Academic literature on the topic 'Jacket substructure'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Jacket substructure.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Jacket substructure"
1
Han, Chen, Zhou, Zhang, and Gho. "Strength Performance of an Eccentric Jacket Substructure." Journal of Marine Science and Engineering 7, no. 8 (August 10, 2019): 264. http://dx.doi.org/10.3390/jmse7080264.
Full textAbstract:
An eccentric jacket substructure is comprised of circular hollow section tubular joints with complete overlap of braces. The joint is formed with the lap brace overlapping the diagonal through the brace joining the chord face. In this study, the jacket substructure is subjected to a static vertical load due to self-weight and facilities, and four horizontal loads to simulate the environmental loads applied at four different horizontal angles. The maximum stresses at each level of the eccentric jacket are found lower than that of the traditional jacket. For the eccentric jacket substructure, the high stress critical area is mostly located at the short segment of the diagonal through brace joining the chord face. From the parametric study, the ultimate strength of the joint with the complete overlap of braces of the eccentric jacket reduces with increasing the gap size-to-through brace diameter ratio, ξ. With the short segment of the through-brace joining the chord face, the high-stress area is transferred from the joint intersection of the chord and the braces to the lap brace and the diagonal through-brace. It could; therefore, be concluded, based on the strength performance, that the eccentric jacket performed better with maximum stresses and high-stress critical areas.
2
Tran, Thanh-Tuan, Sangkyun Kang, Jang-Ho Lee, and Daeyong Lee. "Directional Bending Performance of 4-Leg Jacket Substructure Supporting a 3MW Offshore Wind Turbine." Energies 14, no. 9 (May 10, 2021): 2725. http://dx.doi.org/10.3390/en14092725.
Full textAbstract:
A comprehensive investigation of the directional bending performance of a 4-leg jacket substructure, supporting a 3 MW offshore wind turbine, has been carried out in this study. The jacket substructure with a Pratt bracing system which is already installed in the southwest offshore wind farm in South Korea has been chosen as a reference support structure. A numerical model of the 3MW support structure (i.e., tower, transition piece, and jacket structure) is configured, and its structural performances are evaluated under the conditions of (1) extreme environmental loads (Env), (2) critical Design Load Cases (DLCs), and (3) a total of 288 combined load cases (CBs). For the case of Env (i.e., wind, wave, and current loads), loading directions varying from 0° to 360° at intervals of 15° are considered. The DLCs are provided from the 3 MW wind turbine manufacturer, in a 6 × 12 matrix format. The selected 4-leg jacket substructure in this study showed the smallest bending stiffness at the loading angles of 135° and 315° under the condition of Env, and at the loading angles between 105° and 150° under the CBs. From these results, critical bending directionality of the 4-leg jacket substructure is identified. This study also found that the effects of Env loads are not small compared to the total structural responses of the 4-leg jacket substructure which is supporting a 3 MW offshore wind turbine.
3
Häfele, Jan, Cristian G. Gebhardt, and Raimund Rolfes. "A comparison study on jacket substructures for offshore wind turbines based on optimization." Wind Energy Science 4, no. 1 (January 22, 2019): 23–40. http://dx.doi.org/10.5194/wes-4-23-2019.
Full textAbstract:
Abstract. The structural optimization problem of jacket substructures for offshore wind turbines is commonly regarded as a pure tube dimensioning problem, minimizing the entire mass of the structure. However, this approach goes along with the assumption that the given topology is fixed in any case. The present work contributes to the improvement of the state of the art by utilizing more detailed models for geometry, costs, and structural design code checks. They are assembled in an optimization scheme, in order to consider the jacket optimization problem from a different point of view that is closer to practical applications. The conventional mass objective function is replaced by a sum of various terms related to the cost of the structure. To address the issue of high demand of numerical capacity, a machine learning approach based on Gaussian process regression is applied to reduce numerical expenses and enhance the number of considered design load cases. The proposed approach is meant to provide decision guidance in the first phase of wind farm planning. A numerical example for a National Renewable Energy Laboratory (NREL) 5 MW turbine under FINO3 environmental conditions is computed by two effective optimization methods (sequential quadratic programming and an interior-point method), allowing for the estimation of characteristic design variables of a jacket substructure. In order to resolve the mixed-integer problem formulation, multiple subproblems with fixed-integer design variables are solved. The results show that three-legged jackets may be preferable to four-legged ones under the boundaries of this study. In addition, it is shown that mass-dependent cost functions can be easily improved by just considering the number of jacket legs to yield more reliable results.
