A model to assess the fatigue behaviour of ageing aircraft fuselage

A computer efficient model for assessing the fatigue behaviour of ageing ai rcraft components in the presence of multiple site damage is introduced. Th e model involves the computation of crack initiation scenarios on the basis of a probabilistic approach and the estimation of the fatigue behaviour of complex, highly loaded aircraft structures using a deterministic concept. To reduce the computing effort because of the model size and mesh difficult ies in crack propagation calculations, a sub-structuring procedure under th e FE method is utilized. An incremental approach for calculating crack init iation and crack propagation has been involved; it leads to a further essen tial reduction of the computing effort. Computer simulation is compared wit h experimental results for characteristic multiple site damage problems of aluminium 2024 lap and butt joints.