SIMPLE STRESS AND STRAIN
Simple Stresses and Strains 1. Concept of stress and strain The internal resistance set up per unit cross sectional area called as stress, or intensity of stress or unit stress. It is denoted by sigma Sigma = R/A In the equilibrium condition, the internal resistance R is equal to external load P L.e. R=P Sigma = R/A = PA Where o = Stress I P = Load acting on the body A= Cross sectional area of the body Mathematically, stress may be defined as the force per unit area S.I. Unit Is N/m2 1Pa = 1N/m Mathematically, stress may be defined as the force per un area S.I. Unit is N 1Pa = 1N 1.1.1. Normal stress The stresses which are act normal to the plane on which the forces act are called as normal stress or direct stres There are two type 1. Tensile stress 2. Compressive stress 1.1.2. Strain Strain is simply a measure of deformation produced in a member due to the loads acting on it. It is defined as the ratio of change in dimension to the original dimension of the members Strain = Change