Wind Turbine Blade Manufacturing Research Articles

Parameter estimation of epoxy resin cure kinetics by dynamics DSC data

AbstractThis study focused on determining the curing kinetic parameters of amine‐epoxy resin by performing dynamic DSC tests. The Kissinger and Crane equations were used to determine the activation energy, the pre‐exponential factor, and the reaction order as kinetic parameters for curing. The Ozawa equation was also used to determine the activation energy that changes at different levels of cure during the reaction. The average activation energy obtained by the Ozawa method was compared with the Kissinger activation energy. In addition, the T‐β extrapolation method was used to determine the optimum curing temperature. The kinetic parameters obtained from the Kissinger and Crane equations were used in the nth‐order kinetic model to predict the degree of cure at a given time and temperature. The linear regression fitting method was used in Minitab software to determine the curing parameters. The results were evaluated based on the fitting parameters. This study provides a theoretical basis for the curing mechanisms of epoxy matrix fiber composites used in the manufacture of wind turbine blades.

Parametric study on the effect of material properties, tool geometry, and tolerances on preform quality in wind turbine blade manufacturing

Increasing throughput in wind turbine blade production can be achieved by separately manufacturing pre-shaped binder-stabilised dry preforms, and subsequently placing them in the blade mould. To avoid manufacturing defects, a trade-off between the formability and the handleability of the preform is necessary. In this paper, an experimentally validated preform model is used to study how variations in material properties, tool geometry, and placement tolerances influence defect generation. The results from three studies are presented. In the first study, a preform is formed over a ramp transition with variations in geometry. The results from this study indicate that a short ramp promotes transverse shearing of the preform. In the second study, the material properties of the preform are varied. The results indicate that a high mode I cohesive law of the binder and a high bending stiffness of the fabric promote transverse shearing and remove wrinkles. In the last study, placement tolerances for a pre-shaped preform are studied. The results show that if the preform can shear between the preform edge and the tool edge, it can conform to the mould even with large placement offsets. Process engineers and blade designers can readily use these results to help reduce forming-induced wrinkles.

The Petiole of the Miriti Palm: A sustainable material for wind turbine blades?

The Miriti Palm (Mauritia flexuosa) grows abundantly in the Amazon Region of Brazil. The petiole (PMP) that supports the leaves, has a density of about one-half of Balsa wood (BW), which is used in the manufacture of wind turbine blades. A further possible advantage of PMP is that harvesting does not kill the palm tree, in contrast to the harvesting of BW. Because the mechanical properties of PMP have not been measured, we determined the shear and tensile properties of 16 samples of PMP and BW to allow a preliminary assessment of PMP as a possible material for blades. The absolute shear and tensile strengths for BW are higher, but specific properties (normalized by the density) are similar and can favour PMP. Direct substitution of BW by PMP would reduce the weight of a typical large blade by around 2%.

Lessons learned from the sustainable recycling process of a wind blade made with a new thermoplastic resin

The use of thermoplastic resins instead of thermoset ones in wind turbine blade manufacturing is being investigated and validated in a global scale due to some theoretical improvements such as costs saving during production, shorter cycle’s time and a better circular recovery of the raw materials at the End of Life. The initial objective of this paper was to manufacture and test a small wind turbine blade (SWTB) glass fiber-reinforced thermoplastic (GFRT) resin composites, recycle it, and use the products obtained from the recycling process (fibers and resin) to remanufacture a new thermoplastic SWTB. But loss of fibers higher than estimated during the recycling process made to get away from the original aim of testing both blades (1st and 2nd recyclable blades). At least, some lessons learned were obtained to improve future developments. Nevertheless, this study provides an example of how to recycle a small WT blade and to remanufacture it using the same raw materials.

Toolpath generation for automated wind turbine blade finishing operations

AbstractIncorporating automation into wind turbine blade manufacturing is important for reducing costs to meet current offshore wind energy production goals in the United States. This work proposes a process for automating three operations in wind blade manufacturing: trimming to remove flashing left over after bonding two blade skins together, grinding to produce a desired leading‐edge shape, and sanding to prepare the blade for bonding overlamination or adding paint to the surface. The majority of this work focuses on the toolpath generation. The algorithms were tested on a 5‐m blade section, and the results were analyzed in terms of operation speed and accuracy. Finally, future work is discussed to improve the performance of the system.

