基于三维Copula函数的蚀坑预测模型

Pit Prediction Model based on Three-Dimensional Copula Function

通过盐雾腐蚀试验研究了钢绞线在不同应力幅作用下的腐蚀规律,并且观测了钢绞线的腐蚀形态.从概率角度出发,得到了钢绞线蚀坑长度、宽度和深度的独立分布形式,然后基于三维Copula函数得到三者之间的联合分布规律,提出了三维蚀坑预测模型,并通过显著性检验对该模型进行了验证.结果表明:Clayton Copula函数对于模拟蚀坑三维联合分布具有较高的精度;蚀坑使得钢绞线的抗拉强度和延伸率急剧下降,是钢绞线疲劳寿命下降的主要原因;三维蚀坑预测模型的提出,可以为预测钢绞线的腐蚀疲劳寿命提供参考.

The corrosion law of steel strand in chloride salt environment under different stress amplitudes was simulated by the salt spray corrosion test.The independent distribution form of long axis,minor axis and depth of erosion pit was obtained from the perspective of probability.Besides,the joint distribution model include the three parameters was set up based on the three-dimensional Copula function and the correctness of the model is verified by significance test.The results show that Clayton Copula function has high accuracy in simulating the distribution of pits.In addition,it is found that the tensile strength and elongation of steel strands decreased mainly caused by corrosion and then the fatigue life of steel strand will be reduced.The three-dimensional corrosion pit prediction model is conducive to further study of the corrosion fatigue life of steel strands.