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Improved test method for very low fatigue-crack-growth-rate data

2010; Wiley; Volume: 34; Issue: 4 Linguagem: Inglês

10.1111/j.1460-2695.2010.01516.x

8756-758X

James C. Newman, J.J. Ruschau, Michael R. Hill,

Material Properties and Failure Mechanisms

Fatigue & Fracture of Engineering Materials & StructuresVolume 34, Issue 4 p. 270-279 Improved test method for very low fatigue-crack-growth-rate data J. C. NEWMAN Jr., J. C. NEWMAN Jr. Department of Aerospace Engineering Mississippi State University Mississippi State, MS 39762, USASearch for more papers by this authorJ. J. RUSCHAU, J. J. RUSCHAU Structural Integrity Division, University of Dayton Research Institute Dayton, OH 45469, USASearch for more papers by this authorM. R. HILL, M. R. HILL Department of Mechanical and Aerospace Engineering, University of California, Davis, CA 95616, USASearch for more papers by this author J. C. NEWMAN Jr., J. C. NEWMAN Jr. Department of Aerospace Engineering Mississippi State University Mississippi State, MS 39762, USASearch for more papers by this authorJ. J. RUSCHAU, J. J. RUSCHAU Structural Integrity Division, University of Dayton Research Institute Dayton, OH 45469, USASearch for more papers by this authorM. R. HILL, M. R. HILL Department of Mechanical and Aerospace Engineering, University of California, Davis, CA 95616, USASearch for more papers by this author First published: 29 October 2010 https://doi.org/10.1111/j.1460-2695.2010.01516.xCitations: 23 Correspondence: James C. Newman Jr. E-mail: [email protected] Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL ABSTRACT Currently, in North America, the threshold crack-growth regime is experimentally defined by using ASTM Standard E647, which has been shown in many cases to exhibit anomalies due to the load-reduction (LR) test method. The test method has been shown to induce remote closure, which prematurely slows down crack growth and produces an abnormally high threshold. In this paper, the fatigue-crack growth rate properties in the threshold and near-threshold regimes for a titanium alloy, Ti-6Al-4V (STOA), are determined by using the LR test method and an improved test method. The improved method uses ‘compression–compression’ precracking, as developed by Pippan, Topper and others, to provide fatigue-crack-growth rate data under constant-amplitude loading in the near-threshold regime, without load-history effects. Tests were conducted over a wide range in stress ratios (R = 0.1–0.7) on compact C(T) specimens for three different widths (25, 51 and 76 mm). The slitting method was used on 51 mm C(T) specimens to confirm that the material did not contain significant levels of residual stresses from forming and/or machining. A crack-mouth-opening-displacement gage was used to monitor crack growth. Data from the ASTM LR method gave near-threshold values that were found to be dependent upon the specimen width. However, data from the compression precracking constant amplitude (CPCA) loading method gave near-threshold data independent of specimen width. A crack-closure analysis was performed for both the LR and CPCA data, to correlate data at the various stress ratios. The CPCA data correlated well with the effective stress-intensity factor range against rate relation, whereas the LR data exhibited significant threshold fanning with both stress ratio and specimen width. REFERENCES 1 ASTM Standard Test Method for Measurement of Fatigue Crack Growth Rates, ASTM E-647, 2006; pp. 615– 657. 2 Pippan, R., Plöchl, L., Klanner, F. and Stüwe, H. P. (1994) The use of fatigue specimens precracked in compression for measuring threshold values and crack growth, ASTM J. Test. Evaluat., 22, 98. 3 Topper, T. H. and Au, P. (1981) Fatigue Test Methodology, AGARD Lecture Series 118, The Technical University of Denmark, Denmark . 4 Forth, S. C., Newman, J. C., Jr. and Forman, R. G. (2003) On generating fatigue crack growth thresholds, Int. J. Fatigue, 25, 9– 15. 5 Newman, J. C., Jr. Schneider, J., Daniel, A. and McKnight, D. (2005) Compression precracking to generate near threshold fatigue-crack-growth rates in two aluminum alloys, Int. J. Fatigue 27, 1432– 1440. 