The process of progressive localized permanent structural change occurring in a material subjected to conditions that produce fluctuating stresses and strains at some point or points and that may culminate in cracks or complete fracture after a sufficient number of fluctuations.
Source: API RP 7G, Recommended Practice for Drill Stem Design and Operating Limits, Upstream Segment, Sixteenth Edition, August 1998 (Addendum 2: September 2009). Global Standards
Source: API RP 7G-2, Recommended Practice for Inspection and Classification of Used Drill Stem Elements, First Edition, August 2009. Global Standards
Degradation of the material caused by cyclic loading.
Source: Offshore Standard DNV-OS-C101, Design of Offshore Steel Structures, General (LRFD Method, Det Norske Veritas, April 2011. Global Standards