风致涡激振动作用下随桥电缆的疲劳寿命分析

Fatigue Life of Bridge-Along Cables under the Wind-Vortex-Induced Vibration

桥梁的风致涡激振动是影响随桥电缆疲劳寿命的因素之一,采用有限元法对随桥电缆在风致涡激振动作用下的疲劳寿命进行分析。首先,建立桥梁的二维瞬态流-固耦合数值模型,采用动网格和用户自定义函数(UDF)技术实现桥梁的瞬态振动位移响应求解;其次,将桥梁的单位振动位移作为边界条件施加在电缆上,获取电缆在单位振动位移作用下静力学应力求解结果;最后,通过求解的应力结果与一个周期的桥梁振动位移时程构建应力时间历程,并基于材料的S-N曲线和Miner线性累积损伤理论获取电缆的疲劳寿命。结果表明:在风致涡激振动作用下,作用在随桥电缆上的作用力近似为对称等幅循环载荷;电缆的疲劳损伤最大处出现在夹具固定附近的铝护套层上,寿命循环次数达3.3×10^(5)次,寿命约为206.25 h。该研究可为跨海电缆的安全可靠性设计和状态运行维护提供理论指导。

The wind-vortex-induced vibration of bridge is one of the factors affecting the fatigue life of the bridge-along cables.The fatigue life of the bridge-along cables under the effect of wind-vortex-induced vibration was analyzed by using the finite element analysis methods.Firstly,a two-dimensional transient fluid-structure coupling numerical model of the bridge was established,and the dynamic mesh and user-defined functions(UDF)techniques were used to solve the transient vibration displacement response of the bridge.Secondly,the unit vibration displacement of the bridge was applied to the cable as the boundary condition to obtain the static stress solution results of the cable under the action of unit vibration displacement.Finally,the stress time history was constructed by combining the solved stress results with the vibration displacement time history of a periodic vibration of bridge,and the fatigue life of the cable was obtained based on the S-N curve of the material and the Miner's linear cumulative damage theory.The results showed that the wind-vortex-induced vibration of the bridge was a constant amplitude vibration in the steady state.Under the wind-vortex-induced vibration of the bridge,the largest fatigue damage of the cable appeared on the aluminum sheath layer near the clamp.The life repeats of the cable could reach 3.3×105 times,and the service life of the cable was about 206.25 h.It can provide theoretical guidance and reliability research for the operation and maintenance of the bridge-along cables.