STOCHASTIC IMPERFECTION MODELING IN SHELL BUCKLING STUDIES

One possible avenue that may improve design against buckling is to rec ognise and account for the random nature of initial geometric imperfec tions introduced by manufacturing. This paper presents the application of a probabilistic methodology to the design and analysis of cylindri cal shells under axial compression. Results from two cases are present ed and compared. the first involves stringer-stiffened steel cylinders failing elastoplastically, whereas the second examines unstiffened co mposite cylinders buckling elastically. In both cases, the method is u nderpinned by statistical analysis of imperfections measured on nomina lly identical specimens. Nonlinear FE analysis is used for strength as sessment and the results of the statistical analysis are introduced in the imperfection modelling. It is demonstrated that the method has ad vantages over code design based on 'lower bound' curves, in terms of t he calculated buckling loads but also in offering a systematic and rat ional way by which randomness in imperfections can be assessed.