Article

Fatigue crack growth behavior of Al7050-T7451 attachment lugs under flight spectrum variation

Force Measurement and Evaluation Lab., Korea Research Institute of Standards and Science (KRISS), Daejeon 305-701, South Korea; Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-gu, Daejeon 305-701, South Korea
Theoretical and Applied Fracture Mechanics 01/2003; DOI: 10.1016/S0167-8442(03)00041-7

ABSTRACT This paper discusses an analytical and experimental investigations of the fatigue crack growth behavior in attachment lugs subjected to a randomized flight-by-flight spectrum. In the analysis, the stress intensity factors for through-the-thickness cracks initiating from lug holes were compared by weight function method, boundary element method (BEM), the interpolation of Brussat’s solution. The stress intensity factors of a corner crack at a transition region were obtained using two parameter weight function method and correction factors. Fatigue life under a load spectrum was predicted using stress intensity factors and Willenborg retardation model considering the effects of a tensile overload. Experiments were performed under a load spectrum and compared with the fatigue life prediction using the stress intensity factors by different methods. Changes of fatigue life and aspect ratio according to the clipping level of the spectrum were discussed through experiment and prediction. Effect of the spectrum clipping level on the fatigue life was experimentally evaluated by using beach marks of fractured surface.

1 Bookmark
 · 
247 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The treatment technics for substrate was researched and improved by experimentations, the technics and additive research of plating for forming ornamental and functional multicomponents alloy was carried out completely, the optimum technics of plating multi-components alloy was been found. The coatings made by optimum technics were excellent in corrosion-resistance, wear-resistance and oxidation-resistance, and also has a smooth, fine, shining surface. It was proved that phosphorus content in the coating is 8.4% by determinations, the coating is amorphous crystal. The properties of Ni-W-P coating were test, the result shown that the combination force between the substrate and the coating was very good, the properties of coating to resist corrosion and abrasion were much better than that of Ni-P alloy by the tests. And the coating was finery in ornamentally also.
    Physics Procedia. 01/2011; 18:251-255.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Many structures such as aircrafts, risers, and offshore pipelines that are in contact with fluids, become subjected to complex variable amplitude loading (VAL) stress-time histories during their service lives. As a result, the structural life assessment and damage-tolerant analyses of such structures are considered as two important design criteria. In this paper, a VAL stress-time history is used to study the fatigue life of 6061-T651 aluminum alloy, with focus on the retardation effect resulting from the applied peak tensile overload cycles (TOLCs). Various so-called “clipping” levels are tested, and the results are compared with those obtained through an analytical method, using the Willenborg retardation approach, in conjunction with the Walker fatigue crack growth model. The results would demonstrate the significant influence of the TOLC present within VAL scenarios on retarding the fatigue crack growth rate of the material. The study also investigates the influence of various clipping levels on the fatigue response of the material, also highlighting the limitations of the analytical approach in estimating the resulting crack growth rate. It is observed that the analytical method predicts a higher fatigue life for the material subjected to VAL, which is non-conservative for design purposes. Some suggestions are provided for fatigue life estimation of the material when subjected to VAL scenarios.
    Journal of Materials Engineering and Performance 07/2013; · 0.92 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Tests with middle-crack tension (M(T)) specimens made of Al 2324-T39 and Al 7050-T7451 are conducted to investigate the influence of low load truncation level on fatigue crack growth. The six different truncated spectra are obtained by removing the small cycles of which amplitudes are less than the specified percentages of the maximum amplitude in the basic flight-by-flight loading spectrum and the remainder of the spectrum is untouched. The tests indicate that the mean level of fatigue crack growth life (FCGL) increases as the load truncation level is enhanced. Considering both the time saving and the influence on FCGL, there is an applicable choice (i.e. spectrum S2 or spectrum S3 in this investigation) for full scale fatigue test. The scatter of FCGL becomes much larger than that under the basic spectrum when the load truncation level is increased to a specified high level, mainly due to the occurrence of crack slanting and branching under the high level truncated loading spectra.
    Chinese Journal of Aeronautics - CHIN J AERONAUT. 01/2009; 22(4):401-406.

Full-text (2 Sources)

Download
558 Downloads
Available from
Jun 2, 2014