X-Ray Microtomography of Fatigue Crack Closure as a Function of Applied Load in Al-Li 2090 T8E41 Samples

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.

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References

  1. 1.

    KT. Venkateswara Rao, W. Yu and R.O. Ritchie, Met Trans 19A (1988) 549–569.

    Article  Google Scholar 

  2. 2.

    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.

  3. 3.

    P.S. Pao, M.A. Imam, L.A. Cooley and G.R. Yoder, Scr Met 23 (1989) 1455–1460.

    CAS  Article  Google Scholar 

  4. 4.

    G.R. Yoder, P.S. Pao, M.A. Imam and L.A. Cooley, Scr Met 22 (1988) 1241–1244.

    CAS  Article  Google Scholar 

  5. 5.

    J.D. Haase, “Microbeam Diffraction Mapping of Microtexture in Al-Li 2090 T8E41,” MS Thesis, Georgia Institute of Technology, 1998.

    Google Scholar 

  6. 6.

    J.D. Haase, A. Guvenilir, J.R. Witt and S.R. Stock, Acta Mater 46 (1998) 4791–4799.

    CAS  Article  Google Scholar 

  7. 7.

    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.

    Google Scholar 

  8. 8.

    R.H. Christensen, Appl Mater Res October (1963) 207–210.

    Google Scholar 

  9. 9.

    W. Elber, in Damage Tolerance in Akciaft Structures. ASTM STP 486 (1971) 230–242.

    Google Scholar 

  10. 10.

    R.O. Ritchie, in Fatigue Thresholds. J. Backland, A. Blom and C.J. Beevers, Eds., (Eng Adv Serv, Warley, UK, 1981) 503–526.

  11. 11.

    R.O. Ritchie, Mater Sci Eng A103 (1988) 15–28.

    CAS  Article  Google Scholar 

  12. 12.

    A. Guvenilir, T.M. Breunig, J.H. Kinney and S.R. Stock, Acta Mater 45 (1997) 1977–1987.

    CAS  Article  Google Scholar 

  13. 13.

    A. Guvenilir and S.R. Stock, Fatigue Fracture Eng Mater Structures 21(1998) 439–450.

    CAS  Article  Google Scholar 

  14. 14.

    A. Guvenilir, T.M. Breunig, J.H. Kinney and S.R. Stock, Phil Trans Roy Soc (Lon) 357 (1999) 2755–2775.

    CAS  Article  Google Scholar 

  15. 15.

    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.

  16. 16.

    K.T. Venkateswara Rao and R.O. Ritchie, Int Mater Rev 37#4 (1992) 153–185.

    Google Scholar 

  17. 17.

    J.C. Newman, Jr., NASA Langley, 1999, personal communication.

    Google Scholar 

  18. 18.

    G.R. Davis and J.C. Elliott, Nucl Instrum Meth A394 (1997) 157–162.

    Article  Google Scholar 

  19. 19.

    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.

    Google Scholar 

  20. 20.

    T.M. Breunig, S.R. Stock, A. Guvenilir, J.C. Elliott, P. Anderson and G.R. Davis, Composites 24 (1993) 209–213.

    CAS  Article  Google Scholar 

  21. 21.

    H.Y. Jung and S.D. Antolovich, Scr Met Mater 33 (1995) 275–281.

    CAS  Article  Google Scholar 

  22. 22.

    S.R. Stock, Int Mater Rev 44 #6 (1999) 1–24.

    Google Scholar 

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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.

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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

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