STRAIN, STIFFNESS AND YOUNG'S MODULUS

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STRAIN, STIFFNESS AND YOUNG'S MODULUS

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STRAIN

Strain is described as, the change in the measurement of a sample of material, when a force is applied.
The material sample below, has been placed in a tensile testing machine. It is ‘longer’ when a tensile force (a stretching force) has been applied to it.

STIFFNESS

When force is applied to a material (in the way shown below), it tends to bend. Most materials tend to resist a force, up to a point. The ability to resist bending is a mechanical property called ‘stiffness’. This is related directly to the strength of a material, as the stronger the material the more it resists bending and the greater it’s ‘stiffness’.

YOUNG'S MODULUS

Young’s Modulus, is the direct relationship between the ‘stress’ and ‘strain’ of a material (the ratio of ‘stress’ to ‘strain’). It is shown by the formula below and measures the ‘stiffness’ of a solid material.

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