STRESS AND STRAIN

STRESS

The force of the resistance per unit area offered by the material of abody ,against deformation of the body,is known as intensity of stress or stress.

STRESS= LOAD/Resisting area

The unit of stress is   N/M²

simple stress may be either normal stress or shear stress.when the resisting area is normal to the line of action of external force,the resulting stress is called normal stress and when the resisting area is tangential to the line of the action of the external force. the resulting stress is called shear or tangential stress.the normal stress may be  either tensile or compressive.

when the force are directed away from the bar,the force are known as tensile force.this force is resisted by the cross-sectional area of the bar.        Therefore tensile stress, which is denoted by f, σ ,p

when the forces are directed towards the bar , the forces are known as compressive forces and the stress is called compressive stress.

Therefore compressive stress, =P/A.

STRAIN

when an elastic body is subjected to external force , there will be some deformation of the body. strain is the measure of deformation of the body due to external forces.

If there is some increases in the length of a body due to external force,then the ratio of increase in the length to the original length of the body is known as tensile strain. if there is some decrease in the length of the body then the ratio of decreases in the body.

To the original length is known as compressive strain.

strain=dl/l

The ratio of change in volume of the body to its original volume  is known as volumetric strain. normal strain is denoted by e  and volumetric strain is denoted by,e_v

e_v =dV/V