What is time temperature superposition rule?
The principle of time-temperature superposition states that the change in temperature from T to T0 is equivalent to multiplying the time scale by a constant factor aT which is only a function of the two temperatures T and T0.
What is the use for WLF equation?
The WLF equation is typically used to describe the time/temperature behavior of polymers in the glass transition region. The equation is based on the assumption that, above the glass transition temperature, the fractional free volume increases linearly with respect to temperature.
What is WLF shift factor?
The Williams–Landel–Ferry Equation (or WLF Equation) is an empirical equation associated with time–temperature superposition. Once constructed, the WLF equation allows for the estimation of the temperature shift factor for temperatures other than those for which the material was tested.
Is viscoelasticity time-dependent?
Viscoelasticity is the time-dependent anelastic behaviour of materials. This means that the response to a stimulus is delayed, and there is a loss of energy inside the material. Viscoelastic behaviour normally occurs at different time scales (relaxation times) in the same material.
What is the difference between viscosity and viscoelasticity?
Viscosity is related to shear stress σ and shear strain ε, without reference to E. Viscoelasticity is related to all the three parameters, with E being of primary importance. The second type describes the purely theoretical approaches to viscosity.
What is shift factor?
The shift factor is the percentage of shift that a plan can move if not completed on time. For example, if a maintenance plan is due Sept. 5, the shift factor will determine the next plan due date.
How are shift factors calculated?
To calculate a PTDF (or shift factor), we consider an injection of power at one bus and a withdrawal at another bus. That is, the shift factor is the ratio of the change in the flow on a line to a change in the injection and a corresponding change in the withdrawal.