Experimental and finite element analysis of fatigue performance of copper power conductors

Fatigue performance of a 95 mm2 stranded copper conductor was investigated. Individual copper wires were tested in tension–tension loading with a stress ratio R = 0.1. The specimens were taken from the core wire and from the inner and outer layer of the conductor. Due to the compacting process that was applied during manufacturing, geometrical irregularities were observed on the wires from the outer and inner layers. Finite element (FE) analyses were performed to investigate the combined effects of these irregularities and of material plasticity on the fatigue performance. The FE models were validated by convergence studies. Full cross section conductors were tested in a specially designed rig providing constant tension and variable (reversed) curvature simulating bending inside a bellmouth. In this test the fatigue failures were found to be governed by local bending effects in individual wires. The data from the single wire tests are presented on S–N format and applied in a model for prediction of fatigue strength of full section copper conductors.