Shear Morphing Skins - Simulation and Testing of Optimized Design

Abstract

Previous work designed and tested novel morphing wing designs that were enabled by ‘shear-morphing’ skins capable of withstanding 400 psf (19.15 kPa) airloads while simultaneously undergoing shear strains over 100%. These ad hoc skin designs consisted of high-strain silicone facesheets supported by thin, closely spaced aluminum strands glued to the facesheets and bounded by pin-jointed frames. While these performed well in wind tunnel and flight tests, two areas for improvement were identified: reduction in manufacturing complexity and reduction in actuation force requirements. In this research, with the use of high-fidelity modeling (ANSYS) and in-house testing, a new design was obtained that met both of the desired objectives using novel materials and single-piece support structure fabrication. Using an optimized design from analysis, the ANSYS code was validated through manufacture and testing of panels. This article details the results of testing and compares them to predictions of both the ANSYS code and N-MAS baseline designs values by various test setups. Results presented include shear morphing forces/energy, out-of-plane displacement under air loading, and 3D photometric analysis of shearing panels for identification of stresses/strains and wrinkling initialization in the skin. Testing provided substantiation of the ANSYS code, matching the general predicted trends despite a wide variability in material properties.