stress and strain

strength of material : 

when the external force act on body then deformation is accrue in the body.

the elastic body resist this deformation . this resistance is called strength of material .

stress:

the internal resisting force develop in the body when external deforming force is applied in the body is known as stress.

OR

stress is define as stress per unit area .

mathematically :

            

stress  = ( load ) / ( area )  

types of stress:

1. tensile stress :

stress induced in body when two equal and opposite  forces are applied on the body due to which there is increase in length of the body is known as tensile stress . 

2. compressive stress:

stress induced in body when two equal and toward forces are applied on the body due to which there is decrease in length of the body is known as compressive stress . 

3. shear stress:

the stress induced in body . when tangential forces acts on body .

strain :

types of strain:

( note : tensile and compressive stain are simile or same in calculation . there is miner changes .  )

1. tensile strain:

the ratio of  change (increase)   in length to original length of the body is known as tensile stain.

                          strain  ( e) = change in length  (d L) / original length ( L)

2. compressive strain:

the ratio of  change (decrease)   in length to original length of the body is known as tensile stain.

                          strain  ( e) = change in length  (d L) / original length ( L)

3. shear strain:

shear strain = traveled distance of upper face / hight of body

hookes's  law :

it stat that within elastic limit stress id directly prepositional to strain .

that men within elastic limit stress to strain ratio is constant . and this constant is known as modulus of elasticity or modulus of rigidity or elastic modulus .

young's modulus : 

it define as ratio of tensile or compressive stress to corresponding tensile or compressive stress .

this is known as young's modulus or modulus of elasticity

it is generally denoted by E

             E =  tensile stress / tensile strain

or 

             E = compressive stress / compressive strain

modulus of rigidity or shear modulus :

the ratio of shear stress to corresponding shear strain is known as  modulus of rigidity or shear modulus 

it is denoted by  C ,G ,N .