基于Gerber模型的DFR腐蚀折算系数及其试验测定
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摘要
为了将细节疲劳额定值(DFR)法的适用范围扩展到腐蚀条件下,采用腐蚀折算系数对DFR进行当量折算的方法,建立了基于Gerber模型的DFR法在腐蚀条件下的分析方法,并通过腐蚀折算系数的分解使此法可用于单独研究地面预腐蚀和空中腐蚀疲劳对DFR的影响。通过设置九组不同时长(0 h、6 h、12 h、24 h、36 h、72 h、108 h、144 h和180 h)的预腐蚀疲劳试验,测定了2024-T3铝合金的地面停放腐蚀折算系数;比较了基于Gerber模型和Goodman模型的DFR法在一般条件和腐蚀条件下的计算结果。结果表明:随着预腐蚀时间的延长,2024-T3铝合金的细节疲劳额定值截止值(DFR_(cutoff))下降;在九组不同时长下,基于Gerber模型计算的DFR_(cutoff)依次为84.251 MPa、84.722 MPa、79.683 MPa、80.745 MPa、77.026 MPa、74.996 MPa、75.613 MPa、76.186 MPa和73.798 MPa,地面停放腐蚀折算系数为1、1.006、0.946、0.958、0.914、0.890、0.897、0.904、0.876,拟合得到DFR_(cutoff)与预腐蚀时长满足:DFR_(cutoff)=84.521[lg(t+10)]~(-0.149 8)。在未考虑腐蚀影响的条件下N_(95/95)>10~5时,考虑腐蚀影响的条件下N_1>10~5时,基于Gerber模型计算的DFR均大于基于Goodman模型的计算结果。
In order to extend the applicability of the new DFR method to corrosion conditions, via transfer the influence of corrosion environment on fatigue life to the DFR equivalently, the DFR method based on Gerber model under corrosive environment for fatigue analysis was established, and the decomposition of DFR-corrosion-influence-factors enables this method to study the effect of ground-corrosion-influence and air-corrosion-fatigue-influence on DFR independently. The ground-corrosion-influence-factor of 2024-T3 aluminum alloy was determined by nine different pre-corrosion fatigue tests. Under normal conditions and corrosion conditions, the calculation results of the DFR method based on Goodman model and Gerber model were compared. Results show that as the pre-corrosion time increases, the DFR_(cutoff) of 2024-T3 aluminum alloy decreases; the DFR_(cutoff) based on Gerber model are 84.251 MPa, 84.722 MPa, 79.683 MPa, 80.745 MPa, 77.026 MPa, 74.996 MPa, 75.613 MPa, 76.186 MPa and 73.798 MPa respectively, and the ground-corrosion-influence-factor is 1, 1.006, 0.946, 0.958, 0.914, 0.890, 0.897, 0.904, 0.876 the fitting curve of the DFR_(cutoff) with the pre-corrosion time is DFR_(cutoff)=84.521[lg(t+10)]~(-0.149 8). Calculating found under the condition of neglecting the influence of corrosions when N_(95/95)>10~5 cycle, under the condition of considering the influence of corrosions when N_1>10~5 cycle, the calculation results of DFR method based on Gerber model is greater than that of DFR method based on Goodman model.
In order to extend the applicability of the new DFR method to corrosion conditions, via transfer the influence of corrosion environment on fatigue life to the DFR equivalently, the DFR method based on Gerber model under corrosive environment for fatigue analysis was established, and the decomposition of DFR-corrosion-influence-factors enables this method to study the effect of ground-corrosion-influence and air-corrosion-fatigue-influence on DFR independently. The ground-corrosion-influence-factor of 2024-T3 aluminum alloy was determined by nine different pre-corrosion fatigue tests. Under normal conditions and corrosion conditions, the calculation results of the DFR method based on Goodman model and Gerber model were compared. Results show that as the pre-corrosion time increases, the DFR_(cutoff) of 2024-T3 aluminum alloy decreases; the DFR_(cutoff) based on Gerber model are 84.251 MPa, 84.722 MPa, 79.683 MPa, 80.745 MPa, 77.026 MPa, 74.996 MPa, 75.613 MPa, 76.186 MPa and 73.798 MPa respectively, and the ground-corrosion-influence-factor is 1, 1.006, 0.946, 0.958, 0.914, 0.890, 0.897, 0.904, 0.876 the fitting curve of the DFR_(cutoff) with the pre-corrosion time is DFR_(cutoff)=84.521[lg(t+10)]~(-0.149 8). Calculating found under the condition of neglecting the influence of corrosions when N_(95/95)>10~5 cycle, under the condition of considering the influence of corrosions when N_1>10~5 cycle, the calculation results of DFR method based on Gerber model is greater than that of DFR method based on Goodman model.
