Related Experiment Video
Updated: Apr 16, 2026
08:42
Challenges in Rheological Characterization of Highly Concentrated Suspensions — A Case Study for Screen-printing Silver Pastes
Published on: April 10, 2017
20.7K
Macroscopic discontinuous shear thickening versus local shear jamming in cornstarch
A Fall1, F Bertrand1, D Hautemayou1
1Laboratoire Navier (UMR CNRS 8205), Université Paris Est, 77420 Champs-sur-Marne, France.
Physical Review Letters
|March 21, 2015
Summary
Discontinuous shear thickening (DST) in cornstarch occurs when flow separates into distinct low-density flowing and high-density jammed regions. Local measurements reveal the flowing part is often shear thinning, not DST.
Area of Science:
- Rheology
- Material Science
- Soft Matter Physics
Background:
- Discontinuous shear thickening (DST) is a phenomenon where viscosity abruptly increases under shear stress.
- Understanding the microstructural origins of DST is crucial for predicting material behavior.
Purpose of the Study:
- To investigate the local flow dynamics during discontinuous shear thickening (DST) in cornstarch.
- To reconcile macroscopic DST observations with local rheological properties.
Main Methods:
- Combined macroscopic rheometry with local magnetic resonance imaging (MRI).
- Analyzed the coexistence of flowing and jammed regions in shear-thickened cornstarch.
Main Results:
- Macroscopic DST emerges only when flow separates into low-density flowing and high-density jammed regions.
- The local rheology within the flowing region is frequently shear thinning, not shear thickening.
- The observed stress jump in DST does not represent a high-viscosity branch of local rheology.
Conclusions:
- DST in cornstarch is driven by the formation of distinct flowing and jammed phases.
- Shear jamming limit, occurring below random close packing, explains the macroscopic stress jump.
- Local shear-thinning behavior in flowing regions challenges conventional understanding of DST mechanisms.
Related Concept Videos
01:22Problem Solving on Stress and Strain
2.2K
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...
2.2K
01:17Colloids and Suspensions
3.9K
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles visible to the naked eye or seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. The suspended particles in a suspension settle out after some time of mixing. The separation of particles from a suspension is...
3.9K
01:20Elastic Strain Energy for Shearing Stresses
630
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...
630
01:20Shearing Strain
1.9K
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...
1.9K
01:18Shearing Stress
2.7K
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.
2.7K
01:27Types of Fluids
1.2K
Fluids can be classified into Newtonian and non-Newtonian fluids based on their response to shear stress. Newtonian fluids have a linear relationship between shear stress and the shear strain rate, following Newton's law of viscosity. Their viscosity remains constant regardless of the shear rate, making their behavior predictable and easier to analyze. Common examples include water, air, oil, and gasoline.
In contrast, non-Newtonian fluids do not follow Newton's law of viscosity, and...
In contrast, non-Newtonian fluids do not follow Newton's law of viscosity, and...
1.2K