What is the Heckel equation?

What is the Heckel equation?

Heckel (1961a) developed his equation by assuming similarity to a first-order chemical reaction, where the concentration is substituted with porosity and the time with pressure. (1) d D/ d P=K ∗ (1 − D) where P is the pressure, D the relative density of the compact and K is a constant.

What is Kawakita equation?

The Kawakita equation. This equation has been promoted, especially by Japanese workers, since about 1960. Work is summarised in the paper by Kawakita and Ludde [8]. The equation is:(1) P a C = 1 ab + P a a where C is the relative volume decrease, i.e.:(2) C= V 0 −V V 0 and a and b are constants.

What are Heckel plots?

The Heckel plot shows that the curve begins to adopt a tendency corresponding to the elastic deformation of the solid compact and therefore further compression does not affect the plastic deformation of the particles and also does not affect the formation of new bonds between the particles.

How do you calculate elastic and plastic strains?

The plastic strain is obtained by subtracting the elastic strain, defined as the value of true stress divided by the Young’s modulus, from the value of total strain (see Figure 1). Figure 1. Decomposition of the total strain into elastic and plastic components.

What is elastic and plastic?

When energy goes into changing the shape of some material and it stays changed, that is said to be plastic deformation. When the material goes back to its original form, that’s elastic deformation.

How is compaction pressure calculated?

compact (measured in g/cm3). Porosity: φ = 1 – δ/δth ( number without dimension). Compacting Pressure (die compacting): P = compacting force/face area of compact (measured in N/mm2 or MN/m2). Compacting Pressure (isostatic compacting): P = pressure of the hydraulic medium (measured in MPa or MN/m2).

What is pre compression force?

Pre-compression force mainly required for removing the entrapped air during compression. The hardness of the compressed tablet prominently governed by main compression force.

What is mottling in tablets?

‗Mottling’ is the term used to describe an unequal. distribution of colour on a tablet, with light or dark spots. standing out in an otherwise uniform surface. Reason: One cause of mottling may be a coloured drug, whose colour differs from the colour of excipients used for.

How do you calculate strain?

We calculate the strain is the rod according to the formula: ε = ΔL/L₁ = 3/2000 = 0.0015 . We calculate the stress, using the stress formula: σ = F/A = 30*10³ / (1*10⁻⁴) = 300*10⁶ = 300 MPa . Finally, we divide the stress by strain to find the Young’s modulus of steel: E = σ/ε = 300*10⁶ / 0.0015 = 200*10⁹ = 200 GPa .

How is plastic deformation calculated?

The plastic strain is obtained by subtracting the elastic strain, defined as the value of true stress divided by the Young’s modulus, from the value of total strain (see Figure 1).

What is viscoelastic deformation?

In materials science and continuum mechanics, viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials, like water, resist shear flow and strain linearly with time when a stress is applied.