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Fatigue and Fracture Mechanics of Marine Structures

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A special issue of Journal of Marine Science and Engineering (ISSN 2077-1312). This special issue belongs to the section "Ocean Engineering".

Deadline for manuscript submissions: closed (20 February 2023) | Viewed by 24821

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Special Issue Editors

Prof. Dr. Sören Ehlers

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Guest Editor

Institute for Ship Structural Design and Analysis, Hamburg University of Technology, Hamburg, Germany
Interests: ship and offshore structural analysis under service and extreme conditions; Arctic engineering and ship design for extreme conditions

Dr. Moritz Braun

E-Mail Website
Guest Editor

Institute for Ship Structural Design and Analysis, Hamburg University of Technology, Hamburg, Germany
Interests: fatigue and fracture mechanics assessment of welded and non-welded structures and components; temperature and environmental effects on fatigue and fracture; effect of post-fabrication treatment on fatigue strength

Special Issue Information

Dear Colleagues,

Fatigue and fracture are important design criteria for marine structures subjected to static and cyclic loading. In particular, the ability to ensure structural integrity under all design conditions is of utmost importance due to the risk towards humans and the environment. Over the years, significant efforts have been allocated to the development of fatigue and fracture mechanics methods; however, for a number of reasons, discrepancies between predicted and actual strength remain.

The focus of this Special Issue is descriptions of the fatigue and fracture mechanics behaviour of marine structures. We seek studies aimed at novel methods (either analytical, empirical or numerical), as well as presentations of case studies or innovative test studies. Discussions of parameters which influence the fatigue and fracture behaviour of materials, welded joints, or structural components, such as loading conditions, scale effects, etc., will also be considered.

Finally, methods of improving the fatigue and fracture mechanics prediction of marine structures, either during design, fabrication or service may be addressed. Both original and review papers are welcome.

Prof. Dr. Sören Ehlers
Dr. Moritz Braun
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Journal of Marine Science and Engineering is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

fatigue and fracture of welded joints of thin and thick structures
ultimate and fatigue limit state assessment of marine structures
material relationships for finite element analysis of fracture onset and propagation
numerical assessment for structural integrity assessment
weld quality measurements for fatigue life assessment
welding simulation

Published Papers (13 papers)

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Editorial

Jump to: Research

4 pages, 194 KiB

Open AccessEditorial

Special Issue on Fatigue and Fracture Mechanics of Marine Structures

by Moritz Braun and Sören Ehlers

J. Mar. Sci. Eng. 2023, 11(5), 974; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse11050974 - 04 May 2023

Viewed by 1053

Abstract

Fatigue and fracture are important design criteria for marine structures subjected to static and cyclic loading [...] Full article

(This article belongs to the Special Issue Fatigue and Fracture Mechanics of Marine Structures)

Research

Jump to: Editorial

20 pages, 5968 KiB

Open AccessArticle

Improved Fatigue Reliability Analysis of Deepwater Risers Based on RSM and DBN

by Liangbin Xu, Pengji Hu, Yanwei Li, Na Qiu, Guoming Chen and Xiuquan Liu

J. Mar. Sci. Eng. 2023, 11(4), 688; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse11040688 - 24 Mar 2023

Cited by 3 | Viewed by 1500

Abstract

The fatigue reliability assessment of deepwater risers plays an important role in the safety of oil and gas development. Physical-based models are widely used in riser fatigue reliability analyses. However, these models present some disadvantages in riser fatigue reliability analyses, such as low computational efficiency and the inability to introduce inspection data. An improved fatigue reliability analysis method was proposed to conduct the fatigue reliability assessment of deepwater risers. The data-driven models were established based on response surface methods to replace the original physical-based models. They are more efficient than the physics-based model, because a large number of complex numerical and iterative solutions are avoided in fatigue reliability analysis. The annual crack growth model of the riser based on fracture mechanics was established by considering the crack inspection data as a factor, and the crack growth dynamic Bayesian network was established to evaluate and update the fatigue reliability of the riser. The performance of the proposed method was demonstrated by applying the method to a case. Results showed that the data-driven models could be used to analyze riser fatigue accurately, and the crack growth model could be performed to analyze riser fatigue reliability efficiently. The crack inspection results update the random parameters distribution and the fatigue reliability of deepwater risers by Bayesian inference. The accuracy and efficiency of fatigue analysis of deepwater risers can be improved using the proposed method. Full article

(This article belongs to the Special Issue Fatigue and Fracture Mechanics of Marine Structures)

