Energies | Free Full-Text | Numerical Simulation of Aging by Water-Trees of XPLE Insulator Used in a Single Hi-Voltage Phase of Smart Composite Power Cables for Offshore Farms

Energies | Free Full-Text | Numerical Simulation of Aging by Water-Trees of XPLE Insulator Used in a Single Hi-Voltage Phase of Smart Composite Power Cables for Offshore Farms

Submarine power cables are expected to last 20 years without maintenance to be considered technologically reliable enough and economically beneficial. One of the main issues facing this target is the development of what is called commonly water-trees (nanometer-sized flaws filled with residual humidity), that form within XLPE (cross-linked Polyethylene) insulators and then migrate towards copper, thus leading to its corrosion and further to possible shut-down. Water trees are resulting from the coalescence of nanovoids filled with residual humidity that migrate towards copper under the combined effects of electrical forces and plastic deformation. The nanovoids are originated during manufacturing, shipping, handling and embedding in deep seas. The formation of these nanovoids leads to the degradation of the service lifetime of submarine power cables. Current research is intended to come up with a way to go a little further towards the generalization of coalescence of n nanovoids. In the perspective of multi-physics modeling, a preliminary 3D finite element model was built. Although water voids are distributed randomly inside XLPE, in this study, two extreme cases where the voids are present parallel and perpendicular to the copper surface, were considered for simplification. This will enable checking the electric field effect on neighbouring voids, in both cases as well as the influence of the proximity of the conductor on the plasticity of voids, that further leads to their coalescence. It is worthwhile to note that assessing water-trees formation and propagation through an experimental campaign of ageing tests may extend over decades. It would therefore be an exceptional opportunity to be able to get insight into this mechanism through numerical modeling that needs a much shorter time. The premilinary model suggested is expected to be extended in the future so that to include more variables (distribution and shapes of nano-voids, water pressure, molecular modeling, electric discharge. View Full-Text

In-situ condition monitoring of wind turbine blades: A critical and systematic review of techniques, challenges, and futures - ScienceDirect

In-situ condition monitoring of wind turbine blades: A critical and systematic review of techniques, challenges, and futures - ScienceDirect

Blades are critical components in wind turbines (WTs) for power generation, and condition monitoring (CM) of WT blades is a crucial and challenging issue under operating conditions. Several methods have been developed to assess blade health status, and some of them have the potential to achieve in-situ CM. Nevertheless, there is a lack of critical and comprehensive survey concerning CM techniques for operational WT blades, as well as unsolved problems and research prospects. In this paper, typical causes and types of blade damage that deserve to be considered during the running time are presented. Besides, in-situ CM techniques for WT blades are reviewed in terms of four sub-targets: damage detection, localization, classification, and evaluation. Further, the investigation and development timeline of in-situ CM methods and types of damage that have been verified to be recognizable in field tests are concluded for the first time. The paper ends with discussions on research impediments and prospects that indicate promising development tendencies.

On the Effect of Dielectric Breakdown in UD CFRPs Subjected to Lightning Strike Using an Experimentally Validated Model | SpringerLink

On the Effect of Dielectric Breakdown in UD CFRPs Subjected to Lightning Strike Using an Experimentally Validated Model | SpringerLink

To meet worldwide increases in energy demands Wind Turbine (WT) manufacturers are producing turbines with longer blades to generate more electrical energy. To lightweight these blades, Carbon Fibre Reinforced Polymers (CFRP) have been introduced in load carrying structures such as the WT blade sparcaps. The introduction of CFRPs presents new challenges in integrating protection from lightning strikes. The semi-conductive nature of CFRPs adds an additional electrical path to ground, and the anisotropic nature of the material properties, in particular the thermal and electrical conductivities, creates large amounts of resistive heating. The aim of this paper is to develop and validate a modelling approach to predict lightning damage in unidirectional (UD) CFRP materials. The proposed model uses an approximate approach that includes the electric field dependency to simulate dielectric breakdown. The model predictions are validated against experimental data and observations obtained from simulated direct lightning strike tests conducted on UD CFRP laminates. A comparison between the experimental results and the proposed model shows good ability to accurately predict the shape, volume, and depth of the inflicted damage. Furthermore, the proposed model is benchmarked against conventional damage models reported in literature, and a clear improvement of the predictive capability is demonstrated, especially with respect to the predicted depth of damage.

