提出了一种多部位损伤全寿命分析的工程方法，该方法包含3部分内容。对多裂纹萌生问题，通过研究多细节结构中裂纹萌生机理，将裂纹萌生寿命的取值事件转化为3个独立事件的积事件，前者的发生概率等于3个独立事件发生概率的乘积，3个独立事件的发生概率可由单细节结构裂纹萌生寿命的概率分布求得。从而可由单细节结构裂纹萌生寿命概率分布得到多细节结构中依次出现的各条裂纹的萌生寿命的概率分布。对多裂纹扩展问题，先通过有限元方法计算出多裂纹指定长度组合下的应力强度因子，然后引入响应面法，定量地建立了裂纹长度与应力强度因子之间的函数关系，由响应面模型得到多裂纹任意长度组合下的应力强度因子，最后采用循环接循环法进行裂纹扩展分析。对多裂纹结构失效分析，采用亚临界条件判断结构是否失效，认为结构上萌生的首条裂纹与第2条裂纹的位置相邻，裂纹发生首次连通时，结构失效。进行了单细节带孔板与多细节带孔板的裂纹萌生扩展试验，并对多细节带孔板的裂纹萌生扩展寿命和首次裂纹连通寿命进行了预测。预测结果和试验结果吻合良好，表明该方法是有效的。
An engineering method of full life for structure with multiple site damage is proposed. consists of three parts. For multiple crack initiation, the incident crack initiation life of multiple detail structure with a certain value is transformed into the intersection of three independent incidents. The probability of the former incident is the product of the probability of the latter three independent incidents derived from the probability distribution function of crack initiation life of single detail structure. Thus, the probability distribution functions of initiation for cracks occurring in turn in multiple detail structure are obtained. For multiple crack propagation, the stress intensity factor the specified length combination of multiple cracks is calculated the finite element method. The response surface method is introduced functional relationship between crack length and stress intensity factor. The stress intensity factor of the multiple crack arbitrary length combination is obtained from the response surface model. Finally, the crack propagation analysis is performed using the cycle-by-cycle technique. For failure analysis of multiple crack structure, subcritical conditions are to determine the failure. he first crack in the structure is adjacent to the position of the second crackthe crack linkup failure. Crack initiation and propagation specimens with a hole notch and hole notches carried out model. agreement testing results this model.
[1] Federal Aviation Administration. Aging airplane program:Widespread fatigue damage, final rule:FAA-2006-24281-2010[S].Washington, D.C.:FAA, 2010.
[2] SILVA L F M, GONÇALVES J P M, OLIVEIRA F M F, et al. Multiple-site damage in riveted lap-joints:Simulation and finite element prediction[J]. International Journal of Fatigue, 2000, 22(4):319-338.
[3] PROPPE C. Probabilistic analysis of multi-site damage in aircraft fuselages[J]. Computational Mechanics, 2003, 30(4):323-329.
[4] PIDAPARTI R M V, PALAKAL M J, RAHMAN Z A. Simulation of structural integrity predictions for panels with multiple site damage[J]. Advances in Engineering Software, 2000, 31(2):127-135.
[5] 薛景川, 弓云昭. 结构初始广布疲劳损伤发生预估的概率模型[C]//第18届全国结构工程学术会议论文集. 北京:工程力学杂志社, 2009:597-600. XUE J C, GONG Y Z. The probability model to preestimate onset of initial widespread fatigue damage[C]//Proceedings of the 18th National Academic Conference on Structural Engineering. Beijing:Engineering Mechanics Press, 2009:597-600(in Chinese).
[6] 王传胜, 张建宇, 鲍蕊, 等. 飞机结构多部位损伤发生的可能性分析[J]. 北京航空航天大学学报, 2006, 32(8):899-902. WANG C S, ZHANG J Y, BAO R, et al. Reliability analysis on structure with multiple site damage[J]. Journal of Beijing University of Aeronautics and Astronautics, 2006, 32(8):899-902(in Chinese).
