The mooring chains for offshore floaters are typically designed to withstand only tension loads in axial direction and the bending moments on the chain links particularly at the vessel-chain interface connections are generally ignored. However, the unprecedented failure of four mooring lines of the Girassol Buoy mooring system exposed the significant gaps in the existing failure assessment methodology. The root cause investigations of this failure revealed the critical role of out-of-plane (OPB) bending induced fatigue which reduced the fatigue life of the chain links by 95%. However, the methodology to include OPB/IPB fatigue for failure assessments involves a complex process due to numerous parameters required in the formulations and the variability of mooring configurations.

    This paper focus on understanding the underlying mechanism of OPB fatigue failure by addressing the problem from two key aspects which includes the assessment of main excitation source for OPB failures and studying the dominant parameters that influence chain bending inducing OPB fatigue failures. The Part A of this paper analyzes the main sources that generates OPB excitation moments and its responses causing OPB failures, by systematically studying the hydrodynamic parameters, skirt plate geometry and second order responses of the CALM Buoy. The Part B of this paper studies the key OPB inducing parameters like chain diameter, types, pre-tension, instantaneous tensions, proof loading, residual stress, material properties, boundary condition etc., and evaluates their inter-dependencies, proportionalities and relative sensitivities to understand their overall contribution to OPB failures.

    The findings from these studies shall be used to understand the key design aspects of CALM Buoy that excites OPB loading and identify the dominant OPB sensitive parameters that influence OPB failures. The conclusions will be used for understanding the physics of OPB/IPB mechanism and defining generalized methodology for simplified assessments using numerical methods.


    Zugriff

    Zugriff prüfen

    Verfügbarkeit in meiner Bibliothek prüfen

    Bestellung bei Subito €


    Exportieren, teilen und zitieren



    Titel :

    Assessment of CALM Buoys Motion Response and Dominant OPB/IPB Inducing Parameters on Fatigue Failure of Offshore Mooring Chains


    Weitere Titelangaben:

    Lecture Notes in Civil Engineering


    Beteiligte:
    Okada, Tetsuo (Herausgeber:in) / Suzuki, Katsuyuki (Herausgeber:in) / Kawamura, Yasumi (Herausgeber:in) / Edward, Ceasar (Autor:in) / Kr. Dev, Dr Arun (Autor:in)

    Kongress:

    Practical Design of Ships and Other Floating Structures ; 2019 ; Yokohama, Japan September 22, 2019 - September 26, 2019



    Erscheinungsdatum :

    2020-10-04


    Format / Umfang :

    32 pages





    Medientyp :

    Aufsatz/Kapitel (Buch)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch





    MOORING SYSTEM COMPRISING BUOYS AND ANCHORS

    MORITZ BERTIL | Europäisches Patentamt | 2023

    Freier Zugriff

    Mooring of Buoys in Restricted Waters

    Oestergaard, C. / Schellin, T. E. / Gerhard-Mercator-Universitat Duisburg; Institut fur Schiffstechnik Duisburg | British Library Conference Proceedings | 1997


    MOORING SYSTEM COMPRISING BUOYS AND ANCHORS

    MORITZ BERTIL | Europäisches Patentamt | 2022

    Freier Zugriff

    Mooring system with submerged buoys and pulleys

    QU YANMING | Europäisches Patentamt | 2016

    Freier Zugriff