22 June 2000 Active deformable sheets: prototype implementation, modeling, and control
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Active deformable sheets are integrated smart planar sheet structures performing off-plane deformations under computer actuation and control, to take up a desired dynamic morphology specified in CAD software or obtained by 3-D scanning of a solid surface. The sheet prototypes are implemented in the laboratory by elastic neoprene foil layers with embedded asymmetric grids of SMA wires (Nitinol), which upon electrical contraction bend the sheet to the necessary local curvature distribution. An analytical model of such prototypes, consisting of an electrical, a thermal, a material and a mechanical module, as well as a more complex finite element thermomechanical simulation of the sheet structure have been developed and validated experimentally. Besides open-loop control of the sheet curvatures by modulation of the SMA wire actuation current, a closed-loop control system has been implemented, using feedback of the wire electrical resistance measurements in real time, correlating to the material transformation state. The active deformable sheets are intended for applications such as reconfigurable airfoils and aerospace structures, variable focal length optics and electromagnetic reflectors, flexible and rapid tooling and microrobotics.
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Robert J. Lind, Robert J. Lind, Norbert Johnson, Norbert Johnson, Charalabos C. Doumanidis, Charalabos C. Doumanidis, "Active deformable sheets: prototype implementation, modeling, and control", Proc. SPIE 3985, Smart Structures and Materials 2000: Smart Structures and Integrated Systems, (22 June 2000); doi: 10.1117/12.388872; https://doi.org/10.1117/12.388872


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