Fatigue and crack-growth analyses on 7075-T651 aluminum alloy coupons under constant- and variable-amplitude loading
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Abstract
Abstract The wings on two Navy aircraft, EA-6B and P-3, are made of 7075-T651 aluminum alloy. These aircraft are both involved in extensive life-extension programs being conducted by the US Navy. The objective of this paper is to present some of the efforts to conduct fatigue and crack-growth analyses with the FASTRAN life-prediction code using Small-Crack Theory. FASTRAN is an advanced non-linear life-prediction code based on cyclic plasticity and the crack-closure concept. For aluminum alloys, such as those used in the older naval aircraft, the fatigue process has been shown to be primarily crack growth from microstructural features, such as inclusion-particle clusters, voids or pits. This paper presents the results of small- and large-crack-growth-rate tests conducted on the 7075-T651 alloy over a wide range of constant-amplitude loading to establish the baseline crack-growth-rate curves for the fatigue analyses. Crack-growth behavior was found to be different in the thickness and in-plane directions. These test data are compared with results from a NASA/CAE Cooperative Program on small- and large-crack growth in a 7075-T6 thin-sheet alloy. Using inclusion-particle-cluster sizes and shapes, like those that are observed in tests, the fatigue and crack-growth lives are predicted on various specimens used to simulate details in a wing panel under either constant-amplitude or simulated wing spectrum loading. The predicted results compared well with the test data.
Source: openaire · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: Fatigue and fracture mechanics · Probabilistic and Robust Engineering Design · High Temperature Alloys and Creep
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (48)
Show source-provided references
1. Fatigue crack closure under cyclic tension10.1016/0013-7944(70)90028-7 ↗
2. Elber W. The significance of fatigue crack closure. In: Damage tolerance in aircraft structures, ASTM STP 486. Philadelphia (PA): American Society for Testing and Materials; 1971. p. 230–42.10.1520/STP26680S ↗
3. Schijve J. Fatigue crack closure observations and technical significance. In: Mechanics of fatigue crack closure, ASTM STP 982. Philadelphia (PA): American Society for Testing and Materials; 1988. p. 5–34.10.1520/STP27198S ↗
4. NASGRO reference manual version 5.2. Southwest Research Institute and NASA Johnson Space Center; 2008.
5. AFGROW users guide and technical manual. AFRL-VA-WP-TR-2002, Version 4.0005.12.10. Air Force Research Laboratory, WPAFB OH; 2002.
6. Newman Jr JC. FASTRAN II – A fatigue crack growth structural analysis program. NASA TM 104159; 1992.
7. Newman Jr JC. A crack-closure model for predicting fatigue crack growth under aircraft spectrum loading. In: Methods and Models for Predicting Fatigue Crack Growth under Random Loading, ASTM STP 748. Philadelphia (PA): American Society for Testing and Materials; 1981. p. 53–84.10.1520/STP28334S ↗
8. de Koning AU, ten Hoeve HJ, Henriksen TK. Description of crack growth using the strip-yield model for computation of crack opening loads, crack tip stretch, and strain rates. In: ASTM STP 1343. West Conshohocken (PA): American Society for Testing and Materials; 1999. p. 459–74.10.1520/STP15774S ↗
9. Initiation of fatigue cracks in commercial aluminum alloys and the subsequent propagation of very short cracks10.1016/0013-7944(75)90004-1 ↗
10. Kitagawa H, Takahashi S. Applicability of fracture mechanics to very small cracks or the behaviour in the early stages. In: Proceedings of second international conference on mechanical behavior of materials. Boston (MA); 1976. p. 627–31.
11. Zocher H, editor. Behaviour of short cracks in airframe components. AGARD CP-328; 1983.
12. 1986
13. Miller KJ, de los Rios ER, editors. The behaviour of short fatigue cracks. European Group on Fracture, Publication No. 1; 1986.
14. Newman Jr JC, Edwards PR. Short-crack growth behaviour in an aluminum alloy – an AGARD cooperative test programme. AGARD R-732; 1988.
15. Edwards PR, Newman Jr JC, editors. Short-crack growth behaviour in various aircraft materials. AGARD R-767; 1990.
16. Newman Jr JC, Wu XR, Venneri S, Li C. Small-crack effects in high-strength aluminum alloys. NASA RP-1309; 1994.
17. Newman · 1986
18. Swain MH, Everett RA, Newman Jr JC, Phillips EP. The growth of short cracks in 4340 steel and aluminum–lithium 2090. AGARD R-767 1990;7.1–7.30.
