Aerodynamic Control of Micro Air Vehicle Wings Using Electroactive Membranes

Abstract

Electrically controlled adaptive materials are ideal candidates for developing high agility micro-air-vehicles (MAV) due to their intrinsic multi-functionality. The dielectric elastomer VHB 4910 is one such material, where deformation occurs with an applied electric field. Here, we study the aerostructural response and control authority of a VHB 4910 membrane wing. An experimental membrane-wing platform was constructed by stretching VHB 4910 over a rigid elliptical wing-frame. The low Reynolds number (chord Reynolds number < 106) aerodynamics of the elliptical wing were characterized with different electrostatic fields applied. We observe an overall increase in lift with maximum gains of 20% at 4.5 kV, and demonstrate the ability to delay stall. Aerodynamic effects are investigated with membrane displacement and strain data obtained through visual image correlation (VIC). The VIC data is compared to a finite deforming finite element shell model to help understand structural shape changes under electrostatic fields and low Reynolds number aerodynamic flows. The model is formulated to directly input three dimensional membrane displacements to quantify aerodynamic loads on the electroactive membrane surface.

Fluid–structural dynamic characterization of an electroactive membrane wing

“…Previous work has demonstrated time-averaged aerodynamic effects of an electric field tunable membrane wing (Hays et al, 2013). Increases in lift on the order of ;20 % were achieved and a delay of stall of ;5°was observed.…”

“…This wing shape and geometry was chosen for comparisons with prior research on the electrostatic behavior of this type wing as well as studies on the passive behavior of latex membranes and rigid plates having the same elliptical geometry (Albertani and Babcock, 2008;Hays et al, 2013) To ensure reasonable uniformity in the pre-stretch over the area of the ellipse, a square grid with ;10 mm resolution was drawn on the membrane prior to stretching. It was then mounted onto a rectangular wooden frame such that the elliptical frame could be placed on the pre-stretch membrane and adhered over night to minimize delamination during wind tunnel testing.…”

“…Although fluid-structure interactions on membrane wings at relatively low Reynolds numbers have been studied at length (Albertani et al, 2007;Gordnier, 2009;Gursul et al, 2006;Rojratsirikul et al, 2011;Song et al, 2008;Stanford et al, 2008;Swartz et al, 2007), less work has been done to investigate active changes in membrane tension (Curet et al, 2014;Hays et al, 2013). It has been shown elsewhere that the amount of tension in the membrane has a large effect on the overall performance of the wing (Rojratsirikul et al, 2010).…”

“…These unlike charges generate a Maxwell electrostatic stress causing compression in the membrane thickness direction and thus an in-plane reduction in tension (Bustamante et al, 2009;McMeeking and Landis, 2005;Zhao et al, 2007). In experimental wind tunnel test, this reduction in tension leads to small out-of-plane displacements (relative to the characteristic length of the wing), but significant changes in fluid-structural interactions when the material is exposed to a flow field (Hays et al, 2013).…”

Electro-aeromechanical modelling of actuated membrane wings

“…To the authors' knowledge only Hays et al (2013) and Curet et al (2014) have to date experimentally tested the use of DEs for integral actuation of membrane wings. From the computational point of view, the only high-fidelity models in the literature for actuated membrane wings consider only two of the three fields involved and the problem (see Fig.…”