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International audience; Tidal current turbine is one of the innovative and emerging technologies of marine renewable energies because it offers constant and predictable energy source that can be very beneficial, especially for commercial scale production of electrical power. Hydrofoils (HF) are essential elements of tidal current turbine (TCT) and should be properly designed as they play a vital role in improving the turbine output and providing adequate resistance to the blade structure. In connection with the hydrofoil designs, it is noteworthy that the primary objectives in their designs are to increase the coefficient of lift and to reduce the coefficients of drag and pitching moment, thus delaying the cavitation phenomenon. In this paper, the technology developments of the hydrofoil designs used in the horizontal axis TCT industry are reviewed, including the hydrodynamics design and the mechanical structure design. Besides, an up-todate review and the newest achievements of marine TCT technologies with their developing histories are further explored. Included are also reviews on the numerical models used to assess the performance of TCT and optimization methods applied to design the hydrofoils. This in turn significantly contributes to a better knowledge on the recent designs of TCT hydrofoils for the researchers working in the marine turbine energy domain. Such information could also have important implications in the design of more sophisticated hydrofoils for the exploitation in diverse tidal current energy technologies for reaching a sustainable future.

International audience; In this work, two desalination systems combined with a solar energy cycle, MED-PF and MED-PF-TVC are analyzed and evaluated thermo-economically. Solar energy is directly transferred from the solar collector field via the evaporator heat exchanger to MED-PF. In the second technique, the thermal energy produced is transmitted to the steam ejector of the MED-PF-TVC. The comparisons are handled according to 5000 m3/day of distilled product as a case study. A reduction in consumption and specific energy costs is possible due to the reduction in the value of the compression ratio and the increase in the number of evaporators.

International audience; Tidal energy has clear potential in producing large amounts of energy as the world's capacity exceeds 120 GW. Despite being one of the oldest renewable energy sources exploited by man, the technology is still in its pre-commercialisation stage and so lags behind other renewable sources such as wind and geothermal energy in terms of development and energy produced. One of the emerging energy extraction technologies in the tidal energy field is the Horizontal Axis Hydrokinetic Turbine (HAHT) which harness tidal stream energy the same way Horizontal Axis Wind Turbine (HAWT) extract energy from the wind. While HAHT has been the topic of many researches over the past decade, design of hydrofoils plays a vital role in increasing the structural strength of the blade and maximizing the output of the marine current turbines. In this context, a numerical investigation is conducted in this research in which new hydrofoil for marine current turbines underwater conditions was designed and evaluated. The turbine blade is designed using XFLR5 code and QBlade which is a Blade-Element Momentum solver with a blade design feature. Then, the hydrodynamic performance of hydrofoil was tested using Computational Fluid Dynamics (CFD) consisting of lift and drag coefficients, and velocities distribution. The results showed that the new design of the hydrofoil of marine current turbine blade maintained a CPower value of 50% more from normal range at the TSR 5 to 9 and 51% more at TSR = 6,5 in the performance curve.

International audience; Throughout their operating life, offshore wind turbine blades are subjected to considerable wind forces. In order to ensure their durability and strength the intrados and extrados are bounded around spars, which are the skeleton that provide the necessary rigidity to the blade. Wind turbine blades are complex structures given the various scientific fields involved in their study, from aerodynamic to composite fatigue and failure analysis. Wind turbine blade is under coupled process of forces, so when we have the same natural frequency for the blade and exciting forces, the resonance is occurred. Which make the modal analysis of the blade of great importance, hence the scope of the present work, which deal with determining, the natural modes shapes and frequencies of three spars forms during free vibration, as well as for a 5MW horizontal axis floating wind turbine blade, to prevent and avoid resonance effect, using ABAQUS Finite element analysis software. The results show that the resonance effect does not occur for the blade and the proposed layup model provide enough resistance to the structure.

International audience; The 3D printing technology used for small tidal and wind turbines has great potential to change and overcome certain weaknesses in traditional manufacturing techniques. In rural areas and isolated communities, small turbine systems could be locally fabricated and assembled by using additive manufacturing machines and also can be employed to decrease residential energy consumption. The objective of the paper is to study the thermomechanical performance of 3D printing of a small-scale tidal turbine blade and their process using Digimat-AM because more research efforts are needed in this area. In this work, the tidal turbine blade is printed by using the selective laser sintering (SLS) method with polyamide 12 (PA12) and polyether ether ketone (PEEK) polymers reinforced by carbon beads (CB) and glass beads (GB). This research examines conceptual considerations of small tidal turbines including material properties and aerodynamic parameters. Once the finite element evaluation has been completed, the deflection, residual stresses, temperature distribution, and the deformed blade or warpage can be obtained. It is concluded that PA12-CB has warpage higher than PA12-GB by 3.78%, and PEEK-CB has warpage lower than PEEK-GB by 8.4%. Also, the warpage of PA12-CB is lower than PEEK-CB by 10.31%, and the warpage of PA12-GB is lower than PEEK-GB by 20.95%. Therefore, the lowest warpage is observed for PA12-GB. Finally, the results showed that 3D printing presents an excellent opportunity in the design and development of tidal energy systems in the future.

