Untangling the mechanics of the clove hitch knot

ORAL

Abstract

Knots can impart unique mechanical function to filamentary structures, with examples ranging across length scales, including DNA, polymer-chains, shoelaces climbing ropes, tennis racket, and surgical sutures. Still, the predictive understanding of the mechanics of this class of structures is limited. The fundamental challenge arises from the complex interplay between topology, geometry, elasticity, and friction. Here, we focus on the clove hitch knot, which typically attaches a flexible rod/filament/rope to a rigid post. The clove hitch can sustain a remarkably large tension ratio between the two ends of the rod when compared to the simpler strategy of spooling the rod around the rigid post in a helical configuration. In our study, we combine experiments (mechanical testing and X-ray tomography), finite element and a theory based on the Kirchhoff equations. We find that the twist in the rod increases with the ratio of the tensions applied to the two ends. Furthermore, in contrast to helical spooling, the clove hitch loses a significant amount of its tension at the regions of self-contact, thereby enhancing its mechanical performance.

*We acknowledge financial support in the form of Grants-in-Aid for JSPS Overseas Research Fellowship.

–

Presenters

  • Tomohiko Sano

    • École polytechnique fédérale de Lausanne
    • Flexible Structures Laboratory, Institute of Mechanical Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
    • Ecole Polytechnique Federale de Lausanne

Authors

  • Tomohiko Sano

    • École polytechnique fédérale de Lausanne
    • Flexible Structures Laboratory, Institute of Mechanical Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
    • Ecole Polytechnique Federale de Lausanne

  • Paul Grandgeorge

    • École polytechnique fédérale de Lausanne
    • Flexible Structures Laboratory, Institute of Mechanical Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
    • Ecole Polytechnique Federale de Lausanne

  • Paul Johanns

    • Flexible Structures Laboratory, Institute of Mechanical Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
    • Ecole Polytechnique Federale de Lausanne

  • Changyeob Baek

    • Department of Mechanical Engineering, Massachusetts Institute of Technology
    • Department of Mechanical Engineering, Massachusetts Institute of Technology, USA
    • Massachusetts Institute of Technology

  • Harmeet Singh

    • École polytechnique fédérale de Lausanne
    • Ecole Polytechnique Federale de Lausanne

  • John Maddocks

    • École polytechnique fédérale de Lausanne
    • Ecole Polytechnique Federale de Lausanne

  • Pedro Reis

    • Institute of Mechanical Engineering, École Polytechnique Fédérale de Lausanne
    • School of Engineering, Ecole polytechnique federale de Lausanne
    • Ecole Polytechnique Federale de Lausanne
    • École polytechnique fédérale de Lausanne
    • Flexible Structures Laboratory, Institute of Mechanical Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
    • FlexLab, Ecole Polytechnique Federale de Lausanne