Stress-Strain Relations and Deformation Models

This chapter first presents an introduction to true stress and strain by establishing relationships between engineering/true stress and engineering/true strain while taking into consideration the stress-strain curves. In order to cover both elastic and plastic deformations, three moduli (Young’s modulus, plastic modulus, and tangent modulus) have been introduced; and a mathematical relationship between them have been derived with the aid of a comprehensive stress-strain diagram. Work hardening has also been explained by considering strength coefficient and strain-hardening exponent. Finally, various deformation models indicating yield criteria are presented along with the examples from industrial practice. This chapter contains 3 diagrams, 13 mathematical models, 8 worked examples (solved problems) and 5 MCQs, with their answers given at the end of the book.