Role of fluid-structure interactions in mechanosensation during hovering flapping flight

Abstract

Insect wings, known for their intricate structure and function, inherently deform during flapping motion. These deformations can be classified into chordwise cambering, spanwise bending, and root-to-tip twisting, arising from non-uniform venation distribution, aerodynamic loading, and wing inertia. Crucially, such deformations play a vital role in enhancing both aerodynamic performance and mechanosensory function. To investigate the complex interplay between wing structure, unsteady aerodynamics, and mechanosensation, we developed a fully coupled three-dimensional fluid-structure interaction (FSI) solver. This framework integrates an in-house Navier-Stokes equations solver for resolving the flow field with the open-source Vega FEM code to solve the solid structure dynamics. Our FSI simulations reveal that venation structures significantly enhance aerodynamic efficiency by enabling complex deformation patterns. Wings with moderate stiffness (reduced stiffness K = 3.94) values strike an optimal balance between lift generation and energy efficiency, outperforming both rigid and excessively flexible configurations (6 % higher lift generation and 89 % higher power efficiency, compared to rigid wings). In contrast with uniform wings, at K = 3.94, wings with venation structure generate 8 % less lift but the power efficiency is 25 % higher. Additionally, the time history of strain energy density closely mirrors the trend of aerodynamic forces, suggesting that local strain energy sensed by embedded mechanosensors could potentially predict aerodynamic forces. This finding highlights a direct functional link between unsteady aerodynamics and sensory feedback in insect wings. These results underscore the critical roles of wing stiffness, venation structures, and unsteady aerodynamics in shaping both the aerodynamic and sensory performance of insect-inspired wings. By elucidating how insects derive aerodynamic and sensory benefits from wing flexibility, this study provides valuable insights into insect flight mechanisms and offers inspiration for the design of efficient and adaptive flapping-wing Micro Air Vehicles.