Numerical investigation of ice accretion on an offshore composite wind turbine under critical loads

In northern regions, wind turbines are affected by the formation of ice on the surface of their structures, which usually occurs on moving blades, resulting in a significant decrease in aerodynamic performance and then the output power tends to reduce. This research evaluates the mechanical behavior and damage of the proposed composite blade structure under icing conditions. A comparative evaluation was carried out considering three ice configurations and three blade positions. The results are then examined and analysed. During this study, the blade in service was subjected to three different critical loads. A numerical simulation is adopted using finite element method (FEM) with ABAQUS software to localize damage in the composite wind turbine blade. The method developed is based on the failure criteria of HASHIN to detect failure modes in large structures and to identify the most sensitive zones. Major damage appeared in the transition region and was the principal reason for the composite blade failure. Furthermore, greater strength and stiffness were found with Carbon (CC) fibers blade designs, whereas configuration 3 was found to be the best one, and the optimal blade position was when the ice structure was placed vertically

Marine renewable energies and study of the performance of composite materials : case of a tidal current turbine

Les énergies marines renouvelables (EMR) apparaissent aujourd’hui comme une formidable opportunité et un véritable choix écologique et industriel pour répondre à la demande croissante de l’énergie et pour lutter contre le réchauffement climatique. Au cours de cette thèse, on se propose d’étudier l’un de ces types qui s’appelle l’énergie hydrolienne qui présente un immense potentiel dans le bouquet énergétique mondial. une nouvelle forme de pale d’une hydrolienne à axe horizontale a été développé par l’optimisation d’un hydrofoil existant en utilisant la méthode BEM (Blade Element Momentum) afin d’améliorer ses performances hydrodynamiques. La deuxième partie a été consacrée à étudier les performances mécaniques des matériaux composites comme composants structurels des pales d’hydrolienne et de la tuyère. Ces structures sont sujettes à de nombreux types de chargements, tels que les impacts de corps externes, la fatigue due à la variation des courants, mais également à diverses agressions liées à l’environnement marin telles que la variation de la température et l’humidité qui peuvent induire du vieillissement et de la corrosion. Une compréhension approfondie du comportement à long terme de ces parties mobiles est donc essentielle afin de doter les bureaux d’études, confrontés au dimensionnement des structures d’énergies marines, d’outils leur permettant de faire le choix des matériaux (couplefibre/matrice), architectures fibreuses (nappe, tissus), séquence d’empilement des stratifiées minimisant la sensibilité aux chargements appliqués des structures travaillantes. L’objectif final de cette thèse est le développement d’outils et de méthodologies tant numériques qu’expérimentales capables de simuler l’impact du courant et du comportement de ces systèmes de façon couplée ce qui constitue un enjeu majeur de dimensionnement. En effet le but est d’identifier les voies d’optimisation qui permettront d’aller sur la phase commerciale avec un gain de LCOE (Levelized Cost of Energy) substantiel.Recently, Renewable Marine Energies (RME) has emerged as a tremendous opportunity for a real ecological and industrial choice to meet the growing demands for energy and also to fight global warming. The study conducted in this thesis is with in this framework of research and is focused on the investigation of one of the most promising categories of RMEs which is tidal current turbine. A new hydrofoil for the turbine was designed using BEM (Blade Element Momentum) methods and CFD (Computational Fluid Dynamics) calculations with improved hydrodynamic efficiency. Furthermore, a series of numerical studies were conducted to investigate and examine the damage behavior of composite materials under critical loadings by developing DLOAD and VUMAT routines. This numerical study assisted in understanding the problems of structural lightening, resistance to fatigue and impact loading, and other degradation phenomena of themechanical properties of a composite turbine in severe marine environments and solving the needs of the manufactures. Moreover, study about the dynamic behavior of a composite/composite bonded assembly was also conducted because joint assembly plays a vital role in reducing the mass of the structure which is of extreme relevance in the field of marine and offshore structures. Another important obstacle regarding the application of composite and bonded structures in marine was the control of hygro-mechanical coupling. Therefore in this context, additional campaign of tests was carried out on bonded composite specimens by studying the hygrothermal effect on their dynamic behavior at different deformation rates using Hopkinson bar method. This hybrid study of hygro-thermal effect of the dynamic properties of the bonded composites will aid in optimization of the structures and to move into the commercial phase with a substantial gain in LCOE (Levelized Cost of Energy) in future

Énergies marines renouvelables et étude des performances des matériaux composites : cas d'une hydrolienne

