| Summary: | Material damage state can be depicted by a restraining stress zone. A trans-scale fatigue crack model with coupling the macro / micro effects is developed. The proposed model can describe the whole process of fatigue failure from a microflaw（ fatigue source） to the final fracture. The distribution of restraining stresses depends on the material damage state in the restraining stress zone. A linear distribution of restraining stresses is assumed. Under the remotely applied uniform tension,the trans-scale crack model is analytically solved using Muskhelishivili approach. Analytical expressions of crack opening displacement and trans-scale strain energy density factor are obtained. The trans-scale strain energy density factor serves as the controlling parameter of fatigue crack growth from micro-scale to macro-scale. Numerical simulations for the whole process of fatigue failure are completed. By application of the present model,the experimental S-N curves of LC4 aluminum alloy plates under the different loading conditions are accurately re-produced. The scatter of fatigue test data owing to the microscopic effects is also reflected by the present model. Moreover,the influences of microscopic effects on the fatigue crack growth are also discussed.
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