International audience; Additive manufacturing, which is referred to as 3D printing, is a new developed process of fabricating metallic, ceramic, plastic and concrete materials. The goal of this article is to provide an overview of 3D printing processing methods and discuss their pros and cons. A comparison with other technologies such as injection molding and cutting-based machinery was discussed. Various modeling approaches and tools at all scale levels were depicted. We have presented a case study concerning the effect of pores formation in the mechanical properties of 3D printed polymer composites using FDM process. The mechanical behavior of 3D printed composites was determined using the homogenization technique based on the RVE notion. Recent uses of this technology in the area of electronics, aerospace and biomedical engineering were highlighted. Finally, important benefits and limitations were identified in order to clarify and motivate future works in this field.

International audience; Wind turbine blades are highly complex structures with complex 3 dimensional forms governed by their aerodynamics that allow a maximum of power output and efficiency. On the structural side there is always an immense interest in keeping the blades as light and as rigid as possible. No structure being perfectly rigid, the wind turbine blades are specifically designed to keep their deformation in check. Deflection twist couplings are also designed into the blades to have favorable aerodynamic properties even in the deformed state. A combination of experimental and numerical work has been used to address the most critical failure mechanisms and to get an understanding of the complex structural behavior of wind turbine blades. Different failure mechanisms observed during the tests performed for reduced scale tests (smaller test specimens) and the corresponding FE-analysis are presented.

International audience; In the far north, low temperatures and atmospheric icing are a major danger for the safe operation of wind turbines. It can cause several problems in fatigue loads, the balance of the rotor and aerodynamics. With the aim of improving the rigidity of the wind turbine blade, composite materials are currently being used. A numerical work aims to evaluate the effect of ice on composite blades and to determine the most adequate material under icing conditions. Different ice thicknesses are considered in the lower part of the blade. In this paper, modal analysis is performed to obtain the natural frequencies and corresponding mode shapes of the structure. This analysis is elaborated using the finite element method (FEM) computer program through ABAQUS software. The results have laid that the natural frequencies of the blade varied according to the material and thickness of ice and that there is no resonance phenomenon.

International audience; Wind turbine blades are the key components that allow the extraction of energy from the wind; these blades are often subjected to accidental impacts which usually occurs on moving blades with maintenance tools, hail, or flying birds, resulting in a significant degradation of the structural integrity of the blade. In this paper, a numerical simulation is adopted using finite element method (FEM) with ABAQUS software to investigate the mechanical behavior of a GRP composite wind turbine blade under low-velocity impact in operating conditions. On the other hand, damage modeling was formulated based on Hashin criteria for intra-laminar damage to detect failure modes in large wind turbine blade, the sensitive zones, and the size of damaged areas. To investigate this situation, a comparative evaluation was carried out considering many impact scenarios and the main parameters such as the impactor geometry, velocity, and weight. The results are then examined and analyzed, which show that major damage appeared at the tip of the blade and on trailing edge. Furthermore, the impactor geometry affects the type of damage, the weight affects the size of the damaged area, while the impact velocity influences the mechanical response of the composite wind turbine blade.

International audience; In recent years, several wind turbines have been installed in cold climate sites and are menaced by the icing phenomenon. This article focuses on two parts: the study of the aerodynamic and structural performances of wind turbines subject to atmospheric icing. Firstly, the aerodynamic analysis of NACA 4412 airfoil was obtained using QBlade software for a clean and iced profile. Finite element method (FEM) was employed using ABAQUS software to simulate the structural behavior of a wind turbine blade with 100 mm ice thickness. A comparative study of two composite materials and two blade positions were considered in this section. Hashin criterion was chosen to identify the failure modes and determine the most sensitive areas of the structure. It has been found that the aerodynamic and structural performance of the turbine were degraded when ice accumulated on the leading edge of the blade and changed the shape of its profile.

International audience; The composite tidal turbine nozzle can be exposed to impact loads during maintenance or installation operations, which may result in invisible damage. Therefore, it is very important to analyse the induced damage in order to conceive hybrid composite nozzles with better resistance to damage. The low-velocity impact behaviour (LVI) of a carbon/glass hybrid composite nozzle has been investigated based on this motivation. The configurations of stacking sequences were constituted of glass and carbon fibers. The results acquired were compared between five various laminated. Indeed, the impact was studied in the leading edge region of the nozzle. The damaged laminates were inspected by the finite element method (FEM) based on Hashin failure criterion using the ABAQUS software. The energy conservation of the nozzle was verified to validate the numerical model. Futhermore, the effect of accidental impact on dynamic response and the damage induced on a hybrid composite nozzle have been investigated. According to results, the formation of damage like matrix cracking on the external/internal surfaces and radial cracking may occur. In addition, the hybrid nozzle with CCC (carbon/carbon/carbon), and CGG (carbon/glass/glass) stacking has greater impact resistance compared to other configurations.

International audience; The blades of wind turbines placed in cold climate regions are exposed to the risk of icing phenomena which impact their lifetimes. This paper proposes a numerical model to simulate 50 mm ice thickness localized on the tip side of a horizontal wind turbine blade, and to study its mechanical behavior. The wind turbine blade wasmodeled with the finite element method (FEM)in ABAQUS software taking into account aerodynamic, centrifugal and inertial loads under the conditions of service of the blade.Numerical tests haveevaluated the behavior of different composite materials and compared with each other. Damage mode based on the Hashin criteria was defined. Carbon fibers were considered to be the most rigid material which results in thinner, stiffer and lighter blades.

