Download - Fatigue frct mech-appr
Fatigue Analysis using Fracture Mechanic ApproachProf. Ir. Eko Budi Djatmiko, MSc., PhD.Nur Syahroni, ST., MT.
Fat
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& F
ract
ure
Mec
hani
cs
(MO
-091
334)
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Fatigue crack propagation test
Fat
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& F
ract
ure
Mec
hani
cs
(MO
-091
334)
2Small & medium scale specimen
Large scale specimen
Fatigue crack behavior
Fat
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& F
ract
ure
Mec
hani
cs
(MO
-091
334)
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• Region I: • fatigue-threshold• Cracks do not propagate if
ΔKI< ΔKth
• Region II:• stable fatigue crack
propagation (FCP)• apply Paris law
• Region III:• Unstable FCP
Region I: fatigue thresholdΔKth can be predicted:• R≤0.1:• ΔKth = 6.4(1-0.85R) ksi in1/2
• ΔKth = 7(1-0.85R) MPa m1/2
• R>0.1• ΔKth = 55 ksi in1/2 =6 MPa m1/2
Fat
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& F
ract
ure
Mec
hani
cs
(MO
-091
334)
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Region II: Stable FCP• Martensitic steels: • ASTM A514, ASTM A517 Grade F, ASTM A533 Grade B, Class 1,
ASTM A533 Grade A, & ASTM A645
Fat
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& F
ract
ure
Mec
hani
cs
(MO
-091
334)
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Region II: Stable FCP
• Ferrite-Pearlite steels: • ASTM A36, ABS-C, A302-B, A537-A
Fat
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& F
ract
ure
Mec
hani
cs
(MO
-091
334)
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Region II: Stable FCP
• Austenitic stainless steels: • AISI 304, 305
Fat
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& F
ract
ure
Mec
hani
cs
(MO
-091
334)
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Effect of mean stress or stress ratio
• R = Pmin/Pmax = Kmin/Kmax
Fat
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& F
ract
ure
Mec
hani
cs
(MO
-091
334)
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