Skin-based camber morphing utilizing shape memory alloy composite actuators in a wind tunnel environment
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© 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. Shape memory alloys (SMA) enable morphing structures by virtue of their compact and high-force actuation, despite a relatively low energy efficiency. SMA wires are commonly used as the most simplistic and energy-dense actuators. Embedding the wires into an elastomer matrix and these composites into the skin of an airfoil provides a continuous outer mold line without hindering morphing capabilities. Following this paradigm, a novel and robust fabrication method for SMA actuators has been developed, and the capabilities of the actuators have been assessed for a morphing wing. For this application, 12 actuators are designed and embedded in the bottom skin of an avian-inspired, four foot span wing section, which is then morphed toward increased camber in a wind tunnel environment. The manufactured morphing wing consists of a XLPE foam core, fiberglass wing skin, and composite SMA actuators. All materials utilized are characterized and their determined properties used is a finite element model to determine optimal dimensions and locations of the SMA actuators. Experimental results show that single 2.5 cm x 10 cm (1” x 4”) SMA composite actuator can generate up to 746 N, which is sufficient to induce outer mold line morphing between designed configurations under aerodynamic loads. Furthermore, the manufactured composite SMA wing demonstrates the capability to generate relevant outer mold line modifications in an environment of interest (i.e., a low-speed wind tunnel).
author list (cited authors)
Leal, P. B., Stroud, H., Sheahan, E., Cabral, M., & Hartl, D. J.