Design and Analysis of a Self-Folding SMA-SMP Composite Laminate

Abstract

Shape memory alloy (SMA) wires have the ability to create large actuation forces and displacements. When arranged in a planar configuration (e.g., in a mesh) and embedded near the surface of a polymer matrix, they can be used to create flat sheets that are self-folding and reconfigurable. Shape memory polymers (SMP) exhibit changes in material properties that allow them soften when heated above their glass transition temperature and then freeze when cooled back below it, retaining any deformation applied when they were softened. This work considers the design and analysis of key engineering features of a shape memory composite (SMC) laminate consisting of thermally activated SMA wires in a mesh pattern embedded in such an SMP matrix. Such a laminate would represent a relatively stiff reconfigurable structure with no need for continued power to retain actuated shapes. The results of the design study described herein will be an optimized configuration that maximizes the deflection of the laminate in its locked state while respecting conventional constraints against overstressing and overheating the SMA and SMP materials.