Reports

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Full scale aircraft structural optimization for electric flight concepts

(Netherlands Aerospace Centre NLR, 2023) Brink, W.M. van den ; Koenis, T.P.A. ; Dorigo, J.C.M. ; Straatsma, J.

The aviation industry, responsible for about 2% of global CO2 emissions and for local air pollution around airports, faces a need for transition to more sustainable propulsion systems. Electric aircraft driven by battery-powered propulsion have emerged as a potential solution. However to achieve a useable range for these battery powered electric aircraft very large battery packs are needed. These batteries are significant in weight and will increase the structural load of the aircraft and in particular the fuselage to wing connection. Therefore the structural airframe design of battery electric aircraft needs to be changed and potentially further optimized. This research explores the potential for structural topology optimization of a battery-powered ATR 42-600 with a focus on minimizing weight while ensuring structural integrity. A detailed analysis of loads including gravity, internal pressure, flight controls, battery loads, cockpit pressure and others was conducted. The study employed a comprehensive methodology based on 3D finite element modelling that combined shell and solid elements, utilizing Abaqus software. Topology optimization was carried out with strain energy and structural volume as design responses, subject to specified volume and symmetry constraints. Three distinct battery placement configurations were investigated, each impacting load paths and structural performance. A start has been made to translate the optimized design to actual aircraft structural features such as frames and door surround structures. The results showed interesting insights into the intricate load paths within different battery placement configurations. These configurations not only demonstrated the adaptability of the structure to varying loads but also highlighted the critical role of battery placement in shaping load distribution. As the findings indicated, a balance between weight reduction and structural robustness can be attained through innovative structural design, effectively addressing the challenges of battery integration. However currently due to the topology optimization approach in combination with the relative coarse mesh with centimetre sized element the optimized structural mass is too high. Therefore it is challenging to derive representative metrics on weight reduction and robustness of the structure. Further research is needed to translate these new insights into actual structural design and detailed design from which weight metrics can be derived. The research addresses questions concerning aircraft-level feasibility, optimization features, inertia relief, and mesh size influence. The findings show the potential for optimizing battery-powered aircraft wings through innovative structural design, contributing to potentially lower weight and further reduced environmental impact. This study serves as a first step towards future electric aircraft design and underscores the importance of integrating innovative solutions to reduce climate impact of the aviation industry.

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Geluidsanalyses voor MKBA krimp op Schiphol

(Netherlands Aerospace Centre NLR, 2023)