Numerical investigation of rain droplet impact on offshore wind turbine blades under different rainfall conditions: A parametric study - ScienceDirect
The leading edge of a fiber composite wind turbine blade (WTB) is prone to erosion damages due to repeated rain droplet impact during its service life. Such damages are critical to the blade’s aerodynamic as well as structural performance, ultimately resulting in substantial repair costs. An effective design of a coating material for WTB is necessary and its analysis must include variables associated with erosive rain droplets such as (1) droplet diameter, (2) impact velocity, and (3) droplet impact angle......
4 mars 2020
Improving four-point bending performance of marine composite sandwich beams by core modification - F Balıkoğlu, N Arslan, TK Demircioğlu, O İnal, M İren, A Ataş, 2020
Improving four-point bending performance of marine composite sandwich beams by core modification - F Balıkoğlu, N Arslan, TK Demircioğlu, O İnal, M İren, A Ataş, 2020
The aim of this study was to improve four-point bending performance of foam core sandwich composite beams by applying various core machining configurations. Sandwich composites have been manufactured using perforated and grooved foam cores by vacuum-assisted resin transfer moulding method with vinyl-ester resin system. The influence of grooves and perforations on the mechanical performance of marine sandwich composite beams was investigated under four-point bending test considering the weight gain. Bending strength and effective bending stiffness increased up to 34% and 61%, respectively, in comparison to a control beam without core modification. Analytical equations were utilised for calculating the mid-span deflection, equivalent bending stiffness and ultimate bending strength of the sandwich beams. Finite element analysis was also performed to analyse the flexural response of the specimens taking into account the combined effect of orthotropic linear elasticity of the face sheet and the non-linear behaviour of the foam core.
The aim of this study was to improve four-point bending performance of foam core sandwich composite beams by applying various core machining configurations. Sandwich composites have been manufactured using perforated and grooved foam cores by vacuum-assisted resin transfer moulding method with vinyl-ester resin system. The influence of grooves and perforations on the mechanical performance of marine sandwich composite beams was investigated under four-point bending test considering the weight gain. Bending strength and effective bending stiffness increased up to 34% and 61%, respectively, in comparison to a control beam without core modification. Analytical equations were utilised for calculating the mid-span deflection, equivalent bending stiffness and ultimate bending strength of the sandwich beams. Finite element analysis was also performed to analyse the flexural response of the specimens taking into account the combined effect of orthotropic linear elasticity of the face sheet and the non-linear behaviour of the foam core.
Observation of edge effect in flexural fatigue test of composites using large field of view microscopy - Ulrich A Mortensen, Tom L Andersen, Lars P Mikkelsen,
Observation of edge effect in flexural fatigue test of composites using large field of view microscopy - Ulrich A Mortensen, Tom L Andersen, Lars P Mikkelsen,
Free-edge effects in fibre reinforced composites can produce premature damage at the composite edges due to mechanical, geometrical and hygro–thermal effects. Observation of damage on the free-edge of a composite plate is therefore different than what can be observed inside the material. The amount of individually broken fibres in a composite is counted by observing a test specimen with a polished edge and by cutting test specimens to observe damage inside the material. The amount of damage observed on a polished edge is found to greatly exceed that which is observed inside test specimens subjected to the same testing conditions. It is shown that the progression of important damage mechanisms can be observed on polished edges, but also that invalid damage mechanism may be observed using free-edge microscopy.
Free-edge effects in fibre reinforced composites can produce premature damage at the composite edges due to mechanical, geometrical and hygro–thermal effects. Observation of damage on the free-edge of a composite plate is therefore different than what can be observed inside the material. The amount of individually broken fibres in a composite is counted by observing a test specimen with a polished edge and by cutting test specimens to observe damage inside the material. The amount of damage observed on a polished edge is found to greatly exceed that which is observed inside test specimens subjected to the same testing conditions. It is shown that the progression of important damage mechanisms can be observed on polished edges, but also that invalid damage mechanism may be observed using free-edge microscopy.
Preparation and Anti-Icing of Hydrophobic Polypyrrole Coatings on Wind Turbine Blade
Preparation and Anti-Icing of Hydrophobic Polypyrrole Coatings on Wind Turbine Blade
This paper describes the method of preparing strong hydrophobic polypyrrole (PPy) on wind turbine blades. The water contact angle of strong hydrophobic PPy coatings was 127.2°. The strong hydrophobic PPy coatings exhibited excellent anti-icing properties. The maximum icing weight of strong hydrophobic PPy coating blade was almost 0.10 g while the maximum icing weight of no coating blade was found to be 26.13 g. The maximum icing thickness of a strong hydrophobic PPy coating blade was only 1.08 mm. The current research will provide a better technique to create anti-icing coatings on wind turbine blades and other outdoor equipment.
