摘要
为研究坑蚀对钢材低周疲劳性能的影响,以中国常用的结构钢材Q345为例,通过有限元分析并基于微观断裂判据循环空穴扩张模型(CVGM),对坑蚀钢材试件进行低周疲劳断裂预测,并通过与完好试件的结果对比,分析了蚀坑对钢材低周疲劳寿命的影响机理。在此基础上,研究了蚀坑的几何特征、分布形式以及荷载的应变幅等因素对钢材低周疲劳寿命的影响规律。结果表明:由于蚀坑断裂起始点等效塑性应变的加倍累积,与均匀锈蚀相比,蚀坑的存在更显著地改变了钢材的应力分布,进而降低其低周疲劳寿命,降低幅度可达50%以上;蚀坑深度和直径分别达到截面宽度的5%和厚度的20%以上时,断裂起始点的等效塑性应变随蚀坑深度增大而增加,低周疲劳寿命相应减小;多蚀坑试件的低周疲劳寿命总体上比单蚀坑试件明显降低,降幅为20%~30%;随应变幅增大,坑蚀对钢材低周疲劳性能的影响逐渐增大;基于强度等效原则的等效厚度设计方法无法反映坑蚀对钢材低周疲劳性能的影响。
In order to investigate the effect of pitting corrosion on the low fatigue behavior of steel,the commonly used structural steel Q345 in China was taken as example.Through finite element analysis and based on the micromechanical fracture criteria of cyclic void growth model(CVGM),the low fatigue fracture initiation of the pitting corrosion steel specimens was predicted,and the results were compared with those of intact specimens to explore the effect mechanism of pitting on low cycle fatigue life of steels.On the basis,the effects of the geometrical characteristics,distribution and strain amplitude of the pits on the low cycle fatigue life of steel were studied.The results show that in comparison with uniform corrosion,pitting corrosion can obviously change the stress distribution of steel,and further significantly reduce the low cycle fatigue life of steel by more than 50%,which mainly due to the multiply accumulation of equivalent plastic strain at the fracture initiation points in the pits.When the depth and diameter of pit reach 5%of the width and 20%of the thickness of the section,respectively,the equivalent plastic strain at the fracture initiation points in the pits increases with increasing of pit depth,and the low cycle fatigue life decreases accordingly.Besides,the low cycle fatigue life of multi-pit specimens is significantly lower by 20%-30%than that of single pit ones.Furthermore,as the strain amplitude increases,the effect of pitting corrosion on the low cycle fatigue properties of steel increases gradually.The equivalent thickness design method based on strength equivalence principle can not reflect the effect of pitting on low cycle fatigue properties of steel.
作者
沈玲华
AMOAKO-ATTA Godwin
王彤
SHEN Ling-hua;AMOAKO-ATTA Godwin;WANG Tong(School of Civil Engineering and Architecture,Zhejiang University of Science & Technology,Hangzhou 310023,Zhejiang,China;College of Civil Engineering and Architecture,Zhejiang University,Hangzhou 310058,Zhejiang,China;Zhejiang Provincial Key Laboratory of Space Structures,Zhejiang University,Hangzhou 310058,Zhejiang,China)
出处
《建筑科学与工程学报》
CAS
北大核心
2019年第3期83-90,共8页
Journal of Architecture and Civil Engineering
基金
国家自然科学基金项目(51708506)
浙江省空间结构重点实验室开放基金项目(201702)
关键词
钢材
坑蚀
低周疲劳
循环空穴扩张模型
等效塑性应变
steel
pitting corrosion
low cycle fatigue
cyclic void growth model
equivalent plastic strain
