Reducing design time: the impact of evolutionary structural optimisation on structural trade studies during preliminary design

Aircraft design is an inherently multi-disciplinary decision making process. In many design processes, the vehicle configuration is selected based on aerodynamic considerations in the concept design stage, before the structural layout is considered during preliminary design. Selection of the best vehicle configuration relies on an estimate of weight to determine the required lift of the aircraft. Structural topology optimisation is an efficient method for automatically generating a structural design layout that fits within a given design space and meets a given set of design criteria. By comparison to parametric structural optimisation approaches, topology optimisation permits a much greater design freedom. Though often difficult to manufacture using conventional methods, this design freedom can be exploited by using additive manufacture. In this thesis, an integrated concept and preliminary aerostructural design framework is proposed, which incorporates topology optimisation as a means of structural layout generation and weight estimation. The framework is utilised to optimise the wing geometry of an unmanned air vehicle, while generating a fuselage structure, intended for construction using additive manufacture, which satisfies a von Mises stress constraint. By comparison to an equivalent shell thickness optimisation study, the topology optimisation approach is shown to generate much lighter structural designs for the same aerodynamic efficiency