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19 pages, 3575 KiB

Open AccessArticle

An Improved Method for Optimizing CNC Laser Cutting Paths for Ship Hull Components with Thicknesses up to 24 mm

by Xuan Liu and Daofang Chang

J. Mar. Sci. Eng. 2023, 11(3), 652; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse11030652 - 20 Mar 2023

Cited by 1 | Viewed by 1513

Abstract

In this paper, the essence and optimization objectives of the hull parts path optimization problem of CNC laser cutting are described, and the shortcomings of the existing optimization methods are pointed out. Based on the optimization problem of the hull parts CNC laser cutting path, a new part-cutting constraint rule based on partial cutting is proposed, which aims to overcome the drawbacks of the traditional algorithms with serial cutting constraint rules. This paper addresses the problem of optimizing the path for CNC laser cutting of hull parts, including an empty path and the order and directions used for the provided cut contours. Based on the discretization of the part contour segments, a novel toolpath model for hull parts called hull parts cutting path optimization problems based on partial cutting rules (HPCPO) is proposed in this paper. To solve the HPCPO problem, a segmented genetic algorithm based on reinforcement learning (RLSGA) is proposed. In RLSGA, the population is viewed as an intelligent agent, and the agent’s state is the population’s diversity coefficient. Three different segmented crossover operators are considered as the agent’s actions, and the agent’s reward is related to the changes in the population’s fitness and diversity coefficients. Two benchmark problems for HPCPO were constructed to evaluate the performance of RLSGA and compared with four other algorithms. The results showed that RLSGA outperformed the other algorithms and effectively solved the HPCPO problem. Full article

(This article belongs to the Special Issue Fatigue and Fracture Mechanics of Marine Structures)

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15 pages, 5521 KiB

Open AccessArticle

On the Fatigue Strength of Welded High-Strength Steel Joints in the As-Welded, Post-Weld-Treated and Repaired Conditions in a Typical Ship Structural Detail

by Antti Ahola, Kalle Lipiäinen, Juuso Lindroos, Matti Koskimäki, Kari Laukia and Timo Björk

J. Mar. Sci. Eng. 2023, 11(3), 644; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse11030644 - 19 Mar 2023

Cited by 5 | Viewed by 1803

Abstract

Weld quality and life extension methods of welded details in ship structures made of high-strength and ultra-high-strength steels are of high importance to overcome the issues related to the fatigue characteristics of welded high-strength steels. The current work experimentally and numerically investigated the fatigue strength of a longitudinal stiffener detail, typically present in the bulkhead connections of ship hull. Two high-strength steel grades, namely EQ47TM and EQ70QT steels, were studied in welded plate connections using gas metal arc welding with rutile-cored wires. Fatigue tests were carried out on both small-scale specimens under axial and large-scale beam specimens under four-point bending loading. In addition to the joints tested in the as-welded condition, the high-frequency mechanical impact (HFMI) treatment was considered as a post-weld treatment technique in the fatigue test series. Furthermore, the large-scale beam specimens were pre-fatigued until substantial fatigue cracks were observed, after which they were re-tested after weld repairing and post-weld treatments to investigate the potential to rehabilitate fatigue-cracked ship details. The joints in the as-welded condition were performed in accordance with the current design recommendations. Due to the severe transition from the base material to the weld reinforcement in the joints welded with the rutile-cored wire, a successful HFMI treatment required geometrical modification of weld toe using a rotary burr to avoid any detrimental sub-cracks at the HFMI-treated region. Alternatively, the use of solid filler wires could potentially overcome these issues related to the welding quality. Repaired and post-weld-treated welds performed well in the re-tests, and the fatigue strength was almost twice higher than that of tests in the as-welded condition. Full article

(This article belongs to the Special Issue Fatigue and Fracture Mechanics of Marine Structures)

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14 pages, 5644 KiB

Open AccessArticle

Fatigue Strength of AH36 Thermal Cut Steel Edges at Sub-Zero Temperatures

by Marten Beiler, Jan-Hendrik Grimm, Trong-Nghia Bui, Franz von Bock und Polach and Moritz Braun

J. Mar. Sci. Eng. 2023, 11(2), 346; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse11020346 - 04 Feb 2023

Cited by 1 | Viewed by 1481

Abstract

Cruise ships or yachts that operate in areas with seasonal freezing temperatures have large openings in the outer shell. Those are thermal cut edges, and they are exposed to very low temperatures. From fatigue crack growth testing of base materials, it is known that low temperatures can accelerate the crack growth, which may reduce the fatigue life of a structure. However, the current guidelines and rules of classification societies do not provide design curves for the fatigue assessment of thermal cut steel edges at sub-zero temperatures. Therefore, fatigue tests of thermal cut edges are conducted at −20

