Compact LET Arrays for Origami-Based Mechanisms

Lamina Emergent Torsional (LET) arrays can be used to replace creases in origami-based mechanisms. They can be made of planar materials, which makes them compatible with many designs. However, LET arrays can take up a lot of area and can exhibit significant parasitic motion, which makes them less ideal for some applications, such as in origami-based robotics and deployable space structures. This work presents a compact variation of the conventional LET array, which resolves these issues. An experimental method for fabricating these compact LET arrays, or C-LET arrays, from carbon fiber-reinforced polymer is given. Deflection models for C-LET array torsion segments, with and without interference with other torsion segments, are given. Bending stress and shear stress equations are provided, and the deflection models are combined into a final model that can solve for the deflections of multiple torsion segments in series. The concepts described are demonstrated in a prototype origami-based deployable reflectarray incorporating C-LET arrays. The prototype demonstrates that C-LET arrays provide the desired motion while maximizing the usable area of the deployable reflectarray.