| It has been shown that the structures of aging airplanes can be of the characterized as Multiple Cracks,which has badly threatened the residual strength and the crack growth life of airplane structures.For providing a more advanced,ideal and practical damage tolerance analysis method,the stress,the stress intensity factor,reliablilty life and fatigue life prediction of typical structures are obtained by finite element method in this paper,based on the elastic-plastic and fatigue fracture mechanics.First of all,in this paper, the fatigue crack growth procedure, research methods of fatigue cracks were studied in detail, then through the model of aircraft skin was simulated,know that collineation of multiple holes were more important model,at last, fitting collinear multiple cracks by stress intensity factor formula and the use of paris formulas program which was used by fatigue life prediction, utilization of existing test verified by comparing fatigue life prediction accuracy.Theories and simulation were used to research the fatigue life as Multiple Cracks.It had shown that the method was believeable and practical.this method has a good capacity of predication for any structure and can be also applied in engineering. |
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