Bistable morphing panels through SMA actuation

Abstract

This work introduces a numerical solution scheme for the prediction of the morphing mechanism in smart composite structures. Morphing relies on bistable plates actuated through nitinol shape memory wires. Bistable panels are obtained by exploiting the anisotropic thermal expansion of anti-symmetric composite laminates, which directly influences the post-cured shape. The numerical model accounts for the thermal distortions introduced upon cooling of the laminate as a result of the production process, and for the shape memory behavior of nitinol wires. The stress-strain behavior of the nitinol wire has been evaluated experimentally and implemented in the numerical model. A bistable composite plate has been manufactured for the purpose and results about its post-cured curvature have been utilized to tune the numerical model. The verified numerical scheme has been finally utilized to investigate the possibility to morph the panels by exploiting the actuation capabilities of Nitinol wires through thermal activation. Particular interest has been devoted to the analysis of prestrain, dimension, position, and the number of wires to cyclically actuate the panel. The numerical model can serve as tool to highlight the role of plate dimension, material properties, lamination sequence, and thermal cycle on the post-cured stable configurations, and for the identification of number and location of wires to best perform the morphing cycle.