fatigue frct mech-appr
TRANSCRIPT
Fatigue Analysis using Fracture Mechanic ApproachProf. Ir. Eko Budi Djatmiko, MSc., PhD.Nur Syahroni, ST., MT.
Fat
igue
& F
ract
ure
Mec
hani
cs
(MO
-091
334)
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Fatigue crack propagation test
Fat
igue
& F
ract
ure
Mec
hani
cs
(MO
-091
334)
2Small & medium scale specimen
Large scale specimen
Fatigue crack propagation test
Fat
igue
& F
ract
ure
Mec
hani
cs
(MO
-091
334)
3
Fatigue crack behavior
Fat
igue
& F
ract
ure
Mec
hani
cs
(MO
-091
334)
4
• 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
igue
& F
ract
ure
Mec
hani
cs
(MO
-091
334)
5
Region II: Stable FCP• Martensitic steels: • ASTM A514, ASTM A517 Grade F, ASTM A533 Grade B, Class 1,
ASTM A533 Grade A, & ASTM A645
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igue
& F
ract
ure
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hani
cs
(MO
-091
334)
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Region II: Stable FCP
• Ferrite-Pearlite steels: • ASTM A36, ABS-C, A302-B, A537-A
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igue
& F
ract
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hani
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(MO
-091
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Region II: Stable FCP
• Austenitic stainless steels: • AISI 304, 305
Fat
igue
& 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
igue
& F
ract
ure
Mec
hani
cs
(MO
-091
334)
9
Design example
Fat
igue
& F
ract
ure
Mec
hani
cs
(MO
-091
334)
10
Design example
Fat
igue
& F
ract
ure
Mec
hani
cs
(MO
-091
334)
11
Design example
Fat
igue
& F
ract
ure
Mec
hani
cs
(MO
-091
334)
12
Design example
Fat
igue
& F
ract
ure
Mec
hani
cs
(MO
-091
334)
13
Design example
Fat
igue
& F
ract
ure
Mec
hani
cs
(MO
-091
334)
14
Design example
Fat
igue
& F
ract
ure
Mec
hani
cs
(MO
-091
334)
15
Design example
Fat
igue
& F
ract
ure
Mec
hani
cs
(MO
-091
334)
16
Design example
Fat
igue
& F
ract
ure
Mec
hani
cs
(MO
-091
334)
17