The landing gear structure of carrier-based aircraft is subject to not only erosion by marine atmosphere, salt spray and sea wave splashes, but also large ejection take off and arresting landing load. Under the combined action of marine environment and fatigue load, the bearing capacity of ultra-high strength steel landing gear structure is significantly deteriorated, posing a serious challenge to its safe use. Based on the marine environment in which the carrier-based aircraft is in service, corrosion fatigue tests were conducted on two kinds of test specimens of ultra-high strength steel: shot peened and unpeened. The variation rule of fatigue life was obtained. Through the analysis of roughness, grain size, micro-hardness, residual stress and fatigue fracture, the action mechanism of shot peening on fatigue life enhancement, the mechanism of alternate action of corrosion and fatigue damage and the mechanism of pre-corrosion fatigue damage were revealed. The results show an average increase of 93.1% in fatigue life after shot peening. For the shot peened specimen, a slight pitting with a depth of about 20 μm results in a fatigue life decay of about 30%. A competition mechanism exists between shot peening and corrosion. The damage mechanism of alternating corrosion and fatigue has a considerably more serious effect on the service life of the ultra-high strength steel than the pre-corrosion fatigue damage mechanism. Under the same conditions, the fatigue life of the former is only 47%-54% of that of the latter.
[1] 谭晓明,陈跃良,段成美. 飞机结构搭接件腐蚀三维裂纹扩展特性分析[J]. 航空学报,2005,26(1):66-69. TAN X M, CHEN Y L, DUAN C M. Analysis of growth characterization of 3-D cracks in corroded lap joints of aircraft structure[J]. Acta Aeronautica et Astronautica Sinica, 2005,26(1):66-69(in Chinese).
[2] TAN X M, CHEN Y L, JIN P. Corrosion fatigue life prediction of aircraft structure based on fuzzy reliability approach[J]. Chinese Journal of Aeronautics, 2005,18(4):346-351.
[3] 张丹峰,谭晓明,陈跃良. 海洋环境下飞机结构腐蚀疲劳研究现状[J]. 装备环境工程,2009, 6(2):5-8. ZHANG D F, TAN X M, CHEN Y L. Research progress of corrosion fatigue of aircraft structure under marine environment[J]. Equipment Environmental Engineering, 2009, 6(2):5-8(in Chinese).
[4] BROOKS C L, SIMPSON D. Integrating real time age degradation into the structural integrity process[C]//Proceedings AGARD Workshop on Fatigue in the Presence of Corrosion, 1998.
[5] 贺小帆,梁超.腐蚀退化加速因子模型与分析[J].机械强度,2010,32(2):299-304. HE X F, LIANG C. Model and analysis on the acceleration corrosion factor[J]. Journal of Mechanical Strength, 2010,32(2):299-304(in Chinese).
[6] 李玉海,贺小帆,陈群志. 铝合金试件腐蚀深度分布特性及变化规律研究[J]. 北京航空航天大学学报,2002,28(1):98-101. LI Y H, HE X F, CHEN Q Z. Investigation on distribution and variable rule for corrosion depth of aluminum alloy specimen[J]. Journal of Beijing University of Aeronautics and Astronautics,2002,28(1):98-101(in Chinese).
[7] 李旭东,穆志韬,孔光明.金属腐蚀形貌的分形表征[J].理化检验(物理分册),2014,50(9):639-642. LI X D, MU Z T. KONG G M. Fractal characterization of corrosion morphology of metallic material[J]. Physical Testing and Chemical Analysis(Part A:Physical Testing),2014,50(9):639-642(in Chinese).
[8] JONES K, SHINDE S R, CLARK P N, et al. Effect of prior corrosion on short crack behavior in 2024-T3 aluminum alloy[J]. Corrosion Science, 2008,50:2588-2595.
[9] JONES K, HOEPPNER D W. Prior corrosion and fatigue of 2024-T3aluminum alloy[J]. Corrosion Science, 2006,48:3109-3122.
[10] BIRBILIS N, CAVANAUGH M K, BUCHHEIT R G. Electrochemical behavior and localized corrosion associated with Al7Cu2Fe particlesin aluminum alloy 7075-T651[J]. Corrosion Science, 2006,48:4202-4215.
[11] HARLOW D G, ROBERT P W. Probability modeling and material microstructure applied to corrosion and fatigue of aluminum and steel alloys[J]. Engineering Fracture Mechanics,2009,76:695-708.
