| The fatigue crack growth tests of compact tension (CT) specimens of2024-T4aluminumalloy were conducted under constant amplitude loading with different R-ratios,0.05,0.1,0.5,0.75, respectively. The thickness of the specimen is3.8mm. All the fatigue crack growthexperiments were carried out in ambient air without a pre-crack. The early crack growthregion reflects the influence of the notch. The size of the notch together with the loadingconditions has a great influence on the early crack growth within the notch influenced region.Beyond the notch influenced zone, the stable fatigue crack growth is reached and can becharacterized by the Paris law. The experimental results indicate that fatigue crack growthrate increases with the R-ratio for a given stress intensity factor amplitude.By studied a uniform model of Jiang and combined with the experiment result, the sixmaterial constants that is suitable for2024-T4aluminum alloy in this model can be calculate.The fatigue crack growth rate can be obtained with this damage model. By compared theresult to experiment result, it shows that this model can describe the crack growth of2024-T4aluminum alloy very well.Based on FEM and experiment, the Paper did the work about a simulation of fatiguecrack growth behavior of2024-T4aluminum alloy under a cyclic loading, and full analysisabout the whole crack closure process and the effective factor of crack closure. It shows thatboth the maximum loading and crack length have no influence to the crack closure. It issensitive with the R-ratio. As the increase of the R-ratio, the phenomenon of crack closurebecomes weaken until disappeared. |
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