Wo, Z., & Filipov, E. “Bending Stability of Corrugated Tubes with Anisotropic Frustum Shells.” ASME. J. Appl. Mech. doi: 10.1115/1.4053267
ABSTRACT: Thin-walled corrugated tubes that have a bending multistability, 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 cross-sections and other 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. We then explored how the bending stability changes as the cross-section becomes elongated or distorted with concavity. We found the bending bi-stability is favored by deep and convex cross-sections, while wider cross-sections with a large concavity remain mono-stable. 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. The findings from this work can enable informed design of corrugated tube systems with desired bending stability behavior.
Wo, Z., Raneses, J., & Filipov, E. “A Numerical and Experimental Study on the Energy Absorption Characteristics of Deployable Origami Tubes.” Proceedings of the ASME 2021 IDETC/CIE. doi: 10.1115/DETC2021-66723 (Invited to and being reviewed by ASME J. Mech. Rob.)
ABSTRACT: Energy absorption devices are widely used to mitigate damage from collisions and impact loads. Due to the inherent uncertainty of possible impact characteristics, passive energy absorbers with fixed mechanical properties are not capable of serving in versatile application scenarios. Here, we explore a deployable design concept where origami tubes can extend, lock, and are intended to absorb energy through crushing (buckling and plasticity). This system concept is unique because origami deployment can increase the crushing distance between two impacting bodies and can tune the energy absorption characteristics. We show that the stiffness, peak crushing force, and total energy absorption of the origami tubes all increase with the deployed state. We present numerical and experimental studies that investigate these tunable behaviors under both static and dynamic scenarios. The energy-absorbing performance of the deployed origami tubes is slightly better than conventional prismatic tubes in terms of total absorbed energy and peak force. When the origami tubes are only partially deployed, they exhibit a nearly-elastic collapse behavior, however, when they are locked in a more deployed configuration they can experience non-recoverable crushing with higher energy absorption. Parametric studies reveal that the geometric design of the tube can control the nonlinear relationship between energy absorption and deployment. A physical model shows the potential of the self-locking after deployment. This concept for deployable energy-absorbing origami tubes can enable future protective systems with on-demand properties for different impact scenarios.
Wo, Z., Raneses, J.M., & Filipov, E.T., “A Numerical and Experimental Study on the Energy Absorption Characteristics of Deployable Origami Tubes.” ASME IDETC/CIE, Virtual, 2021 (Oral Presentation)
Wo, Z., Raneses, J.M., & Filipov, E.T., ” Using tunable origami for active energy absorption.” American Physical Society March Meeting, Boston, 2019 (Oral Presentation)
Wo, Z., & Filipov, E.T., “Geometric implications for stress concentration in Miura origami.” World Congress on Computation Mechanics, New York, 2018 (Poster & Oral Presentation)