Modulus of Elasticity – Definition, Young’s Modulus, Types
By BYJU'S Exam Prep
Updated on: September 25th, 2023
Modulus of elasticity is the properties of the material that do not vary with respect to temperature, age of the material, and loading condition. Modulus of elasticity is an important phenomenon to understand the elongation rate when applying load (in terms of stress). Stress is evaluated depending upon the magnitude of load and surface area.
The modulus of elasticity varies with respect to the type of material. The elastic properties are identified by the value of modulus of elasticity and elastic constant (E and μ). Modulus of elasticity is further divided into several types depending upon the type of load (tangential, perpendicular, or symmetric load overall surface). It has a major role in bending equations while finding the stress on a beam. Let us discuss more the Modulus of Elasticity.
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What is Modulus of Elasticity?
Within proportionality limit modulus of elasticity, the ratio is stress to strain. proportional limit. It measures the rigidity or stiffness of a material. If the material is greater in the modulus, the material will be stiffer, or smaller than the elastic strain that results from the application of a given stress.
The modulus of elasticity is the important design parameter used for computing elastic deflections. Elastic modulus is called modulus of elasticity. The modulus of elasticity is also known as Young’s modulus.
Types of Modulus of Elasticity
Depending upon the type of force applied to the body and change in deformation. Modulus of elasticity is divided into the following types.
- Young’s Modulus
- Shear Modulus
- Bulk Modulus of Elasticity
Young’s Modulus
Elastic modulus is explained only for one axis of the substance. Young’s modulus of a material is an important attribute to understanding how the material will behave when applied to a force. It is represented by E.
The Dimensional formula of E is [M^{1}L^{-1}T^{-2}].
Shear Modulus
The shear modulus of the material is the ratio of shear stress to shear strain in a body. When the shear force is increased, the value of the shear modulus also increases. It is represented by G or C.
The Dimensional formula of G is [M^{1}L^{-1}T^{-2}].
Bulk Modulus of Elasticity
Bulk modulus is defined when uniform pressure is applied from all directions to the change in volume. The bulk modulus is the measure of the ability of a substance which changes in volume when under compression on all sides. It is represented by K.
Bulk modulus of elasticity,
K= – P/ (ΔV/V)
Dimensions of K are [M^{1}L^{-1}T^{-2}].
Relationship Between Modulus of Elasticity
The different types of Modulus of elasticity can be related to each other with the following equations:
Modulus of Elasticity Formula
E = 3K(1-2μ)
E = 2G(1+μ)
E = 9KG/(G+3K)
Where μ = Poisson’s ratio
Analysis of Modulus of Elasticity
As per Hooke’s law, The modulus of elasticity is the slope of the stress-strain curve up to the linear proportionality of stress to strain. In the Stress-Strain Curve of steel, the area under the curve up to the yield point represents the modulus of resilience and from the yield point to the fracture of material represents the modulus of toughness.
E = stress/strain = (P/A)/(ΔL/L)
E = modulus of elasticity or young’s modulus within proportionality limit.
Unit of Young’s Modulus
The elastic modulus is a material property that elaborates its stiffness and is, therefore, one of the most important properties of solid materials. It is the ratio of stress to strain when deformation is elastic in any direction.
- SI unit: Pascal (or) N/mm^{2}
- CGS unit: Dyne/cm^{2}
- MKS unit: Kg/cm^{2}
Different materials with their value of Young’s modulus as per the elastic in nature. Higher the value of Young’s modulus refers to high elasticity in nature when a load is applied to that material.
Material |
Young’s Modulus (GPa) |
Diamond |
1000 |
Mild Steel |
200 |
Copper |
120 |
Aluminum |
69 |
Concrete |
30 |
Glass |
65 |
Bone |
18 |
Plastic |
3 |
Rubber |
0.02 |
Wood |
15 |
Note: Usually 2 materials (concrete and steel) we use in the design of RCC structure. The concrete young’s modulus depends on the grade of concrete.
Modulus of Elasticity of Concrete
In the stress-strain curve of concrete, The tangent modulus is the slope of the stress-strain curve at any specified stress or strain. Below the proportional limit (the limit of linear elastic regime), the tangent modulus is equivalent to Young’s modulus.
Young’s modulus of concrete, E_{c}= 5000√f_{ck} for a short-term period
E_{c}= 5000√f_{ck}/1+Θ for long-term period
Where
- Θ= creep coefficient depends on the age of concrete
- f_{ck}= characteristic strength of concrete after 28 days.
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