Fluid-Structure Interaction and Gyroscopic Sensing in Flapping, Flexing Bio-Inspired Wings

Abstract

Flying animals use the flexibility of their wings to perform impressive aerodynamic maneuvers that are not yet achievable using engineered systems. Since insects do not possess muscles within their wings, these animals must depend on the passive interactions between wing flexibility, wing actuation, and fluid-structure interaction to determine wing shape. As a result, insect wings serve as useful models for understanding the biological principles that govern the design of flexible-winged flyers. This work investigates two key aspects of insect wing flexibility: fluid-structure interaction and gyroscopic sensing. First, to explore the relationship between wing flexibility and fluid-structure interaction, a 2D wing model was developed by coupling a vortex particle method to a finite element model. For a range of actuation frequencies and flexural stiffnesses that are relevant for insect flight, we show that peak lift and thrust forces coincide with the structural resonance of the system. Second, to understand the mechanism(s) that might allow insect wings to serve as gyroscopic sensors, a 3D structural dynamics model of a flapping, flexing, and rotating wing was created along with a robotic model for validation. We show that the rotation of an insect’s body might induce torsion in the wing, which could stimulate an insect’s mechanoreceptors and trigger reflexive responses to body rotations. Since halteres, the quintessential examples of biological gyroscopes, are dumbbell-shaped structures that were derived from hind wings, evolution suggests that wings and halteres likely possess similar gyroscopic sensing capabilities. To understand more about gyroscopic sensing in nature, we used analytical and finite element models to re-examine haltere dynamics. Finally, we used quasi-steady aerodynamics and rigid body dynamics to investigate how the aerodynamic and gyroscopic forces differ for halteres and wings. These results provide the first combined experimental and computational evidence that wings may serve as both flight-force actuators and gyroscopic sensors.