Probabilistic buckling analysis of sandwich composite cylindrical shells based on measured imperfections

The paper presents a probabilistic methodology for the buckling analysis of sandwich composite cylindrical shells. The sensitivity to experimentally-measured imperfections is probabilistically assessed in terms of a loading factor, named probabilistic buckling factor. This factor corresponds to a required level of probability that shell withstands compressive load, and allows for a first evaluation of the buckling response and the imperfection sensitivity of the shells. In particular, the imperfections considered in this study include geometric imperfections, thickness variation, ply misalignment and boundary imperfections. An application is reported taking into account the geometric imperfections and thickness variation measured on a scaled shell of the Dual Launch System (SYLDA) of Ariane 5 launcher. Because only a scaled shell was available and was measured, the probabilistic buckling factor here obtained cannot be considered as the lower bound factor for the buckling response of the cylindrical shells manufactured nominally-identical to the SYLDA shell, but nevertheless allows to illustrating the complete methodology.