^{\circ}

C and −50

^{\circ}

C as well as at room temperatures for reference. The specimens are plasma-cut and tested in a temperature chamber under uniaxial loading with a resonant testing machine. The test results are statistically evaluated using linear regression and the maximum likelihood method. The results show that the fatigue strength at sub-zero temperatures is significantly higher compared to room temperature. The test results of this study indicate that sub-zero temperatures down to −50

^{\circ}

C do not seem to cause a reduced fatigue life of thermal cut steel edges. Full article

(This article belongs to the Special Issue Fatigue and Fracture Mechanics of Marine Structures)

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19 pages, 11026 KiB

Open AccessArticle

Fatigue Strength of Structural Steel-Welded Connections with Arc-Sprayed Aluminum Coatings and Corrosion Behavior of the Corresponding Coatings in Sea Water

by Andreas Gericke, Michél Hauer, Benjamin Ripsch, Michael Irmer, Jonas Nehlsen and Knuth-Michael Henkel

J. Mar. Sci. Eng. 2022, 10(11), 1731; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10111731 - 11 Nov 2022

Cited by 5 | Viewed by 1816

Abstract

The influence of thermally sprayed aluminum coatings (Al99%; arc spraying) on the fatigue strength of gas metal arc welded (GMAW) non-alloyed structural steel specimens with respect to foundations for offshore wind turbines was investigated. Additionally, the corrosion protection effect of such coatings for water conditions similar to the Baltic Sea was determined. Wöhler tests were carried out on test specimens with different weld details in the as-welded condition as well as in the thermal spray coat under the consideration of different kinds of surface preparation (blast cleaning with corundum and grit). Substrate and coating were characterized by scanning electron microscopy and the influence on the residual stress states was determined. Corrosion rate monitoring via LPR measurements was carried out as well as the monitoring of the galvanic current between coated and uncoated steel to characterize the coatings’ sacrificial capability for minor defects. Fatigue strength was significantly increased through thermal spraying, especially for test specimens with welded transverse stiffeners (Δσ_c,var = 127 MPa after coating compared to Δσ_c,var = 89 MPa as welded). With a characteristic value of the stress range of Δσ_c,var = 153 MPa, the welded butt joint specimens already exhibited a high fatigue strength in the as-welded condition. The corrosion studies demonstrated that thermally sprayed Al99% coatings have a high resistance to corrosion in seawater environments and are suitable as planar sacrificial anodes sufficiently polarizing bare steel below 0.8 V. The combination of fatigue strength improvement and corrosion protection makes the thermally sprayed Al coatings promising for design and operation of e.g., offshore structures. Full article

(This article belongs to the Special Issue Fatigue and Fracture Mechanics of Marine Structures)

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21 pages, 11617 KiB

Open AccessArticle

Study on Fatigue Spectrum Analysis and Reliability Analysis of Multilayer Flexible Riser

by Jianxing Yu, Fucheng Wang, Yang Yu, Haoda Li, Xin Liu and Ruoke Sun

J. Mar. Sci. Eng. 2022, 10(10), 1561; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10101561 - 21 Oct 2022

Cited by 2 | Viewed by 1608

Abstract

Multilayer composite flexible risers have been widely used in engineering. However, this type of structure is complex, as there are influences between layers. Moreover, a range of uncertain factors need to be considered in fatigue analysis. Therefore, it is difficult to perform the fatigue analysis research of multilayer flexible risers. In this paper, the fatigue spectrum analysis and reliability analysis method of a nine-layer flexible riser structure are proposed, and a complete fatigue and reliability analysis process for multilayer structures is developed. The theoretical basis of the fatigue spectrum analysis method is introduced, and the calculation program is described. Finite element software is used to analyze the stress of the multilayer flexible riser under the influence of the upper platform structure movement and the ocean current. Moreover, the stress response of the riser structure of each layer is obtained. According to this, the irregular wave load is simulated by the method of random number simulation, and the stress response spectrum is formed. Then, the appropriate S-N curve is selected to calculate the fatigue damage degree of each layer, and the fatigue damage nephogram is displayed, so as to analyze the structural fatigue damage. Finally, the uncertainty in the process of fatigue damage calculation is analyzed. According to the results, the methods of multilayer riser analysis are summarized and the future research directions are put forward. Full article

(This article belongs to the Special Issue Fatigue and Fracture Mechanics of Marine Structures)

