High temperature deformation behavior and optimization of ...
Mechanical Behavior of Materials - I-Shou · PDF file1 Mechanical Behavior of Materials...
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1 Mechanical Behavior of Materials Applied force (Stress) ↔ Deformation (Strain) Applied force (Stress) ↔ Deformation (Strain) How to obtain the - relation? - relation: one kind of the mechanical properties of materilas 7. Mechanical Behavior of Materials 1 — by experiments Mechanical Behavior of Materials Comparableness of test results: need standards to require specimen size, test methods, etc. ASTM (American Society for Testing and Materials) Standards are the most popular one in the world 7. Mechanical Behavior of Materials 2 popular one in the world
Transcript of Mechanical Behavior of Materials - I-Shou · PDF file1 Mechanical Behavior of Materials...
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Mechanical Behavior of Materials
Applied force (Stress) ↔ Deformation (Strain)Applied force (Stress) ↔ Deformation (Strain)
How to obtain the - relation?
- relation:one kind of the mechanical properties of materilas
7. Mechanical Behavior of Materials 1
— by experiments
Mechanical Behavior of Materials
Comparableness of test results:
need standards to require specimen size, test methods, etc.
ASTM (American Society for Testing and Materials) Standards are the most popular one in the world
7. Mechanical Behavior of Materials 2
popular one in the world
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Tensile Test
1. Scope2. Referenced Documents3. Terminology4 Significance and Use
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4. Significance and Use5. Apparatus6. Test Specimens7. Procedures8. Report9. Precision and Bias10. Keywords
Tensile Test
Standard 0.500-in. Round Tension Test Specimen with 2 in. Gage Length and E l f S ll Si S iExamples of Small-Size Specimens Proportional to the Standard Specimen
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Tensile Test
Test Specimens:
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Tensile Test
Apparatus :
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Tensile Test
Apparatus :
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Tensile Test
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Tensile Test
Strain or displacement measurement:
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Tensile Test
Definition of stress and strain:P Stress
0A
L0L
A
P Stress
Stress) (True
Stress) ng(Engineeri 0
A
P
SA
P
Strain
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P Strain) (True
Strain) ng(Engineeri 0
0
0
dL
dL
eL
LL
L
L
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Tensile Test
Stress-strain Curve of Pure Copper (99.99%):
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Tensile Test
Stress-strain Curve of Pure Aluminum:
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Tensile Test
Stress-strain Curve of 1070 Aluminum
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Tensile Test
Proportional Limit: PL
Elastic Limit: EL
Offset Yield Strength: YS
PL
EL
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Elastic Deformation
2. Small load
b d
1. Initial 3. Unload
F
bonds stretch
return to initial
F Linear
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Elastic means reversible!
F F
Linear-elastic
Non-Linear-elastic
Plastic Deformation (Metals)
1. Initial 2. Small load 3. Unload
planesbonds
planes
still
sheared
elastic + plastic
stretch
& planes
shear
plastic
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Plastic means permanent!
F
linear elastic
linear elastic
plastic
F
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Tensile Test
UTS: Ultimate Tensile Stress u
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Tensile Test
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Tensile Test
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Tensile Test
Ductile Materials:LL
%100area of reductionPercent
%100elongationPercent
0
0
0
0
A
AA
L
LL
f
f
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Tensile Test
Brittle Materials:
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Brittle Materials
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Brittle Materials
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Temperature Effects
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Hooke’s Law
The stress-strain diagrams of most engineering materials exhibit a linear relationship within elastic rangeg
Hooke’s law: in memory of Robert Hooke in 1676 using spring to observe this phenomenon
E: modulus of elasticity or Young’s modulus (named after Thomas Young in 1807 published this result)
E: same unit as stress ksi GPa
E
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E: same unit as stress, ksi, GPa
GPa 200ksi 10290.0012
ksi 35 3 steelE
Young’s Modula of Different Materials
GPa14~7.0
GPa70
GPa200
plastic
aluminum
steel
E
E
E
Hardness decreases assoftness of materials
VHE
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Poisson’s Ratio
n)compressio:tension;:(
:strain Axial
La
a
l
n)compressio: tension;:(
:strain Laterial
n)compressio:tension;:(
rl
P i ’ ti F h i ti t
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Poisson’s ratio: French scientistS. D. Poisson realized this constantwithin elastic range in the early 1800s:0.25~0.35 for most of engineeringmaterials
Summary
Mechanical properties of materials from tensile test:tensile test:
E: Young’s modulusY: Yield stress: Poisson’s ratio
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: Poisson s ratioUTS: ultimate tensile strength
f : elongation to failure
