scholarly journals Revaluation of Fatigue Thickness Effect Based on Fatigue Test Database

2020 ◽  
Author(s):  
Wangwen Zhao ◽  
Wei-Ting Hsu
Keyword(s):  
Fatigue Strength ◽  
Offshore Wind ◽  
Thickness Effect ◽  
Exposure Level ◽  
Corrosive Environment ◽  
Current Standard ◽  
Tubular Joint ◽  
Offshore Oil ◽  
Test Database ◽  
Offshore Wind Industry

This paper reassesses the detrimental effect on fatigue performance due to thicker sections based on extensive fatigue strength test database, taken from research program worldwide over the past half of a century in offshore oil & gas and renewable industry. The data entries in the database have been evaluated to ensure its data integrity. Statistical analyses on these S-N data are performed with or without the thickness correction at different exposure level to corrosive environment, in order to re-evaluate the suitability of current standards in regard to the thickness effect. The study has concentrated on T-joint, transverse butt welded joint and tubular joint as these are the most commonly used joint types in the offshore wind industry. The analysis indicates general agreement of fatigue strength with the thickness effects in current standard for in air conditions but great conservatism for corrosive environment.

scholarly journals Re-Evaluation of Fatigue Thickness Effect Based on Fatigue Test Database

2020 ◽  
Vol 8 (11) ◽  
pp. 895 ◽  
Author(s):  
Wangwen Zhao ◽  
Wei-Ting Hsu
Keyword(s):  
Fatigue Strength ◽  
Oil And Gas ◽  
Offshore Wind ◽  
Thickness Effect ◽  
Research Programmes ◽  
Offshore Oil And Gas ◽  
Corrosive Environments ◽  
Steel Joints ◽  
Test Database ◽  
Current Standards

This paper reassesses the detrimental effect on fatigue performance of welded structural steel joints due to thicker sections based on an extensive fatigue strength test database, taken from research programmes worldwide over the past half century, mostly from the offshore oil and gas and marine industries. The data entries in the database were evaluated to ensure its data integrity. Statistical analyses on these S-N data were performed with or without the thickness correction at different exposure levels to a corrosive environment, in order to re-evaluate the suitability of current standards in regard to the thickness effect. The study concentrated on T-joints, transverse butt-welded joints and tubular joints, as these are the most commonly used joint types in the offshore wind industry. The analysis indicates a general agreement of fatigue strength with the thickness effects in current standards for in-air conditions, but great conservatism for corrosive environments. In addition, the statistical models determined in this study can be used for a broader range of studies, such as probabilistic fatigue analysis.

scholarly journals Calibration of Design Fatigue Factors for Offshore Wind Turbine Support Structure Based on Fatigue Test Database

2020 ◽  
Author(s):  
Wangwen Zhao ◽  
Wei-Ting Hsu
Keyword(s):  
Probabilistic Models ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Corrosion Condition ◽  
Structural Fatigue ◽  
Multiple Factors ◽  
Fatigue Design ◽  
Test Database ◽  
Current Standards ◽  
Offshore Wind Industry

The concept of Design Fatigue Factors (DFFs) was introduced for providing desired level of safety in structural fatigue design, often associated with damage calculated from S-N curves. Calculation of fatigue damage from S-N curves can be affected by multiple factors, e.g. types of weld class, corrosion condition, loading conditions, stress concentration on different geometries etc. Each of them can be subject to different level of uncertainties. This study intends to recalibrate the DFFs from a detailed reliability analysis by investigating the probabilistic models derived from the database of S-N curves that has been most frequently used in offshore wind industry. The results of such study indicate that the DFFs can be reduced substantially for the corrosive environmental fatigue models from current standards to the same level of target reliability.