4
Wong, Geoff, Phillip Howard, and Shaun Holmes. "Float-on/float-off wharves: one prepared earlier." APPEA Journal 53, no. 2 (2013): 490. http://dx.doi.org/10.1071/aj12101.
Full textAbstract:
The recently considered concepts for a wharf development identified a number of options, including conventional wharf topside modules on steel tubular piled foundations, steel-jacket-type modules anchored to the seabed, concrete caissons, and a hybrid wharf substructure with a Gravity Base Structure (GBS) connected into a steel jacket sub-frame. Due to the unprecedented demand for site-based skilled labour and a marine construction plant on the Australian coast from numerous major resource projects, further consideration was given to the pre-assembled hybrid wharf alternative and the associated cost, fabrication yard availability, and transport issues. To overcome the potential limits and risks of constructing and sea-towing a concrete base structure, the preferred option is to use a multi-cell steel base instead of concrete. The GBS method of construction is to use mature technology in the offshore oil and gas industry and can take advantage of modularisation of the substructure and topsides by fully fitting out larger units in overseas fabrication yards. For alternate wharf applications, the GBS has the potential of allowing pre-assembly and pre-commissioning of equipment and systems, or the ability to enhance the substructure installation in readiness for topsides installation (either floatover integral topsides or modular lift). It also opens up a wide choice of existing fabrication yards and shops in China or Korea that either fabricate wharf or jacket substructure components now, or are in close proximity to existing loading-dock facilities. This can result in considerable schedule and cost savings by reducing site (offshore) labour and plant costs.
5
Lin, Tsung-Yueh, Yi-Qing Zhao, and Hsin-Haou Huang. "Representative Environmental Condition for Fatigue Analysis of Offshore Jacket Substructure." Energies 13, no. 20 (October 20, 2020): 5494. http://dx.doi.org/10.3390/en13205494.
Full textAbstract:
The 20-year cumulative fatigue damage of an offshore jacket substructure was estimated under the long-term local environmental conditions in the Taiwan Strait. Because of the nonlinearity of wave load for slender members of the structure, time-domain simulations of the dynamic finite element model were conducted for each sea state. By utilizing the Dirlik method to process the stress signals, the fatigue damages of joints were computed. Concerning the computational time, we propose a probability-based method of using a representative combination of environmental conditions in this study, which can considerably reduce the required number of evaluations prior to determining fatigue damage, thereby improving the process of preliminary design. The results show that only three sea states among 120 can represent 28% of the average damage ratio, and up to 17 sea states fully resolved the fatigue life.
6
Augustyn, Dawid, Ursula Smolka, Ulf T. Tygesen, Martin D. Ulriksen, and John D. Sørensen. "Data-driven model updating of an offshore wind jacket substructure." Applied Ocean Research 104 (November 2020): 102366. http://dx.doi.org/10.1016/j.apor.2020.102366.
Full text
7
Sun, Min Young, Ki Yeol Lee, and Byung Young Moon. "A Study on the Structural Analysis of Jacket Substructure Related to Offshore Wind Power Environment." Advanced Materials Research 1125 (October 2015): 387–91. http://dx.doi.org/10.4028/www.scientific.net/amr.1125.387.
Full textAbstract:
The currently applied structure and fatigue assessment of support structure for offshore wind energy converter was based on common design rules. The accurate evaluation for environments of sea floor as to installation of support structure, loads of generator, dynamic loads in operation, and offshore environmental loads might be an essential requirement to acquire a safety design for the substructure. This study aims at dedicating to offshore-relevant technology fields by suggesting design methods of structures and estimating their safety in relation to the structural analysis of the substructure requiring high safety to various environment conditions. Especially, with respect to 5MW Offshore Wind Power System, this study will provide information about major wind directions and duration in combination with the developing wave climate at the test field. In this study in the dynamic analysis for 5MW offshore wind power substructure which is considered to be proper in Korea, it is expected that reliability of domestic technology is confirmed with respect to its structural stability.