International audience; In order to meet the growing demand for energy and also to fight against global warming, Renewable Marine Energies (RME) appeared as a great opportunity for a real ecological and industrial choice. Tidal current turbines are used to extract this energy and installed on the seabed at locations where the nozzle can be prone to the accidental impact and critical loads. The principal objective of this research is to investigate the effects of environmental exposure on the mechanical properties of composite tidal current turbine, the most advanced features currently available in finite element (FE) Abaqus/Explicit have been employed to simulate the behavior of the composite nozzle under static and dynamic loading conditions. To investigate this situation, a parametric analysis is conducted which deals with the effect of velocity and geometry of the impactor. The mechanical behavior has been analyzed as both kinematic effect due to deflection of the composite structure and dynamic effect caused by the interaction between the impactor and the hydrodynamic and hydrostatic pressures over the loading. The stress and the deformation distribution are presented. On the other hand, damage modeling was formulated based on Hashin criteria for intra-laminar damage. This has been accomplished by forming a user-created routine (VUMAT) and executing it in the Abaqus software.

International audience; Currently, the emergence of a novel human coronavirus disease, named COVID-19, has become a great global public health concern causing severe respiratory tract infections in humans. Yet, there is no specific vaccine or treatment for this COVID-19 where anti-disease measures rely on preventing or slowing the transmission of infection from one person to another. In particularly, there is a growing eort to prevent or reduce transmission to frontline healthcare professionals. However, it is becoming an increasingly international concern respecting the shortage in the supply chain of critical single-use personal protective equipment (PPE). To that scope, we aim in the present work to provide a comprehensive overview of the latest 3D printing eorts against COVID-19, including professional additive manufacturing (AM) providers, makers and designers in the 3D printing community. Through this review paper, the response to several questions and inquiries regarding the following issues are addressed: technical factors connected with AM processes; recommendations for testing and characterizing medical devices that additively manufactured; AM materials that can be used for medical devices; biological concerns of final 3D printed medical parts, comprising biocompatibility, cleaning and sterility; and limitations of AM technology.

Conforming to the factor characteristics of electricity–water cogeneration power plants, an improved multieffect desalination (MED) and reverse osmosis (RO) are the most current techniques for seawater desalination. A principal change between these operations consists of their various energy requirements, thermal energy for MED and mechanical energy for RO plants. The main improvement ideas of RO and MED are the recovery of large quantities of heat produced during the production of sulfuric acid, which exhibits an exothermic reaction where a part of this heat will be used for the thermal power plant and subsequently reverse osmosis and another amount of heat recovery system will be used to desalinate seawater by the MED system. In this work, the sulfuric acid is used to recover heat energy; this energy is used in a hybrid system of RO–MED in order to desalinate the seawater. A thermodynamic steady-state study of this system is investigated to select the optimum cogeneration system. These improvements could make the benefits of cogeneration to the energy consumption of an RO and MED which will be remarkably reduced.

International audience; Wind energy is one among the most promising renewable energy sources, and hence there is fast growth of wind energy farm implantation over the last decade, which is expected to be even faster in the coming years. Wind turbine blades are complex structures considering the different scientific fields involved in their study. Indeed, the study of blade performance involves fluid mechanics (aerodynamic study), solids mechanics (the nature of materials, the type of solicitations horizontal ellipsis ), and the fluid coupling structure (IFS). The scope of the present work is to investigate the mechanical performances and structural integrity of a large offshore wind turbine blade under critical loads using blade element momentum. The resulting pressure was applied to the blade by the use of a user subroutine "DLOAD" implemented in ABAQUS finite element analysis software. The main objective is to identify and predict the zones which are sensitive to damage and failure as well as to evaluate the potential of composite materials (carbon fiber and glass fiber) and their effect on reduction of rotor's weight, as well as the increase of resistance to wear, and stiffness.

International audience; Generally, when marine vessels encounter the water surface on entry and subsequently re-enter the water at high speed, this can subject the bottom section of the vessels to high hydrodynamic loads, especially over very short durations. This phenomenon generates high hydrodynamic loads, which can cause a catastrophic failure in the structure. In contrast, the interaction between deformable structures and free water surface can be modified the fluid flow and changed the estimated hydrodynamic loads comparing with rigid body, due to appearance of hydroelastic effects. These effects are considered active challenge areas in structural ship design. This work presents an experimental study of the water impact for composite laminate wedge at different constant entry velocities. The aim of this study is to investigate the dynamic structural response of panels and predicts the hydrodynamic loads to meet the specific requirements of marine vessels. In order to better describe hydroelastic influence, two composite panels with different thicknesses namely 8 mm and 13 mm are subjected under constant impact velocities of 4, 6 and 8 m/s with the deadrise angle of 10 degrees. The obtained experimental results were indicated that more flexible panels had a higher peak force and significant dynamic noise compared with higher stiffness panels. In addition, the maximum deformation occurred in the centre and close to the chine edge of the panel due to changes in local velocity and local deadrise angle. For this reason, special attention requires in both design phase and operation phase.

