Design, Manufacture, and Structural Dynamic Analysis of a Biomimetic Insect-Sized Wing for Micro Air Vehicles

The exceptional flying characteristics of airborne insects motivates the design of biomimetic wing structures that can exhibit a similar structural dynamic behavior. For this purpose, this investigation describes a method for both manufacturing a biomimetic insect-sized wing using the photolithography technique and analyzing its structural dynamic response. The geometry of a crane fly forewing (family Tipulidae) is acquired using a micro-computed tomography scanner. A computer-aided design model is generated from the measurements of the reconstructed scanned model of the insect wing to design the photomasks of the membrane and the venation network required for the photolithography procedure. A composite material wing is manufactured by patterning the venation network using photoresist SU-8 on a Kapton film for the assembling of the wing. A single material artificial wing is fabricated using the photoresist SU-8 for both the membrane and the network of veins. Experiments are conducted using a modal shaker and a digital image correlation (DIC) system to determine the natural frequencies and the mode shapes of the artificial wing from the fast Fourier transform of the displacement response of the wing. The experimental results are compared with those from a finite element (FE) model of the wing. A numerical simulation of the fluid-structure interaction is conducted by coupling the FE 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. Wind-tunnel experiments are conducted using the DIC system to determine the structural deformation response of the artificial wing under different freestream velocities and angles of attack. 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 of the wing to the tip of the wing with Reynolds number. The aerodynamic performance, defined as the ratio of the coefficient of lift to the coefficient of drag, of the artificial wing increases with Reynolds number and angle of attack up to the critical angle of attack