Dynamic Analyses of Sandwich Structures Through Variable-Fidelity Beam Models

This work discusses some advances in the nonlinear dynamic analysis of sandwich structures. Based on the Carrera Unified Formulation (CUF), geometrically linearized and full nonlinear governing equations are derived to investigate vibrations, transient responses, and dynamic instabilities of loaded and unloaded sandwich beams. According to CUF and using all terms of the full Green-Lagrange strain tensor, the proposed methodology can detect simple and complex nonlinear phenomena, including those related to deep nonlinear regimes. Particular attention is given to characterizing the response of sandwich structures under various conditions, including mechanical or thermal loads and parametric excitations. Low kinematics models can be adopted whenever stable conditions exist with no loss of generality. In contrast, in the case of unstable regimes, and when the stress state is complex, high-order kinematics and full displacement-strain relations must be used to describe vibrations. The results, discussed and compared with commercial software solutions, demonstrate the excellent accuracy and reliability of the proposed numerical methodology.