8
김호선, Kwak, Dongyoup, 윤세웅, and 장화섭. "Seismic Analysis of Jacket Substructure of Offshore Wind Turbine Applying Conditional Mean Spectrum." Journal of Wind Energy 10, no. 1 (March 2019): 36–47. http://dx.doi.org/10.33519/kwea.2019.10.1.005.
Full text
9
Zhang, Jianhua, Won-Hee Kang, Ke Sun, and Fushun Liu. "Reliability-Based Serviceability Limit State Design of a Jacket Substructure for an Offshore Wind Turbine." Energies 12, no. 14 (July 18, 2019): 2751. http://dx.doi.org/10.3390/en12142751.
Full textAbstract:
The development of a structurally optimized foundation design has become one of the main research objectives for offshore wind turbines (OWTs). The design process should be carried out in a probabilistic way due to the uncertainties involved, such as using parametric uncertainties regarding material and geometric properties, and model uncertainties in resistance prediction models and regarding environmental loads. Traditional simple deterministic checking procedures do not guarantee an optimized design because the associated uncertainties are not fully considered. In this paper, a reliability analysis framework is proposed to support the optimized design of jacket foundations for OWTs. The reliability analysis mainly considers the serviceability limit state of the structure according to the requirements of the code. The framework consists of two parts: (i) an important parameter identification procedure based on statistical correlation analysis and (ii) a finite element-simulation-based reliability estimation procedure. The procedure is demonstrated through a jacket structure design of a 3 MW OWT. The analysis results show that the statistical correlation analysis can help to identify the parameters necessary for the overall structural performance. The Latin hypercube sampling and the Monte Carlo simulation using FE models effectively and efficiently evaluate the reliability of the structure while not relying on a surrogate limit state function. A comparison between the proposed framework and the deterministic design shows that the framework can help to achieve a better result closer to the target reliability level.
10
Lai, Wen-Jeng, Chin-Yu Lin, Chin-Cheng Huang, and Rong-Mao Lee. "Dynamic Analysis of Jacket Substructure for Offshore Wind Turbine Generators under Extreme Environmental Conditions." Applied Sciences 6, no. 10 (October 21, 2016): 307. http://dx.doi.org/10.3390/app6100307.
Full textDissertations / Theses on the topic "Jacket substructure"
1
Häfele, Jan [Verfasser]. "A numerically efficient and holistic approach to design optimization of offshore wind turbine jacket substructures / Jan Häfele." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2019. http://d-nb.info/1182532586/34.
Full text
2
Forni, Fabio. "Investigating the axial response of pile foundations for offshore wind turbines." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Find full textAbstract:
I crescenti problemi legati ai cambiamenti climatici rendono l'impiego delle energie rinnovabili sempre più interessante.
In questa ottica, in Germania si sta pianificando di aumentare la produzione di energia pulita attraverso lo sfruttamento dell’energia eolica. Nuovi impianti di turbine eoliche sono previsti nel Mare del Nord in acque medio profonde (25-45m) dove la parte immersa della struttura della turbina eolica (chiamata sottostruttura) è spesso costituita da una struttura jacket (traliccio) o tripod (a treppiedi). Questo tipo di sottostrutture trasmettono principalmente carichi assiali alle fondazioni (in genere fondazioni su palo), e il carico a trazione è la forza che maggiormente ne influenza il dimensionamento.
Molte compagnie energetiche tedesche sono interessate a migliorare l’efficienza e i costi dei loro impianti eolici e, per questo, incaricano università ed istituti di ricerca (come il Fraunhofer IWES) per indagarne gli aspetti, come ad esempio il comportamento delle fondazioni offshore.
All’autore di questa tesi è stata data l’opportunità di studiare e lavorare al Fraunhofer IWES e perciò questa tesi tratterà del compramento di pali caricati assialmente e staticamente pensati per sottostrutture jacket o tripod per turbine eoliche.
