Finite element analysis of the fatigue strength of copper power conductors exposed to tension and bending loads

The paper presents FE analyses for predicting longitudinal stresses from tension-tension and tension-bending fatigue tests of a 95 mm2 stranded copper power conductor. As fatigue test results indicated that the fatigue performance was dominated by longitudinal stresses, the models were formulated by a combination of elastic beam and elastic-plastic beam-contact elements that included the friction. Two contact conditions were investigated: the point (trellis) contact between adjacent layers and the inline contact within each layer and between centre wire and inner layer. Due to the plastic deformations of the wires obtained from the manufacturing procedure, a simplified description of the contact behaviour was adopted and calibrated by axial tension testing. The FE models were further validated by calibration testing and mesh sensitivity checks. The simulated stresses were applied to attempt bridging the gap between the SN data obtained from full cross-section tension-tension and tension-bending testing and SN data obtained from individual wires testing.