How do you calculate the shear rate of a viscometer?
Shear rate, gamma dot, is defined as v/h, where v is the velocity of the moving geometry of your viscometer and h is the separation of the plates or the thickness of your sample. Given the dimensions of your plate, you could convert RPM into a speed and use this to calculate shear rate.
How do you calculate shear rate of viscosity?
The shear rate is the velocity of the upper plate (in meters per second) divided by the distance between the two plates (in meters). Its unit is [1/s] or reciprocal second [s-1]. According to Newton’s Law, shear stress is viscosity times shear rate. Therefore, the viscosity (eta) is shear stress divided by shear rate.
How do you calculate shear rate?
Shear Rate = (Distance / Time) / Distance = Time-1 Using seconds as the unit of time, Time-1 becomes seconds-1. expressed in units of reciprocal seconds (sec-1).
How do you calculate shear stress on a viscometer?
The form of the relation between shear stress and rate of strain depends on a fluid, and most common fluids obey Newton’s law of viscosity, which states that the shear stress is proportional to the strain rate: τ = µ dγ dt . ν = µ ρ .
What are the units of shear rate?
Shear rate is the speed of deformation in the shear mode (which is typical of fluids and can be represented as layers sliding one onto another). It is expressed (SI units) in reciprocal seconds [1/s], since it derives from radiant per second, with radiant being dimensionless (just a number).
Does shear rate affect viscosity?
The viscosity changes with each shear rate. Generally, the viscosity decreases as the shear rate increases. This is called a “shear-thinning” fluid.
What is shear strain formula?
Shear strain is defined by the ratio of the largest displacement Δx to the transverse distance L0. shear strain=ΔxL0. shear strain = Δ x L 0 . Shear strain is caused by shear stress. Shear stress is due to forces that act parallel to the surface.
How is viscosity measured with a rotational viscometer?
Incoming liquid raw materials also have to be checked using viscosity measurements. Rotational viscometers are perfectly suited for the determination of the viscosity of a wide range of different samples. Liquid up to semi-solid samples are suitable for viscosity testing with rotational viscometers.
How is revolution per minute converted into shear rate?
When we perform rheological experiments with a viscometer, usually it gives us shear stress values corresponding to particular revolution per minute (rpm). Then we convert rpm into a shear rate by multiplying a factor 1.7. After that we have a set of values shear stress and shear rate.
How is the gamma dot of shear rate defined?
Shear rate is another name for velocity gradient in a direction normal to flow. Shear rate, gamma dot, is defined as v/h, where v is the velocity of the moving geometry of your viscometer and h is the separation of the plates or the thickness of your sample.
How is rotational viscometer used in asphalt construction?
The Rotational Viscometer (RV) (Figure 1 and Figure 2) is used to determine the viscosity of asphalt binders in the high temperature range of manufacturing and construction. This measurement is used in the Superpave PG asphalt binder specification.