Nello studio effettuato per questa tesi, i dati seprimentali, ottenuti da una campagna sperimentale condotta (in larga scala 1:10 1:5) su pali infissi in terreno sabbioso, sono confrontati attraverso l’impiego delle load-transfer curves (funzioni che descrivono il comportamento d’interfaccia palosuolo) usando sia un’approccio classico (fornito dal metodo di calcolo API Main Text) sia approcci più recenti (dati dai metodi di calcolo CPT).
Uno script Matlab creato appositamente dall’autore di questa tesi riesce ad implementare 11 diversi tipi di load-transfer curves. Il lavoro di tesi si conclude con un esempio pratico in grado di fornire un’idea di come questo script può essere usato nella progettazione.
3
Conti, Claudio. "Small-scale physical modelling of piled foundations for offshore wind turbines application." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textAbstract:
Nowadays, finding alternative energy sources is becoming more and more important. Europe is particularly focusing on wind energy and in offshore wind energy especially. An issue concerning offshore wind energy which is gaining more and more attention is the noise emissions due to impact driven pile foundation. The noise caused by the installation process has been judged as “potentially dangerous for marine fauna” from the German Authorities.
This research thesis is part of a project which examines a viable alternative installation method for the displacement of pile foundations for offshore wind energy called pile jacking. This technology should be developed to be cost-efficient, flexibly scalable and to produce considerably reduced vibration and air pollution emissions during its placement in the sea bed. Jacked piles technology would eliminate almost any noise deriving from the hammer impact.
As most offshore piled foundations have been installed by impact driving technology, the question arises as to how piles with different the stiffness and the capacity , can otherwise be installed.
In order to delineate the significant variables affecting the load-bearing capacity and especially the ultimate uplift capacity of a pile in saturated sand, a small-scale test campaign in scale 1:30 has been performed at the Test Center for Support Structures in Hanover. The campaign was supervised by the Department for Support Structures of Fraunhofer IWES. A testing schedule comprising of 15 small-scale geotechnical physical experiments was conducted on open-ended piles to an embedded length of 75 cm using two method of pile installation: static jacking and impact driving.
The aim of this thesis is to obtain preliminary experimental data and set out the main features of this technology.
The results obtained by this study reveal that static jacking installation lead to higher resistances and is overall beneficial to the mechanical load bearing behavior of pile foundations.
4
Zhao, Yi-Qing, and 趙奕晴. "The Recommendation of the Representative Environmental Condition in Spectral Fatigue Analysis of Jacket Substructures for Offshore Wind Turbines." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/y8c258.
Full textAbstract:
碩士國立臺灣大學
工程科學及海洋工程學研究所
107
This paper is to perform frequency-domain analysis of the jacket support structure for OC4 5MW offshore wind turbine in Fuhai Offshore in 50m of water under Taiwan’s local environmental sea state, and estimate the cumulative fatigue damage values of 20 year lifetime. SACA software is employed to analyze the dynamic response at each significant wave height and time period of the wave environment. After extracting the FA, IPB, and OPB structures response of the observation joints and multiplying the stress concentration factors, we Fourier transform the autocorrelated strss signal into a power spectral density, then apply the spectral fatigue analysis by Dirlik method. Palmgren-Miner rule is employed to evaluate the fatigue life under the consideration of 20 year lifetime. This paper takes the sea conditions of the Taiwan Strait as an example, and compares the damage caused by the combination of various representative sea conditions with the actual damage of 120 environmental conditions, then explore whether it is possible to approximate the real situation with a less number of environmental combinations. Because of the assumption of the linear system, frequency domain fatigue analysis can be greatly reduced by 90% compared with the time domain method. This study proposes a method of using a representative environment combination, which can greatly reduce the analysis quantity, it is recommended to use the combination of the top nine probability sea conditions (not considering the lower wave height), only need to spend 1/12 of the original time, the average damage ratio can reach 60.3 %, and the coefficient of variation is 37.7 %.
Book chapters on the topic "Jacket substructure"
1
Hartt, W. H., M. Rapa, and R. G. Powers. "A CONDITION ASSESSMENT OF PILE JACKETS UPON FLORIDA COASTAL BRIDGE SUBSTRUCTURES." In Challenges of Concrete Construction: Volume 6, Concrete for Extreme Conditions, 263–76. Thomas Telford Publishing, 2002. http://dx.doi.org/10.1680/cfec.31784.0026.
