Low-cycle fatigue assessment of offshore mooring chains under service loading

Gemilang, Gilang Muhammad; Reed, P.A.S.; Sobey, Adam

doi:10.1016/j.marstruc.2020.102892

Cited by 3 publications

(3 citation statements)

References 40 publications

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“…For different LBEMs, the equivalent occurrence probability of the RSS can be calculated with the same principle, which is identical to the sum of the occurrence probability of the OSSs in the block, as shown in Equation (1).…”

Section: Conventional Lbemsmentioning

confidence: 99%

“…A floating offshore structure generally composed of large-scaled floaters and slender mooring lines is the infrastructure used for the exploitation of natural resources in deep and ultra-deep water [1,2]. When the floating offshore structure is in operational conditions, the stochastic wave acting on the structure can be considered as the cyclic hydrodynamic load, which can lead the mooring lines to experience fatigue failure, even if the mooring line's tension is much smaller than its minimum breaking load [3,4].…”

Section: Introductionmentioning

confidence: 99%

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A Novel Wave Energy Equivalence Based Lumping Block Method for Efficiently Predicting the Fatigue Damage of Mooring Lines

Guo,

Wang,

Guo

et al. 2023

JMSE

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The lumping block equivalent method (LBEM) is widely used to reduce the computational effort in the fatigue damage assessment of offshore structures, and the wave parameters of the representative sea states (RSSs) resulting from LBEM are of vital importance for the accurate prediction of offshore structures’ fatigue damage. In this study, a novel wave energy equivalence (WEE)-based LBEM is proposed to determine the wave parameters of the RSS accurately. The novelty of the proposed method is that a compact relationship between the input wave energy component and mooring lines’ fatigue damage is derived, and the modified statistical relationships between the wave parameters and spectral moments are provided by incorporating the effects of the peak enhancement factor of the input wave spectrum, the number of original sea states (OSSs) and the equivalence bandwidth of the OSSs. Based on the compact relationship, the wave energy component of the RSS can be determined from the wave energy component of the OSSs for each wave frequency from the viewpoint of the fatigue damage equivalence criterion. The wave energy distribution of the RSS can be accurately characterized with the wave energy distribution of the OSSs, and the spectral moments of the RSS can be calculated by its energy distribution directly, without any approximation. Moreover, the wave parameters of the RSS can be determined from the modified statistical relationships easily. The effectiveness of the proposed WEE LBEM is numerically investigated with a moored semi-submersible platform. Results show that the proposed WEE LBEM is robust, efficient and accurate within engineering expectations, and it outperforms the conventional LBEMs both in accuracy and robustness.

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Section: Conventional Lbemsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Novel Wave Energy Equivalence Based Lumping Block Method for Efficiently Predicting the Fatigue Damage of Mooring Lines

Guo,

Wang,

Guo

et al. 2023

JMSE

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show abstract

“…Numerous approaches for incorporating material cyclic properties have been developed. Comparison between currently leading methods and the aforementioned challenges in their application are comprehensively provided in [8][9][10][11][12][13]. Most high-end modern commercial FEA (finite element analysis) software fatigue packages eliminate the need for tedious cyclic solutions and the fatigue assessment is performed solely at the post processing level, as extensively described in [14][15][16][17].…”

Section: Fig 2 -Materials Response Under Fatigue Regimementioning

confidence: 99%

Force Controlled Low Cycle Fatigue (LCF) Life Evaluation Methodology Based on Unstabilized Material Properties

Men

2021

AEF

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Low Cycle Fatigue (LCF) is a prominent failure mechanism in many design components; therefore, an evaluation of cycles to failure in this regime is of high importance. Most international standards recommend a closed loop strain-controlled mode specimen testing in this regime. However, the ꜪN data obtained from this test is not suitable for life evaluation of parts enduring force-controlled history during actual service without correction for control mode. Many existing procedures, which accounts for cyclic strain stabilization during force-controlled loading may significantly complicate the finite elements analysis (FEA) at solving or post processing stages and are often an inherent source of uncertainty. A heuristic, cost effective and sufficiently accurate approach for LCF life estimation is advocated. The method involves only two force loading FEA simulations, one of the actual parts and the other of the test specimen, using initial unstabilized stress strain curve, followed by a limited number of force-controlled specimens testing. Actual part and specimen life correlation performed using first loading unstabilized equivalent plastic strain value Ꜫp1 under locality and similitude assumptions. Unstabilized strain vs. number of cycles to failure curve Ꜫp1N is constructed and discussion regarding specimen geometry considerations for providing sufficient accuracy is included. Method validation and crack propagation study are provided.

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Optimisation of mooring line parameters for offshore floating structures: A review paper

Ja’e

Ali

Yenduri³

et al. 2022

Ocean Engineering

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Low-cycle fatigue assessment of offshore mooring chains under service loading

Cited by 3 publications

References 40 publications

A Novel Wave Energy Equivalence Based Lumping Block Method for Efficiently Predicting the Fatigue Damage of Mooring Lines

A Novel Wave Energy Equivalence Based Lumping Block Method for Efficiently Predicting the Fatigue Damage of Mooring Lines

Force Controlled Low Cycle Fatigue (LCF) Life Evaluation Methodology Based on Unstabilized Material Properties

Optimisation of mooring line parameters for offshore floating structures: A review paper

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