The deployment dynamics and multistability of tubular fluidic origami

Abstract

This research for the first time investigates the deployment dynamics of fluidic origami tubular structures, driven by internal pressurization using working liquid or air. Utilizing fluidics is attractive given that it is readily available in many engineering systems and is easy to realize and control, and embedding it in tubular origami is an effective innovation to create various advanced functionalities, which are not achievable in traditional origami even with adaptive materials. Despite fluidic origami’s potential as a promising inflatable deployable structure, the dynamics of its deployment have not been explored. This research advances the state of the art with intriguing new findings that have not been observed in previous studies and cannot be derived with traditional quasi-static analysis. In this investigation, the origami tube is constructed using the Miura origami pattern with the ends of the tube sealed and fluidic pressure applied in the chamber. We develop a structural dynamic model based on the bar-and-hinge approach, where the panel flexibility and inertia effects are captured. We restrict movement on one end of the tube in the axial direction and release the other end to move freely. We derive discretized non-dimensionalized equations of motion and apply equivalent nodal forces on the facets to emulate the effect of internal fluidic pressure. Through quasi-static analyses, the tube’s deployed configuration is shown as a function of the fluidic field pressure. It is illustrated that given the same pressure level, the structure will deploy to a lesser length/volume as the crease folding stiffness increases, and that the effect of the variation in panel deformation stiffness is not as significant. We then perform analysis of the tubular structure’s dynamic deployment process, by assuming a space-invariant pressure field first applied as a step function in time. The results reveal that the internal pressure level can effectively influence the structure’s transient response during deployment and its final configuration. Increasing the pressure level may increase the tube oscillation frequency, and may also cause the system behavior to change from overdamped to underdamped. These results indicate that adjusting the fluidic field pressure would vary the system effective stiffness and damping ratio properties, and thus would affect the tube’s transient dynamic response during deployment. Additionally, the multistability landscape of the fluidic tubular origami will further enrich the deployment dynamics. Under certain values of the fluidic pressure, the tubular structure exhibits significant global bending motion, and settles at a distorted stable equilibrium configuration with large transverse deformation. By applying the fluidic pressure as a ramp function in time, we show that through controlling the pressurization rate, the tube will possess different transient behaviors and settle at different stable configurations. Overall, this investigation enables a deeper understanding of the physics behind the dynamics of tubular origami deployment utilizing internal pressure and pave the way for potential applications of fluidic origami-based structures, such as space boom, morphing surfaces, soft robotics, and many others.