenomenon. However, the majority of the available results are for the wire-to-wire contact configuration, while little interest has been brought to the wire-to-clamp contact configuration, which is typically a critical interface for conductor fatigue. A new experimental test bench intended to perform fretting fatigue tests on individual strands of overhead conductors is used to study the wire-to-clamp and the wire-to-wire contact configurations. Variable displacement amplitude (VDA) tests under different normal contact forces were carried out on 1350-H19 aluminium wires for both contact types. The experimental results showed a slight difference between the studied contact configurations in terms of the friction coefficient values and the transition sliding amplitude. To complete this analysis, constant displacement amplitude (CDA) tests were carried out sweeping the displacement range and replacing the tested specimen for each test. The resulting contact marks are observed using an optical microscope and a good correlation is found between both types of tests in terms of friction coefficient and transition sliding amplitude. This study allowed characterizing the sliding conditions of wire-to-clamp contact in the context of fretting fatigue of aluminium conductors and is an important step in the development of a method to evaluate the fatigue life of conductors using fretting fatigue tests of individual wire-to-clamp contacts.