Eberle A L, Reinhall P G, Daniel T L
Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA.
Bioinspir Biomim. 2014 Jun;9(2):025005. doi: 10.1088/1748-3182/9/2/025005. Epub 2014 May 22.
Insect wings deform significantly during flight. As a result, wings act as aeroelastic structures wherein both the driving motion of the structure and the aerodynamic loading of the surrounding fluid potentially interact to modify wing shape. We explore two key issues associated with the design of compliant wings: over a range of driving frequencies and phases of pitch-heave actuation, how does wing stiffness influence (1) the lift and thrust generated and (2) the relative importance of fluid loading on the shape of the wing? In order to examine a wide range of parameters relevant to insect flight, we develop a computationally efficient, two-dimensional model that couples point vortex methods for fluid force computations with structural finite element methods to model the fluid-structure interaction of a wing in air. We vary the actuation frequency, phase of actuation, and flexural stiffness over a range that encompasses values measured for a number of insect taxa (10-90 Hz; 0-π rad; 10(-7)-10(-5) N m(2)). We show that the coefficients of lift and thrust are maximized at the first and second structural resonant frequencies of the system. We also show that even in regions of structural resonance, fluid loading never contributes more than 20% to the development of flight forces.
昆虫翅膀在飞行过程中会发生显著变形。因此，翅膀可作为气动弹性结构，其中结构的驱动运动与周围流体的气动载荷可能相互作用，从而改变翅膀形状。我们探讨了与柔性翅膀设计相关的两个关键问题：在一系列驱动频率和俯仰 - 升沉驱动相位范围内，翅膀刚度如何影响（1）产生的升力和推力，以及（2）流体载荷对翅膀形状的相对重要性？为了研究与昆虫飞行相关的广泛参数，我们开发了一种计算效率高的二维模型，该模型将用于流体力计算的点涡方法与结构有限元方法相结合，以模拟空气中翅膀的流固相互作用。我们在一个涵盖多个昆虫类群测量值的范围内（10 - 90Hz；0 - π弧度；10^(-7) - 10^(-5) N·m²）改变驱动频率、驱动相位和弯曲刚度。我们表明，升力系数和推力系数在系统的第一和第二结构共振频率处达到最大值。我们还表明，即使在结构共振区域，流体载荷对飞行力发展的贡献也从不超过20%。
