An Experimental Study of the Structural Dynamic Response of a Biomimetic Insect-Sized Wing

This investigation describes a method for both manufacturing a biomimetic insect-sized wing using the photolithography technique and experimentally analyzing its structural dynamic response. The wing geometry of a crane fly forewing is captured using a micro-computed tomography scanner for its replication. A photomask of the membrane and venation pattern is designed from a computer-aided design model developed from the reconstructed scanned model of the wing. The photolithography process is conducted using the negative photoresist SU-8 and the Kapton film to biomimic the veins and the membrane of the crane fly forewing, respectively. A digital image correlation (DIC) system is used in conjunction to a shaker vibrational setup to determine the natural frequencies of the artificial wing from the fast Fourier transform of the time-varying out-of-plane displacement data. Wind-tunnel experiments are conducted using the DIC system to determine the structural response of the artificial wing under different freestream velocities and angles of attack within the regime of insect flight. The vibration modes are dominated by a bending and torsional deformation response. The deformation along the span of the wing increases nonlinearly from the root to the tip of the wing with Reynolds number.

Design of a Beetle Inspired Deployable Wing

This study primarily proposes a procedure to design a crease pattern for beetle-inspired deployable wings based on the hindwings in relatively large-sized beetles like horn beetle or chafer. First, we discuss the representative patterns of wing supports and crease lines based on previous entomological research and propose a basic geometry for the artificial wing. Next, the flat foldability and rigid foldability of the proposed crease pattern are discussed based on origami geometry. Geometrical restrictions for flat- and rigid-foldable wings are numerically expressed as a function of the design parameters, and the Newton-Raphson method is used to compute the actual solutions. Although researchers have attempted to characterize the representative crease patterns found in beetles, only flat foldability has been considered in previous research. Our proposed method enables the design of rigid-foldable wings based on beetle-inspired patterns, which is considered beneficial in designing the deployable structures.

An Investigation of the Aerodynamic Performance of a Biomimetic Insect-Sized Wing for Micro Air Vehicles

Biologically-inspired micro air vehicles (MAVs) are miniature-scaled autonomous aircrafts which attempt to biomimic the exceptional maneuver control during low-speed flight mastered by insects. Flexible wing structures are critical elements of a nature-inspired MAV as evidence supports that the wings of aerial insects experience highly-elastic deformations that enable insects to proficiently hover and maneuver in different airflow conditions. For this study, a crane fly (family Tipulidae) forewing is selected as the target specimen to replicate both its structural integrity and aerodynamic performance. The artificial insect-sized wing is manufactured using photolithography with negative photoresist SU-8 to fabricate the vein geometry. A Kapton film is attached to the vein pattern for the assembling of the wing. The natural frequencies and mode shapes of the artificial wing are determined to characterize its vibrations. A numerical simulation of the fluid-structure interaction is conducted by coupling a finite element model of the artificial wing with a computational fluid dynamics model of the surrounding airflow. From these simulations, the deformation response and the coefficients of drag and lift of the artificial wing are predicted for different freestream velocities and angles of attack. The deformation along the span of the wing increases nonlinearly with Reynolds number from the root to the tip of the wing. The coefficient of lift increases with angle of attack and Reynolds number. The coefficient of drag decreases with Reynolds number and angle of attack. The aerodynamic efficiency, defined as the ratio of the coefficient of lift to the coefficient of drag, of the artificial wing increases with angle of attack and Reynolds number.

Fabrication of Comb Shape of Leading Edge Wing of Dragonfly

Research on Micro air vehicle (MAV) has been carried out by many researchers to gather information in environmental monitoring, security and so on. When the earthquake, fire, smoke take place, it is difficult for human beings to investigate the detail because of dangerous condition. However, MAV has possibility to investigate the detail because MAV can fly freely around. Recently, dragonfly is highly focused by many researchers because dragonfly has high flight performances those are high efficiency flight, unintended acceleration, rapid turn and hovering. In general, these characteristics have root that wing is corrugation shape. We focus on microstructures on wing and its aerodynamic characteristics because there are many unique microstructures. We focused on micro spikes on dragonfly wing. Over three thousands of spikes exist on two sides of wing. The length and shape of spikes are 10 to 100 micron meters and oblique circular cone. It is important to clear the aerodynamic effect of the oblique circular cone. Artificial wing was fabricated by following processes. We fabricated micro spikes utilizing electro polishing. Fabricated micro spikes were set on plate utilizing micro spot bonding. We investigated the flow around the artificial wing and found that the flow around wing was controlled by micro spikes on wing. In this paper, we focused on comb shape of leading edge of wing. Comb shape is fabricated utilizing micro-EDM. We investigate flow characteristics of comb shape.