管板焊接节点多轴疲劳性能及寿命预测方法  

Multiaxial fatigue behavior and life prediction of tube-flange welded joints

作　　者：韩庆华[1,2,3] 李洋 芦燕 王培鹏[3,4] HAN Qinghua;LI Yang;LU Yan;WANG Peipeng(Key Laboratory of Earthquake Engineering Simulation and Seismic Resilience of China Earthquake Administration,Tianjin University,Tianjin 300350,China;Key Laboratory of Coast Structure Safety,Ministry of Education,Tianjin University,Tianjin 300350,China;School of Civil Engineering,Tianjin University,Tianjin 300350,China;School of Civil Engineering,Tianjin Chengjian University,Tianjin 300384,China)

机构地区：[1]天津大学中国地震局地震工程综合模拟与城乡抗震韧性重点实验室,天津300350 [2]天津大学滨海土木工程结构与安全教育部重点实验室,天津300350 [3]天津大学建筑工程学院,天津300350 [4]天津城建大学土木工程学院,天津300384

出　　处：《建筑结构学报》2023年第8期234-245,共12页Journal of Building Structures

基　　金：国家自然科学基金项目(52278199,52022067)。

摘　　要：管板焊接节点易处于弯剪扭复杂受力状态,为研究其疲劳失效受多轴疲劳机理,开展了以管轴力控制的Q235B管板焊接节点多轴疲劳试验,考虑轴向与切向应力分量相位差、切向与轴向应力幅值比和加载波形等多轴加载路径因素的影响,获得焊接节点多轴循环受力响应、疲劳裂纹宏观形貌及多轴疲劳性能。研究发现:疲劳加载过程中节点经历稳定循环、刚度退化及断裂失效等三个阶段,对于存在非比例强化的节点在稳定加载时会出现循环软化现象;在刚度退化阶段,轴向刚度与扭转刚度不同步退化;反映非比例强化效应的路径因子越大,疲劳断面的粗糙程度越高;多轴比例加载路径下的节点疲劳寿命大于非比例加载路径下的;非比例加载路径中,圆形加载路径下的节点疲劳寿命最小。采用现有的临界面模型和考虑应变加权的临界面模型计算了管板焊接节点多轴疲劳寿命并进行对比。结果显示,考虑应变加权的临界面模型疲劳寿命预测精度最高,在1.5倍、2倍和2.5倍误差带内预测数据占总数据的比例分别为64.3%、88.1%和100%。Tube-flange welded joints are prone to a complex stress state due to bending,shear,and torsion and the fatigue failure may be controlled by a multiaxial fatigue mechanism.The multiaxial fatigue test of Q235B tube-flange welded joints controlled by force was carried out.Considering the effects of multiaxial loading path,such as phase difference of axial and tangential stress components,tangential and axial stress amplitude ratio and loading waveform,the multiaxial cyclic mechanical response,macro morphology of fatigue cracks and multiaxial fatigue properties of welded joints were obtained.The results show that during the fatigue loading process,joints go through three stages including stable cycle,stiffness degradation,and fracture failure.For the joint with non-proportional strengthening,cyclic softening will occur during stable loading.In the stiffness degradation stage,the axial stiffness and torsional stiffness do not degrade synchronously.The larger the path factor reflecting the non-proportional strengthening effect,the higher roughness of the fatigue section is observed.The fatigue life of joints under multiaxial proportional loading path is greater than that under non proportional loading path.In non-proportional loading paths,the fatigue life of joints under circular loading paths is the smallest.The multiaxial fatigue life of tube-flange welded joints was calculated and compared by using existing critical plane models and weighted critical plane models based on structural strain.The results show that the weighted critical plane model based on structural strain has the highest accuracy in predicting fatigue life,with predicted data accounting for 64.3%,88.1%,and 100%of the total data within the error bands of 1.5 times,2 times,and 2.5 times,respectively.

关 键 词：管板焊接节点 多轴疲劳 非比例加载 应变加权法 疲劳寿命预测 

分 类 号：TU391[建筑科学—结构工程]