International audience; Composite are prone to failure during operation and that's why vast research had been carried out to develop in situ sensors and monitoring systems to avoid their catastrophic failure and repairing cost. The aim of this research was to develop a flexible strain sensor wire for real-time damage detection in the composites. This strain sensor wire was developed by depositing conductive silver (Ag) nanoparticles on the surface of nylon (Ny) yarn by electroless plating to achieve the smallest uniform coating without jeopardizing the integrity of each material. The sensitivity of this Ny/Ag strain sensor wire was calculated experimentally and gauge factor (G.F) was found to be in the range of 21-25. Then, Ny/Ag strain sensor wire was inserted in each composite specimen at different position intentionally through the thickness during their fabrication depending upon the type of damage to detect. The specimens were subjected to flexural deflection using a 3-point bend test at the strain rate of 2 mm/ min. Overall mechanical response of composite specimens and electrical response signal of the Ny/Ag strain sensor wire showed good reproducibility in results however, Ny/Ag sensor showed a specific change in resistance in each specimen because of their respective position. The sensor wire designed, did not only monitor the change in the mechanical behavior of the specimen until final fracture but also identified the type of damage whether it was compressive, tensile or both. This sensor wire showed good potential as a flexible reinforcement in composite materials for in-situ SHM applications before it can become fatal.

International audience; Slamming is a dynamic phenomenon in which a high magnitude pulse peak pressure occurs in a short time duration when the bottom structure of a ship impacted against the sea surface. This phenomenon can cause damage in the structure due to fluid-structure interaction (FSI) thus, plays a vital role in designing and manufacturing of ships for naval applications. In this paper, high performance sandwich structure, having many opportunities and challenges for the marine structural design, were studied experimentally using a high-speed shock test machine to examine the water entry problem. In addition, a velocity control system was used to calibrate and preserve the approximately uniform velocity throughout the slamming impact. Sandwich panels with different thicknesses i.e. 27 mm and 37 mm therefore, having different stiffness's were exposed under constant impact velocities of 6 and 8 m/s at the deadrise angle 10°. Experimental results were then compared and verified by the numerical investigation based on explicit Smoothed Particle Hydrodynamics (SPH) method. This study focuses on the overall structural response, deformation, and hydrodynamic response of the structure during the dynamic impact designed for naval applications.

International audience; In 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.

International audience; Marine energy is gaining more and more interest in recent years and, in comparison to fossil energy, is very attractive due to predictable energy output, renewable and sustainable, the Horizontal Axis Hydrokinetic Turbine (HAHT) is one of the most innovative energy systems that allow transforms the kinetic energy into electricity. This work presents a new series of hydrofoil sections, named here NTSXX20, and was designed to work at different turbine functioning requirement. These hydrofoils have excellent hydrodynamic characteristics at the operating Reynolds number. The design of the turbine has been done utilising XFLR5 code and QBlade which is a Blade-Element Momentum solver with a blade design feature. Tidal current turbine has been able to capture about 50% from TSR range of 5 to 9 with maximum CPower of 51 % at TSR=6,5. The hydrodynamics performance for the CFD cases was presented and was employed to explain the complete response of the turbine.

The current energy policy recommends the idea of energy efficiency over fossil energy as a primary matter for the coming years. The kingdom of Morocco requires restructuring of its power equipment by increasing the percentage of renewable energy supplies, optimizing their systems and power storage. Therefore, increasing energy efficiency is an as important obligation as reducing the overall energy consumption. The purpose of this research is to present the energy transition in Morocco towards renewable energies and to assess the diversity of available marine natural resources. Recent research in conversion of ocean thermal energy, wave energy, tidal energy, offshore wind energy, and osmotic energy into power supply has started to encourage different technologies. This research has led to commercial deployment in some cases such as our 550 km long Mediterranean coast and 3000 km long Atlantic. This does not only result in fossil energies independency but also provides advantages like less cost and no pollution.

Composite materials are used in many marine structures such as renewable marine energy conversion systems because of their fairly good mechanical properties and especially their low densities compared to traditional materials. The most advanced features currently available in finite element (FE) Abaqus/Explicit have been employed to simulate the behavior of the composite nozzle under hydrodynamic and impact loading. A hydrodynamic analysis was considered to design the nozzle turbine and the hydrodynamic pressure obtained was then implemented as boundary conditions to a FE code. The goal of this article is to evaluate the durability of composite materials of a ducted tidal turbine under critical loads (hydrodynamic and hydrostatic pressures) with the implementation of a failure criterion using the finite element analysis (FEA). The mechanical behavior was analyzed for two materials (Carbon–epoxy/ Glass–polyester). This has been accomplished by forming a user-created routine (VUMAT) and executing it in the ABAQUS software. Keywords: Marine composite structures, Ducted tidal turbine, Finite element analysis, VUMAT

The wind turbine blades are complex structures in terms of their geometry and the materials used. They need to be modeled, on the one hand as accurately and precisely as possible, while on the other hand the models should be light enough to be run in a reasonable amount of time using reasonable computational resources. Sub-modeling is a technique used to reduce the domain size of a finite element model to a more manageable size. One of the motivations behind sub-modeling is the capacity to develop highly refined and detailed models, without using increased computational resources, as the refined model domain is small and hence has a smaller number of elements. There are different methods of sub dividing the problem domain into smaller simpler domains, of which the transfer of nodal displacement form one parent model to its child will be used in this study. Furthermore the use of surface to solid sub-models is also discussed.

