钢桥腐蚀斜焊缝十字接头疲劳性能研究

摘要

以45°倾角全熔透承载角焊缝十字接头为研究对象,在试件的边缘焊趾附近构造深度分别为1和2mmn的2种人工半球形蚀坑,通过疲劳试验和有限元方法分析腐蚀对斜焊缝十字接头疲劳行为的影响.结果表明:当蚀坑深度分别为0,1,和2mm时,在200万次循环加载下斜焊缝十字接头疲劳强度分别为92.4,91.3和70.2 MPa,当蚀坑深度等于或小于1 mm时,可以忽略蚀坑对斜焊缝十字接头疲劳强度的影响,但选取斜焊缝十字接头的S—N曲线时应该考虑不同腐蚀程度的影响;蚀坑深度是影响斜焊缝十字接头疲劳强度的主要因素,在蚀坑半径相同情况下蚀坑越深,等效应力越大,应力集中越明显;由于热点应力集中系数与蚀坑深度的相关性要好于深宽比,且非线性函数优于线性函数,因此推荐采用非线性函数拟合热点应力集中系数与蚀坑深度的关系.%In order to study the effect of corrosive damage on the fatigue performance of inclined weld joints in steel bridges,full penetration load-carrying fillet cruciform joint with an inclined angle of 45° are used in this study.Two artificial semi-spherical corrosion pits with the depths of 1 and 2 mm are constructed near the weld toe.The influence of corrosion on the fatigue strength of inclined weld cruciform joint is analyzed by fatigue tests and finite element method.Results show that the fatigue strength of inclined weld cruciform joints with the pit depths of 0,1 and 2 mm at 2 million cycles is 92.4,91.3 and 70.2 MPa,respectively.When the pit depth is less or equal to 1 mm,the effect of pit on fatigue strength can be neglected.The effect of different corrosive degrees on S—N curves of inclined weld cruciform joints should be considered.The pit depth has a significant effect on the fatigue strength of inclined weld cruciform joints.With the increase of pit depth at the same pit radius,the equivalent stress increases and the stress concentration is more evident.Because the correlation of the hot spot stress concentration factor and pit depth is better than depth to width ratio,the nonlinear function is also better than the linear function,the nonlinear function is recommended to fit the relationship between the hot spot stress concentration factor and pit depth.