PPT: Mechanical Properties of Metals | Engineering Materials - Mechanical Engineering PDF Download

 Page 1


Mechanical Properties
• Stiffness - Elastic Modulus or Young’s Modulus (MPa)
• Strength - Yield, Ultimate, Fracture, Proof, Offset Yield. 
Measured as stress (MPa)
• Ductility - Measure of ability to deform plastically 
without fracture - Elongation, Area Reduction, Fracture 
Strain - (no units or mm/mm)
• Toughness, Resilience - Measure of ability to absorb 
energy (J/m
3
).
• Hardness - Resistance to indentation/abrasion (Various 
scales, e.g.; Rockwell, Brinell, Vickers.)
Page 2


Mechanical Properties
• Stiffness - Elastic Modulus or Young’s Modulus (MPa)
• Strength - Yield, Ultimate, Fracture, Proof, Offset Yield. 
Measured as stress (MPa)
• Ductility - Measure of ability to deform plastically 
without fracture - Elongation, Area Reduction, Fracture 
Strain - (no units or mm/mm)
• Toughness, Resilience - Measure of ability to absorb 
energy (J/m
3
).
• Hardness - Resistance to indentation/abrasion (Various 
scales, e.g.; Rockwell, Brinell, Vickers.)
Stress and Strain
• In a simplistic sense, stress may be thought 
of as Load/Area.
• Similarly, strain is the deformation of the 
component/original length.
• A stress may be direct, shear, or torsional -
leading to corresponding deformations.
• Stress cannot be measured directly, but 
deformation can be.
Page 3


Mechanical Properties
• Stiffness - Elastic Modulus or Young’s Modulus (MPa)
• Strength - Yield, Ultimate, Fracture, Proof, Offset Yield. 
Measured as stress (MPa)
• Ductility - Measure of ability to deform plastically 
without fracture - Elongation, Area Reduction, Fracture 
Strain - (no units or mm/mm)
• Toughness, Resilience - Measure of ability to absorb 
energy (J/m
3
).
• Hardness - Resistance to indentation/abrasion (Various 
scales, e.g.; Rockwell, Brinell, Vickers.)
Stress and Strain
• In a simplistic sense, stress may be thought 
of as Load/Area.
• Similarly, strain is the deformation of the 
component/original length.
• A stress may be direct, shear, or torsional -
leading to corresponding deformations.
• Stress cannot be measured directly, but 
deformation can be.
Direct Stress Examples
Load, P
P
Area  
 Ao
Lo
?L/2
?L/2
Direct Stress - Tension
Load, P
P
Area  
 Ao
Lo
?L/2
?L/2
Direct Stress - Compression
S ?
P
A
o
e ?
?L
L
o
Engineering Stress
Engineering Strain
Page 4


Mechanical Properties
• Stiffness - Elastic Modulus or Young’s Modulus (MPa)
• Strength - Yield, Ultimate, Fracture, Proof, Offset Yield. 
Measured as stress (MPa)
• Ductility - Measure of ability to deform plastically 
without fracture - Elongation, Area Reduction, Fracture 
Strain - (no units or mm/mm)
• Toughness, Resilience - Measure of ability to absorb 
energy (J/m
3
).
• Hardness - Resistance to indentation/abrasion (Various 
scales, e.g.; Rockwell, Brinell, Vickers.)
Stress and Strain
• In a simplistic sense, stress may be thought 
of as Load/Area.
• Similarly, strain is the deformation of the 
component/original length.
• A stress may be direct, shear, or torsional -
leading to corresponding deformations.
• Stress cannot be measured directly, but 
deformation can be.
Direct Stress Examples
Load, P
P
Area  
 Ao
Lo
?L/2
?L/2
Direct Stress - Tension
Load, P
P
Area  
 Ao
Lo
?L/2
?L/2
Direct Stress - Compression
S ?
P
A
o
e ?
?L
L
o
Engineering Stress
Engineering Strain
Tension Test
Typical Universal 
Testing Machine
Extensometer
Measures ?L
Measures P
Page 5


Mechanical Properties
• Stiffness - Elastic Modulus or Young’s Modulus (MPa)
• Strength - Yield, Ultimate, Fracture, Proof, Offset Yield. 
Measured as stress (MPa)
• Ductility - Measure of ability to deform plastically 
without fracture - Elongation, Area Reduction, Fracture 
Strain - (no units or mm/mm)
• Toughness, Resilience - Measure of ability to absorb 
energy (J/m
3
).
• Hardness - Resistance to indentation/abrasion (Various 
scales, e.g.; Rockwell, Brinell, Vickers.)
Stress and Strain
• In a simplistic sense, stress may be thought 
of as Load/Area.
• Similarly, strain is the deformation of the 
component/original length.
• A stress may be direct, shear, or torsional -
leading to corresponding deformations.
• Stress cannot be measured directly, but 
deformation can be.
Direct Stress Examples
Load, P
P
Area  
 Ao
Lo
?L/2
?L/2
Direct Stress - Tension
Load, P
P
Area  
 Ao
Lo
?L/2
?L/2
Direct Stress - Compression
S ?
P
A
o
e ?
?L
L
o
Engineering Stress
Engineering Strain
Tension Test
Typical Universal 
Testing Machine
Extensometer
Measures ?L
Measures P
Modern Materials Testing System
Hydraulic
Wedge 
Grips
Specimen
Extensometer