3D Printing for wind turbine blade manufacturing: a review of materials, design optimization, and challenges

3D Printing for wind turbine blade manufacturing: a review of materials, design optimization, and challenges

Exploration of bioinspired small wind turbine blade manufacturing alternatives: Defining materials and processes

In the domain of Horizontal Wind Turbines, the key role of blade material and process selection is discussed. Existing methodologies and manual manufacturing processes, while addressing this issue, suffer from complexity and environmental drawbacks. To mitigate these issues, the study introduces a comprehensive methodology for the selection, implementation, testing and analysis of materials and processes for small blade construction, taking into account various constraints. The research conducts a thorough exploration of manufacturing processes, considering factors such as time, affordability, machine accessibility, repeatability, elements to be manufactured, and adaptability to complex surfaces. A systematic comparison of materials and processes, along with proposed filtering methods, reveals that rotomolding/polyurethane casting exhibits superior performance due to improved energy capture and inertia. The study underscores the importance of careful material and process selection to optimize blade efficiency and highlights the need for further research to address mechanical, economic, environmental, scalability, and material advancement challenges.

Improved soil moisture, nutrients, and economic benefits using plastic mulchs in balsa-based agroforestry systems.

The manufacture of wind turbine blades generally uses balsa wood as the base materials, and it is crucial to explore new regions for cultivating balsa trees to achieve carbon neutrality in the future. Xishuangbanna may be China's only area with a tropical climate suitable for the large-scale planting of balsa trees. The present study investigated the key soil elements influencing the growth of balsa plantations and the effects of different cultivation practices on soil environments and economic benefits in Xishuangbanna, China. We found that the height of balsa stems after growing 4years reached 5.8m; the increment of diameter at breast height (DBH) reached 27.7cm and volume of balsa stems reached 196.0 m3ha-1 in Xishuangbanna of China. It is of the utmost importance to improve the contents of soil exchangeable magnesium (Mg) and available phosphorus (P) for the growth of balsa trees, and exchangeable aluminium (Al) inhibited the growth of balsa trees. The practice of plastic film mulching not only improved soil moisture in the 40‒100-cm soil layer in the dry season and in the 0-60-cm soil layer in the rainy season but also enhanced soil nitrate nitrogen when compared with no plastic-mulching practice in balsa plantations. The comprehensive economic benefits of balsa/coriander/ginger/taro plantations were significantly improved by implementing plastic film mulching, as compared to balsa plantations. We conclude that balsa tree can be cultivated in Xishuangbanna, China, and its successful cultivation provides opportunities for China's wind power development.

Strategic Quality Control Measures to Reduce Defects in Composite Wind Turbine Blades

Wind turbine blades are made from polymer composites to provide high specific stiffness, strength, and good fatigue performance. However, large composite structures are prone to manufacturing defects such as delamination and adhesive failure, which can lead to crack initiation and propagation under cyclic stresses. National renewable energy laboratory, USA statistics shows 26% fatigue failure modes are created by laminate and adhesive joint manufacturing errors. A range of manufacturing processes are used to construct wind turbine blades. Resin transfer infusion is one of the most frequently used methods in wind turbine blade manufacturing industry. This paper provides assessment on regular defects occurring in resin transfer infusion processes which lead to poor quality in wind turbine blade manufacture. The assessment is based on the existing literature and the know-how generated from manufacturing wind turbine blades. The effect of these defects for the structural failure of composite wind turbine blades is analysed. The final phase of the study provides manufacturing quality control measures which can be implemented to improve the composite wind turbine blade manufacturing process.

Characterisation of the transverse shear behaviour of binder-stabilised preforms for wind turbine blade manufacturing

Binder-stabilised preforms are being used increasingly in the production of large composite structures, such as wind turbine blades, to increase the throughput. The transverse shear behaviour of the preform is one of the driving factors in the development of wrinkling during manufacturing but has not previously been characterised in the literature. In this paper, the combined intra- and inter-ply deformations during transverse shearing of a binder-stabilised preforms for wind turbine blade manufacturing are characterised by a new test methodology. The results from two experimental campaigns are presented. In the first campaign, preform specimens are subjected to monotonic loading to a nominal transverse shear angle of 18.0° with three different deformation rates. The results show an increase in maximum load levels with greater deformation rates. In the second campaign, preform specimens are subjected to deformation-controlled cyclic loading with two different deformation amplitudes corresponding to a nominal transverse shear angle of 1.5° and 12.2°, respectively. During cyclic loading, permanent deformation is observed in all preform specimens and the maximum load at the 19th cycle is reduced to 48% of the maximum load at the first cycle for the tests with deformation amplitudes of 12.2°. The data generated in this study is freely available at https://doi.org/10.17632/9m78sg3zwn.1.

