Ductile and brittle fracture - University of California ...maecourses.ucsd.edu/~jmckittr/mae20-wi11/C8 - Failure.pdf · Ductile and brittle fracture 2 Chapter 8 Failure Moderately
Post on 19-Sep-2018
226 Views
Preview:
Transcript
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
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
top related