In-situ condition monitoring of wind turbine blades: A critical and systematic review of techniques, challenges, and futures - ScienceDirect

In-situ condition monitoring of wind turbine blades: A critical and systematic review of techniques, challenges, and futures - ScienceDirect

Blades are critical components in wind turbines (WTs) for power generation, and condition monitoring (CM) of WT blades is a crucial and challenging issue under operating conditions. Several methods have been developed to assess blade health status, and some of them have the potential to achieve in-situ CM. Nevertheless, there is a lack of critical and comprehensive survey concerning CM techniques for operational WT blades, as well as unsolved problems and research prospects. In this paper, typical causes and types of blade damage that deserve to be considered during the running time are presented. Besides, in-situ CM techniques for WT blades are reviewed in terms of four sub-targets: damage detection, localization, classification, and evaluation. Further, the investigation and development timeline of in-situ CM methods and types of damage that have been verified to be recognizable in field tests are concluded for the first time. The paper ends with discussions on research impediments and prospects that indicate promising development tendencies.

Nemertes:Damage detection using phased array ultrasound and data analysis using artificial intelligence

Nemertes:Damage detection using phased array ultrasound and data analysis using artificial intelligence

The present thesis aims to damage detection of composite aeronautical materials with the phased array ultrasonic testing (PAUT) and data analysis artificial intelligence (AI). First, there is an introduction to the source of the project's inspiration and its scientific significance. Secondly, there is a reference on composite materials, how they are used in aeronautical applications, and the damage mechanisms that take place. At that point, after briefly examining some standard non-destructive testing (NDT) methods, the selected technique and its capabilities are analyzed in depth, both at a theoretical and a scientific level. Next, the concept of Artificial Intelligence, Machine and Deep Learning is introduced, and the methods of "Supervised Learning" and "Unsupervised Learning" are analyzed in detail. More specifically, the clustering algorithm K-means and the Deep Neural Networks (DNNs) with emphasis on the convolutional neural networks (CNNs) are examined. Then, after a literature review of the scientific efforts made concerning the analysis of ultrasound data using artificial intelligence, the description of the project is presented, followed by the forming of the research questions and the methodology that was applied in the following research. Subsequently, the experimental setup (materials, equipment), the way of capturing the data, and the pre-processing and post-processing methods are described. Next, the unsupervised machine learning method used for binary classification for two different composites is analyzed, and the respective results are presented. Furthermore, the supervised deep learning method used for binary classification is analyzed, and the relevant results are presented. Finally, the conclusions that emerge from this analysis are presented, and suggestions for improvement and expansion of the work in the future are reported.

Influence of water absorption on the mechanical behavior of CFRPs manufactured by RTM at room temperature - IOPscience

Influence of water absorption on the mechanical behavior of CFRPs manufactured by RTM at room temperature - IOPscience

Deterioration of the physical properties of fiber-reinforced composites is inevitable under a high temperature and humidity environment. The resin transfer molding (RTM) process for large composite parts is often accompanied by micropore formation, making the composite more sensitive to water absorption. In this study, carbon fiber-reinforced composite specimens were manufactured using the RTM process at room temperature, and their water absorption and mechanical properties were investigated. The water absorption was saturated after about 40 d, and the absorption ratio was higher at 75 °C than at 50 °C. The tensile strength of water-soaked specimens was decreased by 15%, exhibiting interlaminar delamination. However, plasticization of the cured epoxy resin by water increased interlaminar fracture toughness. These results indicate that water absorption accelerated interlaminar cracking initiated by micropore and interfacial failure in toughened resin, especially under low-temperature curing condition.

Impact Behavior of Fibre Reinforced Laminates | SpringerLink

Impact Behavior of Fibre Reinforced Laminates | SpringerLink

Fundamentals of Low Velocity Impact and Related Literature on FRP

Full article: A single three-parameter tilted fibre Bragg grating sensor to monitor the thermosetting composite curing process

Full article: A single three-parameter tilted fibre Bragg grating sensor to monitor the thermosetting composite curing process

he unique sensing features of the tilted Fibre Bragg Grating (TFBG) as a single three-parameter optical sensor are demonstrated in this work, to monitor the manufacturing process of composite materials produced using Vacuum Assisted Resin Transfer Moulding (VARTM) process. Each TFBG sensor can measure simultaneously and separately strain, temperature and refractive index (RI) of the material where the optical fibre is embedded. .....

