Design of a morphing winglet trailing edge based on Fluid Actuated Morphing Unit Structures

Abstract

In aeronautical industry the reduction of the fuel consumption is always researched to pollute less as well as to decrease the flight mission costs. Many solutions can be adopted, spacing from more efficient engines, less heavy structures to better aerodynamic performances. The purpose of the thesis is to focus on the use of a winglet morphing trailing edge based on fluid actuated unit structures (FAMoUS) made of elastomeric cells reinforced with constraining rings. The cells can elongate when pressurised, in order to improve aerodynamics in off design conditions and to reduce the structural mass thanks to the load alleviation capability. The conducted research regards investigations on the many geometry variables, such as the thicknesses of all the parts and constraining rings number, to find the most performing design mostly in terms of trailing edge deflection angle, but at the same time without neglecting maximum allowable stress values, free-stream exposed surfaces shape changes and easiness of manufacturing. Finite element analyses with three-dimensional structural and hydrostatic fluid elements are used to model the structural behaviour. The work firstly regards analyses on a single unit structure with all the variables parametrised, and then the design found to be the best has been included in more advanced and complete models with more cells. Throughout the thesis different methodologies have been used to face many problems related to the convergence of the results and to simplify high time consuming models, and, at the end, the design parameters, for the final model worthy to be manufactured, have been provided.