This paper describes the method of preparing strong hydrophobic polypyrrole (PPy) on wind turbine blades. The water contact angle of strong hydrophobic PPy coatings was 127.2°. The strong hydrophobic PPy coatings exhibited excellent anti-icing properties. The maximum icing weight of strong hydrophobic PPy coating blade was almost 0.10 g while the maximum icing weight of no coating blade was found to be 26.13 g. The maximum icing thickness of a strong hydrophobic PPy coating blade was only 1.08 mm. The current research will provide a better technique to create anti-icing coatings on wind turbine blades and other outdoor equipment.
Parameter study and experimental analysis of a thermo-mechanical de-icing concept - IOPscience
Parameter study and experimental analysis of a thermo-mechanical de-icing concept - IOPscience
The removal of ice accumulation on aerodynamic surfaces is a common challenge not only in aviation but also for stationary installations on the ground such as wind turbines. The aim of this paper is to investigate a novel concept for a thermo-mechanical de-icing system based on shape memory alloys. To understand the functional principle in detail, a functional sample is designed, fabricated and experimentally investigated. With a systematic design approach using a morphological box, an optimal configuration is sought and evaluated that harmonizes all relevant functions in the sense of maximum functional conformity. One selected concept forms the basis for the simulation model, which is used to investigate the influence of different parameters on the thermo-mechanical behavior of the functional sample. The results of the parameter study are used to produce a functional sample for investigating the de-icing ability. The experiments on the functional sample serve to validate and improve the simulation model. The comparison of the measurement data with the model prediction shows a good correlation between measurement and prediction with reasonable deviations. The findings on the test methodology, the manufacturing technology and the system behavior allow the further development of the de-icing concept in subsequent steps.
The removal of ice accumulation on aerodynamic surfaces is a common challenge not only in aviation but also for stationary installations on the ground such as wind turbines. The aim of this paper is to investigate a novel concept for a thermo-mechanical de-icing system based on shape memory alloys. To understand the functional principle in detail, a functional sample is designed, fabricated and experimentally investigated. With a systematic design approach using a morphological box, an optimal configuration is sought and evaluated that harmonizes all relevant functions in the sense of maximum functional conformity. One selected concept forms the basis for the simulation model, which is used to investigate the influence of different parameters on the thermo-mechanical behavior of the functional sample. The results of the parameter study are used to produce a functional sample for investigating the de-icing ability. The experiments on the functional sample serve to validate and improve the simulation model. The comparison of the measurement data with the model prediction shows a good correlation between measurement and prediction with reasonable deviations. The findings on the test methodology, the manufacturing technology and the system behavior allow the further development of the de-icing concept in subsequent steps.
26 février 2020
Improving four-point bending performance of marine composite sandwich beams by core modification - F Balıkoğlu, N Arslan, TK Demircioğlu, O İnal, M İren, A Ataş, 2020
Improving four-point bending performance of marine composite sandwich beams by core modification - F Balıkoğlu, N Arslan, TK Demircioğlu, O İnal, M İren, A Ataş, 2020
The aim of this study was to improve four-point bending performance of foam core sandwich composite beams by applying various core machining configurations. Sandwich composites have been manufactured using perforated and grooved foam cores by vacuum-assisted resin transfer moulding method with vinyl-ester resin system. The influence of grooves and perforations on the mechanical performance of marine sandwich composite beams was investigated under four-point bending test considering the weight gain. Bending strength and effective bending stiffness increased up to 34% and 61%, respectively, in comparison to a control beam without core modification. Analytical equations were utilised for calculating the mid-span deflection, equivalent bending stiffness and ultimate bending strength of the sandwich beams. Finite element analysis was also performed to analyse the flexural response of the specimens taking into account the combined effect of orthotropic linear elasticity of the face sheet and the non-linear behaviour of the foam core.
The aim of this study was to improve four-point bending performance of foam core sandwich composite beams by applying various core machining configurations. Sandwich composites have been manufactured using perforated and grooved foam cores by vacuum-assisted resin transfer moulding method with vinyl-ester resin system. The influence of grooves and perforations on the mechanical performance of marine sandwich composite beams was investigated under four-point bending test considering the weight gain. Bending strength and effective bending stiffness increased up to 34% and 61%, respectively, in comparison to a control beam without core modification. Analytical equations were utilised for calculating the mid-span deflection, equivalent bending stiffness and ultimate bending strength of the sandwich beams. Finite element analysis was also performed to analyse the flexural response of the specimens taking into account the combined effect of orthotropic linear elasticity of the face sheet and the non-linear behaviour of the foam core.
