Page 349 - Marine Structural Design
P. 349
Chapter1 6 Mechanism of Fatigue and Fracture 325
16.7 Examples
Example 16.1 : Fatigue Life Cycle Calculation
Problem:
A pipe of 30mm wall thickness is subjected to a long-term stress distribution as shown in the
figure below. What is the fatigue life of this pipe that is welded from one side?
Solution:
The welded component falls in class F2 joint classification. By including thickness effect, the
S-N curve can be formulated as
: (:z)
log N = 1 1.63 - -log - - 3 log S = 1 1.53 - 3.0 log S
According to the damage calculation tabulated below, the total damage ratio is 0.3523. The
number of cycles to failure is then
A0
(MPa:
500
1,
+
400 1,
300
1
2
200 3
100
10
Figure 16.6 Stress Cycles for Fatigue Life Calculation
