DEFORM: Design against Fatigue of Multi-Stable and More Efficient Aerospace Composite Structures Driven by Sequential Buckling for Greener Aviation

Multi-stable composite structures are promising candidates to create adaptive/morphing structures and decrease fuel consumption for aerospace sectors. However, it seems to be a paradox to allow structures being multi-stable and stiff enough to carry loads simultaneously. Repetitive stable-mode switches also cause fatigue damage onset. To support EU aviation emission cut by 2050, DEFORM will deliver a cutting-edge design of next-generation aerospace structures exhibiting both multi-stability and high fatigue performance. Current knowledge gaps are: whether we can modify existing aerospace structures to become multi-stable; how their fatigue damage accumulates under non-linearly large deformation. DEFORM will use a three-phase interdisciplinary framework to fill in the gaps. Phase 1: Tailor non-uniform thermal stress distribution to create sequential-buckling-driven multi-stability for stiffened aerospace composite structures that can perform three stable modes under varying load amplitudes. Phase 2: Implant buckling-mode switch analysis into a virtual-crack-closure-technique-based algorithm for efficient fatigue damage modelling, providing dataset to optimise a down-scaled demonstrator with extended fatigue life and increased fatigue damage resistance. Phase 3: Perform multi-field interactive damage diagnostics in real time to measure optical-acoustic-mechanical properties at a structural level, for evaluation of fatigue damage accumulation scheme of composite structures under repetitive stable-mode switches. Overall, DEFORM will advance state-of-art of against-fatigue design, modelling and testing for multi-stable aerospace structures beyond the known limits, supporting European Green Deal for the EU’s ambition of climate neutral by 2050.