Stress

Stress

We know, when a deforming force is applied on a body then the restoring forces are developed in the body. This restoring force is equal and opposite to the deforming force.

The restoring force per unit area of the body is called stress.

Types Of Stress:

• Normal Stress:

 It is defined as The restoring force per unit area perpendicular to the surface of the body.

Normal Stress has two types:

  

  Tensile Stress:

Tensile Stress

 It is defined as the Restoring Force or Deforming Force acting per unit area perpendicular to the cross-section of the body.

This type of stress is generally associated with the Elongation of a rod.

Compressive Stress

Compressive Stress:

Compressive stress is defined as The restoring Force or deforming force acting perpendicular to the cross - section of the area.

This type of stress is generally associated with the compression of a rod.

• Tangential Stress / Shearing Stress

 Tangential Stress is defined as  The ratio of  the force acting along the tangent to the surface to the area of the surface.

An object under Tangential Stress

• Bulk stress or Volumetric Stress

When an object is immersed in a fluid, the fluid exerts force on the surface of the object as shown in the figure below. As a result, the volume of the object decreases and the object comes under Bulk Stress.
Thus, Bulk Stress is defined as The force acting perpendicular to the surface of the object per unit area of the object.

✦It is important to note that for all the above discusssed types of stress, the stress for each type is defined as (Force/Area).

∴ Stress = Force

                  Area