[12] 陈跃良,卞贵学,衣林,等. 腐蚀和疲劳交替作用下飞机铝合金疲劳性能及断裂机理研究[J].机械工程学报,2010,48(20):70-76. CHEN Y L, BIAN G X, YI L, et al. Research on fatigue characteristic and fracture mechanics of aluminum alloy under alternate action of corrosion and fatigue[J]. Journal of Mechanical Engineering, 2010,48(20):70-76(in Chinese).
[13] 谭晓明,张丹峰,卞贵学,等. 腐蚀对新型高强度铝合金疲劳裂纹萌生机制及扩展行为的作用研究[J].机械工程学报,2014,50(20):76-83. TAN X M, ZHANG D F, BIAN G X. Effect of corrosion damage on fatigue crack initiation mechanism and growth behavior of high strength aluminum alloy[J]. Journal of Mechanical Engineering, 2014,50(20):76-83(in Chinese).
[14] 谭晓明,张丹峰,陈跃良. 基于微观结构的2B06铝合金全寿命概率模拟[J].航空学报,2012,33(8):1434-1439. TAN X M, ZHANG D F, CHEN Y L. Probabilistic simulation approach for holistic life of aluminum alloy 2B06 based on material microstructure[J]. Acta Aeronautica et Astronautica Sinica, 2012,33(8):1434-1439(in Chinese).
[15] QUESNAY D L, UNDERHILL P R, BRITT H J. Fatigue crack growth from corrosion damage in 7075-T6511aluminium alloy under aircraft loading[J]. International Journal of Fatigue, 2003,25:371-377.
[16] JONES K, HOEPPNER D W. The interaction between pitting corrosion, grain boundaries, and constituent particles during corrosion fatigue of 7075-T6 aluminum alloy[J]. International Journal of Fatigue, 2009,31:686-692.
[17] NEWMAN J C J. Fatigue-life calculations on pristine and corroded open-hole specimens using small-crack theory[J]. International Journal of Fatigue, 2009,31:1246-1253.
[18] 刘建华,田帅,李松梅,等. 新型超高强度钢应力腐蚀断裂行为研究[J].航空学报, 2011,32(6):1164-1170. LIU J H, TIAN S, LI S M, et al. Stress corrosion crack of new ultrahigh strength steel[J].Acta Aeronautica et Astronautica Sinica, 2011,32(6):1164-1170(in Chinese).
[19] 张晓云,刘明,汤智慧,等. 40CrNi2Si2MoVA超高强度钢海洋大气环境腐蚀行为研究[J]. 腐蚀科学与防护技术,2014,26(5):413-419. ZHANG X Y, LIU M, TANG Z H, et al. Marine atmospheric corrosion of 40CrNi2Si2MoVA high strength steel[J]. Corrosion Science and Protection Technology,2014,26(5):413-419(in Chinese).
[20] 李松梅,吴凌飞,刘建华. 应力比和腐蚀环境对超高强度钢AerMet100疲劳裂纹扩展的影响[J].航空材料学报,2014,34(3):74-80. LI S M, WU L F, LIU J H. Effect of load ratio and corrosion on fatigue behavior of AerMet100 ultrahigh strength steel[J]. Journal of Aeronautical Materials, 2014,34(3):74-80(in Chinese).
[21] 刘文珽,李玉海. 飞机结构日历寿命体系评定技术[M].北京:航空工业出版社,2004. LIU W T, LI Y H. The calendar life system evaluation technology of aircraft structures[M]. Beijing:Aviation Industry Press,2004(in Chinese).
[22] 中国国家标准化管理委员会.金属材料-疲劳试验-轴向力控制方法:GB/T 3075-2008[S]. 北京:中国国家标准化管理委员会2008. Standardization Administration of China. Metallic materials-fatigue testing-axial force controlled method:GB/T 3075-2008[S]. Beijing:Standardization Administration of China,2008(in Chinese).
[23] 中国国家标准化管理委员会. 金属平均晶粒度测定方法:GB/T 6394-2017[S]. 北京:中国国家标准化管理委员会,2017. Standardization Administration of China. Determination of estimating the average grain size of metal:GB/T 6394-2017[S]. Beijing:Standardization Administration of China,2017(in Chinese).
CJA