Description
Composite structures present a high degree of anisotropy along the thickness direction. This makes an accurate description of the displacement and stress fields quite challenging, especially if moderately thick or thick plates are considered. A vast number of theories have been introduced in the past to deal with this problem. Several axiomatic models have emerged: Equivalent Single Layer theories, in which the displacements are described at plate level, Zig-Zag theories, in which the discontinuity of the slopes of the displacements in the thickness direction is enforced a priori, and Layerwise models, in which the displacement variables are modeled at layer level. The Generalized Unified Formulation is a theoretical architecture which unifies all of the above approaches. All the finite element matrices are generated from six 1 _ 1 theory-invariant arrays. This makes the formulation very general and can be tuned according to the computational requirements of a given problem. GUF was introduced in the framework of static problems. For the first time, a dynamic extension is presented in this thesis with particular focus on the free vibration analysis of sandwich structures.