Introduction to Fibre Reinforced Polymer Composite Laminates | SpringerLink

Introduction to Fibre Reinforced Polymer Composite Laminates | SpringerLink

Fibre reinforced polymer (FRP) composites are becoming well known and finding widespread applications in various industries due to their high specific stiffness and strength compared to conventional metals and their alloys....

Nonlinear modeling analysis of the coupled mechanical strength and stiffness enhancement of composite materials of a Horizontal Axis Wind Turbine Blade (HAWTB) | SpringerLink

Nonlinear modeling analysis of the coupled mechanical strength and stiffness enhancement of composite materials of a Horizontal Axis Wind Turbine Blade (HAWTB) | SpringerLink

In the present paper fatigue behavior of glass/epoxy composite materials under different stress ratios and for various plies orientation angles has been established. Experimental and numerical analysis (Finite Element Method) were performed on various specimens subjected to cyclic tensile tests in order to outline the influences of stress ratios and the stacking sequence ([02/902]s; [902/02]s; [03/90]s; [903/0]s) on glass/epoxy fatigue properties. Static analysis is done experimentally to identify the stress-strain diagrams, strain to failure, Young’s modulus and tensile strength for each stacking sequence. Comparison between experimental and numerical prediction show good agreement. The Results of this investigation can lead us to choose the most optimal stacking sequence for giving boundary conditions to achieve the maximum fatigue life.

Polymers | Free Full-Text | Hygrothermal Damage Monitoring of Composite Adhesive Joint Using the Full Spectral Response of Fiber Bragg Grating Sensors | HTML

Polymers | Free Full-Text | Hygrothermal Damage Monitoring of Composite Adhesive Joint Using the Full Spectral Response of Fiber Bragg Grating Sensors | HTML

Adhesive joints in composite structures are subject to degradation by elevated temperature and moisture. Moisture absorption leads to swelling, plasticization, weakening of the interface, interfacial defects/cracking and reduction in strength. Moisture and material degradation before the formation of defects are not readily revealed by conventional non-destructive examination techniques. Embedded fiber Bragg grating (FBG) sensors can reflect the swelling strain in adhesive joints and offer an economical alternative for on-line monitoring of moisture absorption under hygrothermal aging. Most of the available works relied on the peak shifting phenomenon for sensing. Degradation of adhesive and interfacial defects will lead to non-uniform strain that may chirp the FBG spectrum, causing complications in the peak shifting measurement. It is reasoned that the full spectral responses may be more revealing regarding the joint’s integrity. Studies on this aspect are still lacking. In this work, single-lap joint composite specimens with embedded FBGs are soaked in 60 °C water for 30 days. Spectrum evolution during this period and subsequent tensile and fatigue failure has been studied to shed some light on the possible use of the full spectral response to monitor the development of hygrothermal degradation.

High mechanical strength aluminum foam epoxy resin composite material with superhydrophobic, anticorrosive and wear-resistant surface - ScienceDirect

High mechanical strength aluminum foam epoxy resin composite material with superhydrophobic, anticorrosive and wear-resistant surface - ScienceDirect

By combining organic materials with metal materials, it is easy to obtain new composite materials with excellent properties. Here, an excellent performance aluminum foam epoxy resin composite material (AFE) was prepared by heat-assisted vacuum infusion technology. Owing to the unique foam structure of aluminum foam (AF) and excellent physical and chemical properties of modified epoxy resin, the AFE with an interpenetrating network structure shows excellent wear resistance, bending resistance and corrosion resistance........

Vibration-based damage detection in a wind turbine blade through operational modal analysis under wind excitation - ScienceDirect

Vibration-based damage detection in a wind turbine blade through operational modal analysis under wind excitation - ScienceDirect

In the present study, a vibration-based structural health monitoring (SHM) method for wind turbine blades using Operational Modal Analysis (OMA) is presented. To simulate the dynamic response of the wind turbine, the NREL FAST tool implemented in QBlade was used to calculate the forces in the time domain along the blade in response to the stochastic excitation of the rotating blade by means of the rotationally sampled turbulence spectrum of the wind....

Experimental study on improving the additively manufactured GMAW and TIG beads using FSP - ScienceDirect

Experimental study on improving the additively manufactured GMAW and TIG beads using FSP - ScienceDirect

The beneficial effect of the friction stir processing (FSP) technique for improving the properties of fabricated additive parts through microstructural refinement and repairing of metallurgical defects has shown its ability to be integrated into a hybrid additive manufacturing system. In the present work, conventional GMAW and TIG-based additive manufacturing processes were further post-processed with friction stir process (FSP)....