International audience; This work aims to establish a finite element model to simulate the behavior in cracking failure of a shear test of a single lap joint. The interest of having a satisfactory finite element model is to be able to use it to simulate the cases that have not been the subject of experimental tests. A cohesive zone model (CZM) was used to model the propagation of cracks in bonded joints, using a bilinear traction–separation law implemented in the finite element code Abaqus. The cohesive zone is represented by a row of cohesive elements where the progression of the crack will take place. The parameters of the cohesive law of an adhesive “Adekit A140” were determined by fracture tests, performed on DCB and ENF tests. A damage initiation criterion and a mixed-mode failure criterion are used, respectively, to initiate and perform damage to the interfaces. Two numerical models of single lap joint were tested. In the first model (CZMi), the cohesive zone is represented by a row of cohesive elements placed along a single interface (adhesive–substrate) and the second interface of the model being left intact. In the second model (CZMii), the cohesive elements are placed along the two interfaces of between adhesive and substrate. In this case, the cohesive zone comprises two rows of cohesive elements. Experimental shear tests were performed on single lap joints bonded with Adekit A140 adhesive to determine the force–displacement curve. The numerical model using a single row of cohesive elements has a force–displacement curve shifted backward of the experimental force–displacement curve. It shows a greater initial rigidity and less resistance to crack propagation in the joints. The force–displacement curve of the numerical model using two rows of cohesive elements coincides with the experimental force–displacement curve. The numerical force–displacement curve shows good initial stiffness and good resistance to crack propagation in joints. These latest numerical results (two rows of cohesive elements) are in good agreement with the experimental results and allow us to validate the numerical model applied to shear tests of bonded joints.

International audience; The deformable composite structures subjected to water-entry impact can be caused a phenomenon called hydroelastic effect, which can modified the fluid flow and estimated hydrodynamic loads comparing with rigid body. This is considered very important for ship design engineers to predict the global and the local hydrodynamic loads. This paper presents a numerical model to simulate the slamming water impact of flexible composite panels using an explicit finite element method. In order to better describe the hydroelastic influence and mechanical properties, composite materials panels with different stiffness and under different impact velocities with deadrise angle of 100 have been studied. In the other hand, the inertia effect was observed in the early stage of the impact that relative to the loading rate. Simulation results have been indicated that the lower stiffness panel has a higher hydroelastic effect and becomes more important when decreasing of the deadrise angle and increasing the impact velocity. Finally, the simulation results were compared with the experimental data and the analytical approaches of the rigid body to describe the behavior of the hydroelastic influence.

International audience; Issues such as energy generation/transmission and greenhouse gas emissions are the two energy problems we face today. In this context, renewable energy sources are a necessary part of the solution essentially winds power, which is one of the most profitable sources of competition with new fossil energy facilities. This paper present the simulation of mechanical behavior and damage of a 48 m composite wind turbine blade under critical wind loads. 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 FE analysis using mean values for the material properties and the failure criteria of Tsai-Hill to predict failure modes in large structures and to identify the sensitive zones.

We currently notice a substantial growth in the wind energy sector worldwide. This growth is expected to be even faster in the coming years. This means that a massive number of wind turbine blades will be produced in the forthcoming years. There is a large potential for materials savings in these blades. The analysis of designed blade is done in dynamic loading. Five types of spars cross-section are taken in this work. The blade and spar are of composite material. The Finite element modal analysis of designed blade is done in ABAQUS. The scope of the present work is to investigate the structural modal analysis of full-scale 48m fiberglass composite wind turbine blades for 5MW horizontal axis wind turbine and through this to assess the potential for materials savings and consequent reductions of the rotor weight. The entire wind turbine can benefit from such weight reductions through decreased dynamics loads and thus leave room for further optimization. A numerical work has been used to address the most adequate spar shape and to get an understanding of the complex structural behavior of wind turbine blades. Five different types of structural reinforcements helping to prevent undesired structural elastic mechanisms are presented. Comparisons of the eigenfrequencies observed in the full-scale tests are presented and conclusions are drawn based on the mechanisms found.

International audience; Marine energy is one of the most exciting emerging forms of renewable energy. Tidal turbines are used to extract this energy and installed on the seabed at locations with catastrophic loading. The present paper employs the finite element method to simulate the behavior of GRP composite nozzle of a tidal turbine under low-velocity impact with implementation of a failure criterion. To investigate this situation, a parametric analysis is conducted which deals with the effect of velocity, energy and geometry of the impactor. The mechanical behavior has been analyzed as both kinematic effect due to deflection of the composite structure and dynamic effect caused by the interaction between the impactor and the hydrodynamic and hydrostatic pressures over the loading. The stress and the deformation distribution are presented. On the other hand, damage modeling was formulated based on Hashin criteria for intra-laminar damage. The effects of the impact velocity and the panel's flexibility on the initiation and propagation of damage have been investigated.

