Effect Of Annealing Temperature On Fatigue Life Mechanical Properties Of Wires After Mountain Fire

Transmission line is an important equipment for power transmission in power grid.In recent years,the frequent occurrence of mountain fires in China's power grid transmission lines has seriously damaged the safe operation of transmission lines.Therefore,it is very important to study the mechanical and electrical characteristics of transmission line conductors after fire.The influence of temperature on the tensile stress and fatigue life of overhead transmission line(steel core aluminum stranded wire)was studied by hill fire simulation test.Through finite element simulation,the change of displacement field and equivalent effect force field of wire during fire is analyzed.The main research contents are as follows:(1)the influence of temperature on the fatigue performance of the wire was studied by simulating the fire wire with firewood barbecue wire and tube resistance furnace roast wire.(2)the stress distribution of different layers of the conductor is obtained by modeling the experimental conductor with ANSYS and applying temperature boundary to simulate the tensile condition after hill fire.according to the stress distribution,the fatigue life is calculated and the conclusion is obtained.(3)the whole displacement field and stress field of conductor transmission line are calculated by using ANSYS to simulate the fire scene of mountain fire.the optimization of transmission line has certain guiding function to deal with the real mountain fire.The results of the study show that the trend of tensile times with annealing temperature of three-layered aluminum wire is similar.When the annealing temperature is less than 250 °C,the number of tensile times is large,that is,the number of stretching exceeds 120,000 times;When the annealing temperature is between 250°C and 500°C,the number of fatigue drawing decreases as the annealing temperature increases.The number of stretching of each layer was significantly lowerafter the annealing temperature of 300°C.The fatigue resistance is significantly affected and the fatigue life becomes significantly lower.Therefore,high temperature(?500°C)will significantly reduce its anti-fatigue properties,that is,the conductors of power transmission lines are prone to fatigue failure after high temperature and accidents occur.