Elastic Modulus

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Last updated: May 4, 2019

What Does Elastic Modulus Mean?

Elastic modulus is the ratio of stress, below the proportional limit, to the corresponding strain. It is the measure of rigidity or stiffness of a material. In terms of the stress-strain curve, the modulus of elasticity is the slope of the stress-strain curve in the range of linear proportionality of stress to strain.

The greater the modulus, the stiffer the material, or the smaller the elastic strain that results from the application of a given stress. The modulus is an important design parameter used for computing elastic deflections.

Elastic modulus is also known as modulus of elasticity and is sometimes referred to as Young’s modulus.

Elastic modulus can be used in measuring resistance in materials to elasticity or deformation; i.e., a material with low moduli is floppy and will stretch a lot when pressure forces to. High modulus materials are the opposite as they stretch very little when pulled.

Elastic Modulus, or simply Modulus, is used for quantifying a material's ability to resist a non-permanent (elastic) deformation or strain. When tested under stress, such materials first exhibit elastic properties. The materials will stretch and return to their previous state once the stress is removed. If stressed too far, the materials will stretch beyond this elastic region and the elastic limit to then enter the plastic region where they will exhibit permanent deformation.


Corrosionpedia Explains Elastic Modulus

The elastic modulus is a material property that describes a substance's stiffness and is therefore one of the most important properties of solid materials. It is the ratio of stress to strain when deformation is totally elastic. Stress is defined as force per unit of area and strain as elongation or contraction per unit of length.

This modulus may be thought of as a material’s resistance to elastic deformation. A stiffer material has a higher elastic modulus. For most typical metals the magnitude of this modulus ranges between 45 gigapascals (magnesium) and 407 gigapascals (tungsten).

There are three types of moduli:

  • Elastic Modulus (Young's Modulus) — the ratio of longitudinal stress to strain.
  • Shear Modulus — the ratio of tangential force per unit of area to the angular deformation of the body.
  • Bulk Modulus — the ratio of stress to the fractional decrease in the volume of the body.

The stress-strain curve is used to measure elastic modulus and shear modulus. The parameters used to describe the stress-strain curve of a material are tensile strength (ultimate strength), yield strength (or yield point), percent elongation and reduction in area. Modulus of elasticity has the same dimension as stress because it results from dividing the stress by the strain.

Values of the elastic modulus for ceramic materials are about the same as for metals; for polymers they are lower. These differences are a direct consequence of the different types of atomic bonding in the three material types. Furthermore, with increasing temperature, the modulus of elasticity diminishes.

Modulus is calculated by dividing the longitudinal stress by the strain using the slope of the straight-line portion that is found in a stress (σ) strain (ε) curve. In an elastic region, in a case where the slope is taken between two stress-strain points, modulus can be seen as the change in stress divided by the change in strain. Modulus =(σ2 – σ1)/(ε2 – ε1), thus stress (σ) is force divided by a specimen's cross-sectional area, while strain (ε) is a change in the length of the material divided by the material's original length.

The modulus of elasticity is the main property that determines the stiffness of a material. In case of automotive sprigs, stiffness plays an important role in vehicle ride and handling. The stiffness depends on geometry. (Also Read: Effect of Corrosion on a Material's Tensile Strength and Ductility)



Modulus of Elasticity

Young’s Modulus


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