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12 pages, 5894 KiB

Open AccessArticle

Experimental and Numerical Study of Cyclic Stress–Strain Response and Fatigue Crack Initiation Life of Mid-Carbon Steel under Constant and Multi-Step Amplitude Loading

by Kasumi Morita, Masashi Mouri, Riccardo Fincato and Seiichiro Tsutsumi

J. Mar. Sci. Eng. 2022, 10(10), 1535; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10101535 - 19 Oct 2022

Cited by 4 | Viewed by 1414

Abstract

This paper investigates the fatigue cyclic deformation behavior of mid-carbon steel. Uniaxial tensile loading tests and fatigue tests under constant and multi-step amplitude loading steps are performed to characterize the influence of loading history. The material is shown to exhibit different uniaxial ratcheting behavior depending on loading history. A smooth and gradual increase in cyclic softening is observed under smaller stress/strain conditions. Based on experimental characterization, numerical investigations are carried out to reproduce the cyclic stress–strain behavior under different variable amplitude load ranges. The nonlinear material behavior is reproduced by means of an elastoplasticity model called the Fatigue SS Model (hereafter, FSS model). The main feature of the FSS model is the ability to describe the cyclic softening behavior within a macroscopically elastic stress state. The good agreement between experimental and numerical results proves the reliability of the model to catch a realistic material response in fatigue problems. Furthermore, the present study introduces a method for the prediction of fatigue crack initiation life under variable loading conditions based on cumulative plastic work. Full article

(This article belongs to the Special Issue Fatigue and Fracture Mechanics of Marine Structures)

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20 pages, 6777 KiB

Open AccessArticle

Application of Equivalent Single Layer Approach for Ultimate Strength Analyses of Ship Hull Girder

by Teguh Putranto, Mihkel Kõrgesaar and Kristjan Tabri

J. Mar. Sci. Eng. 2022, 10(10), 1530; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10101530 - 19 Oct 2022

Cited by 6 | Viewed by 2352

Abstract

The objective of this paper is to present the application of equivalent single layer (ESL) approach for the ultimate strength assessment of ship hull girder in the context of numerical finite element (FE) simulations. In the ESL approach, the stiffened panel is replaced with a single plate, which has the equivalent stiffness of the original panel. Removal of tertiary stiffening elements from the numerical model facilitates time-savings in pre-processing and FE analysis stage. The applicability of ESL approach is demonstrated with two case studies, one compartment model and full-sized double hull tanker model in intact and damaged conditions. The damage extents are determined based on the international association of classification societies from common structural rules (IACS-CSR) for oil tanker. Ship hull girder is exposed to distributed pressure with the sinusoidal shape that bends the hull girder. This pressure load is applied separately to bottom and side structures to obtain the vertical and horizontal bending moments of the hull girder, respectively. Ultimate strength predictions obtained from ESL approach are compared to full three-dimensional finite element method (3D FEM) and IACS incremental-iterative method. The comparison between different methods is provided in terms of longitudinal bending moment and cross sectional stress distribution. Overall, ESL approach yields good agreement compared to the 3D FEM results in predicting the ultimate strength of ship hull girder while providing up to 3 times computational efficiency and ease of modeling. Full article

(This article belongs to the Special Issue Fatigue and Fracture Mechanics of Marine Structures)

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24 pages, 8047 KiB

Open AccessArticle

A New Study on the Fatigue Properties of SA Weld Joints by Considering the Effects of Welded Bead Shape

by Dongpil Cho, Seongkil Nam, Chulho Cho, Dajung Lee, Eunyoung Jeong, Youngcheon Jeong, Jaeyik Lee, Marcus Cridland, Bongjin Kim, Kwangsoo Kim, Jihoon Kim and Myunghyun Kim

J. Mar. Sci. Eng. 2022, 10(10), 1527; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10101527 - 18 Oct 2022

Cited by 1 | Viewed by 1486

Abstract

Tandem SAW (Submerged Arc Welding) is one welding process that has been applied to maximize the welding productivity at the panel stage in ship building field. The weld bead profiles produced by Tandem SA welding exceed the acceptance criteria specified in some international regulations, such as AWS D1.1, ISO 5817 and NORSOK M-101. These regulations limit the applicable weld bead profiles, especially weld bead height, regardless of any consideration of design category. The fundamental reason for the limitation of weld bead profiles is related to the weldment fatigue properties. In this regard, we have investigated the effect of weld profiles on fatigue properties. The effect of weld bead profiles on fatigue properties has been experimentally verified and statistically analyzed, and new criteria for weld bead profiles which satisfy E curve as the design S-N curve are proposed for tandem SA welding. Full article

(This article belongs to the Special Issue Fatigue and Fracture Mechanics of Marine Structures)

