Related Experiment Video
Updated: May 30, 2026
08:42
Challenges in Rheological Characterization of Highly Concentrated Suspensions — A Case Study for Screen-printing Silver Pastes
Published on: April 10, 2017
Impact of shear-thinning and yield-stress drops on solid substrates
Summary
Viscoplastic fluid drops impacting solids can form central peaks after spreading, unlike Newtonian or shear-thinning fluids. This indicates localized deformation due to yield-stress effects, impacting fluid dynamics research.
Area of Science:
- Fluid dynamics
- Rheology
- Materials science
Background:
- Newtonian fluids exhibit predictable behavior under stress.
- Non-Newtonian fluids, like shear-thinning and viscoplastic fluids, show complex responses to stress.
- Understanding fluid drop impact is crucial for various industrial processes.
Purpose of the Study:
- To experimentally investigate the impact behavior of shear-thinning and viscoplastic fluid drops on solid substrates.
- To compare the morphological outcomes of these non-Newtonian fluid impacts with Newtonian fluid impacts.
- To analyze the influence of yield-stress magnitude on the post-impact morphology of viscoplastic drops.
Main Methods:
- High-speed imaging was employed to capture the dynamic process of drop impact.
- Experimental setup focused on the inertial spreading phase of fluid drops.
- Morphological analysis of solidified drops was conducted to identify key features.
Main Results:
- Shear-thinning fluid drop impacts showed morphological similarities to Newtonian fluid impacts.
- Viscoplastic fluid drops exhibited unique central peaks post-impact, a phenomenon not observed in Newtonian or shear-thinning fluids.
- The size of these central peaks correlated with the yield-stress magnitude of the viscoplastic fluid.
Conclusions:
- Viscoplastic fluid behavior during impact is distinct from Newtonian and shear-thinning fluids due to yield-stress dominance.
- Central drop peaks signify localized deformation, where shear stress cannot overcome the fluid's yield stress within a critical radius.
- This localized deformation mechanism is critical for understanding the rheological properties and impact dynamics of viscoplastic fluids.
Related Concept Videos
01:25Yield Criteria for Ductile Materials under Plane Stress
In designing structural elements and machine parts using ductile materials, it is crucial to ensure that these components withstand applied stresses without yielding. Yielding is initially determined through a tensile test, which evaluates the material's response to uniaxial stress. However, tensile stress is insufficient when components face biaxial or plane stress conditions This condition requires advanced criteria to predict failure.
The Maximum Shearing Stress Criterion, also known as the...
The Maximum Shearing Stress Criterion, also known as the...
01:24Stress-Strain Diagram - Ductile Materials
The stress-strain relationship in ductile materials such as structural steel or aluminium is intricate and progresses through several stages. When a specimen is loaded, it initially exhibits a linear length increase, depicted by a steep straight line on the stress-strain diagram. It indicates the material is elastically deforming and will return to its original shape once unloaded. However, when a critical stress value is reached, plastic deformation begins. This stage sees substantial...
01:21Plastic Behavior
A material's elastic behavior is characterized by the disappearance of stress once the load is removed, allowing the material to return to its original state. However, when stress surpasses the yield point, yielding commences, marking the onset of plastic deformation or permanent set. This change from elastic to plastic behavior is influenced by the peak stress value and the duration before the load is removed. An intriguing observation occurs when a specimen is loaded, unloaded, and reloaded.
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.
01:20Shearing 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...
01:20Elastic Strain Energy for Shearing Stresses
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...