Full textConference papers on the topic "Jacket substructure"
1
Brodtkorb, Benedicte, Arne Nestega˚rd, and Atle Johansen. "Prediction of Increased Jacket Substructure Loads Due to Wave in Deck." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57361.
Full textAbstract:
When an extreme wave crest hits the deck of a jacket-type structure, the kinematics in the wave beneath the deck is strongly influenced by the deck itself. The increased fluid particle velocities should be accounted for when assessing the load on obstructions located in a zone below the deck, i.e. on the upper part of the substructure and on under-deck attachments. Usually the wave-in-deck loads and substructure loads are calculated separately by two different analysis programs. The undisturbed velocity field is then applied to the substructure. In this study, we compare two methods, both based on CFD (Computational Fluid Dynamics), for calculating the increased substructure loads due to disturbed fluid particle velocities during extreme wave-in-deck events.
2
O’Neill, Lee A., Emmanuel Fakas, Rodney Pinna, and Timothy Walsh. "Floatover Deck Installation: Case Study — Structural Efficiency of Longitudinally and Transversely-Recessed Structures." In ASME 2004 23rd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/omae2004-51100.
Full textAbstract:
Conventional floatover deck (FOD) installation on a jacket substructure requires the top of the structure to be recessed appropriately, either in the longitudinal or transverse direction to accommodate the vessel transporting the deck. The recess direction is very important to the design of the jacket and influences the outfitting of appurtenances, the shape of the deck and the floatover concept as a whole. This study investigates the structural integrity of typical longitudinal and transverse jackets suitable for FOD installation under both inplace and installation conditions. The study also assesses the structural efficiency of the two options under various installation conditions and benchmarks their structural performance against more conventional jackets associated with lift-installed decks.
3
Aggarwal, Ankit, Tobias Martin, Seimur Shirinov, Hans Bihs, and Arun Kamath. "Numerical Study of Breaking Waves and Associated Wave Forces on a Jacket Substructure for Offshore Wind Turbines." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95233.
Full textAbstract:
Abstract The interest towards offshore wind energy has grown manifolds in the last few decades. Jacket structures are one of the most widely used substructures in the offshore wind turbine installations for intermediate water depths. Offshore structures are exposed to breaking waves. The interaction of breaking waves with the jackets is quite complicated due to the multiple vertical, horizontal and diagonal members. In the present study, a numerical investigation of the wave hydrodynamics and wave forces exerted by regular breaking waves on a jacket is performed. The open-source CFD code REEF3D is used for this purpose, which raises the possibility to model the breaking process physically. The conducted model-scale laboratory experiments have been performed in the past such that a direct comparison is presented.
4
Ashish, C. B., and R. Panneer Selvam. "Static and Dynamic Analysis of Jacket Substructure for Offshore Fixed Wind Turbines." In Eighth Asia-Pacific Conference on Wind Engineering. Singapore: Research Publishing Services, 2013. http://dx.doi.org/10.3850/978-981-07-8012-8_321.
Full text
5
Márquez-Domínguez, S., and J. D. Sørensen. "System Reliability for Offshore Wind Turbines: Fatigue Failure." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10962.
Full textAbstract:
Deeper waters and harsher environments are the main factors that make the electricity generated by offshore wind turbines (OWTs) expensive due to high costs of the substructure, operation & maintenance and installation. The key goal of development is to decrease the cost of energy (CoE). In consequence, a rational treatment of uncertainties is done in order to assess the reliability of critical details in OWTs. Limit state equations are formulated for fatigue critical details which are not influenced by wake effects generated in offshore wind farms. Furthermore, typical bi-linear S-N curves are considered for reliability verification according to international design standards of OWTs. System effects become important for each substructure with many potential fatigue hot spots. Therefore, in this paper a framework for system effects is presented. This information can be e.g. no detection of cracks in inspections or measurements from condition monitoring systems. Finally, an example is established to illustrate the practical application of this framework for jacket type wind turbine substructure considering system effects.
