人工蚀坑对复杂应力场下钢桥焊接接头疲劳寿命的影响  

Effect of Artificial Corrosion Pits on Fatigue Life of Welded Joints of Steel Bridge under Complex Stress Fields

作　　者：揭志羽[1] 李亚东[2] 卫星[2] 诸葛萍[1] 

机构地区：[1]宁波大学建筑工程与环境学院,浙江宁波315211 [2]西南交通大学土木工程学院,四川成都610031

出　　处：《铁道学报》2017年第8期148-153,共6页Journal of the China Railway Society

基　　金：国家自然科学基金(51378430;51378431);浙江省自然科学基金(LQ17E080005)

摘　　要：为研究人工蚀坑对复杂应力场下钢桥焊接接头疲劳寿命的影响规律,以45°倾角全熔透承载角焊缝十字形焊接接头为研究对象,构造两种不同深度的人工半球形蚀坑模拟实际腐蚀情况;对不同蚀坑深度下的焊接接头进行轴向拉伸疲劳试验,建立疲劳缺口系数与蚀坑深度的关系;提出一种考虑蚀坑深度和应力幅的腐蚀疲劳寿命影响系数定义方式。结果表明:在相同蚀坑半径下,随着蚀坑深度的增加,疲劳缺口系数及其变化率均增大,疲劳缺口敏感系数为0.389;不同蚀坑深度和应力幅下焊接接头的疲劳寿命不同,蚀坑深度对疲劳寿命的影响更灵敏;基于腐蚀疲劳寿命影响系数得到的疲劳寿命预测值与试验值最大相对误差为-21.5%,表明两者吻合较好,因此环境腐蚀下应综合考虑蚀坑深度和应力幅对焊接接头疲劳寿命降低程度的影响。In order to study the effect of artificial corrosion pits on fatigue life of welded joints of steel bridges under complex stress fields, firstly, taking full penetration load-carrying fillet cruciform welded joints with 45° inclined angle as the research object, two artificial semispherical pits with different depths were constructed to simulate the real corrosion situations. Secondly, the axial tension fatigue test of welded joints with different corrosion pit depths was conducted to establish the relationship between fatigue notch factor and pit depth. Fi-nally, a method for defining the corrosion fatigue life influence coefficient considering pit depth and stress range was proposed. The results show that both the fatigue notch factor and its change rate increase with the increase of pit depth under the same corrosion pit radius. The fatigue notch sensitivity coefficient is 0. 389. The fatigue life of welded joints under different pit depths and stress ranges is different. The effect of pit depth on fatigue life is more sensitive. The maximum relative error between the predicted values based on the corrosion fatigue life influence coefficient and the test values is -21. 5%, showing good agreement between the predicted values and the test values. The effects of pit depth and stress range on the reduction of fatigue life of welded joints under environmental corrosion should be comprehensively considered.

关 键 词：腐蚀损伤 复杂应力场 焊接接头 疲劳缺口系数 腐蚀疲劳寿命影响系数 

分 类 号：U441.4[建筑科学—桥梁与隧道工程] TG405[交通运输工程—道路与铁道工程]