Application and comparative study of the master curve methodology for predicting fatigue life in overhead conductor

When installing overhead conductors on transmission lines, a static stretching load is applied to maintain the line clearance according to the power line project and protect the conductor against harmful wind vibrations. The everyday stress (EDS) and parameter H/w, which control the stretching load, has been proposed as a means of safely designing power lines against fatigue due to wind excitation. As the stretching tension increases, the conductor becomes more vulnerable to Aeolian vibration, as its self-damping capacity is reduced and mean stress increases, can cause premature failure. However, there is a gap in the literature regarding the mean stress effect study on the fatigue life of conductors, as the modeling of the EDS (or H/w) effect on conductors. The diversity of conductor types (shape, materials, and arrangement) is one of the main reasons for this gap. Therefore, this work develops a master curve that allows predicting the fatigue life for any conductor about the effects of mean stress. To assess the mean stress effect on fatigue life, the SWT and Walker approaches with fatigue test results (carried out using different values of stretching load) were used to create the master curves and validate the application of such criteria to the fatigue life of different conductor families. This master curve provides a practical and simple tool that allows the prediction of fatigue life with an elevated level (three times the lifetime) at low cost, covering a variety of conductors. The power line transmission community could use a more conservative curve.