Folding patterns and shape optimization using SMA-based self-folding laminates

Origami engineering, a discipline encompassing the creation of practical three-dimensional structures from two- dimensional entities via folding operations, has the potential to impact multiple fields of manufacturing and design. In some circumstances, it may be practical to have self-folding capabilities instead of creating folds by external manipulations (as in morphing structures in outer space or on the ocean floor). This paper considers the use of a self-folding laminate composite consisting of two outer layers of thermally actuated shape memory alloy (SMA) wire meshes separated by an inner compliant insulating layer. Methods for designing folding patterns and determining temperature fields to obtain desired shapes and behaviors are proposed. Sheets composed of the self-folding laminate are modeled via finite element analysis (FEA) and the proposed methods are implemented to test their capabilities. One method uses a previously developed and freely available software called Freeform Origami for folding pattern design. The second method entails the use of optimization to determine the localized activation temperatures required to obtain desired shapes or to perform specific functions. The proposed methods are demonstrated to be applicable for the design of folding patterns and determination of activation temperatures for the self-folding laminate by showing successful examples of their implementation. This exploratory study provides new tools that can be integrated into the design framework of self-folding origami structures.