24 février 2020
A review on the historical development of the lift-type vertical axis wind turbine: From onshore to offshore floating application - ScienceDirect
A review on the historical development of the lift-type vertical axis wind turbine: From onshore to offshore floating application - ScienceDirect
This paper discusses the historical evolution of the lift-type vertical axis wind turbine (VAWT) since its inception in the early 1930s. The VAWT received almost no development until the early 1970s when engineers in Canada and the USA began to study the VAWT design as a source of generating electricity. Many curved-bladed VAWTs were tested and are reviewed in this paper. Separately, the straight-bladed VAWT was developed by researchers in the UK and is also discussed. This review highlights that the VAWT received very little engineering development in the 1990s due to dominance of the HAWT in the wind energy market. Although, the literature also indicates that the VAWT has entered a Renaissance period whereby the VAWT is now being adopted for the offshore floating wind turbine industry....
This paper discusses the historical evolution of the lift-type vertical axis wind turbine (VAWT) since its inception in the early 1930s. The VAWT received almost no development until the early 1970s when engineers in Canada and the USA began to study the VAWT design as a source of generating electricity. Many curved-bladed VAWTs were tested and are reviewed in this paper. Separately, the straight-bladed VAWT was developed by researchers in the UK and is also discussed. This review highlights that the VAWT received very little engineering development in the 1990s due to dominance of the HAWT in the wind energy market. Although, the literature also indicates that the VAWT has entered a Renaissance period whereby the VAWT is now being adopted for the offshore floating wind turbine industry....
19 février 2020
Lancement d'un projet de recherche franco-allemand sur l'énergie éolienne en eaux profondes
Lancement d'un projet de recherche franco-allemand sur l'énergie éolienne en eaux profondes
Le ministère fédéral allemand de l'économie et de l'énergie et le regroupement français WEAMEC (WEst Atlantic Marine Energy Community) cofinancent le premier projet de recherche sur l'énergie éolienne flottante. Ce projet, nommé Vamos (pour Validation, mesure et optimisation de l'énergie éolienne flottante) devra permettre d'accroître les connaissances sur cette technique grâce à une campagne de mesure menée sur la première éolienne en mer française, Floatgen. Cette campagne de mesure...
Le ministère fédéral allemand de l'économie et de l'énergie et le regroupement français WEAMEC (WEst Atlantic Marine Energy Community) cofinancent le premier projet de recherche sur l'énergie éolienne flottante. Ce projet, nommé Vamos (pour Validation, mesure et optimisation de l'énergie éolienne flottante) devra permettre d'accroître les connaissances sur cette technique grâce à une campagne de mesure menée sur la première éolienne en mer française, Floatgen. Cette campagne de mesure...
12 février 2020
The use of X-ray computed tomography for design and process modeling of aerospace composites: A review - ScienceDirect
The use of X-ray computed tomography for design and process modeling of aerospace composites: A review - ScienceDirect
Optimization of process parameters of major aerospace composites manufacturing techniques is essential for manufacturing high-quality aerospace components. However, studying many parameters through experimental approaches is time-consuming and labor-intensive. Modern X-ray Computed Tomography (XCT) technology has made it possible to monitor the complete manufacturing process “in-situ,” due to its high spatial resolution and very short acquisition time......
Optimization of process parameters of major aerospace composites manufacturing techniques is essential for manufacturing high-quality aerospace components. However, studying many parameters through experimental approaches is time-consuming and labor-intensive. Modern X-ray Computed Tomography (XCT) technology has made it possible to monitor the complete manufacturing process “in-situ,” due to its high spatial resolution and very short acquisition time......
Effects of microvoids on strength of unidirectional fiber-reinforced composite materials - ScienceDirect
Effects of microvoids on strength of unidirectional fiber-reinforced composite materials - ScienceDirect
Microvoids are common defects generated during manufacturing or prolonged services of composites. Depending on the local physical environment, microvoids may form as two types, namely, matrix voids and interfiber voids. These voids are known to have detrimental effects on the load bearing capacity of composites. However, it is relatively unknown the quantitative influence of these voids on the mechanical strength of composites.....
Microvoids are common defects generated during manufacturing or prolonged services of composites. Depending on the local physical environment, microvoids may form as two types, namely, matrix voids and interfiber voids. These voids are known to have detrimental effects on the load bearing capacity of composites. However, it is relatively unknown the quantitative influence of these voids on the mechanical strength of composites.....
10 février 2020
Mechanical properties of discrete BFRP needles reinforced seawater sea-sand concrete-filled GFRP tubular stub columns - ScienceDirect
Mechanical properties of discrete BFRP needles reinforced seawater sea-sand concrete-filled GFRP tubular stub columns - ScienceDirect
This paper proposes a new type of tubular column, which is composed of glass fiber-reinforced polymer (GFRP) tube and discrete basalt fiber-reinforced polymer (BFRP) needles reinforced seawater sea-sand concrete (SWSSC). The discrete BFRP needles, with an aspect ratio of 10.0, were cut from BFRP bar production scrap and mixed into fresh concrete to replace 20% of the coarse aggregates by volume....
