(A) study on the origami-based reconfigurable tubular structure

Abstract

Reconfigurable structures have attracted numerous interests as having potentials for the emerging engineering field, owing to the nature that a single structure can be utilizable for various purposes without redesigning the system. In the last few decades, the origami design principle has been extensively applied for designing reconfigurable structures, since the sophisticated three-dimensional shape can easily be produced by folding a flat sheet, while the drastic shape changes are achievable with a simple actuation mechanism. The high tunability of mechanical properties and the drastic changes of configuration leads the origami-based reconfigurable structure to a variety of applications in engineering fields. One of the most challenging issues in designing an origami-based reconfigurable structure is to ensure a load-bearing capacity in the operation while keeping the flexibility to avoid mechanical failure during reconfiguration. To address this issue, the structure can either be designed to exhibit kinematical contact during the reconfiguration or to have multiple stable configurations. Several concepts of 3-D origami building blocks have been introduced in the aforementioned aspects. However, the unpredictable behavior in the region of self-blocking or the complicated geometrical shapes with significant deformation in the boundary region remains as obstacles disrupting practical applications. In this dissertation, we present a novel 3-D origami-based tubular structure, which reconfigurable to multiple configurations having significant differences in their axial stiffness while keeping the tubular shapes. The reconfiguration of the proposed structure can be achieved in a multi-stable manner, thus continuous actuation is not necessary to retain a certain configuration. We mathematically identify and classify a complete set of configurations that a single design can be reconfigured. The geometrical analysis is conducted to investigate the effect of the design parameters on the dimension, and some notable geometrical relationships between unit cells of different types of configuration are reported. The stiffness differences in the various configurations are both analytically and experimentally investigated, and a certain regularity in their stiffness differences are discussed. Also, the scaling law of the proposed reconfigurable origami tube is derived based on the dimensional analysis. Further, we demonstrated the self-deployable tubular structure adopting the proposed reconfigurable concept, which automatically reinforces its own stiffness about an order of magnitude through changes in its kinematical composition. As another potential application, the adaptive vibration isolator concept using the reconfigurable origami modules is proposed and validated through the vibration test.