Influence of 1350 and 6201 aluminum alloys on the fatigue life of overhead conductors – A finite element analysis

Wires made of 6201-T81 aluminum alloy are generally more resistant to fatigue than AA1350-H19 (pure aluminum) wires. However, the fatigue lives of conductors composed of AA6201-T81 wires (All Aluminum Alloy Conductors) are lower than those of conductors made of AA1350-H19 wires reinforced with steel (Aluminum Conductor Steel Reinforced). From literature, the underlying reason for this behavior remains unclear. In this study, finite element simulations are carried out to understand the influence of the aluminum alloy type on the conductor life. To support the discussion, experimental data available in the literature for AAAC 900 MCM and ACSR Tern conductors, as well as for the aluminum wires made of alloys 6201-T81 and 1350-H19, are utilized. The study provides valuable insights into the intricate relationship between the tensile strength and fretting fatigue resistance of the 6201-T81 aluminum alloy and their impact on the fatigue resistance of 6201-based conductors. Specifically, it reveals that while the increased tensile strength of this alloy enables the critical wires in the conductor to withstand higher stress levels, its resistance to fretting fatigue falls short in compensating the damaging effects of such elevated stresses. As a consequence, greater fatigue damage occurs in these wires, ultimately leading to a reduction in the overall durability of the conductor. The findings of this study bring a new understanding to the fatigue problem of 6201-based conductors and have the potential to change the design guidelines for transmission lines using these cables.