Mooring system fatigue analysis for a semi-submersible

Xue, Xutian; Chen, Nian Zhong; Wu, Yongyan; Xiong, Yeping; Guo, Yuanxiong

doi:10.1016/j.oceaneng.2018.03.022

Cited by 42 publications

(13 citation statements)

References 18 publications

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“…It is equipped with three mooring lines, spread 120° apart, as depicted in Figure 1. The nonlinear time-domain motion equations, as regards the global reference system with origin on the projection of the FOWT centre of mass on the waterplane area, are provided by Equation (1), which represents the commonly embodied hydrodynamic model for FOWTs [31][32][33]:…”

Section: Model Description Of Dynamic Analysismentioning

confidence: 99%

“…The reliability of long-term mooring systems for floating offshore wind turbines (FOWTs), deployed on intermediate and deep-water depth, is a key factor to move the offshore wind energy sector towards the commercialization phase, provided that in the last two decades several accidents, mainly due to mooring failures, occurred throughout the world [1]. Indeed, one of the expected goals of the Horizon 2020 "Secure, clean and efficient energy" work programme [2] is the development of reliable, sustainable and cost-efficient mooring systems for FOWTs, with the main aim of making the offshore wind energy sector more competitive on the international market, as regards other well-established renewable sources.…”

Section: Introductionmentioning

confidence: 99%

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Fatigue Assessment of Moorings for Floating Offshore Wind Turbines by Advanced Spectral Analysis Methods

Piscopo

Scamardella

Rossi

et al. 2021

JMSE

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The fatigue assessment of mooring lines for floating offshore wind turbines represents a challenging issue not only for the reliable design of the stationkeeping system but also for the economic impact on the installation and maintenance costs over the entire lifetime of the offshore wind farm. After a brief review about the state-of-art, the nonlinear time-domain hydrodynamic model of floating offshore wind turbines moored by chain cables is discussed. Subsequently, the assessment of the fatigue damage in the mooring lines is outlined, focusing on the combined-spectrum approach. The relevant fatigue parameters, due to the low- and wave-frequency components of the stress process, are estimated by two different methods. The former is based on the time-domain analysis of the filtered stress process time history. The latter, instead, is based on the spectral analysis of the stress process by two advanced methods, namely the Welch and Thomson ones. Subsequently, a benchmark study is performed, assuming as reference floating offshore wind turbine the OC4-DeepCWind semisubmersible platform, equipped with the 5 MW NREL wind turbine. The cumulative fatigue damage is determined for eight load conditions, including both power production and parked wind turbine situations. A comparative analysis between time-domain and spectral analysis methods is also performed. Current results clearly show that the endorsement of advanced spectral analysis methods can be helpful to improve the reliability of the fatigue life assessment of mooring lines.

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Section: Model Description Of Dynamic Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fatigue Assessment of Moorings for Floating Offshore Wind Turbines by Advanced Spectral Analysis Methods

Piscopo

Scamardella

Rossi

et al. 2021

JMSE

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“…The numerical simulations results have been validated by the laboratory test in which the environmental incidence directions are the same. Thus, in the following study, the environmental loads are assumed in the same incidence direction following the literature 49 and a total of eight directions are observed and considered. The performance of RBFNN using environmental parameters to predict the extreme tension of mooring lines is assessed and presented in Figure 10.…”

Section: Case Studymentioning

confidence: 99%

Reliability analysis of mooring lines for floating structures using ANN-BN inference

Zhao

Dong

Jiang

2020

Proceedings of the Institution of Mechanical Engineers, Part M:

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The harsh marine environment is a significant threat to the safety of floating structure systems. To address this, mooring systems have seen widespread application as an important component in the stabilization of floating structures. This article proposes a methodology to assess the reliability of mooring lines under given extreme environmental conditions based on artificial neural network–Bayesian network inference. Different types of artificial neural networks, including radial basis function neural networks and back propagation neural networks, are adopted to predict the extreme response of mooring lines according to a series of measured environmental data. A failure database under extreme sea conditions is then established in accordance with the failure criterion of mooring systems. There is a failure of mooring lines when the maximum tension exceeds the allowable breaking strength. Finally, the reliability analysis of moored floating structures under different load directions is conducted using Bayesian networks. To demonstrate the proposed methodology, the failure probability of a sample semi-submersible platform at a water depth of 1500 m is estimated. This approach utilizes artificial neural networks’ capacity for calculation efficiency and validates artificial neural networks for the response prediction of floating structures. Furthermore, it can also be employed to estimate the failure probability of other complex floating structures.

