Related Experiment Video
Updated: Jul 10, 2026
09:30
Introducing an Angle Adjustable Cutting Box for Analyzing Slice Shear Force in Meat
Published on: April 26, 2013
Effect of shear on an onion texture
1MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, New Zealand.
The European Physical Journal. E, Soft Matter
|November 7, 2007
Summary
Shear stress transforms surfactant lamellar systems into spherical onions. Nuclear magnetic resonance (NMR) reveals how onion size and local viscosity change with shear rate, impacting solvent diffusion and slip.
Area of Science:
- Soft Matter Physics
- Materials Science
- Physical Chemistry
Background:
- Lamellar systems are surfactant self-assemblies forming planar bilayers.
- High shear rates induce the formation of spherical multi-lamellar vesicles, known as onions.
- Understanding shear effects on these structures is crucial for materials processing and applications.
Purpose of the Study:
- To investigate the impact of shear rate on multi-lamellar vesicles (onions).
- To characterize solvent diffusion and onion structure under varying shear conditions.
- To determine the relationship between local viscosity, onion size, and shear stress.
Main Methods:
- Utilized nuclear magnetic resonance (NMR) to measure solvent diffusion via time-dependent mean-squared displacements.
- Employed NMR velocimetry to analyze onion structure and dynamics.
- Investigated the role of slip and determined stress-dependent wall slip velocities.
Main Results:
- Identified distinct regimes of onion structure formation as a function of shear rate.
- Established a correlation between local viscosity and onion size across different shear regimes.
- Quantified the stress dependence of wall slip velocities in the sheared lamellar systems.
Conclusions:
- Shear rate significantly influences the structure and dynamics of surfactant onions.
- NMR techniques provide powerful insights into the relationship between macroscopic shear and microscopic structure.
- The findings contribute to understanding the rheology and self-assembly of complex fluids under flow.
More Related Videos
09:00Visualization of Failure and the Associated Grain-Scale Mechanical Behavior of Granular Soils under Shear using Synchrotron X-Ray Micro-Tomography
Published on: September 29, 2019
09:12Live Cell Analysis of Shear Stress on Pseudomonas aeruginosa Using an Automated Higher-Throughput Microfluidic System
Published on: January 16, 2019
Related Concept Videos
01:20Shearing Strain
The shearing strain represents a cubic element's angular change when subjected to shearing stress. This type of stress can transform a cube into an oblique parallelepiped without influencing normal strains. The cubic element experiences a significant transformation when exposed solely to shearing stress. Its shape alters from a perfect cube into a rhomboid, clearly demonstrating the effect of shearing strain. The degree of this strain is considered positive if it reduces the angle between the...
01:22Problem Solving on Stress and Strain
Stress is a quantity that describes the magnitude of a force that causes deformation, generally defined as internal force per unit area. When forces pull on an object and cause its elongation, like the stretching of an elastic band, it is called tensile stress. When forces cause the compression of an object, it is known as compressive stress. When an object is being squeezed uniformly from all sides, like a submarine in the depths of the ocean, we call this kind of stress bulk stress (or volume...
01:18Shearing Stress
Shearing stress, denoted by the Greek letter tau (τ), is stress caused by forces acting transversely on an object. These forces create internal ones within the entity in the plane where the external forces are applied. The resultant of these internal forces is the shear in the section.
The average shearing stress can be calculated by dividing the shear by the area of the cross-section.
The average shearing stress can be calculated by dividing the shear by the area of the cross-section.
01:23Components of Stress
Stress analysis under multiple loading conditions is intricate, necessitating a comprehensive grasp of normal and shearing stresses. Consider a small cube at point O, subjected to stress on all six faces, visible or not. Normal stress components σx, σy, σz act perpendicularly to the x, y, and z axes. Shearing stress components τxy and τxz are exerted on faces perpendicular to these axes.
Interestingly, the hidden cube faces also experience these stresses, equal and opposite to those on the...
Interestingly, the hidden cube faces also experience these stresses, equal and opposite to those on the...
01:15Stress: General Loading Conditions
To grasp the intricacy of real-world conditions where multiple loads are applied simultaneously to a structure, one might visualize a section passing through a specific point within a body, aligned parallel to the xy plane. This section is subjected to various forces, including original loads, normal forces, and shearing forces.
The shearing force, possessing potential directionality within the plane of the section, is simplified into two component forces running parallel to the x and y axes.
The shearing force, possessing potential directionality within the plane of the section, is simplified into two component forces running parallel to the x and y axes.
01:15Thin-Walled Hollow Shafts
In analyzing a thin-walled hollow shaft subjected to torsional loading, a segment with width dx is isolated for examination. Despite its equilibrium state, this segment faces torsional shearing forces at its ends. These forces are quantitatively described by the product of the longitudinal shearing stress on the segment's minor surface and the area of this surface, leading to the concept of shear flow. This shear flow is consistent throughout the structure, indicating a uniform distribution of...