铸造起重机金属结构的疲劳评定方法研究
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摘要
铸造起重机金属结构的疲劳裂纹源主要位于构造形状突变区域的焊趾部位,裂纹从焊趾处萌生并扩展,因此必须引入局部应力概念对其进行疲劳评定。针对某在役铸造起重机金属结构,分别采用基于中值主S-N曲线的等效结构应力法和基于等效结构应力强度因子的断裂力学法,估算了端梁结构4条主焊缝危险点的疲劳寿命。结合铸造起重机实测裂纹数据进行了反推计算,获得了等效结构应力法的适用S-N曲线和断裂力学法的适用初始裂纹表面长度。研究表明,常规参数的等效结构应力法和断裂力学法是一般焊接结构疲劳评定的有效方法,但针对焊缝质量有特殊要求的重要焊接结构,必须采用合理的参数才能获得较准确的估算结果。
The fatigue crack source of casting crane's metal structure is mainly located at the weld toe where the structural shape mutation. The crack initiates and propagates from the weld toe,so the concept of local stress must be introduced to evaluate the fatigue life. According to the metal structure of a casting crane,the fatigue life of the four main welded joints of the end beam structure is estimated. Respectively using equivalent structural stress method based on mean master S-N curve and using fracture mechanics method based on equivalent structural stress intensity factors. The applicable curve of equivalent structural stress method and the applicable crack length for fracture mechanics method is obtained according to the measured crack data of casting crane. Studies have shown that conventional parameters of both equivalent structural stress method and fracture mechanics method are effective for the fatigue evaluation of welded structure,but for the engineering welding structure with specific welding quality must be used to reasonable parameters to obtain a good estimation results.
The fatigue crack source of casting crane's metal structure is mainly located at the weld toe where the structural shape mutation. The crack initiates and propagates from the weld toe,so the concept of local stress must be introduced to evaluate the fatigue life. According to the metal structure of a casting crane,the fatigue life of the four main welded joints of the end beam structure is estimated. Respectively using equivalent structural stress method based on mean master S-N curve and using fracture mechanics method based on equivalent structural stress intensity factors. The applicable curve of equivalent structural stress method and the applicable crack length for fracture mechanics method is obtained according to the measured crack data of casting crane. Studies have shown that conventional parameters of both equivalent structural stress method and fracture mechanics method are effective for the fatigue evaluation of welded structure,but for the engineering welding structure with specific welding quality must be used to reasonable parameters to obtain a good estimation results.
引文
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[8]Kyuba H,Dong P.Equilibrium-equivalent structural stress approach to fatigue analysis of a rectangular hollow section joint[J].International Journal of Fatigue,2005,27(1):85-94.
[9]Baik B,Yamada K,Ishikawa T.Fatigue crack propagation analysis for welded joint subjected to bending[J].International Journal of Fatigue,2011,33(5):746-758.
[10]Sause R,Abbas H H,Driver R G.Fatigue life of girders with trapezoidal corrugated webs[J].Journal of Structural Engineering,2006,132(7):1070-1078.
[11]张玉琴,窦玉香,郜拥军.桥式起重机主梁结构剩余疲劳寿命估算[J].中国重型装备,2008(2):12-14.(Zhang Yu-qin,Dou Yu-xiang,Gao Yong-jun.The residual fatigue life estimatioin of the bridge crane main beam[J].China Heavy Equipmen,2008(2):12-14.)
[2]徐格宁,范小宁,陆凤仪.起重机焊接箱形梁疲劳可靠度及初始裂纹的蒙特卡罗仿真[J].机械工程学报,2011(20):41-44.(Xu Ge-ning,Fan Xiao-ning,Lu Feng-yi.Monte carlo simulation of fatigue reliabilities and initial cracks for welded box girders of crane[J].Journal of Mechanical Engineering,2011(20):41-44.)
[3]熊刚,吴晓,罗友红.含缺陷起重机箱形梁结构断裂分析与有限元仿真[J].机械设计与制造,2016(4):207-210.(Xiong Gang,Wu Xiao,Luo You-hong.Fracture analysis and finite element simulation of crane box girder structure containing defects[J].Machinery Design&Manufacture,2016(4):207-210.)
[4]申本超,许三宜.520t铸造起重机主梁关键焊缝质量控制工艺[J].起重运输机械,2015(9):111-113.(Shen Ben-chao,Xu San-yi.Quality control of key weld in 520t casting crane[J].Lifting the Transport Machinery,2015(9):111-113.)
[5]Tong X,Tuan C Y,Yang J.Fatigue strength of end-coped crane runway girders[J].Journal of Structural Engineering,2007,133(12):1783-1791.
[6]周超,万金镇,郑健.基于等效结构应力法的起重机箱形结构焊缝疲劳强度分析[J].机械设计与制造,2013(5):232-234.(Zhou Chao,Wan Jin-zhen,Zheng Jian.The weld fatigue strength analysis of box girder with equivalent stress method[J].Machinery Design&Manufacture,2013(5):232-234.)
[7]Dong P.A structural stress definition and numerical implementation for fatigue analysis of welded joints[J].International Journal of Fatigue,2001,23(10):865-876.
[8]Kyuba H,Dong P.Equilibrium-equivalent structural stress approach to fatigue analysis of a rectangular hollow section joint[J].International Journal of Fatigue,2005,27(1):85-94.
[9]Baik B,Yamada K,Ishikawa T.Fatigue crack propagation analysis for welded joint subjected to bending[J].International Journal of Fatigue,2011,33(5):746-758.
[10]Sause R,Abbas H H,Driver R G.Fatigue life of girders with trapezoidal corrugated webs[J].Journal of Structural Engineering,2006,132(7):1070-1078.
[11]张玉琴,窦玉香,郜拥军.桥式起重机主梁结构剩余疲劳寿命估算[J].中国重型装备,2008(2):12-14.(Zhang Yu-qin,Dou Yu-xiang,Gao Yong-jun.The residual fatigue life estimatioin of the bridge crane main beam[J].China Heavy Equipmen,2008(2):12-14.)