引文
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2 Chen X M,Liao J H,Dong D K,et al.Journal of Machine Design,2014(12),16 (in Chinese).陈先民,廖江海,董登科,等.机械设计,2014(12),16.
3 Liu W T.Military aircraft structural fatigue design detail fatigue rating methodological guide,National Defense Industry Press,China,2012 (in Chinese).刘文珽.军用飞机结构疲劳设计细节疲劳额定值方法指南,国防工业出版社,2012.
4 Li G L,Xue J C.Aircraft Design,2008,28(6),35 (in Chinese).李戈岚,薛俊川.飞机设计,2008,28(6),35.
5 Yang Y G,Xue J C,Jiao K F,et al.Journal of Mechanical Strength,2004,26(s1),52 (in Chinese).杨玉恭,薛景川,焦坤芳,等.机械强度,2004,26(s1),52.
6 Dong D K,Yang Y G,Xue J C,et al.In:National Conference on Structural Engineering.Xinjiang,2013,pp.196 (in Chinese).董登科,杨玉恭,薛景川,等.全国结构工程学术会议.新疆,2013,pp.196.
7 Gong Y S,Xie Y H,Zang M,et al.Study of Structural Srength,2006(3),38 (in Chinese).弓云昭,谢宇航,张茂,等.结构强度研究,2006(3),38.
8 Guan D,Sun Q.Journal of Mechanical Strength,2012,34(1),131 (in Chinese).关迪,孙秦.机械强度,2012,34(1),131.
9 Chen X M,Dong D K,Li S S.Chinese Journal of Applied Mechanics,2014 (3),473 (in Chinese).陈先民,董登科,李珊山.应用力学学报,2014 (3),473.
10 Huang X,Liu J Z,Ma S J,et al.Acta Aeronautica et Astronautica Sinica,2012,33(5),863 (in Chinese).黄啸,刘建中,马少俊,等.航空学报,2012,33(5),863.
11 Fan J L.Journal of Aeronautical Materials,2016,36(2),80 (in Chinese).樊俊铃.航空材料学报,2016,36(2),80.
12 Zhang J Y,Bao R,Chen B,et al.Journal of Beijing University of Aeronautics and Astronautics,2004,30(6),547 (in Chinese).张建宇,鲍蕊,陈勃,等.北京航空航天大学学报,2004,30(6),547.
13 Bao R,Zhang J Y,Zheng X L,et al.Journal of Beijing University of Aeronautics and Astronautics,2006,32(6),639 (in Chinese).鲍蕊,张建宇,郑晓玲,等.北京航空航天大学学报,2006,32(6),639.
14 Li Y H,Liu W T,Jiang D B,et al.Journal of Beijing University of Aeronautics and Astronautics,2002,28(1),30(in Chinese).李玉海,刘文珽,蒋冬滨,等.北京航空航天大学学报,2002,28(1),30.
15 Zhang J Y,Liu A M,Fei B J.Journal of Beijing University of Aeronautics and Astronautics,2000,26(5),556(in Chinese).张建宇,刘爱民,费斌军.北京航空航天大学学报,2000,26(5),556.
16 He X F,Liu W T,Wang Z B,et al.Journal of Mechanical Strength,2009,31(4),664(in Chinese).贺小帆,刘文珽,王忠波,等.机械强度,2009,31(4),664.
17 Bian G X,Chen Y L,Zhang D F,et al.Acta Aeronautica et Astronautica Sinica,2008,29(6),1526(in Chinese).卞贵学,陈跃良,张丹峰,等.航空学报,2008,29(6),1526.
18 Deng J H,Chen J P,Fu Y.Acta Aeronautica et Astronautica Sinica,2018(2),146(in Chinese).邓景辉,陈平剑,付裕.航空学报,2018(2),146.
19 Li Y B,Chen L,Dong D K,et al.Journal of Mechanical Strength,2012,34(6),934(in Chinese).李宴宾,陈莉,董登科,等.机械强度,2012,34(6),934.
20 Xue J C,Guo D W,Shao C.Study of Structural Strength,2006(1),1(in Chinese).薛景川,郭定文,邵闯.结构强度研究,2006(1),1.