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Acoustic levitation in air provides a containerless, gravity-free platform for investigating driven many-particle systems with nonconservative interactions and underdamped dynamics. In prior work the interactions among levitated particles were limited to attractive forces from scattered sound and repulsion from hydrodynamic microstreaming. We report on experiments in which contact cohesion provides a third type of interaction. When particle size and separation are both much smaller than the sound wavelength, this interplay of three interactions results in forces that are attractive over several particle diameters, become repulsive at close approach, and are again attractive at contact. In the presence of sound-induced athermal fluctuations that generate particle collisions, the interplay of these three forces enables the formation of particle chains with anisotropic interactions that depend on chain size and shape due to multibody effects. With the control of the kinetic pathways and the strength of the contact cohesion, different patterns can be assembled, from triangular lattices to labyrinthine patterns of chains to lacelike networks of interconnected rings. These results shed light on the multibody character of acoustic interactions and can be utilized to direct the self-assembly of particles. Published by the American Physical Society2025
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This content will become publicly available on May 1, 2026
Elastic Interaction of Pressurized Cavities in Hyperelastic Media: Attraction and Repulsion
Abstract This study computationally investigates the elastic interaction of two pressurized cylindrical cavities in a 2D hyperelastic medium. Unlike linear elasticity, where interactions are exclusively attractive, nonlinear material models (neo-Hookean, Mooney–Rivlin, Arruda–Boyce) exhibit both attraction and repulsion between the cavities. A critical pressure-shear modulus ratio governs the transition, offering a pathway to manipulate cavity configurations through material and loading parameters. At low ratios, the interactions are always attractive, while at high ratios, both attractive and repulsive regimes exist depending on the separation between the cavities. The effect of the strain-stiffening on these interactions is also analyzed. These insights bridge theoretical and applied mechanics, with implications for soft material design and subsurface engineering.
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- Award ID(s):
- 1757371
- PAR ID:
- 10581579
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Journal of Applied Mechanics
- Volume:
- 92
- Issue:
- 5
- ISSN:
- 0021-8936
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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