National Offshore Wind Strategy: Facilitating the Development of the Offshore Wind Industry in the United States

2016 ◽  
Author(s):  
Patrick Gilman ◽  
Ben Maurer ◽  
Luke Feinberg ◽  
Alana Duerr ◽  
Lauren Peterson ◽  
...  
Keyword(s):  
United States ◽  
The United States ◽  
Offshore Wind ◽  
Offshore Wind Industry

Prevention of Offshore Wind Power Cable Incidents by Employing Offshore Oil/Gas Common Practices

2021 ◽  
Author(s):  
David McLaurin ◽  
Alan Aston ◽  
John Brand
Keyword(s):  
Wind Power ◽  
Oil And Gas ◽  
Early Stage ◽  
Offshore Wind ◽  
Power Cables ◽  
Manufacturing Testing ◽  
Static Conditions ◽  
Offshore Oil ◽  
Oil Gas ◽  
Oil And Gas Sector

Abstract It has been observed that, although submarine power cables have a critical role to wind power arrays and power export to shore, they are often overlooked at early stages of projects and oversimplified during late stages. This leads to lack of attention given during cable design and planning, as well as pressured schedules during manufacturing, testing and installation. The significant number of incidents attributed to offshore submarine cables during construction has increased overall project risk, lowered system average power availability and increased insurance costs. Lack of proper routing can also result in an inability to maintain asset integrity for the project design life. Despite the attention that submarine power cables have received over the past few years, the number and cost of incidents does not appear to be decreasing. A comparison can be made between offshore HVAC and HVDC cables used for wind power and offshore umbilicals and MV cables used in the oil and gas sector. These umbilicals are often similar in weight, size and bending stiffness, and have similar design, manufacturing, routing and installation challenges, but with a fraction of the incidents observed with offshore wind array and export cables. An additional caveat is that the offshore oil and gas sector has achieved a reliable track record while installing and maintaining these umbilicals and cables in fully dynamic conditions (ultra-deep water) as well static conditions. One primary difference between how the oil and gas sector executes these systems are design, planning and specification from an early stage of the project. Significant attention is given at an early stage to quality control, including offshore routing and umbilical testing specifically to avoid incidents resulting in umbilical damage due to the tension and crushing forces during installation as well as ambient seawater and seabed interaction. Management of these risks are documented, and optimal mitigation strategies are implemented early in the design phase. This paper will discuss the types of incidents which have been observed during construction and installation of submarine HVAC/HVDC cables in the wind power sector and how they could have been prevented by normal practices of the offshore oil/gas sector from early design and planning all the way to installation and commissioning.

Fatigue Strength Assessment of a Structure Considering Corrosion Wastage and Corrosion Fatigue

2018 ◽  
Author(s):  
Norio Yamamoto ◽  
Tomohiro Sugimoto ◽  
Kinya Ishibashi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Corrosion Fatigue ◽  
Life Assessment ◽  
Actual State ◽  
Corrosive Environment ◽  
Corrosion Fatigue Crack ◽  
Long Life

It is known that the fatigue strength decreases in corrosive environment and many experiments were carried out to comprehend the decrease in fatigue strength in corrosive environment. In order to comprehend the actual state, a cycle speed of fatigue test loads should correspond to a wave frequency. Therefore, an experiment in the long life region is practically difficult, then the corrosion fatigue data available for the life assessment of the structure is quite limited. In this study, the fatigue strength of the welded joints in long life service was evaluated according to the calculations of corrosion fatigue crack propagation subjected to the random loadings which followed an exponential distribution. In the crack propagation calculations, the progress of corrosion wastage from the plate surface and the resultant stress increase were considered simultaneously. In the high stress and the short life region, the decrease in fatigue strength due to the accelerated crack propagation in corrosive environment was dominant because the progress of corrosion wastage was little. On the other hand, in the low stress and the long life region, the decrease in fatigue strength became dull as longer the fatigue life because the corrosion fatigue crack propagation was suppressed by the corrosion wastage, but after that the fatigue strength showed the precipitous decrease due to the increase in stress resulted by the progress of corrosion wastage.

