Abstract
Crack closure is held to be responsible for very low fatigue crack growth rates in many alloys such as Al-Li 2090 T8E41, and early crack face contact during unloading or prolonged contact during loading seems to reduce the driving “force” for crack extension. High resolution x-ray computed tomography (i.e., microtomography) allows one to image the entire volumes of samples and to quantify opening as a function of applied load over the entire crack surface. Crack closure results are reported for a fatigue crack grown under load ratio R=0.1 in a compact tension sample of Al-Li 2090 T8E41; the crack was free to choose its path unconstrained by side-grooves which are normally used to suppress crack deflection. The inter-relationship between crack path, crack face contact and applied load level are discussed.
Similar content being viewed by others
References
KT. Venkateswara Rao, W. Yu and R.O. Ritchie, Met Trans 19A (1988) 549–569.
G.R. Yoder, P.S. Pao, M.A. Imam, and L.A. Cooley, in Proc 5th Int Conf on Aluminum-Lithium Alloys. T.H. Sanders Jr. and E.A Starke Jr., Eds., (Mater Comp Eng Publ Ltd, Birmingham, UK, 1989) 1033–1041.
P.S. Pao, M.A. Imam, L.A. Cooley and G.R. Yoder, Scr Met 23 (1989) 1455–1460.
G.R. Yoder, P.S. Pao, M.A. Imam and L.A. Cooley, Scr Met 22 (1988) 1241–1244.
J.D. Haase, “Microbeam Diffraction Mapping of Microtexture in Al-Li 2090 T8E41,” MS Thesis, Georgia Institute of Technology, 1998.
J.D. Haase, A. Guvenilir, J.R. Witt and S.R. Stock, Acta Mater 46 (1998) 4791–4799.
Jake D. Haase, Abbas Guvenilir, Jason R. Witt, Morten A. Langøy and Stuart R. Stock, in Mixed-Mode Crack Behavior. ASTM STP 1359 (1999) 160–173.
R.H. Christensen, Appl Mater Res October (1963) 207–210.
W. Elber, in Damage Tolerance in Akciaft Structures. ASTM STP 486 (1971) 230–242.
R.O. Ritchie, in Fatigue Thresholds. J. Backland, A. Blom and C.J. Beevers, Eds., (Eng Adv Serv, Warley, UK, 1981) 503–526.
R.O. Ritchie, Mater Sci Eng A103 (1988) 15–28.
A. Guvenilir, T.M. Breunig, J.H. Kinney and S.R. Stock, Acta Mater 45 (1997) 1977–1987.
A. Guvenilir and S.R. Stock, Fatigue Fracture Eng Mater Structures 21(1998) 439–450.
A. Guvenilir, T.M. Breunig, J.H. Kinney and S.R. Stock, Phil Trans Roy Soc (Lon) 357 (1999) 2755–2775.
A. Guvenilir, S.R. Stock, M.D. Barker and R.A. Betz, in 4th Int Conf on Al Alloys: Their Physical and Mechganical Properties. Vol. II, T.H. Sanders Jr. and E.A. Starke Jr., Eds. (Georgia Institute of Technology, 1994)413–419.
K.T. Venkateswara Rao and R.O. Ritchie, Int Mater Rev 37#4 (1992) 153–185.
J.C. Newman, Jr., NASA Langley, 1999, personal communication.
G.R. Davis and J.C. Elliott, Nucl Instrum Meth A394 (1997) 157–162.
R. Morano, “Effect of R-ratio on Crack Closure in Al-Li 2090 T8E41, Investigated Non-destructively with X-ray Microtomography,” MS Thesis, Georgia Institute of Technology, 1998.
T.M. Breunig, S.R. Stock, A. Guvenilir, J.C. Elliott, P. Anderson and G.R. Davis, Composites 24 (1993) 209–213.
H.Y. Jung and S.D. Antolovich, Scr Met Mater 33 (1995) 275–281.
S.R. Stock, Int Mater Rev 44 #6 (1999) 1–24.
Acknowledgments
The US portion of this research was supported by the US Office of Naval Research through grants N00014-94-1-0306, -94-1-0726 and -97-1-0557 and the UK portion through EPSRC Grant GR/J25628. We thank R. Brown of MPRL and M.A. Langøy for their help with fatigue crack propagation and J.D. Haase, D.J. Ryan and A. Guvenilir for help with computers.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Morano, R., Stock, S., Davis, G. et al. X-Ray Microtomography of Fatigue Crack Closure as a Function of Applied Load in Al-Li 2090 T8E41 Samples. MRS Online Proceedings Library 591, 56–60 (1999). https://doi.org/10.1557/PROC-591-31
Published:
Issue Date:
DOI: https://doi.org/10.1557/PROC-591-31