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MECSOL 2019
7th International Symposium on Solid Mechanics
A study on the fatigue of mooring chains under out-of-plane bending
Submission Author:
Edgar Mamiya , DF , Brazil
Co-Authors:
Guilherme Ferreira, Raniere Silva Neves, Felipe Azevedo Canut, Lucival Malcher, Edgar Mamiya, Fábio Castro
Presenter: Edgar Mamiya
doi://10.26678/ABCM.MECSOL2019.MSL19-0082
Abstract
The study focuses on the fatigue failure of mooring chains of Floating Production Storage and Offloading (FPSO) units which have exhibited fatigue cracks after less than one year of service. Crack initiation is correlated to out-of-plane bending of the links as a result of the interaction between the chain and the FPSO’s fairlead sheave. The device designed to replicate the out-of-plane bending on chain links consists of a horizontal frame which submits a set of nine chain links to a static tensile preload, while a hydraulic actuator applies variable transversal loads upon the central link. The larger deformed contact surface between the links due to the proof load, together with the static preload during tests, makes rolling between adjacent chain links (as they interact with the fairlead’s chain sheave) harder, resulting in out-of-plane bending of the chain elements. The experiment provides the data necessary to understand the fatigue failure mechanisms, as well as to assess the modeling of the multiaxial fatigue problem.
Keywords
mooring systems, FPSOs, out-of-plane bending, fatigue failure
