Actuation performance of fluidic origami cellular structure: a holistic investigation

Motivated by the sophisticated geometries in origami folding and the fluidic actuation principle in nastic plant movements, the concept of fluidic origami cellular structure was proposed for versatile morphing and actuation. The idea is to assemble tubular Miura-ori modules into a cellular architecture, and apply fluidic pressure to induce folding and hence actuation. Despite the promising potentials, the actuation capabilities of fluidic origami, such as free stroke and block force, are not elucidated. In particular, the effects of the thick facet material stiffness and pressure-sealing end caps are not understood. These gaps in our knowledge prevent the practical implementations of fluidic origami. Therefore, this study aims to address these issues by incorporating realistic considerations into the design, fabrication, and analysis of fluidic origami. We construct CAD models of the fluidic origami modules based on realistic design parameters to ensure that they can be fabricated via commercially accessible 3D printers while remaining pressure proof. We then use both simplified analytical methods, such as the equivalent truss frame model, and the more comprehensive finite element methods to examine the actuation performance. Comparing the results from these different methods can reveal the influences of end caps and thick facet material stiffness. Based on these insights, a customized generic algorithm is used to identify the optimal fluidic origami designs for fluidic actuation. It is found that an optimal folding angle exists to maximize the actuation capability, while the sector angle of Miura-ori can be tailored to effectively program the actuation performance.