抄録
Flapping flights seen in birds and insects have been studied for purpose of the development of small aerial robots with flapping wings for many years. Biological wings are flexible so that they passively deform depending on aerodynamic force and inertia force. The wing deformation is structurally tuned with multiscale complex structures such as feathers of birds. On the other hand, typical structure of artificial wings is quite simple: The wing consists of a flat film supported by a simple framework. Here we have proposed a wing with anisotropic micro wrinkles in order to achieve fine tuning of wing deformation in artificial flapping wings. The micro wrinkles were created by utilizing self-organization phenomena in which micro wrinkles spontaneously emerge on the centimeter-scale elastomeric substrate. In this study, we first studied the influence of anisotropic wrinkles on the film stiffness by using finite element method simulation. Then we tested the fabricated wings with different wrinkle arrangements using a hummingbird-inspired tethered flapping mechanism. It was found that wrinkles perpendicular to the leading edge prevented undesirable twist of the wing film, resulting in improvement of cyclic average lift and efficiency.