This paper proposes a new type of tubular column, which is composed of glass fiber-reinforced polymer (GFRP) tube and discrete basalt fiber-reinforced polymer (BFRP) needles reinforced seawater sea-sand concrete (SWSSC). The discrete BFRP needles, with an aspect ratio of 10.0, were cut from BFRP bar production scrap and mixed into fresh concrete to replace 20% of the coarse aggregates by volume....
Hyperspectral imaging applied for the detection of wind turbine blade damage and icing - ScienceDirect
Hyperspectral imaging applied for the detection of wind turbine blade damage and icing - ScienceDirect
Despite the enhancement in the wind energy sector, the wind turbine industry still faces certain limitations due to some manufacturing and environmental factors. Blades are one of the major components of the wind turbine. During their lifetime, these blades are susceptible to deterioration and normal wear and tear that limit their efficiency and result in higher maintenance costs and longer turbine downtime. Periodic inspections must be performed to detect faults at an early stage and help in mitigating these shortcomings.....
Despite the enhancement in the wind energy sector, the wind turbine industry still faces certain limitations due to some manufacturing and environmental factors. Blades are one of the major components of the wind turbine. During their lifetime, these blades are susceptible to deterioration and normal wear and tear that limit their efficiency and result in higher maintenance costs and longer turbine downtime. Periodic inspections must be performed to detect faults at an early stage and help in mitigating these shortcomings.....
7 février 2020
Réforme de la recherche : vers des jeunes chercheurs toujours plus précaires - Libération
Réforme de la recherche : vers des jeunes chercheurs toujours plus précaires - Libération
En s'attaquant aux spécificités du modèle de la recherche publique française, la future loi de programmation pluriannuelle risque de renforcer les difficultés de début de carrière des jeunes chercheurs, alerte un collectif.
En s'attaquant aux spécificités du modèle de la recherche publique française, la future loi de programmation pluriannuelle risque de renforcer les difficultés de début de carrière des jeunes chercheurs, alerte un collectif.
US20200025178A1 - Wind turbine blade and a wind turbine - Google Patents
US20200025178A1 - Wind turbine blade and a wind turbine - Google Patents
Provided is a wind turbine blade for a wind turbine, the wind turbine blade including a support element having first fibers being electrically conductive, and a fiber material having second fibers being electrically conductive, wherein the fiber material has a free portion and an overlapping portion which is at least partially attached and electrically connected to the support element, wherein an extension direction of the second fibers changes along an extension path of the second fibers, wherein a first angle is provided between the second fibers in the overlapping portion and the first fibers, wherein a second angle is provided between the second fibers in the free portion and the first fibers, and wherein the second angle is larger than the first angle.
Provided is a wind turbine blade for a wind turbine, the wind turbine blade including a support element having first fibers being electrically conductive, and a fiber material having second fibers being electrically conductive, wherein the fiber material has a free portion and an overlapping portion which is at least partially attached and electrically connected to the support element, wherein an extension direction of the second fibers changes along an extension path of the second fibers, wherein a first angle is provided between the second fibers in the overlapping portion and the first fibers, wherein a second angle is provided between the second fibers in the free portion and the first fibers, and wherein the second angle is larger than the first angle.
5 février 2020
A review of structural health monitoring methods for composite materials - ScienceDirect
A review of structural health monitoring methods for composite materials - ScienceDirect
Health monitoring techniques with regard to structural assessment has the attention of researchers worldwide owing to their potential in providing crucial information regarding structural damage and the reassurance of expected performance of critical infrastructures during service. These must operate with optimal system performance and against natural hazards. Such systems utilize state of the art sensing networks. The still high costs linked to the application of Structural Health Monitoring (SHM) does dictate that they are mainly incorporated to structures of high value. It can be expected that composite materials are increasingly utilized in such applications. The main difficulty posed by their use is that their failure mechanisms are much more complex......
Health monitoring techniques with regard to structural assessment has the attention of researchers worldwide owing to their potential in providing crucial information regarding structural damage and the reassurance of expected performance of critical infrastructures during service. These must operate with optimal system performance and against natural hazards. Such systems utilize state of the art sensing networks. The still high costs linked to the application of Structural Health Monitoring (SHM) does dictate that they are mainly incorporated to structures of high value. It can be expected that composite materials are increasingly utilized in such applications. The main difficulty posed by their use is that their failure mechanisms are much more complex......
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