Mechanical Properties of Metals

1. Mechanical Properties of Metals

4. Direct Stress Examples Direct Stress - Tension Direct Stress - Compression Engineering Stress Engineering Strain

5. Tension Test Typical Universal Testing Machine Extensometer Measures  L Measures P

6. Modern Materials Testing System Hydraulic Wedge Grips Specimen Extensometer

7. ASTM Tension Test Specimen 2” Gauge Length A o =0.20 in 2 L o

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

12. Modulus of Elasticity - Stiffness

13. Atomic Origin of Stiffness

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

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

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.

20. Elastic Recovery Strain Stress Loading Unloading Loading Unloading Reloading elastic strain Strain

24. Toughness, U t Engineering Strain, e =  L/Lo) Engineering Stress, S=P/Ao S u S y

25. Resilience, U r Engineering Strain, e =  L/Lo) Engineering Stress, S=P/Ao S u S y E e y

26. Typical Mechanical Properties Metals in annealed (soft) condition