Stress and strain

STRESS AND STRAIN

1. STRESS

Intensity of Stress: The internal resistance or internal force developed per unit area of the cross section of the material is known as Intensity of Stress. In practice, this intensity of stress is often called simply as Stress.

• Unit of stress is Newton/meter². It is expressed in N/m² or Pascal. Pascal is denoted as Pa in S.I. Units. [1 Pascal = 1 N/m²]

• Stress is denoted as f. Symbol P is the external load. Symbol A is the area of cross-section of the body.

• f = External Force (Load) / Cross-sectional Area = P / A

2. STRAIN

Strain is defined as the deformation of the material per unit length. That is, strain is the ratio of change in dimension to the original dimension. This is known as Linear or Longitudinal Strain.

• Strain is denoted as e. Symbol I is the initial length of the body. Symbol dl is the change in length of the body.

• Strain has no unit.

• e = Change in Dimension / Original Dimension = Change in length of the body / Initial length of the body = dl / l