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Title: Aeroelastic tailoring of aeroplane wings using composite laminates
Author: Canale, Giacomo
ISNI:       0000 0004 2705 1094
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2010
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This thesis concerns aeroelastic tailoring, i. e. the discipline that studies the induced deformation of an aeronautical structure, such as wings, tails, or vertical fins, in order to improve a particular aeroelastic performance. Aeroelastic tailoring is achieved here via passive actuation, obtained by exploiting the anisotropy of composite materials. This research has shown the potential benefits of anisotropic composite laminates for the static and dynamic aeroelastic performances of an aircraft wing, modelled as a thin-walled composite box. A specific kind of anisotropy has been considered: bend-twist coupling effect, obtained using unbalanced and symmetric composite plates. Two simple models have been developed to study static and dynamic aeroelasticity. Results obtained with the static aeroelastic model have shown that unbalanced composite laminates can be potentially used to improve the flight range of an aircraft. A potential increase of the structural weight of the wing, however, was observed. The static aeroelastic model introduces novel features. Potential improvements of flight range have been identified by exploiting the anisotropy of composite materials. Furthermore, the "optimum" fibre orientation was found by using procedures based on the physical understanding of the problem, rather than optimisation routines. Results obtained with the dynamic model show that bend-twist coupling has potential to increase the critical flutter speed of a wing. Also, the flutter model presents some points of novelty. A study of the variation of critical flutter speed with the fibre orientations of the laminates of a composite box is given. Besides the aeroelastic models, two underlying models have been enhanced. The first was the development of a simplified analytical formulation to evaluate the relevant stiffnesses of a composite box, used in both aeroelastic tools, to model the wing. Previously, it has been shown that three stiffnesses mainly control aeroelastictailoring: bending, torsional and bend-twist coupling stiffnesses. Models previously presented in the literature for these stiffnesses show a lack of precision when evaluating wing-boxes with different geometries and lay-ups. Consequently, a new model has been formulated and tested by using a commercial finite element code. The second enhanced model is a new algorithm of combinatorial optimisation to determine the optimum stacking sequence of a composite laminate. It can be used to study plates with fixed thickness and fixed number of ply orientations (i. e. plates whose membrane properties are predetermined). This algorithm gives excellent results when the performance (objective function) to be optimised is strictly related to the flexural stiffness matrix of the laminate. 3
Supervisor: Weaver, Paul Sponsor: Not available
Qualification Name: Thesis (Ed.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available