Using New Closed-form Solutions to Set up Design Rules and Numerical Investigations for Global and Local Buckling of Sandwich Beams

This paper is dedicated to the study of global (at the sandwich scale) and local (at the component scale) buckling in sandwich structures. This approach relies on the basis of an analytical model able to capture both local and global instabilities [Leotoing, L., Drapier, S. and Vautrin, A. (2002). First Applications of a Novel Unified Model for Global and Local Buckling of Sandwich Columns, European Journal of Mechanics A/SOLIDS, 21(4): 683–701]. Results from this model are used to provide simple design rules by assessing the combinations of geometrical and material parameters which control these instabilities. From there, design diagrams are extracted which permit very quickly to select sandwich configurations more susceptible to develop local or global phenomena. These design diagrams constitute a precious guide at the predesign stage of sandwich structures. Then, two distinct FE models are presented and compared. The ability of a reduced size FE model to capture local as well as global instabilities is demonstrated. Eventually, the predicted loads and wavelengths from both FE simplified model and analytical model are shown to correlate very well. Thus, analytical wavelengths give accurate evaluations of the mesh element size for a low time-consuming but accurate FE model which can be easily extended to fully non-linear computations of sandwich panels.