Page 285 - Failure Analysis Case Studies II
P. 285
270
Fig. 3. The openings in the outer surface of the inside middle layer.
Fig. 4. The fracture appearance of an A type hospipe.
fatigue cracks were possibly initiated at the interface between the cotton thread and the inner layer.
Finally, there were no obvious defects in the fatigue initiation zone (Fig. 5).
Smaller cracks had similar fatigue characteristics (Fig. 7).
4.2. Fracture analysis of outer layer
Opening the outer layer fractures and observing by SEM, it was concluded that cracks initiated
from the outer surface and propagated towards the inner surface. Multiple initiation sites and
some fatigue striations were observed (Fig. 8).