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14 pages, 3703 KiB

Open AccessArticle

Estimation of Fracture Toughness of API 2W Gr.50 Steel in Ductile to Brittle Transition Behavior Using Master Curve Approach

by Jihoon Kim, Jeongyeol Park and Myunghyun Kim

J. Mar. Sci. Eng. 2022, 10(8), 1066; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10081066 - 03 Aug 2022

Cited by 2 | Viewed by 1547

Abstract

Welding is used as the main joining method in various industries, including the shipbuilding industry. In the case of welded structures, structural integrity assessment is essential to ensure the safety of the structure because many defects inevitably exist during the manufacturing process. The value of reliable fracture toughness is required for structural integrity assessment. It is obtained by the fracture toughness test, but the fracture toughness test requires a lot of time and effort. Therefore, many studies have been conducted on efficient methods to evaluate fracture toughness. Among the various studies that estimate fracture toughness, some have been conducted using the Charpy impact test, which is relatively simple compared to the fracture toughness test. This study conducted a series of experimental investigations on API 2W Gr.50 steel applied with different welding conditions. Based on the Charpy impact test results, the fracture behavior was well estimated in the ductile to brittle transition region according to the temperature. However, there was a difference in the accuracy of predicting fracture behavior depending on the welding process. Therefore, additional consideration reflecting the various welding conditions is required to ensure the safety of welded structures. Full article

(This article belongs to the Special Issue Fatigue and Fracture Mechanics of Marine Structures)

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20 pages, 49316 KiB

Open AccessArticle

Optimizing the Voce–Chaboche Model Parameters for Fatigue Life Estimation of Welded Joints in High-Strength Marine Structures

by Alice Petry, Pasquale Gallo, Heikki Remes and Ari Niemelä

J. Mar. Sci. Eng. 2022, 10(6), 818; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10060818 - 14 Jun 2022

Cited by 7 | Viewed by 2572

Abstract

This work studies the Voce–Chaboche (V–C) material model parameter optimization for high-strength steel welded joints subjected to cyclic loading. The model parameters of each material zone in a S690 steel butt-welded joint were determined using an optimization algorithm based on the Newton trust region (NTR) method and an accumulated true strain parameter. The model parameters were fitted to stress–strain histories from uniaxial strain-controlled cyclic tests. To validate the model, fully-reversed variable amplitude fatigue experiments were performed under load control. The experimental results were then compared to numerical results from a finite element analysis. When the elastic modulus is optimized as a V–C parameter, the results indicate that the V–C model slightly underestimates the strain range, leading to conservative fatigue life estimates. However, the results can be improved by using an elastic modulus obtained experimentally. In this case, the resulting material model slightly overestimates the strain range, leading to a non-conservative, but more accurate, fatigue life estimation. It can be concluded that the NTR-based accumulated true strain approach successfully determined the V–C model parameters for different material zones in the welded joint, and closely estimated the strain range and the fatigue life for a variable amplitude load history. Full article

(This article belongs to the Special Issue Fatigue and Fracture Mechanics of Marine Structures)

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19 pages, 2521 KiB

Open AccessArticle

Mechanical Reliability Analysis of Flexible Power Cables for Marine Energy

by Pär Johannesson, Xiao Lang, Erland Johnson and Jonas W. Ringsberg

J. Mar. Sci. Eng. 2022, 10(6), 716; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10060716 - 24 May 2022

Cited by 2 | Viewed by 2138

Abstract

Marine power cables connected to moving devices at sea may experience millions of load cycles per year, and thus they need to be flexible due to the movements of the cable and designed for mechanical loads. In this study, the focus is on the mechanical life of flexible low- and medium voltage power cables connecting devices to hubs. The reliability design method Variational Mode and Effect Analysis (VMEA) is applied, based on identifying and quantifying different types of uncertainty sources, including scatter, model and statistical uncertainties. It implements a load–strength approach that combines numerical simulations to assess the loads on the cable and experimental tests to assess the strength of the cable. The VMEA method is demonstrated for an evaluation of bending fatigue, and is found to be a useful tool to evaluate uncertainties in fatigue life for WEC (Wave Energy Converter) system cables during the design phase. The results give a firm foundation for the evaluation of safety against fatigue and are also helpful for identifying weak spots in the reliability assessment, thereby motivating actions in the improvement process. Uncertainties in terms of scatter, statistical uncertainty and model uncertainty are evaluated with respect to the WaveEL 3.0, a WEC designed by the company Waves4Power, and deployed in Runde, Norway. A major contribution to the overall uncertainty is found to originate from the fatigue life model, both in terms of scatter and model uncertainty. Full article

(This article belongs to the Special Issue Fatigue and Fracture Mechanics of Marine Structures)

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