Elastic instabilities between two cylinders confined in a channel

2021 ◽  
Vol 33 (7) ◽  
pp. 074107
Author(s):  
Manish Kumar ◽  
Arezoo M. Ardekani
Keyword(s):  
Elastic Instabilities

scholarly journals Stabilization of purely elastic instabilities in cross-slot geometries

2021 ◽  
Vol 922 ◽  
Author(s):  
Mahdi Davoodi ◽  
Gemma Houston ◽  
Jenna Downie ◽  
Mónica S. N. Oliveira ◽  
Robert J. Poole
Keyword(s):  
Elastic Instabilities

Abstract

scholarly journals Auxeticity in Metals and Periodic Metallic Porous Structures Induced by Elastic Instabilities (Phys. Status Solidi B 1/2019)

2019 ◽  
Vol 256 (1) ◽  
pp. 1970010 ◽  
Author(s):  
Duc Tam Ho ◽  
Cao Thang Nguyen ◽  
Soon-Yong Kwon ◽  
Sung Youb Kim
Keyword(s):  
Porous Structures ◽  
Elastic Instabilities

scholarly journals Characterization of Effective Diffusion within Viscoelastic Fluids with Elastic Instabilities

Fluids ◽  
2022 ◽  
Vol 7 (1) ◽  
pp. 33
Author(s):  
Valerie Hietsch ◽  
Phil Ligrani ◽  
Mengying Su
Keyword(s):  
Diffusion Coefficient ◽  
Couette Flow ◽  
Effective Diffusion Coefficient ◽  
Effective Diffusion ◽  
Flow Shear ◽  
Shear Rates ◽  
Flow Environment ◽  
Disk Rotation ◽  
Elastic Instabilities ◽  
Fluorescein Dye

We considered effective diffusion, characterized by magnitudes of effective diffusion coefficients, in order to quantify mass transport due to the onset and development of elastic instabilities. Effective diffusion coefficient magnitudes were determined using different analytic approaches, as they were applied to tracked visualizations of fluorescein dye front variations, as circumferential advection was imposed upon a flow environment produced using a rotating Couette flow arrangement. Effective diffusion coefficient results were provided for a range of flow shear rates, which were produced using different Couette flow rotation speeds and two different flow environment fluid depths. To visualize the flow behavior within the rotating Couette flow environment, minute amounts of fluorescein dye were injected into the center of the flow container using a syringe pump. This dye was then redistributed within the flow by radial diffusion only when no disk rotation was used, and by radial diffusion and by circumferential advection when disk rotation was present. Associated effective diffusion coefficient values, for the latter arrangement, were compared to coefficients values with no disk rotation, which were due to molecular diffusion alone, in order to quantify enhancements due to elastic instabilities. Experiments were conducted using viscoelastic fluids, which were based on a 65% sucrose solution, with different polymer concentrations ranging from 0 ppm to 300 ppm. Associated Reynolds numbers based on the fluid depth and radially averaged maximum flow velocity ranged from 0.00 to 0.5. The resulting effective diffusion coefficient values for different flow shear rates and polymer concentrations quantified the onset of elastic instabilities, as well as significant and dramatic changes to local mass transport magnitudes, which are associated with the further development of elastic instabilities.

scholarly journals Elastic-instability–enabled locomotion

2021 ◽  
Vol 118 (8) ◽  
pp. e2013801118
Author(s):  
Amit Nagarkar ◽  
Won-Kyu Lee ◽  
Daniel J. Preston ◽  
Markus P. Nemitz ◽  
Nan-Nan Deng ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Scaling Laws ◽  
Multiple Scales ◽  
Symmetric Cone ◽  
Simple Approach ◽  
Inertial Forces ◽  
Elastic Instability ◽  
Anisotropic Friction ◽  
Buckling Instability ◽  
Elastic Instabilities

Locomotion of an organism interacting with an environment is the consequence of a symmetry-breaking action in space-time. Here we show a minimal instantiation of this principle using a thin circular sheet, actuated symmetrically by a pneumatic source, using pressure to change shape nonlinearly via a spontaneous buckling instability. This leads to a polarized, bilaterally symmetric cone that can walk on land and swim in water. In either mode of locomotion, the emergence of shape asymmetry in the sheet leads to an asymmetric interaction with the environment that generates movement––via anisotropic friction on land, and via directed inertial forces in water. Scaling laws for the speed of the sheet of the actuator as a function of its size, shape, and the frequency of actuation are consistent with our observations. The presence of easily controllable reversible modes of buckling deformation further allows for a change in the direction of locomotion in open arenas and the ability to squeeze through confined environments––both of which we demonstrate using simple experiments. Our simple approach of harnessing elastic instabilities in soft structures to drive locomotion enables the design of novel shape-changing robots and other bioinspired machines at multiple scales.

The Friction Effect on Buckling Behavior of Cellular Structures Under Axial Load

2018 ◽  
Vol 10 (02) ◽  
pp. 1850013 ◽  
Author(s):  
Jianying Hu ◽  
Yu Zhou ◽  
Zishun Liu
Keyword(s):  
Nonlinear Response ◽  
Structural Response ◽  
Cellular Structures ◽  
Future Perspectives ◽  
Euler Buckling ◽  
Simple Theoretical Model ◽  
Buckling Behavior ◽  
Elastic Instabilities ◽  
Switching Mode ◽  
Periodic Materials

When soft cellular structures are compressed axially beyond critical limits, elastic instabilities induce buckling behavior. Although the nonlinear response of periodic materials with different shape voids has been widely investigated, the effect of the friction on the structural response has not yet been explored. In this paper, we develop a simple theoretical model for the buckling of holey column with holes. Meanwhile, we also numerically and experimentally explore the effect of friction on the buckling behavior of the cellular structures. We find out that friction could prevent conventional, global Euler buckling for holey column, which tends to choose the pattern switching mode, and our study also provides future perspectives for mechanics of buckling or optimal design for the cellular structures.

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