【摘要】 2011年四川西昌地区月普一回线在覆冰气象条件下发生断线事故。基于现场调查资料,LGJ-630/45钢芯铝绞线截面上的12根铝线为平齐的脆断断口,其余均为典型韧断断口。本文基于有限元法的ANSYS计算平台,从悬垂线和大挠度弯曲梁单元模型的静力学角度及梁单元模型的动力学角度分析了断线原因。研究表明:事故现场采集的脆性平断断口系疲劳所致,导线先因疲劳产生低应力脆断平断口,引起有效截面减小,继而发生应力过载断裂,产生杯锥状韧性断口。事故发生原因为覆冰及脉动风使导线运行应力由55.4 MPa增至97.9 MPa。在脉动风作用下,导线发生一阶共振,促使非对称疲劳的疲劳载荷应力均值增大,大大降低了导线的疲劳寿命,部分铝线发生断股,引起导线有效截面减小,使其运行应力超过导线破坏应力,最终导致导线过载韧断。更多还原

【Abstract】 Accident of icing induced line break occurred for the electric power transmissionline connecting Yucheng to Pugein the winter of 2011. Based on the observation and measured data, a broken section of the LGJ- 630/45- type power line of stranded aluminum wires with steel core exhibited 12 broken aluminum wires with typical brittle fracture characteristics, but the rest wires were ductile fractured.On the basis of the theory of statics and dynamics of catenary beam element mode and large deflection bending beam element mode, the line breaking was analyzed by using ANSYS finite element method. Results show that the brittle fracture of 12 broken wires may be caused by fatigue, then the effective section of power line decreases, which further caused the rest wires to be broken due to overload. Icing and fluctuating wind lead the stress of the operating power line to be increased from 55.4 MPa to 97.9 MPa,which is the main cause to the line breaking. The power line resonate induced by the fluctuating wind,thus the mean stress of asymmetric fatigue increases,, and the fatigue life of the line significant decreases. Corresponding to all the above considerations, the realstress of the operating line increases from97.9 MPa to 275.2 MPa and thereby the ductile fracture occurs due to that the real stress exceeded the failure stress of 221 MPa of the operating line.更多还原