6 Ruschau, J. J. and Newman, J. C., Jr. (2008) Compression precracking to generate near threshold fatigue-crack-growth rates in an aluminum and titanium alloy, J. ASTM Int. 5. 7 Yamada, Y. and Newman, J. C., Jr. (2009) Crack closure behavior of 2324-T39 aluminum alloy near threshold conditions for high load ratio and constant Kmax tests, Int. J. Fatigue 31, 1780– 1787. 8 Newman, J. C., Jr. and Yamada, Y. (2010) Crack-closure behavior of 7050 aluminum alloy near threshold conditions for wide range in load ratios and constant Kmax tests, J. ASTM Int. 7. 9 Yamada, Y. and Newman, J. C., Jr. (2009) Crack closure under high load-ratio conditions for Inconel 718 near threshold behavior, Engng. Fract. Mech., 76, 209– 220. 10 Damage tolerance and fatigue evaluation of structure, Federal Aviation Regulations, Title 14 Code of Federal Regulations, Part 25, Section 571. 11 Pearson, S. (1975) Initiation of fatigue cracks in commercial aluminum alloys and the subsequent propagation of very short cracks, Engng. Fract. Mech. 7, 235– 247. 12 Newman, J. C., Jr. (1983) A nonlinear fracture mechanics approach to the growth of small cracks, Behavior of Short Cracks in Airframe Components, AGARD CP- 328, 6.1– 6.27. 13 Newman, J. C., Jr. (1997) The Merging of Fatigue and Fracture Mechanics Concepts A Historical Perspective, Fatigue and Fracture Mechanics—28th Volume, ASTM 1321, pp. 3– 51. 14 Minakawa, K. and McEvily, A. J. (1981) On near-threshold fatigue crack growth in steels and aluminum alloys, Proceedings of International Conference on Fatigue Thresholds, Vol. 2, Stockholm , Sweden , pp. 373– 390. 15 Newman, J. C., Jr. (2000) Analysis of Fatigue Crack Growth and Closure Near Threshold Conditions. ASTM STP-1372, pp. 227– 251. 16 Donald, J. K. and Paris, P. C. (1998) An Evaluation of ΔKeff Estimation Procedures on 6061-T6 and 2024-T3 Aluminum Alloys. In: Proceedings of Fatigue Damage of Structural Materials II, Cape Cod , MA . 17 Gallagher, J. et al ., Advanced High Cycle Fatigue (HCF) Life Assurance Methodologies, AFRL-ML-WP-TR-2005–4102, July 2004. 18 Schindler, H. J., Cheng, W. and Finnie, I. (1997) Experimental determination of stress intensity factors due to residual stresses, Exp. Mech., 37, 272– 279. 19 Schindler, H. J. and Bertschinger, P. (1997) Some steps towards automation of the crack compliance method to measure residual stress distributions, Proceedings 5th International Conference on Residual Stress. 20 Newman, J. C., Jr., Yamada, Y. and James, M. A. (2010) Stress-intensity-factor equations for compact specimen subjected to concentrated forces, Engng. Fract. Mech. 77, 1025– 1029. 21 Newman, J. C., Jr., Vizzini, A. J. and Yamada, Y. (2010) Fatigue-crack-growth databases and analyses for threshold behavior in rotorcraft materials, DOT/FAA/AR-10/3 22 James, M. A., Forth, S. C. and Newman, J. A. (2005) Load history effects resulting from compression precracking, Fatigue Fract. Mech. 34, ASTM 1461, 43– 59. 23 Yamada, Y., Newman, J. C., III and Newman, J. C., Jr. (2008) Elastic-plastic finite-element analyses of compression precracking and its influence on subsequent fatigue-crack growth, J. ASTM Int., 5. 24 Döker, H. and Peters, M. (1984) Fatigue threshold dependence on material, environment and microstructure, Fatigue 84, Vol. 1, C. J. Beevers, ed., Engineering Materials Advisory Services, U. K. , pp. 275– 285. 25 Newman, J. C., Jr. (1992) FASTRAN-II—A Fatigue Crack Growth Structural Analysis Program, NASA TM 104159. 26 Newman, J. C., Jr. (1984) A crack opening stress equation for fatigue crack growth, Int. J. Fracture 24, R131-Rl35. 27 Newman, J. C., Jr. (2007) Analyses of Fatigue-Crack-Growth Databases for Use in Damage-Tolerance Approach for Aircraft Propellers and Rotorcraft, DOT/FAA/AR-07/49. 28 Garr, K. R. and Hresko, G. C. (2000) A size effect on the fatigue crack growth rate threshold of alloy 718, ASTM STP 1372, W. Conshohocken, PA , pp. 155– 174. 29 Hudak, S., Jr., Saxena, S., Bucci, R. and Malcolm, R. (1978) Development of Standard Methods of Testing and Analyzing Fatigue Crack Growth Rate Data—Final Report, AFML TR 78–40, Materials Laboratory, WPAFB, OH. 30 Elber, W. (1971) The significance of fatigue crack closure, ASTM STP 486, pp. 230– 242. Citing Literature Volume34, Issue4April 2011Pages 270-279 ReferencesRelatedInformation