Stress And Strain: Definition & Diagram

Stress And Strain: Definition & Diagram

Stress: When a force acts on the body, tending to produce deformation, resistance is developed within the body to this external force. This internal resistance of the body to the external force is called “Stress”.

Stress = \(\frac{\text { Force }}{\text { Area }}=\frac{\mathrm{F}}{\mathrm{A}}\)

Types of Stresses

1. Tensile stress.
2. Compressive stress.
3. Shear stress.

1. Tensile stress:

Results in a body when it is subjected to two sets of forces that are directed away from each other in the same straight line. The load tends to stretch or elongate a body.

2. Compressive stress:

Results when a body is subjected to two sets of force in the same straight line but directed towards each other. The load tends to shorten a body.
Compressive stress

3. Shear stress:

Shear stress is a result of two forces directed parallel to each other, stress that tends to resist a twisting motion. Shear stress

Complex Stresses :

These may be a combination of tensile, compressive, and shear stresses. These multiple stresses are called complex stress, for example, When a wire is stretched the predominant stress is tensile, but shearing and compressive stresses will also be present because the wire is getting thinner as it elongates.

Strain Stresses:

If the stress (internal resistance) produced is not sufficient to withstand the external force (load) the body undergoes a change in shape

Each type of stress is capable of producing a corresponding deformation in the body.

The deformation resulting from tension is an elongation of a body, whereas compression causes shortening or compression of the body.

Strain = \(\frac{\text { Deformation/Change in length }}{\text { Original length }}=\frac{E}{L}\)