6
Xia, J., S. Hayne, G. Macfarlane, D. Field, and Y. Drobyshevski. "Investigation Into Float-Over Installations of Minimal Platforms by Hydrodynamic Model Testing." In ASME 2005 24th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2005. http://dx.doi.org/10.1115/omae2005-67092.
Full textAbstract:
The idea of using float-over installations for minimal facilities platforms was shown to offer significant advantages, especially when coupled with a substructure installed by a jack-up rig. Recently, float-over installations of minimal facilities have been conducted by the cantilevered method by ICON Engineering Pty Ltd (ICON). The operation involves the platform topsides being loaded and transported to site on a barge, skidded over the barge bow, and lowered onto the jacket. The paper presents results of a research project undertaken by the Australian Maritime College (AMC) in conjunction with ICON, with the objective to investigate motions of a barge and loads exerted on the jacket when the two are docked together for a smooth load transfer operation. The model of an installation barge has been tested in the AMC wave basin and response amplitude operators of the barge motions have been determined for both the free floating and docked conditions. A range of wave periods and heights has been investigated. Model test results have been used to verify numerical predictions used in the design, and to get insight into uncertainties, which may otherwise be difficult to assess using standard software.
7
Chaitanya, Krishna, and Sajith B. Nair. "Design of Leg Mating Unit for Float-Over Installation of Decks." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10707.
Full textAbstract:
The Leg Mating Unit (LMU) is a critical component in ensuring safe method of installing topsides of offshore oil and gas platforms by the float-over method. Traditionally, topsides are lifted onto the substructure (e.g. jacket) using heavy lift crane vessels. However, the ‘lift’ method of installation is constrained by the availability of a limited number of heavy lift vessels in the region, with high day rates. As an alternative to modular installation with light crane vessels, float-over installation enables installation of a single pre-commissioned integrated deck, minimizing offshore hook-up time and cost. Further, float-over method is particularly suited to shallow water depth locations, remote locations (with no access to crane vessels). In a float-over installation, the deck is transported on a cargo barge to the pre-installed substructure location. The barge is guided into the jacket slot and positioned so that the stabbing cone on each leg is aligned with the corresponding jacket leg. The barge is then ballasted down (aided by the falling tide) so that the topside load is transferred from the barge to the jacket. Once the load is transferred and sufficient clearance is achieved between the deck structure and barge support structure, the barge is withdrawn from the slot. The transfer of load is the crucial step of a float-over installation and should occur in a controlled manner under the dynamic influence of environmental forces. This smooth load transfer is achieved using LMU’s. LMU’s are customized leg and deck mating units, used to dampen the impact loads generated during the mating process. They consist of steel structures with elastomer elements and are designed to perform three primary functions, absorb shocks, limit hammering onto the structures and provide defined stiffness between deck and sub-structure. The objective of this paper is to outline the design philosophy of a LMU and address the behavior of the LMU under the combination of vertical and horizontal loads during the mating process. The paper also recommends guidelines on the selection of elastomer stiffness based on load-displacement relationship. The LMU is analysed in ABAQUS, a commercially available finite element (FE) analysis package considering a non-linear time-domain analysis. The results from the FE analysis are compared with the qualification tests for the elastomer and LMU assembly performed on-site to establish correlation.
8
Damiani, Rick R., Huimin Song, Amy N. Robertson, and Jason M. Jonkman. "Assessing the Importance of Nonlinearities in the Development of a Substructure Model for the Wind Turbine CAE Tool FAST." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11434.
