摘要
针对焊接结构的疲劳裂纹演化过程,将焊接结构的疲劳寿命定义为裂纹萌生寿命Ni和裂纹扩展寿命N_p之和,提出一种结合S-N曲线和断裂力学理论的疲劳寿命分析方法.采用等效结构应力法和99%下限主S-N曲线计算焊接结构的裂纹萌生寿命,并将这一阶段结束时的裂纹看作为半椭圆表面裂纹.采用Paris裂纹扩展模型和半椭圆表面裂纹应力强度因子ΔK计算裂纹扩展寿命N_p.参照某起重机走行梁的疲劳试验结果进行对比和验证研究.结果表明,等效结构应力可以较好地表征复杂焊接结构的裂纹萌生特性,结合S-N曲线和断裂力学的疲劳寿命计算结果与试验结果具有较好的一致性.
According to the evolution of fatigue cracks in welded structures,the fatigue life of welded structures was defined as the sum of crack initiation life Ni and crack propagation life Np,and the SN curve and fracture mechanics combined with fatigue life evaluating method was proposed. Equivalent structural stress method and the lower 99% boundary of master SN curve were utilized to evaluate the crack initiation life,and cracks at the end of the initiation stage was regarded as semi-elliptical surface crack. Paris Equation and the stress intensity factor range of semi-elliptical surface cracks were utilized to evaluate the crack propagation life. Fatigue test data of 5 crane runway girder specimens from a reference were utilized to the comparisons and Validation investigation. Result showed that equivalent structural stress can characterize the crack initiation state of complex welded structures well,and there is a good consistency between the calculating fatigue life and the test life.
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2017年第2期23-27,共5页
Transactions of The China Welding Institution
基金
国家自然科学基金资助项目(51575408)
湖北省自然科学基金资助项目(2014CFB803)
武汉工程大学化工装备强化与本质安全湖北省重点实验室开放课题(2016KA02)
关键词
焊接结构
疲劳寿命
等效结构应力
S-N曲线
断裂力学
welded structures
fatigue life
equivalent structural stress
S-N curve
fracture mechanics
