Geometrically nonlinear models of initially imperfect sandwich plates and shells incorporating non-classical effects

A comprehensive geometrically nonlinear theory of initially imperfect doubly curved sandwich shells is developed in the context of 3D elasticity theory. It encompasses sandwich structures with dissimilar faces constructed of anisotropic composite laminates incorporating transverse shear effects, and with the core modelled as an orthotropic body featuring strong or soft behaviors. The theory includes the dynamic as well as the temperature and the moisture effects. As a special case, the theory of sandwich shells with soft core is presented and, in this connection, a range of applications involving the buckling and postbuckling of flat and circular cylindrical shells compressed by uniaxially edge loads are displayed and the influence played by a number of geometrical and physical parameters is highlighted. We also compare buckling results obtained in the context of the present theoretical model with the ones obtained experimentally; reasonable agreements are reported. (Author)