Structural, technological and Aesthetical Considerations for the Detailing of Steel Tubular Joints

2018 ◽  
Author(s):  
Vasil Georgiev Georgiev ◽  
Dimitar Dakov ◽  
Yavor Mihov
Keyword(s):  
Fatigue Strength ◽  
Stress Concentration ◽  
Civil Engineering ◽  
Fatigue Cracks ◽  
High Stress ◽  
Traffic Sign ◽  
Tubular Joints ◽  
Joint Repair ◽  
Tubular Joint ◽  
Supporting Structures

<p>For the majority of steel outdoor facilities (towers, masts, billboards and traffic-sign supporting structures) wind loading is the governing factor for determining their resistance and stiffness. In many cases fatigue-related issues appear, with cracking and failure in the welded connections of tubular joints or in the parent metal adjacent to the welds.</p><p>Structural detailing of the joints in steel tubular structures subjected to repeated cyclic loading is of great importance for their fatigue strength. Sharp changes in the shape, sharp turns in the welds and notches give rise to high stress concentration. The combined effect of discontinuities and stress concentration is the main cause for the formation and propagation of fatigue cracks. When detailing the erection joints it is also necessary to observe technological requirements related to efficiency of fabrication. For the civil engineering works exposed to public it is indispensable to include additional requirements for the aesthetic appearance of their visible structural parts. The design experience shows that applying aesthetic considerations to steel tubular joint detailing may contribute to satisfying the increased fatigue strength requirements.</p><p>The paper presents a study on the wind action on a specific kind of civil engineering works (traffic- sign supporting structures) and the approach used for its determination. The leading structural, technological and aesthetic criteria to be implemented in the detailing of tubular erection joints are formulated. An example of tubular joint destroyed due to propagation of fatigue crack is given and possible options for the joint repair are proposed. Numerical modeling and analyses of the original and repaired joints have been carried out in order to make conclusions for the advantages and shortcomings of the joint repair options.</p>

Floating Wind Turbine Model Test to Verify a MoorDyn Modification for Nonlinear Elastic Materials

2021 ◽  
pp. 1-41
Author(s):  
William M West ◽  
Andrew J. Goupee ◽  
Christopher Allen ◽  
Anthony M. Viselli
Keyword(s):  
Test Data ◽  
Offshore Wind ◽  
Strain Response ◽  
Design Load ◽  
Jacket Structures ◽  
Scale Test ◽  
Numerical Tools ◽  
Nonlinear Elastic ◽  
Strain Responses ◽  
Offshore Wind Industry

Abstract As the Floating Offshore Wind industry matures it has become increasingly important for researchers to determine the next generation materials and processes that will allow platforms to be deployed in intermediate (50-85 m) water depths which challenge the efficiency of traditional catenary chain mooring systems and fixed-bottom jacket structures. One such technology, synthetic ropes, have in recent years come to the forefront of this effort. The challenge of designing synthetic rope moorings is the complex nonlinear tension-strain response inherent of some rope material choices. Currently, many numerical tools for modeling the dynamic behavior of FOWTs are limited to mooring materials that have a linear tension- strain response. In this paper an open source FOWT design and analysis program, OpenFAST, was modified to capture the more complex tension-strain responses of synthetic ropes. Simulations from the modified OpenFAST tool were then compared with 1:52-scale test data for a 6MW FOWT Semi- submersible platform in 55m of water subjected to representative design load cases. A strong correlation between the simulations and test data was observed.

scholarly journals Musculoskeletal pain among offshore wind industry workers: a cross-sectional study

2020 ◽  
Vol 93 (7) ◽  
pp. 899-909
Author(s):  
Marcial Velasco Garrido ◽  
Janika Mette ◽  
Stefanie Mache ◽  
Volker Harth ◽  
Alexandra M. Preisser
Keyword(s):  
Musculoskeletal Pain ◽  
Cross Sectional Study ◽  
Offshore Wind ◽  
Sectional Study ◽  
Cross Sectional ◽  
Offshore Wind Industry

scholarly journals Thickness Effect on Fatigue Strength of Welded Joint Improved by HFMI

2016 ◽  
Vol 34 (4) ◽  
pp. 249-259 ◽  
Author(s):  
Toshiaki IWATA ◽  
Toshio NIWA ◽  
Yoshihisa TANAKA ◽  
Takahiro ANDO ◽  
Yosuke ANAI
Keyword(s):  
Fatigue Strength ◽  
Welded Joint ◽  
Thickness Effect
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