Free-vibration tailoring of single- and multi-bay laminated box structures by refined beam theories

By employing refined beam theories, free vibration analysis and tailoring of laminated composite box structures are discussed in this work. Higher-order models are implemented utilizing the Carrera Unified Formulation (CUF), according to which the mechanical variables are expressed in terms of arbitrary expansion of the generalized unknowns. The proposed 1D models have only pure displacement variables, are geometrically consistent and have component-wise capabilities because Lagrange polynomials are used in the framework of CUF to formulate refined kinematics theories. Moreover, since the finite element method is used to interpolate the generalized unknowns, arbitrary anisotropy, geometry and boundary/loading conditions can be considered with no loss of generality. The resulting methodology is exploited to analyse single- and multi-bay composite laminated box beams for aerospace applications. Particular emphasis is given to the parametric study and tailoring of the lamination scheme versus free vibration characteristics for various box structures. Also, the effects of cut-offs are investigated. The numerical results are compared to those from the literature and commercial finite element software tools. The study widely demonstrates the high computational efficiency and the refined capabilities of the proposed CUF-based models, which can be considered as ideal candidates for the detailed tailoring of aerospace composite structures and, possibly, for future implementation into an optimization procedure.