This paper reports on a study on creep-fatigue crack growth resistance of a precipitation hardened 2650 T6 aluminium alloy selected for fuselage panels of a future civil supersonic aircraft. The objective is to develop a methodology to predict crack growth under very low frequency loading at elevated temperatures. With this aim, creep crack growth rates (CCGRs), fatigue crack growth rates (FCGRs), creep-fatigue crack growth rates (CFCGRs) have been measured at 130 deg C and 175 deg C in laboratory air and in vacuum at R = 0.5 under different load frequencies and waveshape signals. It is shown that, for a given temperature, CFCGRs are unaffected by frequency below a critical value of the load period Tc. Above this value CFCGRs are directly proportional to the load period. This time-dependent crack growth regime is assisted by a significant creep damage as indicated by the large amount of intergranular decohesions induced by cavitation on fracture surfaces. CFCGRs are calculated under the assumption that fatigue damage and creep damage can be linearly summed. In vacuum the predictions are in good agreement with experimental data at both temperatures. In air however a discrepancy is observed for low frequency loading, suggesting the occurrence of a creep-fatigue-environment interaction. As a consequence the time-dependent crack growth behaviour affected by this interaction is different from creep crack growth behaviour, although the reasons for this are still unclear. A methodology is then proposed to predict CFCGRs in air. This methodology, if assessed by very low frequency experimental results, could be extended to different structural components made of aluminium alloys operating at elevated temperatures, provided that the mechanisms are unchanged.


    Access

    Access via TIB

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Prediction of creep-fatigue crack growth rates in inert and active environments in an aluminium alloy


    Contributors:
    Henaff, G. (author) / Odemer, G. (author) / Benoit, G. (author) / Koffi, E. (author) / Journet, B. (author)

    Published in:

    International Journal of Fatigue ; 31 , 11-12 ; 1943-1951


    Publication date :

    2009


    Size :

    9 Seiten, 14 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English




    Modelling of fatigue crack growth in 7075-T651 aluminium alloy plate

    Wanhill, R. J. H. / Koning, A. U. / Schra, L. | TIBKAT | 1985


    An equivalent crack growth model for creep fatigue life prediction of metals

    Pan, Dong / Tahir, Fraaz / Liu, Yongming | AIAA | 2016


    Fatigue-crack propagation in aluminium-alloy tension panels

    Whaley, Richard E. / Kurzhals, Peter R. | TIBKAT | 1960


    Corrosion Fatigue Crack Growth Rates in Aluminium Alloys subjected to Variable Ripple Sequences

    Paulson, A. D. / Hoeppner, D. W. / International Committee on Aeronautical Fatigue | British Library Conference Proceedings | 1993


    Fatigue Crack Growth in Anodised Aluminium Alloys

    Cree, A. M. / Weidmann, G. W. / Royal Institution of Naval Architects | British Library Conference Proceedings | 2006