International audience; The use of composite materials begin to normalize in various sectors, however, these structures are very susceptible to degradation of their properties and consequently a catastrophic failure. The response of deformable composite subjected to water-entry impact can cause a phenomenon called hydro-elastic effect due to water-flexible laminate interaction. This phenomenon may be large enough to cause the damage in composite panels. This paper employs the finite element method to simulate the behavior of composite wedges under slamming impact with presence of damage. To investigate this situation, the hydro-elastic influence has been analysis as both kinematic effect due to deflection of the composite panel and dynamic effect caused by the interaction between the water and the structure. On the other hand, damage modeling was formulated based on continuum damage mechanics for intra-laminar damage. A user-defined material subroutine VUMAT has been incorporated into explicit Abaqus FE software to enhance the damage simulation, which includes Hashin criteria for degradation of the panel stiffness with failure onset criteria and fracture mechanics. To reinforce the methodology adopted, numerical results are compared with the previous experimental data. A good agreement was observed. Effects of impact velocity and the panels flexibility on the damage have been investigated.

International audience; The use of composite materials is on the rise in different engineering fields. Following this trend the wind turbine industry has adopted composites as their primary material of choice. For wind turbine blades having large unsupported functional aerodynamic surfaces; the structural stiffness is very important. Stiffness is required to keep the deformations to a minimum under aerodynamic forces. The blade is thus stiffened using sandwich structures at high strain locations within the structure. The lightweight foam cored sandwiches though add stiffness, at the same time pose a challenge for design as the difference in stiffness of both the face-plate and the foam core is very high. The resistance to fracture in any part of the structure is an important design parameter to be determined. The determination of fracture resistance quantified here as the Strain Energy Release Rate (SERR) poses some unique challenges when dealing with highly heterogeneous materials in terms of stiffness. In this study some approaches have been analyzed while others are developed to tackle this problem and to measure the Mode I & II SERR of the face-plate foam-core interface. The sandwich core varies in both thickness and density depending on the loading and thus the location along the blade length. However for this study we have used a single density of foam core for the most part of the turbine blade. Different thicknesses of the foam cores are used to determine the effect of scale on the calculated SERR.

International audience; Sandwich structures have been widely used in marine applications due to their properties such as high weight/strength ratio. In contrast, the failure mechanism of these structures has a significant effect on the local and global dynamic responses. In the present study, sandwich panels with polymeric skins and PVC foam cores subjected to slamming impact are investigated experimentally and numerically. A high speed shock machine is used to keep approximately a constant velocity during the impact event. The dynamic resistance was analysed in terms of hydrodynamic loads, dynamic deformation and failure mechanisms for different impact velocities. On the other hand, the slamming model was implemented in Abaqus/Explicit software based on Coupled Eulerian Lagrangian model approach. In addition, different damage modes are incorporated in the numerical model, including the intralaminar, debonding in skin/core interface, and core shear to cover all possible damage modes throughout structures. Two failure criteria (Hashin criteria for the laminate composite and Christensen criteria for the core in sandwich structure) are defined and integrated into VUMAT sub-routine. In addition, the cohesive zone model is used to predict the debonding skin/core. A good agreement in both hydrodynamic loads and damage prediction were found between numerical and experimental results.

Marine energy is one of the most exciting emerging form of renewable energy. Tidal turbines are used to extract this energy and installed on the seabed at locations with catastrophic loading. This investigation focuses on the numerical simulation of the damage progressive in tidal turbine used for marine energy application under impact loadings. The optimal design and the dynamic behavior of the turbine are studied. Finally, the hydrodynamic and hydrostatic pressures over the loading and the distribution of the stress, the deformation and damaged zone are presented.

International audience; Within the EUCLID project, ‘Survivability, Durability and Performance of Naval Composite Structures’, one task is to develop improved fibre composite joints for naval ship superstructures. In many practical situations, the structures are subjected to loading at very high strain rates like slamming, impact, underwater explosions or blast effect. Material and structural response vary significantly under such loading as compared to static loading. In this paper, the results from a series of Split Hopkinson Pressure Bar tests on the woven composites are presented. These tests were done in two configurations: in-plane and out-of-plan compression test. It is observed that the failure strength varies with the different loading directions. The results indicate that the stress–strain curves, maximum engineering stresses and strains evolve as strain rate changes. The woven composites have higher values of engineering stress and dynamic stiffness for in-plane than for out-of-plane compression at the same strain rate; however, the in-plane strain at maximum stress is higher than that of out-of-plane compression. During the experiments, a high speed camera was used to determine the damage mechanisms. The specimens are mainly damaged in a crushing and shear failure mode under out-of-plane loading, as for in-plane test, the failure was dominated by fibre buckling and delamination.

International audience; The in-plane compressive behavior of two- and three-dimensional woven composite was investigated at high strain rates. The Split Hopkinson Pressure Bar is employed to test the high strain rate dynamic mechanical properties of E-glass vinylester composite material. For three-dimensional woven composite, two configurations were tested: compression responses along the stitched direction and orthogonal to the stitched direction. Dynamic compression properties for two- and three-dimensional are determined and compared. Experimental results show that the strain rate has a significant effect on the two- and three-dimensional woven composite response. It is observed that the three-dimensional woven composite has higher compression strength and dynamic modulus than the two-dimensional composite at high strain rate. For this study, a high-speed camera was used to determine the damage kinetics under dynamic load. The two-dimensional woven composite is mainly damaged in a mode of matrix cracks and severe delamination, while the mode for three-dimensional woven composite is mainly cracking of matrix and delamination for in-plane along to the stitched direction and shear banding failure for in-plane orthogonal to the stitched direction.