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“…Nijssen (2006) proved that the computational effort of the fracture mechanics approach is not justified by the small advantage over the Palmgren-Miner rule approach. Xue et al (2018) concluded that, if appropriate safety factors as suggested by DNVGL-OS-E301 are considered with the S-N curve method, the two methodologies are generally comparable in terms of predicting the fatigue life. In the present study, the S-N curve approach was employed to estimate the fatigue damage rate and predict the fatigue life of mooring lines.…”

Section: Fatigue Analysismentioning

confidence: 99%

“…They also showed that increasing the analysis duration did not considerably change the results of the fatigue analysis. Xue et al (2018) analyzed the fatigue behavior of the mooring system for a semisubmersible. They compared different fatigue evaluation methods and found that the T-N curve approach is much more conservative than the S-N curve approach.…”

Section: Introductionmentioning

confidence: 99%

Enhancement the Fatigue Life of Floating Breakwater Mooring System Using Tuned Liquid Column Damper

Shahrabi

Bargi

2019

Lat. Am. j. solids struct.

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Safety is a key design criterion for floating structures. A high rate of mooring accidents has been reported over the past decades. Preventing mooring line failure is a key design objective for floating breakwater systems. The mooring system comprises sets of mooring lines anchored to the seabed. These components are exposed to highly cyclic nonlinear load fluctuations induced by an irregular wave climate during their service life. DNVGL-OS-E301 classifies the mooring lines for floating breakwaters as long-term elements that should be evaluated according to the fatigue limit state. Fatigue of mooring lines needs to be monitored and evaluated to warrant the station keeping and integrity of overall system. Applying an additional control device to a floating breakwater mitigates the structural response and hence mobilized tension in mooring system. The focus of present study was to examine the effect of an additional control device on fatigue life of mooring lines for floating breakwaters. To evaluate the effect of a control device on the fatigue behavior of mooring lines, a floating breakwater was simulated with a tuned liquid column damper (TLCD) attached. A time-dependent approach based on S-N curves in conjunction with the Palmgren-Miner rule was employed to evaluate the mooring line fatigue. This paper presents a further parametric study focused on the effect of TLCD on fairlead point displacement, mobilized tension, damage rate, and fatigue life of mooring lines. The results showed that TLCD increased the fatigue life of mooring line and thus dramatically decreased the likelihood of the mooring system being damaged by fatigue. This would reduce the maintenance costs and increase the lifetime and operational safety of floating breakwater. In addition, the presented case study showed that failure probability of mooring lines against fatigue damage was also reduced and was acceptable for the safety factor defined in DNVGL-OS-E301. This proposed approach of applying a TLCD is a practical tool for designing the components of a floating breakwater more efficiently. Keywords floating breakwater (FB); tuned liquid column damper (TLCD); fatigue assessment; mooring system; S-N curves; structural control Enhancement the Fatigue Life of Floating Breakwater Mooring System Using Tuned Liquid Column Damper Mostafa Shahrabi et al.

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Mooring system fatigue analysis for a semi-submersible

Cited by 42 publications

References 18 publications

Fatigue Assessment of Moorings for Floating Offshore Wind Turbines by Advanced Spectral Analysis Methods

Fatigue Assessment of Moorings for Floating Offshore Wind Turbines by Advanced Spectral Analysis Methods

Reliability analysis of mooring lines for floating structures using ANN-BN inference

Enhancement the Fatigue Life of Floating Breakwater Mooring System Using Tuned Liquid Column Damper

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