Fatigue strength evaluation for individual strands of overhead conductors using a biaxial fretting fatigue test bench

This paper presents a biaxial fretting fatigue test bench which provides the capability of performing fretting fatigue experiments on individual wires of a conductor combining the effect of both alternating tension and bending loadings to represent a more realistic state of a conductor individual strand under periodic loading caused by aeolian vibrations. Preliminary tests with only uniaxial alternating tension loading were carried out on 1350-H19 aluminum wires having the same mechanical and geometric characteristics as those of the ACSR Bersfort conductor aluminum strands. Different levels of alternating stress were tested in order to validate the performance of the apparatus. Preliminary results showed that the experimental setup allows reproducing the local loading state which leads to the fretting fatigue damage on the tested wires. Biaxial tests were also conducted at a high level of alternating loadings. The results of these tests reveals that, at high alternating stress amplitudes, the biaxial loading allows to observe some fretting fatigue failures, whereas early plain fatigue failures were observed when applying similar uniaxial loading