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Suppressing torsional buckling in auxetic meta-shells
Aref Ghorbani1, Mohammad J Mirzaali2, Tobias Roebroek3
1Laboratory of Physics and Physical Chemistry of Foods, Wageningen University, 6708 WG, Wageningen, The Netherlands. aref.ghorbani@wur.nl.
Nature Communications
|August 14, 2024
Summary
This study prevents torsional buckling in cylindrical shells using auxetic and orthotropic metamaterials. The novel design exploits local buckling to achieve radial shrinkage, circumventing catastrophic failure under large twists.
Area of Science:
- Materials Science
- Mechanical Engineering
- Applied Physics
Background:
- Thin cylindrical shells are prone to immediate torsional buckling when twisted.
- Torsional buckling can cause critical failures, such as disrupting blood flow in arteries.
- Existing methods struggle to prevent this instability under significant twisting.
Purpose of the Study:
- To develop a novel metamaterial shell that prevents torsional buckling instability.
- To investigate the use of auxeticity and orthotropy in cylindrical metamaterial shells.
- To demonstrate potential applications in biomechanics, soft robotics, and fluidics.
Main Methods:
- Designed cylindrical metamaterial shells incorporating auxetic and orthotropic properties.
- Utilized a holey pattern within the metamaterial structure.
- Analyzed the shell's response to twisting, focusing on local buckling instabilities and stress-strain transitions.
Main Results:
- The meta-shell exhibited radial shrinkage due to local buckling when orthotropic axes aligned with compressive stress.
- A softening-stiffening transition was observed, leading to ordered unit cell stacking.
- The designed shells circumvented usual torsional instability, even under large twist angles.
Conclusions:
- Tailoring anisotropy and programming instabilities in metamaterials offers a robust solution to torsional buckling.
- The developed metamaterial shells have significant potential for applications requiring stable torsional performance.
- A soft torsional compressor was demonstrated, generating pulsatile flows via a torsion release mechanism.
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