Publications

Xu, S. and Guedes Soares, C. (2021), “Mixture distribution model for extreme mooring tension and mooring fatigue analysis due to snap loads”, Ocean Engineering, Vol. 234, 109245 (18 pages)

Three hybrid moorings are proposed for the station keeping of wave energy converters. The hybrid mooring leg consists of top synthetic fibre rope (nylon or polyester), intermediate buoy and bottom chain (with or without clumped weights attached). The dynamic responses of the point absorber wave energy converter-mooring system are experimentally studied in three irregular sea states. A mixture Rayleigh-Gamma-Weibull distribution is proposed for extreme mooring tension and mooring fatigue damage analysis, and the parameters of this mixture model are estimated by the Expectation Maximization algorithm. The performance of this mixture model is studied by comparing its results with that of the other commonly used distributions. A large number of snap loads are found in survival wave conditions, and a de-clustering procedure is used for the extreme tension analysis. The influence of de-clustering procedure settings on predicted extreme tension is investigated. The rainflow counting approach is applied to calculate mooring fatigue damage and the results are acted as reference values. The Rayleigh, Weibull, Gamma and mixture model are applied to fit the probability density function of rainflow counting tension amplitude for mooring fatigue damage analysis. The accuracy of these models is evaluated by comparing corresponding estimated mooring fatigue damage with the reference values.

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