What is pre shear?
Method for controlled blasting involving the blasting of closely spaced holes along the perimeter of the excavation. The pre-shearing is fired before the main blast. A single line of holes that have predetermined spacing dependent on rock tensile strength, are drilled at the perimeter of the planned excavation.
What is a rheology curve?
A flow curve – also known as a rheogram – is a graphical representation of how a flowing material (fluid) behaves when it is subjected to increasing or decreasing shear rates. The corresponding shear stress and viscosity are calculated from the instrument’s parameters.
What does Rheometry mean?
[ rē-ŏm′ĭ-trē ] n. The measurement of electrical current. The measurement of blood flow.
What is the purpose of rheology?
Rheology is used to describe and assess the deformation and flow behavior of materials. Fluids flow at different speeds and solids can be deformed to a certain extent.
Why rheology is important?
Researchers believe that rheological characterization is essential for the development, optimization, and processing of foods. Food rheology also determines the food texture. Rheological flow properties deal with the perception of food when we touch or put it into our mouth.
What is the difference between rheology and viscosity?
Viscosity is a quantitative measurement that is useful in chemistry. These two terms are related to fluids such as liquids and gases. The key difference between rheology and viscosity is that rheology is the study of the flow of matter whereas viscosity is a measure of its resistance to deformation.
Why is Rheometry important?
Rheometry is a critical research and development tool that helps Nye chemists and engineers better understand and characterize the properties of our existing products so that we can more precisely recommend ones that are likely to meet a customer’s specific needs.
What is thixotropic example?
Examples of thixotropic materials include many gels and colloids, as well as common food products such as ketchup and yogurt. However, thixotropic properties are especially essential in paints and coatings.
How does thixotropy work?
‘Thixotropy’ is shear thinning property; when an alloy is sheared it thins, but when it is allowed to stand it thickens again. This behavior is associated with the breakup of agglomerates of solid particles under shear and their reformation when the shear is removed.
What are the examples of rheology?
Many physiological materials and fluids exhibit complicated rheology. Within the eye, examples include the vitreous humour, the liquid in the tear film, and the blood in capillaries.
What are the properties of rheology?
Rheological properties and their usefulness The most common rheological properties are yield stress, relaxation times, viscosity and compliance. Rheological properties study the behavior of fluids under mechanical loading. The solid structure, having a defined shape, deforms and stresses when subjected to a load.
What is the difference between shear rheology and longitudinal rheology?
Shear rheology is applicable at a low frequency range up to roughly 100 kHz. Longitudinal rheology functions only at the megahertz frequency scale. This makes both methods complimentary, not competitive. Second, longitudinal rheology is nondestructive.
What is the phase shift of shear strain and shear stress?
Figure 9.5: With ideally elastic behavior, the sine curves of shear strain γ and shear stress τ do not show any phase shift; the two curve functions reach the amplitude values and the zero crossings at the same time [1].
When does a yield occur in a shear stress profile?
Take a look at the curve below which shows a typical viscosity vs shear stress profile where a significant yield is occurring. You can see that the yield could be said to occur at any point within the stress range marked “yield zone”.
How do you calculate the shear rate of adhesives?
Squeezing an adhesive or paint at 5cm/s from a nozzle that is 0.5cm diameter gives a shear rate of 5/0.5=10 while the same adhesive being squeezed or paint being applied as a 10μm layer at 0.1m/s gives a shear rate of 0.1/10 -5 =10 4. Enter the estimated shear rate and the relevant viscosity and shear stress are calculated.