Periodic Reporting for period 1 - NABUCCO (New Adaptive and BUCkling-driven COmposite aerospace structures)
Reporting period: 2023-05-01 to 2025-10-31
The current quest for highly efficient and green aircraft demands innovative concepts, including aircraft capable of adapting their shape during different flight conditions. The NABUCCO research project is developing new design, analysis and optimization methods to create radically innovative adaptive composite structures by harnessing the phenomenon of structural instability (buckling).
Practical solutions for these innovative concepts require a compromise between two counteracting requirements typical of aircraft structures: the design of a structure that can withstand the requested loads (stiffness requirement), together with the possibility to change its shape without excessive effort (compliance requirement). This is precisely the opportunity offered by modifying and adapting the aircraft wing shape during the flight mission by directly using the buckling phenomena, induced by typical large nonlinear displacements and stiffness redistribution.
In aeronautics, structural instability is generally avoided as it can generate large deformations and, in some cases, cause catastrophic collapse of structures. The NABUCCO project, however, is flipping the concept of buckling on its head: rather than seeing buckling as a phenomenon to be avoided, it is seen as a design opportunity to be explored for its revolutionary potential.
Practical solutions for these innovative concepts require a compromise between two counteracting requirements typical of aircraft structures: the design of a structure that can withstand the requested loads (stiffness requirement), together with the possibility to change its shape without excessive effort (compliance requirement). This is precisely the opportunity offered by modifying and adapting the aircraft wing shape during the flight mission by directly using the buckling phenomena, induced by typical large nonlinear displacements and stiffness redistribution.
In aeronautics, structural instability is generally avoided as it can generate large deformations and, in some cases, cause catastrophic collapse of structures. The NABUCCO project, however, is flipping the concept of buckling on its head: rather than seeing buckling as a phenomenon to be avoided, it is seen as a design opportunity to be explored for its revolutionary potential.
A strongly coupled computational-experimental framework is currently being developed. It relies on innovative analytical formulations, approximations and model reduction using artificial neural networks, large multi-objective optimizations, high-fidelity simulation methodologies, and advanced test techniques. The computational models include a rapid tool for calculating different multi-stable configurations through analytical formulations and deep learning, as well as high-fidelity finite element models to ensure structural reliability in the post-buckling regime.
Given the sensitivity of the buckling phenomenon to various parameters, we are pursuing a robust and reliability-based design optimization strategy. This involves considering the key parameters influencing the buckling phenomena from the initial design stages, treating structures and materials no longer as two separate entities. Additionally, managing multi-stability and the required stiffness to support loads poses challenges, as repeated stable-mode switches can cause fatigue damage. Therefore, we are studying low fatigue algorithms to create more efficient and durable structures.
Our design efforts for buckling focus on increasingly complex aircraft structures. We explore various concepts at the panel level, analyze these concepts on wingbox structures, manufacture and test the most promising ideas, and finally design morphing buckling-driven solutions for adaptive wings.
We have investigated new solutions to modify the aircraft wing shape, primarily the twist span-wise, for various flight conditions by designing selected elements that can switch into different post-buckling configurations as needed. This approach allows us to adjust the structures to the desired aerodynamic shape with minimal energy requirements.
Given the sensitivity of the buckling phenomenon to various parameters, we are pursuing a robust and reliability-based design optimization strategy. This involves considering the key parameters influencing the buckling phenomena from the initial design stages, treating structures and materials no longer as two separate entities. Additionally, managing multi-stability and the required stiffness to support loads poses challenges, as repeated stable-mode switches can cause fatigue damage. Therefore, we are studying low fatigue algorithms to create more efficient and durable structures.
Our design efforts for buckling focus on increasingly complex aircraft structures. We explore various concepts at the panel level, analyze these concepts on wingbox structures, manufacture and test the most promising ideas, and finally design morphing buckling-driven solutions for adaptive wings.
We have investigated new solutions to modify the aircraft wing shape, primarily the twist span-wise, for various flight conditions by designing selected elements that can switch into different post-buckling configurations as needed. This approach allows us to adjust the structures to the desired aerodynamic shape with minimal energy requirements.
The benefits we observe are in terms of both aerodynamic and structural efficiency, primarily due to the ability to reshape the spanwise load distribution. This enables us to have greater control over the wing load distribution, which directly impacts the root bending moment.
The use of composite materials also offers additional benefits for aerospace industries in terms of mechanical properties and design simplification for manufacturing processes.
The computational-experimental framework currently being developed has been applied to an aircraft model representative of a medium-range, single-aisle aircraft similar to the Airbus A321. Preliminary results show that the post-buckling response of certain wing components can effectively reduce peak loads experienced by high aspect ratio wings, especially under gust responses, promoting more sustainable aviation practices.
These advancements demonstrate the potential to create feasible, robust buckling-driven designs for aerospace structures. This contributes to reducing structural weight, lowering dynamic loading, and improving fuel efficiency in the aviation industry.
The use of composite materials also offers additional benefits for aerospace industries in terms of mechanical properties and design simplification for manufacturing processes.
The computational-experimental framework currently being developed has been applied to an aircraft model representative of a medium-range, single-aisle aircraft similar to the Airbus A321. Preliminary results show that the post-buckling response of certain wing components can effectively reduce peak loads experienced by high aspect ratio wings, especially under gust responses, promoting more sustainable aviation practices.
These advancements demonstrate the potential to create feasible, robust buckling-driven designs for aerospace structures. This contributes to reducing structural weight, lowering dynamic loading, and improving fuel efficiency in the aviation industry.