 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
||||
|
|
|
|||||||||||||||||
| Failure Mechanisms | |||||||||||||||||||
| ·
The
crack length increases with time as shown opposite for two different periodic
stress amplitudes.
· In terms of the stress intensity factor, the crack growth rate is given by: (da /dN) = f (σ,a) · The test is at constant stress amplitude, and the crack growth rate is: (da /dN) = A ( ΔK)m with m ~ 2 to 7 and A a constant. |
|||||||||||||||||||
 |
|||||||||||||||||||
| From: Suresh, "Fatigue of Materials," Cambridge (1991) | |||||||||||||||||||
| · The fatigue life of a sample can be estimated by integrating this expression over the crack size range from the initial flaw size up to the critical crack size. | |||||||||||||||||||