Stress and strain defination and explanation

Hello Friends,Now I am going to explain about the two new Concept that is Stress and Strain.In Engineering field stress and strain have different meanings that you should know about this.In Engineering field stress and strain are basically seen in Materials, structures,dams,bridges,trusses etc.It is very important topics because if you are a Mechanical Engineer and if you want to become future Design Engeer then you should know about this.Now Let's start?

Stress:-

According to it's defination ,The internal resisting force acting per unit area, offered by a body against deformation is known as Stress.The force which cause or produced stress called load or external force.
Mathematically it can be written as:

Where force(F)= External force or Load
             Area(A)=Cross-sectional area

S.I units of Stress,here Force is expressed in Newton's (written as N) and area is expressed as m^2 (metre sq.)

Now we should Know about the types of Stress for better understanding of these concepts:
Stress is basically of three types:

1. Tensile Stress
2. Compressive Stress
3. Shear Stress

1.Tensile Stress:- Tensile Stress is induced in a body when it is subjected to two equal and opposite forces or opposite pulls,due to this there is increase of length,is called tensile Stress.And it is also defined as the ratio of change in length to the original length of the body. 

Mathematically it is given in the figure 

2.Compressive stress:-The stress induced ina body,when there is two equal and opposite pushes acting then there is a decrease in length of the body,is known as compressive stress.it is also defined as the ratio of  change in decrease in length to the original length is known as Compressive stress. 

Compressive stress formulaes

3.Shear stress:-the stress induced in a body,when subjected to two equal and opposite forces which acts tangentially across the section,as a result of this the body tends to shear off across the resisting section,is known as shear Stress.

Shear Stress formula

Strain:- It is define as the ratio of  change in dimension in a body to the original dimension is known as strain.

Types of strain are:-

1.Tensile Strain

2.Compressive Strain

3.shear Strain

1.Tensile strain:- It is the ratio of change in length to the original length of the body.

2.Compressive strain :-It is the ratio of Change in decrease in length to the original length is known as Compressive strain.

3.Shear strain:-It is the ratio of change in deformation to the original length perpendicular to the axix of the member due to shear Stress.

And the given formula is mention in the above figures.