International audience; To convert the kinetic energy of marine current into electricity, the most sensible generator is a horizontal axis turbine. The know-how and the tools used for marine propulsion devices find a new range of applications in this field. An academic panel method code developed for the design of bare and ducted marine propellers was applied to design a marine current turbine. The turbine dimension and the tidal current velocity have been taken to fit the conditions in the Race of Alderney. The wing section theory and the optimum rotor theory based on the blade element momentum were used to obtain the design condition and a first geometry approaching the Betz limit for a bare rotor. The panel method was then used to verify the power coefficient obtained in the presence of the 3D effects and if the cavitation constraints are respected. Subsequently, the same panel code was used to verify if the addition of a duct could improve the power output per unit surface.

International audience; Split Hopkinson pressure bar (SHPB) is one of the most important and recognized apparatus used for characterizing the dynamic behavior of materials. In the first part of this study, the results from a series of SHPB tests on the woven composites are presented in this paper. The compressive material properties are determined by testing the [0°/90°]26 laminate systems from low to high strain rates. Samples of cubic geometry are tested in in-plane and out-of-plane direction. Preliminary compressive stress–strain vs. strain rates data obtained show that the dynamic material strength increases with increasing strain rates. The tests show a strong material sensitivity to dynamic loading. For in-plane tests, there is a transitional strain rate, reflecting the dependencies on strain rate observed in experiments. The results indicate that the stress–strain curves, maximum compressive stresses and strains evolve as strain rate changes. During the experiments, a high speed camera was used to determine the kinetics of damage. The specimens are mainly damaged in a crushing and shear failure mode under out-of-plane loading, as for in-plane test, the failure was dominated by fiber buckling and delamination. In the second part of this study, numerical models without damage are developed to investigate the validity of assumptions of compression Split-Hopkinson Pressure Bar technique. Abaqus software was used for the numerical simulation. The results obtained by numerical investigation of SHPB are compared with the in-plane and out-of-plane compression test of a woven composite. A good correlation was noted between the experimental and numerical results, which allows validate the numerical approach.

International audience; In this study, the three-dimensional finite element method is used to determine the stress intensity factor in Mode I and Mixed mode of a centered crack in an aluminum specimen repaired by a composite patch using contour integral. Various mesh densities were used to achieve convergence of the results. The effect of adhesive joint thickness, patch thickness, patch-specimen interface and layer sequence on the SIF was highlighted. The results obtained show that the patch-specimen contact surface is the best indicator of the deceleration of crack propagation, and hence of SIF reduction. Thus, the reduction in rigidity of the patch especially at adhesive layer-patch interface, allows the lowering of shear and normal stresses in the adhesive joint. The choice of the orientation of the adhesive layer-patch contact is important in the evolution of the shear and peel stresses. The patch will be more beneficial and effective while using the cross-layer on the contact surface.

We currently notice a substantial growth in the wind energy sector worldwide. This growth is expected to be even faster in the coming years. This means that a massive number of wind turbine blades will be produced in the forthcoming years. There is a large potential for materials savings in these blades. The analysis of designed blade is done in dynamic loading. Five types of spars cross-section are taken in this work. The blade and spar are of composite material. The Finite element modal analysis of designed blade is done in ABAQUS. The scope of the present work is to investigate the structural modal analysis of full-scale 48m fiberglass composite wind turbine blades for 5MW horizontal axis wind turbine and through this to assess the potential for materials savings and consequent reductions of the rotor weight. The entire wind turbine can benefit from such weight reductions through decreased dynamics loads and thus leave room for further optimization. A numerical work has been used to address the most adequate spar shape and to get an understanding of the complex structural behavior of wind turbine blades. Five different types of structural reinforcements helping to prevent undesired structural elastic mechanisms are presented. Comparisons of the eigenfrequencies observed in the full-scale tests are presented and conclusions are drawn based on the mechanisms found.

This paper presents the results from a study in two parts. The first part involves the identification and modeling of damage initiation and development in glass-reinforced epoxy composite cylinders subjected to drop weight impact. The second is concerned with the evaluation of the influence of this damage on the residual strength under hydrostatic pressure loading. Original results showing the influence of damage on implosion pressure are presented. 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 for underwater applications.

International audience

This work is a theoretical study of the mechanical behavior of two different weave types: plain and twill. Traditional methods permit the study of plain weaves but prove quite difficult for twill weaves. Indeed, the difficulties related to modeling the mechanical behavior of the twill weave are due to its very complex geometry and its nonsymmetry, which require the application of the finite element method. This method requires first a mathematical formulation of the problem and then a mesh of the basic cells of the plain and twill fabrics. The next step is to simulate shearing and tensile tests. Analyzing the results has proved to be very hard and thus demands a study of the stress field of the basic cell.

