腐蚀条件下基于Gerber模型的DFR推导及实测
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摘要
为了研究等寿命曲线模型的选取对细节疲劳额定值计算结果的影响,针对六种典型航空材料对比了Gerber模型和Goodman模型对于高周疲劳数据的拟合精度;推导基于Gerber模型的DFR计算公式、腐蚀折算系数CC的表达式;针对2024-T3铝合金(表面阳极化)进行了预腐蚀0 h、6 h、12 h、24 h、36 h和72 h的疲劳实验并分析预腐蚀72 h的疲劳断口。结果表明:Gerber模型适用于LY12CZ等铝合金,并且在N_(95/95)>10~5次时,基于Gerber模型的DFR法才能发挥延性材料的潜能;随着预腐蚀时间增长,2024-T3铝合金DFR值下降,基于Gerber模型计算的DFR分别为84.251 MPa、84.721 MPa、79.683 MPa、80.745 MPa、77.026 MPa和74.996 MPa,腐蚀折算系数CC为1.006、0.946、0.958、0.914、0.890,拟合得到DFR随预腐蚀时长的变化曲线是DFR=84.251[lg(t+10)]~(-0.15578);断口分析发现预腐蚀产生的蚀坑和材料中的夹杂物会加速疲劳裂纹的形成和扩展,导致结构的疲劳性能降低,但与裸材相比,阳极化过的试件的DFR在腐蚀环境中下降趋势减缓。
In order to study the influence of the equal-life curve models on DFR,the fitting accuracies of Gerber model and Goodman model for high-cycle fatigue data were compared with six typical aviation materials.The formula of DFR based on Gerber model and the expression of corrosion conversion coefficient CC were derived,pre-corrosion fatigue tests for 0 h,6 h,12 h,24 h,36 h,and 72 h of 2024-T3 aluminum alloy(surface anodizing) were carried out,and the fatigue fracture of pre-corrosion for 72 hours was analyzed.The results show that Goodman model is suitable for brittle materials while Gerber model is suitable for ductile materials.As the pre-corrosion time increases,the DFR of 2024-T3 aluminum alloy decreases.The DFR based on Gerber model are 84.251 MPa,84.721 MPa,79.683 MPa,80.745 MPa,77.026 MPa and 74.996 MPa respectively,and the CC is 1.006,0.946,0.958,DFR = 84.251[lg(t+10)]~(-0.15578).It is found that when N_(95/95)>10~5,the DFR method based on Gerber model can give full play to the fatigue performance of ductile materials.Corrosion pits produced by pre-corrosion and inclusions in materials can accelerate the formation and expansion of fatigue cracks,but DFR of the anodized specimens is decreased in a corrosive environment compared with the bare materials.
In order to study the influence of the equal-life curve models on DFR,the fitting accuracies of Gerber model and Goodman model for high-cycle fatigue data were compared with six typical aviation materials.The formula of DFR based on Gerber model and the expression of corrosion conversion coefficient CC were derived,pre-corrosion fatigue tests for 0 h,6 h,12 h,24 h,36 h,and 72 h of 2024-T3 aluminum alloy(surface anodizing) were carried out,and the fatigue fracture of pre-corrosion for 72 hours was analyzed.The results show that Goodman model is suitable for brittle materials while Gerber model is suitable for ductile materials.As the pre-corrosion time increases,the DFR of 2024-T3 aluminum alloy decreases.The DFR based on Gerber model are 84.251 MPa,84.721 MPa,79.683 MPa,80.745 MPa,77.026 MPa and 74.996 MPa respectively,and the CC is 1.006,0.946,0.958,DFR = 84.251[lg(t+10)]~(-0.15578).It is found that when N_(95/95)>10~5,the DFR method based on Gerber model can give full play to the fatigue performance of ductile materials.Corrosion pits produced by pre-corrosion and inclusions in materials can accelerate the formation and expansion of fatigue cracks,but DFR of the anodized specimens is decreased in a corrosive environment compared with the bare materials.
