Related Experiment Video
Updated: Dec 29, 2025
08:50
The Mechanics of Poro-Elastic Contractile Actomyosin Networks As a Model System of the Cell Cytoskeleton
Published on: March 10, 2023
1.1K
Packing transitions in the elastogranular confinement of a slender loop.
David J Schunter1, Regina K Czech1, Douglas P Holmes1
1Mechanical Engineering, Boston University, Boston, MA 02215, USA. djsj@bu.edu dpholmes@bu.edu.
Soft Matter
|January 31, 2020
Summary
A growing elastic loop in soft grains forms distinct circular patterns above a critical density. This reveals novel packing behaviors relevant to natural structures and engineering applications.
Area of Science:
- Physics
- Materials Science
- Biophysics
Background:
- Confined thin structures exhibit unique packing strategies across scales, from DNA in capsids to biological systems like plant roots and the human gut.
- Understanding how growing slender structures interact with deformable boundaries is crucial for various scientific and engineering fields.
Purpose of the Study:
- To investigate the packing behaviors of a growing elastic loop within a deformable granular medium.
- To identify the critical conditions and resulting morphologies of confined elastic structures.
Main Methods:
- Experimentally injecting elastic loops of varying arc lengths into soft, spherical granular arrays.
- Systematically varying the initial number densities of the granular medium.
Main Results:
- At low densities, the elastic loop folds periodically, mimicking interaction with a flat surface.
- Above a critical packing fraction (φc), the granular medium re-orients, forming an effectively curved surface.
- This leads to the emergence of a distinct circular packing morphology for the elastic loop.
Conclusions:
- The study reveals a transition in packing behavior of elastic structures within deformable granular media.
- The findings offer insights into natural phenomena like plant morphogenesis and animal locomotion.
- Results are applicable to the development of advanced tools, such as steerable needles.
Related Concept Videos
01:20Elastic Strain Energy for Shearing Stresses
440
As discussed in previous lessons, strain energy in a material is the energy stored when it is elastically deformed, a concept crucial in materials science and mechanical engineering. This energy results from the internal work done against the cohesive forces within the material. When a material undergoes shearing stress and corresponding shearing strain, the strain energy density, which is the energy stored per unit volume, is calculated. Within the elastic limit, where the stress is...
440
01:18Residual Stresses in Bending
467
In the study of elastoplastic members subjected to bending moments, understanding the loading and unloading phases is crucial for assessing material behavior and structural integrity. During the loading phase, as the bending moment increases, the material initially responds elastically, adhering to Hooke's Law, where stress is directly proportional to strain. When the load exceeds the yield strength, plastic deformation occurs, resulting in permanent strain and deformation that remains even...
467
01:19Members Made of Elastoplastic Material
323
The behavior of elastoplastic materials under bending stresses, particularly in structural members with rectangular cross-sections, is crucial for predicting material responses and understanding failure modes. Initially, when a bending moment is applied, the stress distribution across the section follows Hooke's Law and is linear and elastic. This distribution means the stress increases from the neutral axis to the maximum at the outer fibers, up to the elastic limit.
As the bending moment...
As the bending moment...
323
01:15Relation between Poisson's ratio, Modulus of Elasticity and Modulus of Rigidity
485
Deformation occurs in axial and transverse directions when an axial load is applied to a slender bar. This deformation impacts the cubic element within the bar, transforming it into either a rectangular parallelepiped or a rhombus, contingent on its orientation. This transformation process induces shearing strain. Axial loading elicits both shearing and normal strains. Applying an axial load instigates equal normal and shearing stresses on elements oriented at a 45° angle to the load axis.
485
01:28Protein Translocation Machinery on the ER Membrane
6.4K
The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into the ER membrane.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the...
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the...
6.4K
01:32Pinching-off of Coated Vesicles
3.9K
Vesicle budding is orchestrated by distinct cytosolic proteins such as adaptor proteins, coat proteins, and GTPases. To initiate vesicle budding, membrane-bending proteins containing crescent-shaped BAR domains bind to the lipid heads in the bilayer and distort the membrane to form a protein-coated vesicle bud. Adaptors proteins such as AP2 for clathrin-coated vesicles can nucleate on the deformed membrane. Finally, coat proteins such as clathrin or COPI and COPII assemble into a coat forming...
3.9K