9. Engineering Stress-Strain Curve Elongation 0.2% offset yield stress Proportional Limit E E (Ultimate) Engineering Strain, e = L/Lo) Engineering Stress, S=P/Ao S y S u
14. Shear Stress and Strain shear stress, = Shear Load / Area shear strain, = angle of deformation (radians) shear modulus, G = / (elastic region) Shear Stress Shear Strain
15.
16. Poisson’s Ratio, For most metals, 0.25 < < 0.35 in the elastic range Furthermore :
17. Plastic Deformation Stress Strain 0.002 0.002 0.002 S y S y S y Most Metals - Al, Cu Clad Al-Alloys Low carbon Steel Elastic Plastic Elastic Plastic Elastic Plastic
18.
19. Elastic and Plastic Strain Stress Strain Plastic Elastic e e e p P Total Strain (e,S) The 0.2% offset yield stress is the stress that gives a plastic (permanent) strain of 0.002.