[7] ZHANG J Y, BAO R, ZHANG X, et al. A probabilistic estimation method of multiple site damage occurrence for aircraft structures[J]. Procedia Engineering, 2010, 2(1):1115-1124.
[8] CARTWRIGHT D J, ROOKE D P. Approximate stress intensity factors compounded from known solutions[J]. Engineering Fracture Mechanics, 1974, 6(3):563-571.
[9] 倪惠玲. 多处损伤特性的研究[J]. 航空学报, 1996, 17(3):302-309. NI H L. Study of the behavior of multiple site damage[J]. Acta Aeronautica et Astronautica Sinica, 1996, 17(3):302-309(in Chinese).
[10] MOUKAWSHER E J, GRANDT J A F, NEUSSL M A. Fatigue life of panels with multiple site damage[J]. Journal of Aircraft, 1996, 33(5):1003-1013.
[11] LIEBOWITZ H, MOYER E T. Finite element methods in fracture mechanics[J]. Computers and Structures, 1989, 31:1-9.
[12] SWIFT T. Widespread fatigue damage monitoring-issues and concerns[C]//5th Int Conf on Structural Airworthiness of New and Aging Aircraft, 1993:113-150.
[13] SWIFT T. Damage tolerance in pressurized fuselages[C]//The 11th Plantema Memorial Structure Presented at the 14th Symposium of the International Committee on Aeronautical Fatigue, 1987.
[14] JEONG D Y, BREWER J C. On the linkup of multiple cracks[J]. Engineering Fracture Mechanics, 1995, 51(2):233-238.
[15] 郑晓玲. 民机结构耐久性与损伤容限设计手册[M]. 北京:航空工业出版社, 2003:334-335. ZHENG X L. Durability and damage tolerance design manual for civil aircraft structure[M]. Beijing:Aviation Industry Press, 2003:334-335(in Chinese).
[16] WHIITTAKER I C. Development of titanium and steel fatigue variability model for application of Reliability analysis approach to aircraft structures:AD 758219[R].Fort Belvoir:Defense Technical Information Center,1972.
[17] 王森, 刘马宝, 王国力, 等. 广布损伤的试验研究与有限元分析[J]. 航空学报, 2010, 31(8):1578-1583. WANG S, LIU M B, WANG G L, et al. Test research and finite element analysis on multiple site damage[J]. Acta Aeronautica et Astronautica Sinica, 2010, 31(8):1578-1583(in Chinese).
[18] 李政鸿, 徐武, 张晓晶, 等. 多孔多裂纹平板的疲劳裂纹扩展实验与分析方法[J]. 航空学报, 2018, 39(7):221867. LI Z H, XU W, ZHANG X J, et al. Experimental and analytical analyses of fatigue crack growth in sheets with multiple holes and cracks[J]. Acta Aeronautica et Astronautica Sinica, 2018, 39(7):221867(in Chinese).
[19] IRWIN G R. Analysis of stress and strains near the end of a crack traversing a plate[J]. Journal of Applied Mechanics, 1957, 24:361-364.
[20] 张健萍. 大型民机典型结构广布疲劳损伤发生规律研究[D]. 北京:北京航空航天大学, 2015:22-30. ZHANG J P. The occurrence of widespread fatigue damage for civil aircraft structures[D]. Beijing:Beihang University, 2015:22-30(in Chinese).
[21] PITT S, JONES R. Multiple-site and widespread fatigue damage in aging aircraft[J]. Engineering Failure Analysis, 1997, 4(4):237-257.
[22] 郦正能, 关志东, 张纪奎, 等. 应用断裂力学[M]. 北京:北京航空航天大学出版社, 2012:191-192. LI Z N, GUAN Z D, ZHANG J K, et al. Applied fracture mechanics[M]. Beijing:Beihang University Press, 2012:191-192(in Chinese).
[23] NELSON W. Applied life data Analysis[M]. New York:John Wiley & Sons, 1982:421-425.
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