1 1 Chapter 8 Failure Ductile and brittle fracture 2 Chapter 8 Failure Moderately ductile fracture 100 mm
1
1Chapter 8 Failure
Ductile and brittle fracture
2Chapter 8 Failure
Moderately ductile fracture
100 mm
2
3Chapter 8 Failure
Brittle fracture
4Chapter 8 Failure
3 mm
4 mm160 mm
1 mm
Brittle fracture surfaces
3
5Chapter 8 Failure
Stress concentration factor
σmax
2aσa
ρt
6Chapter 8 Failure
Fracture modes
!
a
4
7Chapter 8 Failure
Temperature effect on impact energy
Impa
ct E
nerg
y
Temperature
σ
Ductile-to-brittle
8Chapter 8 Failure
Cyclic loading
σmax
σmin
σ
time
σmS
5
9Chapter 8 Failure
Cyclic stress
uniaxial loading
torsional loading
flexural loading
10Chapter 8 Failure
Fatigue Design Parameters
Sfat
N = Cycles to failure103 105 107 109
S = stress amplitude
N = Cycles to failure103 105 107 109
S = stress amplitude
6
11Chapter 8 Failure
The S-N curveSt
ress
am
plitu
de, S
(MPa
)
Cycles to failure, N
12Chapter 8 Failure
crack origin
Fatigue Mechanism
7
13Chapter 8 Failure
14Chapter 8 Failure
8
15Chapter 8 Failure
Creep - temperature dependence
secondary
tertiary
16Chapter 8 Failure
Secondary Creep
10-2 10-1 1Steady state creep rate (%/1000hr)ε s
102040
100200 Stress (MPa)
427°C
538°C
649°C
9
17Chapter 8 Failure
Prediction of Creep Rupture Lifetime
103 L (K-h)
Stre
ss (1
03 ps
i)
100
10
112 20 24 2816
data for S-590 Iron
20
24
17
18Chapter 8 Failure 1818
103 L (K-h)
Stre
ss (1
03 ps
i)
100
10
112 20 24 2816
data for S-590 Iron
20
24