Recently, Renewable Marine Energies (RME) has emerged as a tremendous opportunity for a real ecological and industrial choice to meet the growing demands for energy and also to fight global warming. The study conducted in this thesis is with in this framework of research and is focused on the investigation of one of the most promising categories of RMEs which is tidal current turbine. A new hydrofoil for the turbine was designed using BEM (Blade Element Momentum) methods and CFD (Computational Fluid Dynamics) calculations with improved hydrodynamic efficiency. Furthermore, a series of numerical studies were conducted to investigate and examine the damage behavior of composite materials under critical loadings by developing DLOAD and VUMAT routines. This numerical study assisted in understanding the problems of structural lightening, resistance to fatigue and impact loading, and other degradation phenomena of themechanical properties of a composite turbine in severe marine environments and solving the needs of the manufactures. Moreover, study about the dynamic behavior of a composite/composite bonded assembly was also conducted because joint assembly plays a vital role in reducing the mass of the structure which is of extreme relevance in the field of marine and offshore structures. Another important obstacle regarding the application of composite and bonded structures in marine was the control of hygro-mechanical coupling. Therefore in this context, additional campaign of tests was carried out on bonded composite specimens by studying the hygrothermal effect on their dynamic behavior at different deformation rates using Hopkinson bar method. This hybrid study of hygro-thermal effect of the dynamic properties of the bonded composites will aid in optimization of the structures and to move into the commercial phase with a substantial gain in LCOE (Levelized Cost of Energy) in future.Les énergies marines renouvelables (EMR) apparaissent aujourd’hui comme une formidable opportunité et un véritable choix écologique et industriel pour répondre à la demande croissante de l’énergie et pour lutter contre le réchauffement climatique. Au cours de cette thèse, on se propose d’étudier l’un de ces types qui s’appelle l’énergie hydrolienne qui présente un immense potentiel dans le bouquet énergétique mondial. une nouvelle forme de pale d’une hydrolienne à axe horizontale a été développé par l’optimisation d’un hydrofoil existant en utilisant la méthode BEM (Blade Element Momentum) afin d’améliorer ses performances hydrodynamiques. La deuxième partie a été consacrée à étudier les performances mécaniques des matériaux composites comme composants structurels des pales d’hydrolienne et de la tuyère. Ces structures sont sujettes à de nombreux types de chargements, tels que les impacts de corps externes, la fatigue due à la variation des courants, mais également à diverses agressions liées à l’environnement marin telles que la variation de la température et l’humidité qui peuvent induire du vieillissement et de la corrosion. Une compréhension approfondie du comportement à long terme de ces parties mobiles est donc essentielle afin de doter les bureaux d’études, confrontés au dimensionnement des structures d’énergies marines, d’outils leur permettant de faire le choix des matériaux (couplefibre/matrice), architectures fibreuses (nappe, tissus), séquence d’empilement des stratifiées minimisant la sensibilité aux chargements appliqués des structures travaillantes. L’objectif final de cette thèse est le développement d’outils et de méthodologies tant numériques qu’expérimentales capables de simuler l’impact du courant et du comportement de ces systèmes de façon couplée ce qui constitue un enjeu majeur de dimensionnement. En effet le but est d’identifier les voies d’optimisation qui permettront d’aller sur la phase commerciale avec un gain de LCOE (Levelized Cost of Energy) substantiel

Can a three-dimensional composite really provide better mechanical performance compared to two-dimensional composite under compressive loading?

International audienceA series of split Hopkinson pressure bar tests on two-dimensional and three-dimensional woven composites were presented in order to obtain a reliable comparison between the two types of composites and the effect of the z-yarns along the third direction. These tests were done along different configurations: in-plane and out-of-plane compression test. For the three-dimensional woven composite, two different configurations were studied: compression responses along to the stitched direction and orthogonal to the stitched direction. It was found that three-dimensional woven composites exhibit an increase in strength for both: in-plane and out-of-plane tests. compared to two-dimensional composite under compressive loading

Staking lay-up effect on dynamic compression behaviour of E-Glass/epoxy composite materials: experimental and numerical investigation

