ACTA AERONAUTICAET ASTRONAUTICA SINICA >
Fatigue Crack Growth Behavior of Aerospace Aluminum Alloy LD2 Under Corrosion
Received date: 2012-03-30
Revised date: 2012-10-18
Online published: 2013-03-29
Supported by
Ministry Level Project
Corrosion damage increases fatigue crack growth rates of aircraft structures, and shortens the fatigue life of an aircraft. Accelerated corrosion tests simulating the service environment of aircraft and then the fatigue tests on aerospace aluminum alloy LD2 test samples are executed under different corrosion times. The fatigue rupture morphologies of the test samples with different corrosion times are obtained. The crack growth data (a,N) under different corrosion times are measured by judgment of the rupture morphologies. By fitting the data (a,N), it is found that the relationship between crack length and cycle number is exponential, and the crack growth rate is directly proportional to the crack length, while the slope of the crack growth rate vs the crack length depends on the factors of corrosion damage and fatigue load level. Furthermore, by fatigue tests under different corrosion times and different stress levels, it is also found that the relationship between the slope and the corrosion time is linear under the same stress level and the slope values under different stress levels are nearly the same, while the intercept of the lines of crack growth rate also varies linearly with the stress level.
MU Zhitao , CHEN Dinghai , ZHU Zuotao , DING Wenyong , TIAN Shudong . Fatigue Crack Growth Behavior of Aerospace Aluminum Alloy LD2 Under Corrosion[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2013 , 34(3) : 574 -579 . DOI: 10.7527/S1000-6893.2013.0094
[1] Mu Z T. The analyzing method for fatigue life of aircraft structures under corrosive environment. China Engineering Science, 2002, 4(3): 68-72. (in Chinese) 穆志韬. 腐蚀环境下飞机结构疲劳寿命的分析方法. 中国工程科学, 2002, 4(3): 68-72.
[2] Mu Z T, Jin P, Duan C M. The corrosion fatigue and life of aircraft structure in servicing. China Engineering Science, 2000, 2(4): 34-38. (in Chinese) 穆志韬, 金平, 段成美. 现役飞机结构腐蚀疲劳及寿命研究. 中国工程科学, 2000, 2(4): 34-38.
[3] Gruenberg K M, Craig B A, Hillberry B M, et al. Predicting fatigue life of pre-corroded 2024 aluminum. International Journal of Fatigue, 2004, 26(7): 629-640.
[4] Bay G H, Bucci R J, Covin E L, et al. Effects of prior corrosion on the S/N fatigue performance of aluminum alloys 2024-T3 and 2524-T3. Effects of Environment on the Initiation of Crack Growth, ASTM STP 1298. Philadelphia: ASTM, 1997
[5] Sankaran K K, Perez R, Jata K V. Effect of prior corrosion on the fatigue behavior of aluminum alloy 7075-T6: modeling and experimental studies. Material Science and Engineering: A, 2001, 297(2): 223-229.
[6] Liu J Z, Chen B, Ye X B, et al. Fatigue and crack growth behavior of pre-corroded aluminum alloy 2024-T62 and its life prediction based on fracture mechanics. Acta Aeronautica et Astronautica Sinica, 2011, 32(1): 107-116. (in Chinese) 刘建中, 陈勃, 叶序彬, 等. 含腐蚀预损伤铝合金2024-T62的疲劳断裂行为及基于断裂力学的寿命预测. 航空学报, 2011, 32(1): 107-116.
[7] Zhou X Y. Equivalent environment spectrum and accelerated test spectrum of aircraft structure. Acta Aeronautica et Astronautica Sinica, 1996, 17(5): 613-616. (in Chinese) 周希沅. 飞机结构的当量环境谱与加速试验谱. 航空学报, 1996, 17(5): 613-616.
[8] Zhang D. Accelerated corrosion test of the aircraft structure under equivalent environment spectrum and the computing method for the calendar life. Acta Aeronautica et Astronautica Sinica, 2000, 21(3): 196-201. (in Chinese) 张栋. 飞机结构件在当量环境谱下加速腐蚀试验和日历寿命计算方法. 航空学报, 2000, 21(3): 196-201.
[9] Liu W T, Zhao Y X. Back-calculating method for determining parameters of a da/dN equation of relatively small crack. Acta Aeronautica et Astronautica Sinica, 1993, 14(2): B33-B38. (in Chinese) 刘文珽, 赵燕湘. 确定相对小裂纹da/dN公式系数的计算反推法.航空学报, 1993, 14(2): B33-B38.
[10] Polak J. Mechanisms and kinetics of the early fatigue damage in crystalline materials. Material Science Engineering: A, 2007, 33(9): 468-470.
[11] Nakajima M, Tokaji K. Fatigue life distribution and growth of corrosion pits in a medium carbon steel in 3% NaCl solution. Fatigue & Fracture of Engineering Materials & Strucures, 1995: 18(3): 345-351.
[12] Jisa D, Liskutin P, Kruml T, et al. Small fatigue crack growth in aluminum alloy EN-AW 6082/T6. International Journal of Fatigue, 2010, 32(12): 1913-1920
[13] Li X D. Small crack growth of aluminum alloy under corrosive environment. Beijing: Tsinghua University, 2011. (in Chinese) 李旭东. 腐蚀环境下铝合金材料微裂纹扩展分析. 北京: 清华大学, 2011.
[14] Xue Y B. Modeling fatigue small-crack growth with confidence—a multistage approach. International Journal of Fatigue, 2010, 32(3): 1210-1219.
[15] Wang X S, Fan J H. SEM online investigation of fatigue crack initiation and propagation in notched cast magnesium specimens. Journal of Materials Science, 2004, 39(7): 2617-2620.
/
| 〈 |
|
〉 |
CJA