锈蚀断丝对拉索力学性能影响的数值研究

A Numerical Study of the Effect of Corrosion and Breakage of Wires on Mechanical Properties of Cable

钢丝锈蚀、断裂损伤是影响拉索力学性能的主要因素.首先,建立了钢丝径向、索长方向锈蚀损伤分布模型;然后,基于锈蚀钢丝断口形态,分析锈蚀及荷载联合作用下钢丝断裂规律,建立了基于应力强度因子的锈蚀钢丝断裂准则;最后,考虑钢丝间摩擦作用,采用有限元法对拉索钢丝锈蚀、断裂过程进行模拟,研究了拉索中钢丝逐层锈蚀断裂对拉索力学性能的影响.结果表明:拉索钢丝锈蚀断裂后,钢丝应力重分布,断丝对拉索钢丝应力的影响沿截面径向逐渐减小,紧邻断丝层的锈蚀钢丝应力增幅最大,最内层钢丝应力增幅最小;由于钢丝间摩擦作用,断丝应力在恢复长度内呈对数形式恢复且基本同步;恢复长度随断丝百分比增大而增大,与断丝百分比呈二次抛物线关系,并将收敛于3. 3m;拉索索力损失率随断丝百分比增大而增大,拉索少量钢丝的锈蚀断裂对索力影响较小,当拉索锈蚀断丝百分比小于10%时,引起的索力损失率小于4%.

Corrosion and breakage of steel wires are main factors affecting the mechanical properties of the cable.Firstly,corrosion distribution model of cable wires along radial and cable directions is established.Then,on the basis of corroded wire fractured forms,the breakage law of wire under the combined action of corrosion and load was analyzed.A fracture mechanics criterion of corroded wire based on stress intensity factor is established.Finally,by taking friction of wires into consideration,this paper numerically simulates corrosion and fracture process of cable wires,and studies the effect of corrosion and breakage of each layer wires on mechanical properties of cable.Results show that stress redistribution of wire happens after corrosion and fracture of cable steel wires.The effect of wire breakage on the stress decreases gradually in the radial direction.Stress increase of the corroded wires next to the fractured wires layer is the biggest,and stress increase of the inner layer wire is the smallest.Due to the friction between wires,stresses of fractured wires synchronously recover in the recovery length in form of logarithmic.The recovery length increases with the percentage of broken wires,and it has two quadratic parabola relations with the percentage of broken wires,and it will converge to 3.3 m.Cable force loss rate increases with the rise of the percentage of broken wire.The impact of corrosion and breakage of wire is small on cable force.When the percentage of wire breakage is less than 10%,the cable force loss rate is less than 4%.