对接焊缝初始缺陷对疲劳寿命影响规律研究

Effect of initial defect of butt weld on fatigue life

为研究钢桥面板对接焊缝中表面及内部缺陷对疲劳寿命的影响,文章运用FRANC3D与ABAQUS软件对等效后的基本焊接构造进行裂纹扩展分析,得到疲劳寿命随初始缺陷参数的变化关系,结果表明表面及内部缺陷在裂纹扩展中裂纹形状逐渐接近半圆形及圆形。不同初始参数对疲劳寿命的影响程度不同,表面及内部缺陷对缺陷形状比、尺寸、方向变化的敏感程度也不同,锁定形状比不变,短轴长增加3倍时,含内部缺陷试件的疲劳寿命降幅为68.9%,短轴长增加6.5倍时,含表面缺陷试件的疲劳寿命降幅为46.45%;锁定短半轴不变,当形状比从0.1增至0.6时,疲劳寿命平均增幅为88.7%(表面缺陷)和90.2%(内部缺陷);锁定尺寸不变,当缺陷植入角度从30°增至90°时,疲劳寿命的平均降幅为59.7%(表面缺陷)和62.3%(内部缺陷)。

In order to study the influence of surface and internal defects in the butt weld of the steel bridge deck on the fatigue life,the crack propagation of the equivalent basic welding structure is analyzed using FRANC3D and ABAQUS software,and the relationship between the fatigue life and the initial defect parameters is obtained.The results show that surface and internal defects gradually approach semicircular and circular crack shapes during crack propagation.Different initial parameters have different effects on the fatigue life,and the sensitivity of surface and internal defects to changes in defect aspect ratio,size,and direction is also different.Specifically,when the aspect ratio remains unchanged and the short axis length increases by 3 times,the fatigue life of the specimen with internal defects decreases by 68.9%,and when the short axis length increases by 6.5 times,the fatigue life of the specimen with surface defects decreases by 46.45%;when the short axis length remains unchanged and the aspect ratio increases from 0.1 to 0.6,the average increase in the fatigue life is 88.7%(surface defects)and 90.2%(internal defects);when the size remains the same and the defect implant angle increases from 30°to 90°,the average reduction in the fatigue life is 59.7%(surface defects)and 62.3%(internal defects).