International audienceSeveral industrial applications have exposed polymer matrix composite materials to a very high strain rate loading conditions, requiring an ability to understand and predict the material behaviour under these extreme conditions. Many composite aircraft structures such as fuselage, wing skins, engine nacelles and fan blades are situated such that impacts at high strain rates are a realistic threat. To investigate this threat, high velocity impact experiments and subsequent numerical analysis were performed in order to study the compressive loading of composite materials at high strain rates. Specimens are subjected with various orientations from low to high strain rates to determine the compressive ma terial properties. Three fibre orientations such as: ±20°, ±60° and 90° of cubic geometry are tested in in-plane direction. The tests show a strong material sensitivity to dynamic loading and fibre direction. In the second part, the FEA results of the dynamic tests resulting in no damage appeared satisfactory. The FEA gives results which are in coherence with the experimental data. The improved understanding of these phenomena and the development of predictive tools is part of an ongoing effort to improve the long-term integrity of composite structures under dynamic loads

Fluid-structure interaction effects of horizontal axis marine current turbines

National audienc

Assessment of offshore wind potential in Morocco

In this research, a specific study on the evaluation of wind energy resources along the Atlantic coast of Morocco has been developed, utilising numerical modelling data. To evaluate the spatial distribution of wind power, 18 data points were chosen along this coast. Moreover, the adjustment of wind data and the statement of estimation methods related to form and scale parameters of the Weibull distribution was conducted after a thorough literature review. Then, a study and analysis of wind data based on its speed and direction were carried out, taking into account a five-year period between 2013 and 2017. These study findings denote higher energy production in areas where there is no physical barrier all along the Atlantic coast, whereas, in the extreme north and southern sites, the energy resource is considerably lower because of the shadow effect of the Iberian Peninsula and the Canary Islands, respectively

Energy absorption characteristics in hybrid composite materials for marine applications under impact loading: Case of tidal current turbine

The tidal current turbine is the most efficient way to extract energy from the sea. This system can be prone to critical loads such as impact accidental in the installation and maintenance phase. Indeed, several complex modes of damage susceptible to harming the stability of the structure are studied to conceive hybrid composite nozzles with better resistance to damage. For this reason, two scenarios of low-velocity impact of a hybrid composite nozzle (glass/carbon) were investigated. In both cases, the impact was realized in the region of the trailing edge of the nozzle, and the results obtained were compared between three different laminated. On the other hand, damage modeling was formulated using the finite element method based on the Hashin criteria. Energy conservation of the nozzle was verified to validate the numerical model. Also, the effects of the impact velocity and the panel's flexibility on the initiation and propagation of damage have been studied. Depending on the results, the stacking sequence significantly influences the formation of damage. However, the results show that the hybrid nozzle with CGG (carbon/glass/glass) stacking has a higher impact resistance compared to other laminates

Matériaux composites pour les énergies marines renouvelables

International audienceCe travail s'inscrit dans le cadre des travaux de recherche qui visent la modélisation numérique de l'endommagement des matériaux composites. Cet axe de recherche est d'une grande importance dans divers domaines à l'instar des énergies marines renouvelables. Face à l'augmentation des émissions de gaz à effet de serre, les pays les plus industrialisés se sont accordés sur des objectifs communs pour leur réduction de 50% d'ici à 2050. Pour atteindre ces objectifs, le recours aux énergies non polluantes est de mise. Les mers et les océans étant un véritable réservoir d'énergies renouvelables, nombreux sont les pays qui se sont lancés dans la conquête d'exploitation de ces énergies. Compte tenu de sa prévisibilité, l'énergie des courants marins a été identifiée comme l'une des plus prometteuses énergies vertes. A cet égard les matériaux composites joueront un rôle essentiel dans le développement des systèmes de conversion d'énergie marine renouvelable comme les hydroliennes, et pour cette application compte tenu des contraintes liées à la maintenance une excellente durabilité à long terme s'avère indispensable

Design and Optimization of Composite Offshore Wind Turbine Blades

International audienceIn order to obtain an optimal design of composite offshore wind turbine blade, take into account all the structural properties and the limiting conditions applied as close as possible to real cases. This work is divided into two stages: The aerodynamic design and the structural design. The optimal blade structural configuration was determined through a parametric study by using a finite element method. The skin thickness, thickness and width of the spar flange, and thickness, location, and length of the front and rear spar web were varied until design criteria were satisfied. The purpose of this article is to provide the designer with all the tools required to model and optimize the blades. The aerodynamic performance has been covered in this study using blade element momentum (BEM) method to calculate the loads applied to the turbine blade during service and extreme stormy conditions, and the finite element analysis was performed by using ABAQUS code to predict the most critical damage behavior and to apprehend and obtain knowledge of the complex structural behavior of wind turbine blades. The approach developed based on the nonlinear finite element analysis using mean values for the material properties and the failure criteria of Hashin to predict failure modes in large structures and to identify the sensitive zones