04.2 - Aerostructures Design, Structural Dynamics, Aeroelasticity
STRUCTURAL AND AEROELASTIC OPTIMISATION OF A LARGE AIRCRAFT WING WITH A PASSIVE TWIST WINGTIP
Y.J. Pan¹, M. Alam¹, A. Spinelli¹, E. Bragado Aldana¹; ¹Cranfield University, United Kingdom
A multi-fidelity toolset for structural and aeroelastic analysis is needed for the multi-disciplinary optimisation of an overall aircraft design. This paper presents the use of structural analysis and aeroelastic tailoring tools in designing an optimised composite wing for a large aircraft. The optimisation of the composite wing structure is divided into two stages, adhering to multiple design constraints. The first stage focuses on minimising the wing structural weight subject to static strength and aeroelastic constraints, utilising the in-house Structural Layout Tool (SLoT) and Structural Analysis Tool (SAIT) that relies on skin-stringer panel and wing box elements developed at Cranfield University. Here, the skin-stringer panel sizing, including skin thickness, web thickness, and stringer sizing, are used as design variables. The second stage involves aeroelastic tailoring, where skin and spar laminate layups are modified using a high-fidelity Finite Element (FE) based optimisation program integrating NASTRAN with MATLAB. This aims to maximise the flutter speed for the designated wing design. Furthermore, this study explores the incorporation of a passive twist wingtip (PTWT) in the wing design as an additional module within this toolset. The PTWT design has specific length, shaft, and CG locations, and it replaces the fixed wingtip of the FE model built in the optimisation stages of SLoT and SAIT. This PTWT module chooses torque spring stiffness and mass as design variables, focusing on aeroelastic stability and gust response. Overall, this paper aims at demonstrating that using the design and optimisation of the current multi-fidelity toolset not only achieves weight optimisation but also produces advantageous aeroelastic characteristics, particularly in terms of flutter suppression and gust alleviation for large aircraft.