When subjected to tensile stress, fiber will fail if the stress concentration at a flaw site reaches the critical fracture stress. Furthermore, under stress, the flaws will tend to enlarge so as to cause stress concentration at the flaw tip to increase. This results in the flaws to propagate. The speed of propagation increases as the flaw enlarges. As the critical fracture stress is reached at a flaw tip, failure occurs. This is known as a fatigue phenomenon and it governs the durability of the fiber under service conditions.

© 1977 Optical Society of America

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