引文
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[7]樊俊铃.基于Gerber模型的DFR法与结构细节效应[J].航空材料学报,2016,36(2):80-86.(FAN J L.DFR method and structural detail effect based on gerber model[J].Journal of Aeronautical Materials,2016,36(2):80-86.)
[8]吴富民.结构疲劳强度[M].西安:西北工业大学出版社,1985.(WU F M.Fatigue strength of structures[M].Xi’an:Northwest Polytechnic University Press,1985)
[9]高镇同.航空金属材料疲劳性能手册[M].北京:北京航空材料研究所,1981.(GAO Z T.Fatigue performance manual for aviation metal materials[M].Beijing:Beijing Institute of Aeronautical Materials,1981)
[10]吴学仁.飞机结构金属材料力学性能手册[M].北京:航空工业出版社,1996.(WU X R.Handbook on mechanical properties of metal materials for aircraft structures[M].Beijing:Aviation Industry Press,1996)
[11]张建宇,鲍蕊,陈勃,等.腐蚀环境下疲劳分析的DFR方法研究[J].北京航空航天大学学报,2004,30(6):547-550.(ZHANG J Y,BAO R,CHEN B,et al.Study on DFRmethod under corrosive environment for fatigue analysis[J].Journal of Beijing University of Aeronautics and Astronautics,2004,30(6):547-550.)
[12]鲍蕊,张建宇,郑晓玲,等.DFR腐蚀影响系数及其实验测定[J].北京航空航天大学学报,2006,32(6):639-644.(BAO R,ZHANG J Y,ZHENG X L,et al.Theoretical and experimental determination of DFR-corrosion-influence-factors[J].Journal of Beijing University of Aeronautics and Astronautics,2006,32(6):639-644.)
[13]贺小帆,刘文珽,王忠波,等.预腐蚀对30CrMnSiNi2A连接件疲劳寿命影响的实验研究[J].机械强度,2009,31(4):664-669.(HE X F,LIU W T,WANG Z B,et al.Pre-corrosion degradation influence on the fatigue life for 30CrMnSiNi2Aspecimen[J].Journal of Mechanical Strength,2009,31(4):664-669.)
[14]李宴宾,陈莉,董登科,等.结构细节疲劳额定值与结构细节数之间的关系研究[J].机械强度,2012,34(6):934-938.(LI Y B,CHEN L,DONG D K,et al.Research on the relation between DFR and structural detail numbers[J].Journal of Mechanical Strength,2012,34(6):934-938.)
[15]薛景川,郭定文,邵闯.DFR、DCR和DSR疲劳损伤分析体系综论[J].结构强度研究,2012,33(5):863-870.(XUE J C,GUO D W,SHAO C.The analysis system of DFR,DCR and DSR fatigue damage[J].Study of structural strength,2012,33(5):863-870.)
[16]ZHU M L,XUAN F Z.Fatigue crack initiation potential from defects in terms of local stress analysis[J].Chinese Journal of Mechanical Engineering,2014,27(3):496-503.
[17]钟群鹏赵子华.断口学[M].北京:高等教育出版社,2006.(ZHONG Q P,ZHAO Z H.Fractography[M].Beijing:Higher Education Press,2006.)
[2]陈先民,廖江海,董登科.含多相似疲劳细节结构的细节疲劳额定值的估算模型[J].机械设计,2014,(12):16-20.(CHEN X M,LIAO J H,DONG D K,et al.Estimation model of detail fatigue rating for multiple similar fatigue structures[J].Journal of Machine Design,2014,(12):16-20.)
[3]刘文珽.军用飞机结构疲劳设计细节疲劳额定值方法指南[M].北京:国防工业出版社,2012.(LIU W T.Military aircraft structural fatigue design Detail Fatigue Rating methodological guide[M].Beijing:National Defense Industry Press,2012.)
[4]关迪,孙秦.机身典型连接接头DFR值分析方法研究[J].机械强度,2012,34(1):131-136.(GUAN D,SUN Q.Study on analysis method for DFR of the typical lapped joint in airframe[J].Journal of Mechanical Strength,2012,34(1):131-136.)
