Progressive Failure Analysis for 5MW-Class Wind Turbine Composite Blades with Debonding Damage based on CZM Method

Simulation of buckling-driven progressive damage in composite wind turbine blade under extreme wind loads

Wind turbine blades are prone to icing under extreme working conditions, which will reduce the efficiency of wind power generation and seriously affect the service life of wind power system. Therefore, the anti-icing problem of wind turbine blades has become one of the hot topics in wind power technology research. It is of great practical significance to develop anti-icing/deicing technology for wind turbine blades for the safe and effective operation of wind power. In this paper, the numerical simulation optimization design for composite material wind turbine blades anti-/deicing component was studied, and the orthogonal optimization method was employed to optimize the parameters of the wind turbine blade to prevent ice formation. The optimization group parameter group is obtained. Through the wind turbine blade temperature distribution simulation, the correctness of the optimization results of the composite material anti-/deicing component was analyzed. The purpose of this paper is to optimize the heat transfer of anti-/deicing component for composite material wind turbine blade, and lay a theoretical and technical foundation for effectively solving the problem of wind turbine blade icing, which proposing a new composite wind turbine blade anti-/deicing scheme.

An effect assessment and prediction method of ultrasonic de-icing for composite wind turbine blades

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.

Structural validation of a thermoplastic composite wind turbine blade with comparison to a thermoset composite blade

One of the main global engineering challenges for the wind energy sector is to develop efficient wind turbines with high fatigue life. Large wind turbine blades made out of polymer composites elevate specific stiffness, strength and good fatigue performance. However, large composite structures are prone to defects such as delamination and adhesive failure, which can lead to crack initiation and propagation under cyclic stress. The presented study covers an overview of the manufacturing defects of wind turbine blades, in-service damages and the available inspection techniques that are used to identify defects in wind turbine blades. In this paper, the detection capabilities and performance of visual inspection, acoustic emissions, ultrasonic testing and X-ray inspection have been reviewed. The paper describes the importance of developing quality control guidelines for wind turbine manufacturing sectors based on standard inspection methods.

Application of videometric technique to deformation measurement for large-scale composite wind turbine blade

Abstract. The increasing demand for renewable energy has led to the development of several wind energy projects. A rising concern is the aging of these structures that must keep their serviceability and integrity for a long lifetime. That is why recent studies have focused on monitoring systems for data extraction based on accelerometers, fiber optic sensors, and piezoelectric sensors among many other sensing technologies. One of the most promising approaches is the use of fiber-Bragg-grating-based systems taking advantage of their proven benefits such as electromagnetic immunity, low size and weight, and ability to embed numerous sensors in a single optical fiber line. However, most of the reported studies have addressed the operational assessment of the acquisition systems without further deepening the exploitation of the acquired data for structural health monitoring purposes. This work aims to data exploitation of strain measurements acquired by simulated fiber Bragg gratings (FBG) for damage identification in wind turbine blades made of composite materials. A FEM model of a 2.5-meter-long wind turbine blade with 40 virtual FBGs strain sensors was used to obtain strain data under normal operational conditions. Then, strain measurements were calculated after defining several damages to the blade. Once the data were obtained, different data processing techniques following the pattern recognition paradigm were tested comparing their performance in terms of accuracy. The results will contribute to designing real-time automatic damage identification systems using FBGs strain sensors for composite wind turbine blades.

Some interesting studies are made in this paper on the life management of a composite wind turbine blade. It presents the details of finite element modeling and validation, blade response under service loading conditions, power coefficient evaluation for the optimum design parameters of the blade configuration, development of failure envelope and fatigue life estimations. Finite element analysis results are found to be in good agreement with existing test results on a typical composite blade configuration. The failure envelope generated from the present modified failure criterion correlates well with the test results on different composite materials. The procedure adopted in this paper can be utilized for optimum design of large size composite wind turbine blades.

Structural health monitoring (SHM) of wind turbines is critical for maintaining continuous operation, minimizing maintenance expenses, and maximizing energy production. Recent advancements in sensor technology have made it possible to gather extensive ultrasonic guided wave (UGW) data from wind turbine components, enabling assessment of their structural integrity. This research examines UGW-based nondestructive evaluation techniques applied to composite wind turbine blades under varied structural conditions using experimental and numerical analysis. UGW signals recorded through an actuator-sensor network contain essential information on blade health. A Random Forest model is used to predict changes in A0 and S0 mode group velocities and amplitudes due to erosion/corrosion, longitudinal debonding, and transverse debonding across damage sizes ranging from 0 to 40 mm. To assess prediction reliability, 95% confidence intervals are included as uncertainty bands; narrower bands suggest higher confidence, while a wider band indicates greater uncertainty. Sensitivity analysis highlights the impact of damage size and type on UGW signal properties, supporting improved predictions. This study underscores the potential of UGW-based SHM to enhance wind turbine reliability and promote sustainable energy generation.