19. The behaviour of short fatigue cracks and their initiation10.1111/j.1460-2695.1987.tb01153.x ↗
20. J integral application for short fatigue cracks at notches10.1007/BF00042383 ↗
21. Newman Jr JC. A nonlinear fracture mechanics approach to the growth of small cracks. In: Zocher H, editor. Behaviour of short cracks in airframe components., AGARD CP-328; 1983. p. 6.1–6.26.
22. On generating fatigue crack growth thresholds10.1016/S0142-1123(02)00066-X ↗
23. Compression pre-cracking to generate near threshold fatigue-crack-growth rates in two aluminum alloys10.1016/j.ijfatigue.2005.07.006 ↗
24. Schijve J. The practical and theoretical significance of small cracks – an evaluation. In: Fatigue 84. EMAS, Ltd.; 1984. p. 751–71.
25. The growth of small fatigue cracks in 7075-T6 aluminum10.1111/j.1460-2695.1982.tb01251.x ↗
26. The effects of environment on the growth of small fatigue cracks10.1111/j.1460-2695.1983.tb01136.x ↗
27. Yielding of steel sheets containing slits10.1016/0022-5096(60)90013-2 ↗
28. Blom A, Wang G, Chermahini R. Comparison of crack closure results obtained by 3d elastic–plastic fem and modified dugdale model, localized damage: computer-aided assessment and control. In: Aliabadi MH et al. editors. Computational mechanics publications. Berlin: Springer-Verlag; 1990. p. 57–68.
29. Three-dimensional elastic–plastic finite-element analyses of constraint variations in cracked bodies10.1016/0013-7944(93)90299-8 ↗
30. Newman Jr JC. Fracture mechanics parameters for small fatigue cracks. In: Larsen J, Allison JE, editors. Small-crack test methods. ASTM STP-1149; 1992. p. 6–33.10.1520/STP15062S ↗
31. A crack-opening stress equation for fatigue crack growth10.1007/BF00020751 ↗
32. Newman Jr JC. Effects of constraint on crack growth under aircraft spectrum loading. In: Beukers A et al. editors. Fatigue of aircraft materials. Delft University Press; 1992. p. 83–109.
33. Finite-element analysis of specimen geometry effects on fatigue crack closure10.1111/j.1460-2695.1994.tb00816.x ↗
34. Schijve J. Significance of fatigue cracks in micro-range and macro-range. In: Fatigue crack propagation, ASTM STP 415. Philadelphia (PA): American Society for Testing and Materials; 1967. p. 415–59.10.1520/STP47238S ↗
35. On microstructural control on near-threshold fatigue crack growth in 7000-series aluminum alloys10.1016/0036-9748(82)90448-3 ↗
36. Environmental fatigue of an Al–Li–Cu Alloy: Part II. microscopic hydrogen cracking processes10.1007/BF02659499 ↗
37. Fracture analysis of surface- and through-cracked sheets and plates10.1016/0013-7944(73)90046-5 ↗
38. Newman Jr JC. Fracture analysis of various cracked configurations in sheet and plate materials. In: Properties related to fracture toughness, ASTM STP 605. Philadelphia (PA): American Society for Testing and Materials; 1976. p. 104–23.10.1520/STP27802S ↗
39. Back-face strain compliance relation for compact specimens for wide range in crack lengths10.1016/j.engfracmech.2011.07.001 ↗
40. Donald JK, Blair A. Automated Fatigue Crack Growth Testing and Analysis – Series 2001, Version 3.09. Bethlehem (PA): Fracture Technology Associates, LLC; March 2009.
41. ASTM standard test method for measurement of fatigue crack growth rates. ASTM E-647; 2006. p. 615–57.
42. Compression precracking to generate near threshold fatigue crack growth rates in an aluminum and titanium alloy10.1520/JAI101623 ↗
43. Crack closure under high load-ratio conditions for inconel 718 near threshold behavior10.1016/j.engfracmech.2008.09.009 ↗
44. Crack closure behavior of 2324-T39 aluminum alloy near threshold conditions for high load ratio and constant kmax tests10.1016/j.ijfatigue.2008.11.010 ↗
45. Crack-closure behavior of 7050 aluminum alloy near threshold conditions for wide range in load ratios and constant kmax tests10.1520/JAI102490 ↗
46. Effect of stress cycle asymmetry on fatigue crack growth10.1016/0025-5416(72)90038-9 ↗
47. MWM eddy-current arrays for crack initiation and growth monitoring10.1016/j.ijfatigue.2003.08.010 ↗
48. Barter SA. Fatigue crack growth in 7050T7451 aluminum alloy thick section plate with a surface condition simulating some regions of the F/A-18 structure. DSTO-TR-1458. Australia: DSTO Platform Sciences Laboratory; 2003.