Fatigue Life Prediction Of Panels With MSD

The structures of aging airplanes can be often characterized as Multiple site damage(MSD), which is more damage of aircraft structures, because the structures are designed according to the traditional damage tolerance which takes no account of MSD. MSD has been one of the most representative damages styles in the aircraft structures, which has badly threatened the structures integrality of aircraft. To provide a more advanced, ideal and practical damage tolerance analysis method, the stress intensity factor(SIF) of elements with MSD and fatigue life of the panel containing multiple cracks are obtained by finite element method in this thesis, based on the elastic-plastic and fatigue fracture mechanics.This thesis consists of two sections. The first section focuses on the analysis of SIF of elements with MSD. Based on the elastic-plastic and fatigue fracture mechanics, with the help of FRANC2D/L, the SIF of different MSD model is computed and showing that the analysis results have good coherence with the literature data. Based on SIF, some factors that will affect SIF general, such as MSD crack length, the space between cracks, are discussed. Several conclusions valuable to practices are drawn. The second section focuses on fatigue life prediction of MSD panel. Fatigue life is calculated using Paris formulation. The direction is predicted by the maximum circumferential direction stress criterion. The predicated life is conservative to the experiments results.Theories and numerical simulation are used to research the fracture of panels with multiple site damage, in which every main point are studied systematically and supported by theoretical results and/or experimental results. This approach has a good capacity of predication and can be applied in engineering.