交变荷载与腐蚀环境耦合作用下拉索钢丝腐蚀行为特征及预测

Corrosion behavior analysis of wire-steel in cables and its prediction under combined effect of cycling loading and eroded environment

为探究和预测交变荷载和腐蚀环境耦合作用下拉索钢丝的腐蚀行为,通过加速试验制定不同锈蚀等级下的钢丝锈蚀图例,测量了相应锈蚀等级下锈蚀钢丝失重量、名义抗拉强度和断后延伸率,使用图像小波分解技术探讨了HSV和RGB色彩模式在表征钢丝锈蚀图像整体颜色与局部边缘轮廓特征方面的适应性,分析了不同锈蚀等级下钢丝锈蚀图像小波系数分量的L1范数均值和L1范数百分比与锈蚀钢丝平均失重量的相关性,建立了钢丝平均失重量的预测模型。研究发现:交变荷载和盐雾环境耦合作用下拉索钢丝呈现出明显的局部坑蚀现象,且钢丝名义抗拉强度和断后延伸率均随锈蚀失重量的增加而减小;钢丝腐蚀形态的改变主要体现在腐蚀钢丝表观颜色浓度和亮度的改变,而HSV色彩模式中的饱和度分量可较好地反映钢丝锈蚀图像整体颜色的变化,RGB色彩模式中的蓝色分量可较好地反映钢丝锈蚀图像局部蚀坑周围局部亮度的变化;拉索钢丝腐蚀图像与腐蚀失重量、名义抗拉强度之间存在良好的线性回归关系,可用于预测钢丝锈蚀失重量和名义抗拉强度。

In order to investigate and predict the corrosion behaviors of steel wires in stayed cables under cycling loading and eroded environments,several corrosion images of different corrosion degrees and their corresponding weight losses,nominal tensile strength as well as percentage elongation after fracture are obtained through salt spray accelerated test.The adaptability of HSV and RGB color patterns in characterizing the overall color and local edge contours of wire-steel corrosion images is discussed by using wavelet decomposition technique,and correlational analyses of mean values and percentages of L1 norms ofcorrosion image wavelet coefficients associated with weight losses are conducted.A regression model is suggested to predict the weight loss of wire-steels.It is found that local pitting corrosionon steel wires can be obviously observed under combined effect of cycling loading and eroded environment,and the nominal tensile strength and percentages elongation after fracture of steel-wires decrease with their weight loss increasing.Wavelet analysis results of steel-wire corrosion images show that the change of corrosion morphology mainly include the changes of its color saturation and brightness,saturation component in the HSV color mode can better describe the change of the overall color of the corroded image,and the blue component in the RGB color mode can better reflect the change of the local topography of the corroded image.There is a good linear correlation between the corrosion image of wire-steel in cables and its weight loss as well as nominal tensile strength,which can be used to predict the weight loss and nominal tensile strength of corrosion wire-steels.