Full textAbstract:
The design and analysis of wind turbines are performed using aero-servo-elastic tools that account for the nonlinear coupling between aerodynamics, controls, and structural response. The NREL-developed computer-aided engineering (CAE) tool FAST also resolves the hydrodynamics of fixed-bottom structures and floating platforms for offshore wind applications. Primarily due to the required modal characteristics, monopiles become progressively less economical and more difficult (or impossible) to fabricate for multimegawatt turbines and water depths of more than 25–30 m. Derived from the oil and gas industry experience, light and stiff space-frame alternatives have been proposed to alleviate this problem. Lattice structures (e.g., jackets) are more complex to analyze and design than cantilevered monopiles, especially in terms of the structural dynamics of the coupled turbine-support structure system. This paper outlines the implementation of a structural-dynamics module (SubDyn) for offshore wind turbines with space-frame substructures into the current FAST framework, and in particular focuses on the initial assessment of the importance of structural nonlinearities. Nonlinear effects include: large displacements, axial shortening due to bending, cross-sectional transverse shear effects, etc. A nonlinear computational analysis is resource-intensive, thus it is important to assess the applicability of a linear approach to maintain high-fidelity results while still allowing for fast and efficient design simulations. Space-frame structural behavior can be controlled by a number of design parameters (e.g., member cross-sectional properties, number of legs, batter angles). Additionally, nonlinearities may manifest only at certain load levels. Several finite-element analyses were carried out via commercial and open-source codes that can capture nonlinear effects in the structural behavior of turbine substructures under different load cases. Results were compared to the output of the new linear module SubDyn. The configurations considered in this study included 5-MW, 7-MW, and 10-MW platforms: OC3 monopile, OC3 tripod, OC4 jacket, and a full-lattice tower, all supporting a 5-MW turbine; also two jackets for a 7-MW and a 10-MW turbine, respectively, were investigated. These models differed in base geometry, load paths, size, supported towers, and turbine masses. Results showed that nonlinearities (quantified in terms of the maximum differences in displacement and stresses with respect to a linear calculation) amounted to about 4% (3%) at tower top (at tower base), or about 10 cm (1 cm). This means that the absolute effects of nonlinearities are mostly associated with the tower. The linear approach used by the multimember structural module introduced in this paper was therefore deemed suitable to be utilized within FAST to analyze multimember substructures for offshore wind applications.
9
Wåsjø, Kasper, Jorge Vicente Bermúdez Rico, Morten Bjerkås, and Tore Søreide. "A Novel Concept for Self Installing Offshore Wind Turbines." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11439.
Full textAbstract:
The present paper describes a novel concept of a self-installing offshore wind turbine. A concept for combined installation of the substructure and turbine in one single operation without the need of expensive installation vessels is described. The stability of the concept during transport and installation is obtained by two structurally connected standard barges with dimension 92 × 32 m. The concept proves to be stable with weather window equal HS = 4 m for transport and Hs = 1.5 m for installation in the waiting of more accurate analyses. A cost saving potential in this early phase of 17% is identified compared to the more common steel jacket solution. The cost saving is related to the installation process.
10
Van Wittenberghe, Jeroen, Philippe Thibaux, and Maarten Van Poucke. "Large-Scale Resonant Fatigue Testing of Welded Tubular X-Joints for Offshore Jacket Foundations." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-96371.
Full textAbstract:
Abstract Offshore wind turbines are being installed in deeper water and with more powerful generators resulting in more severe loading conditions on its foundations such as jacket structures. Because the main loading is due to wind and currents, the dominant design limit state is fatigue. The fatigue performance of the tubular joints used in jacket structures has been assessed several decades ago based on test results with limited component dimensions (diameter and wall thickness). In addition, improvements of welding methods and evolution of steel grades are not considered in the current design standards. To provide experimental fatigue-life data on large-scale structures a test program has been carried out on 4 welded tubular X-joints. Each X-joint consists of two horizontal braces with a diameter of 711 mm welded to a central vertical tubular member with 806 mm diameter. The X-joint has a total length of 7.5 m and has two identical welds that are fatigue tested. The fatigue tests are carried out on an innovative resonant bending fatigue test rig that allows to load the specimen in in- and out-of-plane direction at a different amplitude to obtain an even stress distribution over the circumference of the welds. The tests are carried out at a speed close to the resonance frequency of the X-joint. During the test, hotspot strains are measured using strain gauges and a limited amount of water pressure is used to detect through-thickness cracks. The tests are carried out in two phases. During the crack initiation phase, the sample is loaded in both the in- and out-of-plane mode. Once cracks are detected, the test is continued in the crack propagation phase with loading in the plane where cracks had been initiated until through-thickness cracking appeared. During this phase the beach marking technique has been used to mark the shape of the fracture surface at different moments during the fatigue tests. The testing program is part of the RFCS project JABACO that aims to reduce offshore wind cost by incrementing prefabrication of the jacket substructure.