Analysis of Fatigue Fracture of High Voltage Overhead Ground Wire of 220 kV Transmission Line
The fractured high voltage overhead ground wire of a 220 kV transmission line is investigated by means of macroscopic inspection,chemical composition analysis,fracture morphology analysis,microstructure inspection,mechanical performance test and finite element analysis.The results show that under the action of long-term aeolian vibration,the overhead ground wire withstands alternating bending stress,which leads to stress concentration cracking at the ends of flexible steel strands and rigid press-connecting-tube.Then the ground wire monofilament brake in a fatigue manner,resulting in a significant decline in the load-bearing capacity.Finally,under the action of external forces such as self weight and wind load,the ground wire with broken strands completely brakes and fells.
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