基于缺口应力法的焊接接头多轴疲劳分析
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摘要
鉴于当前焊接接头疲劳评估曲线只适用于单轴加载情况,基于缺口应力法对焊接接头进行了多轴疲劳分析。通过联合焊接接头的多轴疲劳试验名义应力数据和有限元法所计算的缺口应力集中系数,获得了5种焊接接头的各向缺口应力;根据Von Mises、IIW和EESH 3种多轴疲劳准则计算出等效缺口应力并将其统一在同一坐标系统下;最后采用最小二乘法拟合出适用于多轴疲劳评估的缺口寿命曲线。与IIW标准推荐的单轴曲线相比,这些多轴缺口疲劳曲线具有更低的倾斜度和更高的疲劳等级,即多轴加载时明显降低了10~3~10~6次中周范围内的疲劳强度值,而对10~6~10~7次高周疲劳范围的影响则相对有限。
As the existing fatigue assessment curves of welded joints are only applicable to uniaxial load,we analyzed the multi-axial fatigue of welded joints on the basis of notch stress method.Firstly,through the combination of the nominal stress data in the multi-axial fatigue test of welded joints and the notch stress concentration factor calculated by finite element method,the notch stresses of 5kinds of welded joints in different directions were obtained.Secondly,equivalent notch stresses were respectively calculated according to 3kinds of multi-axial fatigue criteria,i.e.Von Mises,IIW(International Institute of Welding)and EESH(equivalent effective stress hypothesis),and they were unified into the same coordinate system.Finally,the fatigue life curves that were applicable to the assessment of the multi-axial notch fatigue were fitted out with the least square method.Compared with the uniaxial curve recommended by IIW,the multi-axial fatigue curves have lower inclination and higher fatigue class.The fatigue strength value within the mid-circle range from 10~3 to 10~6 circles is obviously reduced when multi-axial is loaded,while the influence on the high circle fatigue range from 10~6 to 10~7 circles is relatively limited.
As the existing fatigue assessment curves of welded joints are only applicable to uniaxial load,we analyzed the multi-axial fatigue of welded joints on the basis of notch stress method.Firstly,through the combination of the nominal stress data in the multi-axial fatigue test of welded joints and the notch stress concentration factor calculated by finite element method,the notch stresses of 5kinds of welded joints in different directions were obtained.Secondly,equivalent notch stresses were respectively calculated according to 3kinds of multi-axial fatigue criteria,i.e.Von Mises,IIW(International Institute of Welding)and EESH(equivalent effective stress hypothesis),and they were unified into the same coordinate system.Finally,the fatigue life curves that were applicable to the assessment of the multi-axial notch fatigue were fitted out with the least square method.Compared with the uniaxial curve recommended by IIW,the multi-axial fatigue curves have lower inclination and higher fatigue class.The fatigue strength value within the mid-circle range from 10~3 to 10~6 circles is obviously reduced when multi-axial is loaded,while the influence on the high circle fatigue range from 10~6 to 10~7 circles is relatively limited.
引文
[1]刘刚,刘英芳,黄一.焊接结构多轴疲劳寿命预测结构应力法[J].船舶力学,2014,18(10):1220-1227.LIU Gang,LIU Yingfang,HUANG Yi.Structural stress approach for multiaxial fatigue life estimation of welded structures[J].Journal of Ship Mechanics,2014,18(10):1220-1227.(in Chinese)
[2]Sonsino C M.A consideration of allowable equivalent stresses for fatigue design of welded joints according to the notch stress concept with the reference radii ref=1.00and 0.05 mm[J].Welding in the World Le Soudage Dans Le Monde,2009,53(3-4):64-75.
[3]Bckstr9m M.Multiaxial fatigue life assessment of welds based on nominal and hot spot stresses[D].Finland:Laapeenranta University,2003.
[4]Takahashi I,Ushijima M,Takada A,et al.Fatigue behaviour of a box-welded joint under biaxial cyclic loads[J].Fatigue&Fracture of Engineering Materials&Structures,1999,22(10):869-877.
[5]Sonsino C M.Multiaxial fatigue of welded joints under in-phase and out-of-phase local strains and stresses[J].International Journal of Fatigue,1995,17(1):55-70.
[6]Yousefi F,Witt M,Zenner H.Fatigue strength of welded joints under multiaxial loading:experiments and calculations[J].Fatigue&Fracture of Engineering Materials&Structures,2001,24(5):339-355.
[7]Sonsino C M,Fricke W,Bruyne F D,et al.Notch stress concepts for the fatigue assessment of welded joints–Background and applications[J].International Journal of Fatigue,2012,34(1):1-16.
[8]Radaj D,Lazzarin P,Berto F.Generalized Neuber concept of fictitious notch rounding[J].International Journal of Fatigue,2013,51:105-115.
