Digital image correlation for continuous mapping of fatigue crack initiation sites on corroded surface from offshore mooring chain
Paul Qvale, Ershad P. Zarandi, Sigmund K. Ås, Bjørn Skallerud
Abstract
The full-field digital image correlation (DIC) technique was used to identify crack initiation and early crack growth on irregular, corroded surfaces from offshore mooring chain. Finite element analysis was paired with the DIC measurements, which made it possible to correlate initiation events with local stress concentrations due to corrosion pits. An initiation S-N curve was established based on this correlation. It included 14 crack initiation events from 4 specimens, in addition to statistical treatment of regions where no initiation occurred. The first cracks initiated at 13–24% of the total lifetimes of the specimens.
Topics & Concepts
Digital image correlationMooringSubmarine pipelineStructural engineeringFinite element methodMaterials scienceGeologyEngineeringComposite materialGeotechnical engineeringMarine engineeringNon-Destructive Testing TechniquesUltrasonics and Acoustic Wave PropagationStructural Integrity and Reliability Analysis