Span-Morphing Wing Using Multistable Honeycomb Metamaterial Structures.

Conventional span-morphing wings are often constrained by structural complexity, heavy weight, and discontinuous aerodynamic surface. Although flexible honeycomb and lattice structures offer lightweight solutions, they usually require external loads to maintain the deformed configuration and often exhibit limited stability under large deformation. In this study, a span-morphing wing section based on multistable honeycomb structures is proposed. The multistable honeycomb acts as the core deformation-load-bearing module, enabling multistage reversible spanwise reconfiguration through the bistable transition of cosine curved beams and the support of honeycomb structures. An equivalent nonlinear force-displacement model is derived to describe the structural response. Finite element analysis and fluid-structure interaction analysis are conducted to evaluate its mechanical and aerodynamic performance, while prototype fabrication and bidirectional morphing experiments are performed to demonstrate its functional feasibility. The results show that the proposed wing section achieves prescribed multistage state transitions, effectively regulates lift through span variation, and maintains good structural strength under typical aerodynamic loads. These findings demonstrate the potential of multistable honeycomb structures for lightweight and stable span-morphing wing design.