Q345等边角钢腐蚀疲劳性能试验研究

Experimental research on the corrosion fatigue properties of Q345 equal angles

针对角钢构件在输电塔线体系服役期间因环境腐蚀与风致振动耦合作用导致疲劳性能退化,而构件腐蚀疲劳试验成本高、耗时久、难度大等限制因素所致试验资料匮乏问题,基于节省成本、提高精度思路,结合单点-似然法与相关系数优化法,提出确定腐蚀疲劳S-N曲线表达式参数的改进回归分析方法,构造与之对应的实现算法,建立随腐蚀时间变化的t-P-S-N曲面表达式;通过三组不同腐蚀时间的18根足尺试件疲劳试验,研究Q345等边角钢腐蚀疲劳破坏模式,分析P-S-N曲面方程中各参数随腐蚀时间的变化规律,并结合理论分析建立Q345等边角钢构件t-P-S-N曲面模型。采用该模型探讨不同腐蚀时间内Q345等边角钢构件疲劳寿命的变化规律。结果表明,相同疲劳荷载水平作用下试件疲劳寿命随腐蚀时间急剧减小;同一腐蚀时间内疲劳寿命受腐蚀因素的影响程度随荷载的减小而增加。

Because of the coupling between environment corrosion and wind-induced vibration,the fatigue properties of angles will degenerate during service period.From the view point of cost saving and precision improving,an improved regression method for estimating S-N curves of corrosion fatigue was proposed by combining the single-point likelihood method （SPLM）with the optimization of correlation coefficient.The implementation algorithm for the improved SPLM was also proposed.According to the improved method,an expression for the t-P-S-N surface of corrosion fatigue was presented.Meanwhile,the corrosion fatigue of three types of 18 Q345 equal angles in different corrosion time duration were tested.The corrosion fatigue failure modes of specimens were observed and the variation of P-S-N curves in different corrosion time duration was investigated.Then the t-P-S-N surface model of Q345 equal angles was achieved and the variation law of Q345 equal angles＇ fatigue life was obtained.It is found that the fatigue life decreases sharply with the increase of corrosion time under the same load;the effect of corrosion on fatigue life becomes more and more serious with the decrease of load in the same corrosion time.