[5]陈先民,董登科,李珊山.细节疲劳额定值法的拓展应用研究[J].应用力学学报,2014(3):473-477.(CHEN X M,DONG D K.LI S S,Developing applications of Detail-Fatigue-Rating method[J].Chinese Journal of Applied Mechanics,2014(3):473-477.)
[6]黄啸,刘建中,马少俊,等.细节疲劳额定强度计算参量取值敏感性研究[J].航空学报,2012,33(5):863-870.(HUANG X,LIU J Z,MA S J,et al.Sensitivity analysis of the parameters in Detail Fatigue Rating equation[J].Acta Aeronautica et Astronautica Sinica,2012,33(5):863-870.)
[7]樊俊铃.基于Gerber模型的DFR法与结构细节效应[J].航空材料学报,2016,36(2):80-86.(FAN J L.DFR method and structural detail effect based on gerber model[J].Journal of Aeronautical Materials,2016,36(2):80-86.)
[8]吴富民.结构疲劳强度[M].西安:西北工业大学出版社,1985.(WU F M.Fatigue strength of structures[M].Xi’an:Northwest Polytechnic University Press,1985)
[9]高镇同.航空金属材料疲劳性能手册[M].北京:北京航空材料研究所,1981.(GAO Z T.Fatigue performance manual for aviation metal materials[M].Beijing:Beijing Institute of Aeronautical Materials,1981)
[10]吴学仁.飞机结构金属材料力学性能手册[M].北京:航空工业出版社,1996.(WU X R.Handbook on mechanical properties of metal materials for aircraft structures[M].Beijing:Aviation Industry Press,1996)
[11]张建宇,鲍蕊,陈勃,等.腐蚀环境下疲劳分析的DFR方法研究[J].北京航空航天大学学报,2004,30(6):547-550.(ZHANG J Y,BAO R,CHEN B,et al.Study on DFRmethod under corrosive environment for fatigue analysis[J].Journal of Beijing University of Aeronautics and Astronautics,2004,30(6):547-550.)
[12]鲍蕊,张建宇,郑晓玲,等.DFR腐蚀影响系数及其实验测定[J].北京航空航天大学学报,2006,32(6):639-644.(BAO R,ZHANG J Y,ZHENG X L,et al.Theoretical and experimental determination of DFR-corrosion-influence-factors[J].Journal of Beijing University of Aeronautics and Astronautics,2006,32(6):639-644.)
[13]贺小帆,刘文珽,王忠波,等.预腐蚀对30CrMnSiNi2A连接件疲劳寿命影响的实验研究[J].机械强度,2009,31(4):664-669.(HE X F,LIU W T,WANG Z B,et al.Pre-corrosion degradation influence on the fatigue life for 30CrMnSiNi2Aspecimen[J].Journal of Mechanical Strength,2009,31(4):664-669.)
[14]李宴宾,陈莉,董登科,等.结构细节疲劳额定值与结构细节数之间的关系研究[J].机械强度,2012,34(6):934-938.(LI Y B,CHEN L,DONG D K,et al.Research on the relation between DFR and structural detail numbers[J].Journal of Mechanical Strength,2012,34(6):934-938.)
[15]薛景川,郭定文,邵闯.DFR、DCR和DSR疲劳损伤分析体系综论[J].结构强度研究,2012,33(5):863-870.(XUE J C,GUO D W,SHAO C.The analysis system of DFR,DCR and DSR fatigue damage[J].Study of structural strength,2012,33(5):863-870.)
[16]ZHU M L,XUAN F Z.Fatigue crack initiation potential from defects in terms of local stress analysis[J].Chinese Journal of Mechanical Engineering,2014,27(3):496-503.
[17]钟群鹏赵子华.断口学[M].北京:高等教育出版社,2006.(ZHONG Q P,ZHAO Z H.Fractography[M].Beijing:Higher Education Press,2006.)