The arrangement, properties and structure of the fibers within the yarn and the yarns within the fabric, generate a complex mechanism of deformation. Therefore the present work intends to develop a theoretical model of the mechanical behavior of the plain weave. The modeling of textile structures by the finite element method is a new approach based on the combination of geometric and mechanical models. The finite element method permits a construction and representation of fabrics by taking into consideration the yarn undulation, the existence or not of symmetries in the basic cell and the type of contact between warp and weft yarns. These different parameters allow the mesh of weaves to be obtained, the closest to the reality, without any restriction and any simplifying assumption. In every model defined by its partial derivative equation of the fabric mechanical behavior, and whatever the method of homogenization employed to obtain a homogeneous model, we will be brought to solve a cellular problem. The three-dimensional structure of the basic cell of the various fabrics is very complex. Therefore, the mathematical study starts by meshing the different fabrics, which will enable us to take the geometry as well as the mechanical characteristics of the yarn into account, as well as the stresses applied. The application of this method first requires a mathematical formulation of the problem and then a mesh of the basic cell. The next step is the simulation of shearing and tensile tests. The analysis of the results has proved to be very hard and, thus, has demanded a study of the stress field in the basic cell. From the analysis of the plain weave behavior under those different tests we can assess that the yarn cross-section is one of the crucial factors that influences the mechanical behavior of fabrics, and the phenomenon of stress concentration appears to be located at the level of contact surfaces between warp and weft yarns. For all models that deal with the mechanical behavior of textile structures and regardless of the method of homogenization, the problem has to be solved at the basic cell level before moving on to the global model. The geometry of the textile structures is very complex due to the nonsymmetrical aspect of the majority of weaves. After having defined the geometrical form and completed the meshes of the basic cells of the plain weave, we have carried on the treatment of the problem from the mechanical point of view by the finite element method.

The arrangement as well as the properties and the structure of the fibres within the yarn and the yarns within the fabric generate a complex mechanism of deformation in such material. Therefore, intends to develop a theoretical model of the mechanical behaviour of the twill weave based on previous researches concerning the simplest plain weave. However, scaling up from the plain to the twill weave is not a direct transformation due to the non‐symmetry of the latter. The finite element method does not require simplifying hypotheses. Thus, it is possible to simulate different stresses, to determine the fabric response and to compare the behaviour of the various structures. This simulation requires the use of a realistic meshing of the basic cell and an accurate characterisation of the physical parameters of the material that composes the basic cell. Assuming the material to be elastic, the derived and, consequently, the discreet mathematical formulations of the problem have both been solved. The coefficients from those formulas are then used in the Modulef software. For each stage of the development, uniaxial, biaxial and perpendicular to the fabric plan, tensile tests have been simulated, as well as pure shear testing. The next step consisted of computing the Tresca and Von Mises stresses within the basic cell and the micro‐stress field within the basic cell components.

We currently notice a substantial growth in the wind energy sector worldwide. This growth is expected to be even faster in the coming years. This means that a massive number of wind turbine blades will be produced in the forthcoming years. There is a large potential for materials savings in these blades. The analysis of designed blade is done in dynamic loading. Five types of spars cross-section are taken in this work. The blade and spar are of composite material. The Finite element modal analysis of designed blade is done in ABAQUS. The scope of the present work is to investigate the structural modal analysis of full-scale 48m fiberglass composite wind turbine blades for 5MW horizontal axis wind turbine and through this to assess the potential for materials savings and consequent reductions of the rotor weight. The entire wind turbine can benefit from such weight reductions through decreased dynamics loads and thus leave room for further optimization. A numerical work has been used to address the most adequate spar shape and to get an understanding of the complex structural behavior of wind turbine blades. Five different types of structural reinforcements helping to prevent undesired structural elastic mechanisms are presented. Comparisons of the eigenfrequencies observed in the full-scale tests are presented and conclusions are drawn based on the mechanisms found.

This paper presents finite element analysis (FEA) of static and dynamic tests of thick filament wound glass/epoxy tubes. The first part involves the validation of elastic properties and identification of damage initiation and its development in dynamic tests. The results of FEA of the dynamic tests without damage appeared satisfactory. An impact model, including material property degradation, is used for damage prediction. The simulated damage is compared with that obtained experimentally. The sizes of projected and cumulated surfaces are of the same order of magnitude as in the experimental measurements.

International audience; Using the Abaqus software, the goal of this work is the numerical study of the effects of the static loads on the mechanical behavior, the damage and the strength of the aluminum/aluminum and composite/composite assemblies, very much used in the naval field. For an elastic behavior of the adhesive, it is also a question of modeling the damage of the substrates in composite. This paper presents a numerical investigation on the behavior of structural adhesive bounding under quasi-static loading. It is shown the effects of the adhesive thickness, superposition length and staking lay up on the strength of the adhesively bonded joints under static tensile. A comparison between the use of aluminum and composite laminate substrates is presented and an attempt was made to find out the damage kinetic.

International audience; This paper presents an experimental investigation on the behaviour of structural adhesive bonding under quasi-static and moderately high loading rates. It addresses the effects of the loading rate on the strength of the adhesively bonded joints under dynamic tensile. A comparison has been achieved between the strength and the damage of specimens' made of aluminium and lamina substrates. High rate tests showed ringing in the force/displacement curves.

In this work the dynamic responses of bonded top hat stiffened panel have been studied by using finite element analysis model (Abaqus). A symmetrical 2D model was performed and used in the simulations. In the first part, dynamic behavior and impact speed effects at such composite structure have been studied. In the second part, other simulations were carried out by using cohesive elements proposed to predict the delamination might happen under such loading.