Simulation and testing to develop an Intelligent Blade for wind turbines is presented in this paper. The concept blade has an integrated sensor system for structural health monitoring that will continuously monitor the condition of the blade, warn of initiating damage, and provide instant information that can be used to regulate loading in the blade to reduce or prevent fatigue damage. This can decrease maintenance costs, improve the reliability of wind power, and may make wind energy more affordable. Modeling and simulation of wave propagation in a plate was performed and different configurations of active and passive piezoceramic sensor systems were evaluated and shown to be capable of measuring propagating strain waves and identifying damage. A preliminary experiment to determine the damage detection capability of the sensors was done during a static test of a wind turbine blade. The stress wave propagation characteristics of the blade were monitored as the load level on the blade was increased until blade failure occurred. The effects of the blade stress and curvature on wave propagation need further study, but the results indicate that the technique has the potential for the detection of evolving damage in composite wind turbine blades.

Structural integrity of offshore wind turbine blade under extreme gust and normal operating conditions

Currently, wind turbine blades are manufactured from a combination of glass and/or carbon fiber composite materials with a thermoset resin such as epoxy, which requires energy-intensive and expensive heating processes to cure. Newly developed in-situ polymerizing thermoplastic resin systems for composite wind turbine blades polymerize at room temperature, eliminating the heating process and significantly reducing the blade manufacturing cycle time and embodied energy, which in turn reduces costs. Thermoplastic materials can also be thermally welded, eliminating the need for adhesive bonds between blade components and increasing the overall strength and reliability of the blades. As well, thermoplastic materials enable end-oflife blade recycling by reheating and decomposing the materials, which is a limitation of existing blade technology. This paper presents a manufacturing demonstration for a 9-m-long thermoplastic composite wind turbine blade. This blade was constructed in the Composites Manufacturing Education and Technology facility at the National Wind Technology Center at the National Renewable Energy Laboratory (NREL) using a vacuumassisted resin transfer molding process. Johns Manville fiberglass and an Arkema thermoplastic resin called Elium were used. Additional materials included Armacellrecycled polyethylene terephthalate foam from Creative Foam and low-cost carbonfiber pultruded spar caps (manufactured in collaboration with NREL, Oak Ridge National Laboratory, Huntsman, Strongwell, and Chomarat). This paper highlights the development of the thermoplastic resin formulations, including an additive designed to control the peak exothermic temperatures. Infusion and cure times of less than 3 hours are also demonstrated, highlighting the efficiency and energy savings associated with manufacturing thermoplastic composite blades.

<div class="section abstract"><div class="htmlview paragraph">Wind energy is clean and renewable source of energy that is an attractive alternative to non-conventional sources of energy. Due to rapid increase in global energy requirements, this form of energy is gaining its share of importance. Unlike nuclear power or tar sand oils, wind energy does not leave a long-term toxic legacy. Using MATLAB algorithms, multi-optimization of wind turbine design can be achieved. Therefore, an aerodynamic mathematical model is developed to obtain the optimal chord length and twist angle distribution along the blade span. Further, a promising generic blade design is used to initialize a detailed structure optimization wherein leading edge panel (LEP), Spar cap, Shear web, Trailing edge panel (TEP) reinforcement are sized using composite laminates so that the blade is according to the intended design standard. Initially blade airfoils are analyzed on 2D platform and then the results are used to construct 3D model of Horizontal Axis Wind Turbine (HAWT) blade. The 3D designing of composite HAWT blade is done by CAD software Solidworks v16.0 through different airfoil for root, primary and tip and optimization of material thickness and overall mass reduction by the use of composite material through optimization of skin thickness of wind turbine is achieved. This paper is focused on the importance of structural design for optimization of HAWT blade. On further analysis, an increase in aerodynamic power generation as well as marked improvements in overall blade deformation and tip deflection characteristics is observed.</div></div>

Lightning strike damage accounts for one of the greatest number of losses for wind turbines and is among the top two most frequently reported causes of loss in the wind energy insurance claims in the United States (USA). The Midwest and Texas area, where the most wind power is produced in the USA, are subjected to high lightning flash activities. Also, since multi-MW wind turbines are pursued in the recent years, the corresponding wind turbine blades are becoming longer than before. The longer the blade, the greater its risk of being hit by the lightning. An increase in the blade size and extensive use of composite materials lead to significant challenges in the development of lightning strike protection systems for wind turbine blades, and a better understanding of the response of polymer-matrix composites to a lightning strike is essential for such developments. In this chapter, the basic physics of lightning strike and lightning interaction with the wind turbines are discussed. The common lightning strike protections for wind turbines as well as typical lightning damage mechanisms are introduced. In addition, the analytical and finite element numerical approach of predicting the lightning strike-induced electric field is presented. The obtained electric fields are used to estimate the lightning dielectric breakdown of the composite wind turbine blade. Furthermore, the other forms of lightning damage for wind turbine blades, including the rapid heat transfer, thermal ablation, and delamination, are also discussed. Future recommendations for such lightning research of wind turbines are provided.