# How is hardness measured? ### How is hardness measured?

Penetration. The measure of hardness by penetration is the most commonly practiced. The principle is always the same: a dimensionally stable indenter leaves an imprint in the material to be tested. We measure the dimensions of the footprint and we deduce the hardness.

### How do we calculate elasticity?

L’elasticity-price is calculated by dividing the percentage change in demand by the percentage change in price. If demand is price elastic, the ratio is greater than 1; if demand is inelastic, the ratio is less than 1.

### What is the unit of hardness?

The measurer of hardness measure the hardness in the units Vickers, Brinell, Rockwell, Leeb and Shore. The PCE-2900 measurement method is Leeb’s rebound principle.

### How to calculate the initial length of a material?

If we apply a constraint the material lengthens and if we cancel the constraint, we return to the initial length. This behavior is defined thanks to the slope of this part of the nominal curve which makes it possible to calculate the modulus of elasticity in tension, or Young’s modulus:

### What are the parameters of a material?

A material can be characterized according to many parameters: its modulus of elasticity; its stress (often denoted σ, its unit is the megapascal. See Stress tensor); its ductility (strain) (see Strain tensor; Elongation at break); its Poisson’s ratio; its hardness.

### What are the physical characteristics of the materials?

Here are some physical characteristics of the materials: density: materials with a high density are used in the manufacture of counterweights (balancing), flywheels, etc. coefficient of expansion: comes into play, for example for materials subjected to significant temperature differences;

### Why use shape memory materials?

For example, shape memory materials can be used (materials that have the ability to memorize an initial shape even after deformation) for the composition of stents, medical devices that prevent arteries from clogging due to clots of blood.