[9]Sonsino C M,Kueppers M,Eibl M,et al.Fatigue strength of laser beam welded thin steel structures under multiaxial loading[J].International Journal of Fatigue,2006,28(5-6):657-662.
[10]Sonsino C M.Multiaxial fatigue assessment of welded joints:Recommendations for design codes[J].International Journal of Fatigue,2009,31(1):173-187.
[11]Hobbacher,A.Fatigue design of welded joints and components[M].Cambridge:Abington Publishing,2007.
[12]邱宝象,高增梁,王效贵,等.基于有限元法的16MnR缺口件疲劳寿命预测方法[J].工程力学,2010,27(8):21-27.QIU Baoxiang,GAO Zengliang,WANG Xiaogui,et al.A fatigue life prediction method for 16mnr steel notched components based on the finite element method[J].Engineering Mechanics,2010,27(8):21-27.(in Chinese)
[13]吴志荣,胡绪腾,宋迎东.多轴载荷下缺口件的疲劳寿命估算方法[J].工程力学,2014,31(10):216-221.WU Zhirong,HU Xuteng,SONG Yingdong.Estimation method for fatigue life of notched specimen under multi-axial loading[J].Engineering Mechanics,2014,31(10):216-221.(in Chinese)
[14]刘旭,张开林,姚远,等.缺口应力法在机车焊接构架疲劳分析中的应用[J].铁道学报,2015,37(1):24-29.LIU Xu,ZHANG Kailin,YAO Yuan,et al.Application of notch stress method in fatigue analysis of locomotive welded frame[J].Journal of the China Railway Society,2015,37(1):24-29.(in Chinese)
[2]Sonsino C M.A consideration of allowable equivalent stresses for fatigue design of welded joints according to the notch stress concept with the reference radii ref=1.00and 0.05 mm[J].Welding in the World Le Soudage Dans Le Monde,2009,53(3-4):64-75.
[3]Bckstr9m M.Multiaxial fatigue life assessment of welds based on nominal and hot spot stresses[D].Finland:Laapeenranta University,2003.
[4]Takahashi I,Ushijima M,Takada A,et al.Fatigue behaviour of a box-welded joint under biaxial cyclic loads[J].Fatigue&Fracture of Engineering Materials&Structures,1999,22(10):869-877.
[5]Sonsino C M.Multiaxial fatigue of welded joints under in-phase and out-of-phase local strains and stresses[J].International Journal of Fatigue,1995,17(1):55-70.
[6]Yousefi F,Witt M,Zenner H.Fatigue strength of welded joints under multiaxial loading:experiments and calculations[J].Fatigue&Fracture of Engineering Materials&Structures,2001,24(5):339-355.
[7]Sonsino C M,Fricke W,Bruyne F D,et al.Notch stress concepts for the fatigue assessment of welded joints–Background and applications[J].International Journal of Fatigue,2012,34(1):1-16.
[8]Radaj D,Lazzarin P,Berto F.Generalized Neuber concept of fictitious notch rounding[J].International Journal of Fatigue,2013,51:105-115.
[9]Sonsino C M,Kueppers M,Eibl M,et al.Fatigue strength of laser beam welded thin steel structures under multiaxial loading[J].International Journal of Fatigue,2006,28(5-6):657-662.
[10]Sonsino C M.Multiaxial fatigue assessment of welded joints:Recommendations for design codes[J].International Journal of Fatigue,2009,31(1):173-187.
[11]Hobbacher,A.Fatigue design of welded joints and components[M].Cambridge:Abington Publishing,2007.
[12]邱宝象,高增梁,王效贵,等.基于有限元法的16MnR缺口件疲劳寿命预测方法[J].工程力学,2010,27(8):21-27.QIU Baoxiang,GAO Zengliang,WANG Xiaogui,et al.A fatigue life prediction method for 16mnr steel notched components based on the finite element method[J].Engineering Mechanics,2010,27(8):21-27.(in Chinese)
[13]吴志荣,胡绪腾,宋迎东.多轴载荷下缺口件的疲劳寿命估算方法[J].工程力学,2014,31(10):216-221.WU Zhirong,HU Xuteng,SONG Yingdong.Estimation method for fatigue life of notched specimen under multi-axial loading[J].Engineering Mechanics,2014,31(10):216-221.(in Chinese)
[14]刘旭,张开林,姚远,等.缺口应力法在机车焊接构架疲劳分析中的应用[J].铁道学报,2015,37(1):24-29.LIU Xu,ZHANG Kailin,YAO Yuan,et al.Application of notch stress method in fatigue analysis of locomotive welded frame[J].Journal of the China Railway Society,2015,37(1):24-29.(in Chinese)