Lightweight Metallic Nanocomposites in Energy Applications | SpringerLink

Lightweight Metallic Nanocomposites in Energy Applications | SpringerLink

The demand from consumers leads to the contemporary design of cars with lightweight components. The renewable energy industry is focused on the design of an optimized shape of the components to increase electricity production and deter the usage of fossil fuels. Composite materials like, metal matrix composites (MMCs) are preferred over the use of pure metals and alloys due to their enhanced high strength to weight ratio and lightweight properties. ...

A life cycle assessment comparison of materials for a tidal stream turbine blade - ScienceDirect

A life cycle assessment comparison of materials for a tidal stream turbine blade - ScienceDirect

Electricity generated from tidal streams via underwater turbines has significantly lower greenhouse gas emissions than fossil-fuel derived electricity. However, tidal stream turbine blades are conventionally manufactured from non-recyclable reinforced polymer composite materials. Tidal stream capacity is forecast to be over 1GW by 2030, which using current methods will ultimately produce around 6000 tonnes of non-recyclable blade waste. ...

A life cycle assessment comparison of materials for a tidal stream turbine blade - ScienceDirect

A life cycle assessment comparison of materials for a tidal stream turbine blade - ScienceDirect

Electricity generated from tidal streams via underwater turbines has significantly lower greenhouse gas emissions than fossil-fuel derived electricity. However, tidal stream turbine blades are conventionally manufactured from non-recyclable reinforced polymer composite materials. ....

Effects of submarine-cable types ... preview & related info | Mendeley

Effects of submarine-cable types ... preview & related info | Mendeley

Submarine cables are indispensable for offshore wind farms (OWFs) connected to a power grid. The submarine cable can cause certain degrees of impact on the system performance due to its different lengths, characteristics, electrical parameters, etc. This paper employs the power-system simulation software of Power System Simulator for Engineering (PSS/E) for modeling a future-scheduled OWF, i.e., a large-scale doubly-fed induction generator-based OWF of 200 MW, connected to Jang-Bin distribution substation of Taiwan Power System through five feeders, five circuit breakers, two step-up power transformers, a commercial submarine cable, and an underground cable. This paper simulates and compares the electrical quantities of the studied OWF with different operating capacities under various lengths of three types of commercial submarine cable. The transient surge peak voltages at the common bus of the OWF and the bus of Jang-Bin distribution substation subject to the switching of one of the five circuit breakers of the studied OWF under different lengths of the three types of commercial submarine cable are also compared using the power-system simulation software of ATPDraw in Alternative Transients Program (ATP) version of Electromagnetic Transients Program (EMTP).

J. Compos. Sci. | Free Full-Text | A Cost Model for 3D Woven Preforms

J. Compos. Sci. | Free Full-Text | A Cost Model for 3D Woven Preforms

Lack of cost information is a barrier to acceptance of 3D woven preforms as reinforcements for composite materials, compared with 2D preforms. A parametric, resource-based technical cost model (TCM) was developed for 3D woven preforms based on a novel relationship equating manufacturing time and 3D preform complexity. Manufacturing time, and therefore cost, was found to scale with complexity for seventeen bespoke manufactured 3D preforms. Two sub-models were derived for a Weavebird loom and a Jacquard loom. For each loom, there was a strong correlation between preform complexity and manufacturing time. For a large, highly complex preform, the Jacquard loom is more efficient, so preform cost will be much lower than for the Weavebird. Provided production is continuous, learning, either by human agency or an autonomous loom control algorithm, can reduce preform cost for one or both looms to a commercially acceptable level. The TCM cost model framework could incorporate appropriate learning curves with digital twin/multi-variate analysis so that cost per preform of bespoke 3D woven fabrics for customised products with low production rates may be predicted with greater accuracy. A more accurate model could highlight resources such as tooling, labour and material for targeted cost reduction. View Full-Text

Using recycled waste glass fiber reinforced polymer (GFRP) as filler to improve the performance of asphalt mastics - ScienceDirect

Using recycled waste glass fiber reinforced polymer (GFRP) as filler to improve the performance of asphalt mastics - ScienceDirect

Fiber Reinforced Polymer (FRP), especially glass fiber reinforced polymer (GFRP), has been widely used in construction, navigation, transportation, and chemical engineering due to its excellent physical and mechanical properties....