Date of Award

5-2016

Document Type

Thesis - Open Access

Degree Name

Master of Aerospace Engineering

Department

Graduate Studies

Committee Chair

Dr. Ali Tamijani

First Committee Member

Dr. Habib Eslami

Second Committee Member

Dr. Frank Radosta

Abstract

In this research, the free vibration analysis of composite wing boxes with curvilinear spars and ribs is performed. Modern manufacturing technologies, such as Electron Beam Freeform Fabrication and Friction Stir Welding, have allowed the manufacturing of arbitrarily shaped stiffeners. Curvilinear stiffeners provide flexibility in design as they can assume an infinite number of paths. Curvilinear spars and ribs can in some instances provide a better vibration and static response than their straight counterparts while reducing the overall mass of the structure. An equivalent continuum plate model of a wing box using energy formulations is proposed at the preliminary design stage to reduce the high and costly CPU time incurred from the optimization of finite element models. In the present plate model, the bottom and top skins of the wing box are treated as plates, and the internal structures are treated as beams. The deformations and strains of the model are developed according to the FSDT. The Chebyshev polynomials are the bases of the displacement and rotation functions in the Ritz method. To assess the accuracy and feasibility of the proposed model, several numerical cases of the free vibration and aeroelastic flutter of stiffened panels have been analyzed. The model of a wing box with straight spars and ribs and models with curvilinear spars and ribs made of graphite/epoxy were compared with ANSYS® models. Reasonable agreement has been achieved.

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