Session: 12-18-01: Functional Origami and Kirigami-inspired Structures and Metamaterials

Paper Number: 99329

99329 - Multi-Stable Origami Corrugated Tubes With Self-Stiffening 

Thin-walled corrugated tubes that have a bending multi-stability, such as the bendy straw, allow for variable orientations over the tube length. Compared to the long history of corrugated tubes in practical applications, the mechanics of the bending stability and how it is affected by the geometric parameters remain unknown. To explore the geometry-driven bending stabilities, we used several tools, including a reduced-order simulation package, a simplified linkage model, and physical prototypes. We found the bending stability of a circular two-unit corrugated tube is dependent on the longitudinal geometry and the stiffness of the crease lines that connect separate frusta. Thinner shells, steeper cones, and weaker creases are required to achieve bending bi-stability. The different geometries influence the amounts of stretching and bending energy associated with bending the tube. The stretching energy has a bi-stable profile and can allow for a stable bent configuration, but it is counteracted by the bending energy which increases monotonically.

We then found that, using origami principles to design corrugated tubes not only preserves the multi-stability, but also provides tunable stiffness in multiple directions. Under appropriate geometric designs, origami corrugated tubes with a Kresling pattern either have straw-like multi-stability of axial inversion and bending, or have multiple axial stable states that occur via a twisting motion. We focused on the latter category and revealed another stable "pop-up" configuration via local buckling of the valley creases. By switching among the three types of stable configurations, the corrugated tube can exhibit drastically different axial and bending stiffness. Moreover, the deformation mode can switch from twisting to inversion after the pop-up. To quantify the tunable mechanical properties, we employed an elasticity-based bar and hinge model and performed parametric studies to discover the relationship between the geometry and the mechanics. This reduced-order model was calibrated to finite-element simulations, and it returns nonlinear predictions rapidly with less convergence issues. The results suggested that Kresling designs with a higher initial twisting and a lower initial slope will provide more significant stiffness and shape tuning, and the frustum stiffness can be increased by four orders of magnitude. To validate the numerical results, we fabricated proof-of-concept origami frusta and corrugated tubes. These prototypes demonstrated the desired multi-stable behavior, the tunable stiffness, and the deformation mode switching. The experimentally measured stiffness values were in good agreement with the bar and hinge predictions. This design of corrugated tubes has potential applications including adaptable ductwork, tunable energy absorbers, deployable traffic cones, reconfigurable robotic arms, and more.

Presenting Author: Zhongyuan Wo The University of Michigan

Presenting Author Biography: A Ph.D. candidate from the Department of Civil & Environmental Engineering at the University of Michigan.

Authors:

Zhongyuan Wo The University of Michigan
Evgueni Filipov The University of Michigan