RESUMEN
Single-mode deformations of two-dimensional materials, such as the Miura-ori zig-zag fold, are important to the design of deployable structures because of their robustness; these usually require careful pre-patterning of the material. Here we show that inward contraction of a curved boundary produces a fine wrinkle pattern with a novel structure that suggests similar single-mode characteristics, but with minimal pre-patterning. Using finite-element representation of the contraction of a thin circular annular sheet, we show that these sheets wrinkle into a structure well approximated by an isometric structure composed of conical sectors and flat, triangular facets. Isometry favours the restriction of such deformations to a robust low-bending energy channel that avoids stretching. This class of buckling offers a novel way to manipulate sheet morphology via boundary forces.
RESUMEN
In [A. S. Pal, L. Pocivavsek and T. A. Witten, arXiv, DOI: 10.48550/arXiv.2206.03552], the authors discuss how an unsupported flat annulus contracted at its inner boundary by fraction Δ, buckles into a radial wrinkling pattern that is asymptotically isometric and tension-free. What selects the wavelength in such a pure-bending configuration, in the absence of any competing sources of work? In this paper, with the support of numerical simulations, we argue that competition between stretching and bending energies at local, mesoscopic scales leads to the selection of a wavelength scale λ* sensitive to both the width w and thickness t of the sheet: λ* â¼ w2/3t1/3Δ-1/6. This scale λ* corresponds to a kinetic arrest criterion for wrinkle coarsening starting from any finer wavelength λ â² λ*. However, the sheet can support coarser wavelengths: λ â³ λ*, since there is no penalty to their existence. Since this wavelength selection mechanism depends on the initial value of λ, it is path-dependent or hysteretic.
RESUMEN
This corrects the article DOI: 10.1103/PhysRevE.91.032706.
RESUMEN
We present a model of soft active particles that leads to a rich array of collective behavior found also in dense biological swarms of bacteria and other unicellular organisms. Our model uses only local interactions, such as Vicsek-type nearest-neighbor alignment, short-range repulsion, and a local boundary term. Changing the relative strength of these interactions leads to migrating swarms, rotating swarms, and jammed swarms, as well as swarms that exhibit run-and-tumble motion, alternating between migration and either rotating or jammed states. Interestingly, although a migrating swarm moves slower than an individual particle, the diffusion constant can be up to three orders of magnitude larger, suggesting that collective motion can be highly advantageous, for example, when searching for food.
