铝合金缺口试样疲劳寿命预测新方法研究
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摘要
借鉴基于断裂力学的Walker裂纹扩展公式的形式,对主ΔSs-N方法中的裂纹扩展公式进行修正,得到一种新的考虑了平均应力影响的等效结构应力ΔSg.由于焊接结构中存在着高值残余应力,平均应力对于焊接接头的疲劳寿命影响并不显著,但对于非焊接缺口件,平均应力的影响是显著的.对11种铝合金缺口试样进行有限元分析,建立以ΔSg为参数的ΔSg-N曲线族,并对得到的数据进行二元线性回归分析,得到不同置信度下的主ΔSg-N曲线.将其与试验得到的以名义应力S和等效结构应力ΔSs为参数的ΔSs-N曲线族进行对比,发现ΔSg-N曲线存在着良好的归一性.
A new equivalent structural stress ΔSgwas obtained when the crack propagation formula in masterΔS-N method was corrected by using the Walker crack propagation formula for reference,the effect of mean stress was also included in this stress. High-value residual stress is found in the welded structures. The fatigue life is not too much influenced by mean stress,but for the non-welded notched specimen,it is significant. 11 kinds of finite element model of aluminum alloy notch specimens were analyzed. The master ΔSg-N curve under different degrees of confidence was obtained through the equation of bivariate linear regression. At last,the ΔSg-N curve was compared with the nominal stress S obtained by test and the equivalent structural stressΔSsin Verity,and the normalization is obvious.
A new equivalent structural stress ΔSgwas obtained when the crack propagation formula in masterΔS-N method was corrected by using the Walker crack propagation formula for reference,the effect of mean stress was also included in this stress. High-value residual stress is found in the welded structures. The fatigue life is not too much influenced by mean stress,but for the non-welded notched specimen,it is significant. 11 kinds of finite element model of aluminum alloy notch specimens were analyzed. The master ΔSg-N curve under different degrees of confidence was obtained through the equation of bivariate linear regression. At last,the ΔSg-N curve was compared with the nominal stress S obtained by test and the equivalent structural stressΔSsin Verity,and the normalization is obvious.
引文
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[10]陈传尧.疲劳与断裂[M].武汉:华中科技大学出版社,2002:59-67.
[2]姚卫星.金属材料疲劳行为的应力场强法描述[J].固体力学学报,1997,18(1):38-48.
[3]何柏林,王斌.疲劳失效预测的研究现状和发展趋势[J].机械设计与制造,2012,51(4):279-281.
[4]DONG P.A structural stress definition and numerical implementation for fatigue analysis of welded joints[J].International Journal of Fatigue,2001,23:865-876.
[5]DONG,P,HONG,JK.Analysis of recent fatigue data using the structural stress procedure in ASME Div2 rewrite[J].Journal of Pressure Vessel Technology,2007,129:355-362.
[6]KYUBA H,Dong P.Equilibrium-equivalent structural stress approach to fatigue analysis of a rectangular hollow section joint[J].International Journal of Fatigue,2005,27:85-94.
[7]DONG P.A robust structural stress method for fatigue analysis of offshore marine structures[J].Journal of Pressure Vessel Technology,2005,127:68-74.
[8]李向伟,兆文忠.基于Verity方法的焊缝疲劳评估原理及验证[J].焊接学报,2010,31(7):9-13.
[9]岳译新,刘永强,李晓峰.基于主S-N曲线法的地铁车体焊缝疲劳分析[J].机车电力传动,2012,53(5):79-81.
[10]陈传尧.疲劳与断裂[M].武汉:华中科技大学出版社,2002:59-67.