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Difference between stress and strain

 






Difference between Stress and Strain

When a material is put under pressure or has a load applied to it, it develops stress and strain. When a solid is put under pressure, it has the ability to deform. The stress is the pressure per unit area of the material, and the resulting strain is the deformation that occurs as a result of this stress. Strain and stress are strongly intertwined because strain occurs solely as a result of stress.


What is stress?

When some external system of forces or loads act on a body, then a internal forces is produced to resist the external forces. This internal resistance  force per unit area at any cross-section is known as unit stress or stress.

Stress is denoted by \sigma

               Stress,    \sigma = \frac{P}{A}

                           Where, P=Force or load acting on the body

                                        A=Cross-Sectional area of the body


Types of stress

1.   Normal stress: When the external loads are acting perpendicular to the cross sectional area it is called normal stress.

Normal stress is two type

a)   Tensile stress: when a body is subjected to two equal and opposite forces and the body tends to increase its length, then the stress is induced which called tensile stress. And the corresponding strain is called tensile strain.

b)   Compressive stress: When a body is subjected two equal force and the body tends to shorten its length, the stress induced which called compressive stress. The corresponding strain is called compressive strain

2.   Shear Stress: When two equal and opposite forces act tangentially on any cross-section of a body, then the internal resistance force per unit area is called shear stress.
















What is strain?

When a body is subjected to a force the body gets deformed, then the body changes its length, the change in length per unit length is called strain.

 Strain is denoted by \varepsilon 

           Strain, \varepsilon = \frac{{\delta l}}{l}

                      Where \delta l= Change in Length

                                       l = Original Length



Difference between stress and strain

 

Stress

Strain

Definition

The internal resistance force per unit area is called stress

The change in length per unit length is called is strain

Unit

N/mm2 or N/m2

It is unit less

Dimension

ML-1T-1

It has no dimension

Formula

\sigma = \frac{P}{A}

\varepsilon = \frac{{\delta l}}{l}

 Sign

 \sigma

 \varepsilon

 Relation 

Stress can be applied on a body without producing strain

 without stress, Strain cannot  occur
 









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