Corso di Eccellenza "Aeroelastic tailoring – modelling, design, manufacturability and experiments" prof. Roeland De Breuker , Delft University of Technology
Aeroelastic tailoring is a methodology to design aircraft lifting surfaces by making use of the directional properties of composite materials. The goal is to minimise the structural weight or to ensure optimal aircraft performance and manoeuvrability. The use of directional properties of composite materials to influence the aeroelastic wing deformations favourably was already topic of research in the 1980s. This was also the era when the swept-forward wing X-29 was launched. Composites were used for the X-29 to avoid divergence issues while ensuring superior roll performance of the experimental combat aircraft.
Aeroelastic tailoring has gained renewed interest in the 2000s because of the availability of novel manufacturing techniques for composite materials. The main differences with the research carried out in the 1980s is that the coupling between in-plane and out-of-plane stiffness, the so-called B matrix, is considered to be zero to avoid warping due to residual thermal stresses after curing of the composite panels. Furthermore, more manufacturing constraints for large scale automated production of commercial airliners are taken into account nowadays.
The major challenges in the design of aeroelastically tailored composite lifting surfaces are multiple. From a modelling point of view, a static and dynamic aeroelastic loads analysis process needs to be created that is suitable to be used for optimisation from a computational efficiency perspective. Furthermore, manufacturability and certification considerations must be implemented in the analysis procedure. From a design point of view, aeroelastic tailoring optimisation problems typically contain O(1e3) design variables and O(1e4) constraints. Hence, the problem parameterisation must be such that the design variables are continuous since gradient based optimisation is the most efficient strategy in case of large-scale optimisation problems where the analysis time is in the order of tens of minutes. Due to the large amount of design variables and relatively long analysis time, the gradients have to be analysed analytically rather than using finite differences. This also poses a numerical challenge.
The analysis tools for aeroelastic tailoring have to be validated using wind tunnel tests to ensure that all relevant physical aerodynamic and structural effects have been taken into account. Wind tunnel tests have to validate both static and dynamic aeroelastic loads. A gust generator has been used for the latter. The ultimate validation is carried out using flight tests of a UAV which is equipped with aeroelastically tailored composite wings. The final part of the research is applying the validated tools to realistic aircraft designs to assess the benefits aeroelastic tailoring can bring to minimising structural aircraft weight.
The short course consists of the following chapters:
- Feb 5, 09:00 - 12:00
- Feb 5, 14:00 - 16:00
- Feb 6, 09:00 - 12:00
- Feb 6, 14:00 - 16:00
- Feb 7, 09:00 - 12:00
- Feb 7, 14:00 - 16:00