Strength of Materials | Introduction to Strength of Materials

Strength of Materials INTRODUCTION * Basic assumptions: 1. Materials are continuous 2. Material is homogeneous 3. Material is isotropic 4. Material is free from internal forces prior to the loading considered (residual stresses are zero). * Fundamental laws 1. Elastic behaviour 2. Law of superposition holds good. 3. St. Venant principle holds good. In other words stress concentrations at the points of load and geometric discontinuities are not considered in the analysis. 5.2 SIMPLE STRESSES AND STRAINS * Stress is resistance per unit area. * Unit of stress is N/m2 or N/mm2 . * 1 MPa = 1 N/m2 \ 1 MPa = 1 N/mm2 . * In case of direct forces, Stress = Strain: Strain is change in dimension for unit of original dimension. Linear strain = Lateral strain = * Behaviour of mild steel in tension: 1. Limit of proportionality: It is the limiting value of the stress up to which stress is proportional to strain. 2. Elastic limit: It is the limiting value of the stress upto which if the material is st...