Challenges in permeability characterisation for modelling the manufacture of wind turbine blades

As wind turbine blades continue to increase in size, and market competition grows, lean manufacturing has become even more important for OEMs. The rapid development of new blade designs, with greater performance, and reduced production waste are driving the need for predictive modelling of the blade infusion process. Such simulations are reliant upon Darcy’s Law for the description of fluid flow through porous materials and therefore depend greatly on the permeability properties of the blade preform materials. The characterisation of fabric permeability, although unstandardised, has been well studied in recent years as the focus of numerous international benchmarking efforts. However, the effective permeability properties of infusion consumables, core materials, and pre-cast elements are not so well defined or validated, despite their significance on infusion behaviour. Hence, the great variety of preform materials, stacking configurations, geometric features, and transition regions in wind turbine blades present considerable challenges in terms of permeability characterisation and subsequent modelling. This article reviews some of the challenges, opportunities, and alternatives for characterising permeability in common blade preform materials, along with examples of how these properties have been applied in numerical models to better simulate the resin infusion manufacturing process for wind turbine blades.

Cure characterisation and prediction of thermosetting epoxy for wind turbine blade manufacturing

In the wind industry, the increasing length of turbine blades and the use of thick composite sections make it vital to understand the thermoset and the underlying curing process. In this study, the curing of a specific thermoset epoxy for application in wind turbine blades is characterised by differential scanning calorimetry. The thermoset is analysed under dynamic and isothermal conditions to determine the complex cure behaviour under these various conditions. The data is fitted to determine firstly; the cure kinetics of the material through a kinetic model. Secondly; the phenomenon of the glass transition temperature Tg is studied to predict the development of Tg as a function of the degree of cure. Thirdly, a Diffusion-Kinetic model was utilised to make more accurate cure predictions based on the interaction between kinetic chemical reactions and diffusion control affecting the reaction rate through the incorporation of the glass transition temperature. A simple experimental framework for validating the diffusion-kinetic model was used to make a final validation of the model predictions on a larger scale. A set of final parameters is presented for application in a full diffusion-kinetic model for cure predictions and simulations beyond this study.

Simulation Study of the Effect of Wind Speed and Material Type on the Mechanical Properties of Vertical Axis Wind Turbine Blades

Wind energy is a clean and fast-growing renewable energy source that can be harnessed using wind turbines. In a Vertical Axis Wind Turbine (VAWT), turbine blades are a crucial factor, and their fiasco leads to wind turbine failure. However, references to VAWT blade structural analysis are very limited. Therefore, the study was carried out to determine the material with the lowest degree of deformation without structural failure. The finding could be used as a recommendation in the material selection of Savonius type vertical axis wind turbine blades. The study used materials such as aluminum, stainless steel, and fiberglass. The analysis was carried out by simulating using ANSYS software. Computational Fluid Dynamics (CFD) was used for determining the loading by providing speed variations at 3 m/s, 4 m/s, 5 m/s, and 6 m/s. The Finite Element Analysis (FEA) method was applied to analyze the structure, which shows the results of total deformation, equivalent stress, and safety factor. The total deformation results from the aluminum blades showed values of 109.55 mm, 190.73 mm, 299.25 mm, and 425.39 mm. The safety factor values of 4.4049, 2.5166, 1.5647, and 1.1348 revealed that it was also technically safe. Aluminum material can be recommended to be used in the manufacture of Savonius type vertical axis wind turbine blades because of its low price, lightweight, corrosion resistance, and sufficient durability, as revealed from the results of total deformation and safety factor values.

Structural performance analysis of hemp fiber-reinforced hybrid composites in wind turbine blade manufacturing

The modern environmental policy encourages the development of green energy industries, including wind turbine industry. The scientific community tests the possibility of introducing and using, in the different structures of the wind turbine, reliable and eco-friendly materials.The objective of this study was to design an optimal wind turbine blade using hemp fibers as composites reinforcement. To do so, first, the blade design was defined using Blade Element Momentum (BEM) theory and done using Catia V5®. Then, a finite element model of the blade was created by PATRAN® software and analyzed by NASTRAN® software. Finally, based on analyses of various scenarios, the choice of the material under the static load was reported.The optimal scenario based on the insertion of hemp fibers showed a 20% reduction in weight between the old and new model, and a cost reduction of approximately 30%, while still conforming to blade design standards.

Towards assessment of fatigue damage in composite laminates using thermoelastic stress analysis

A new approach that utilizes Thermoelastic Stress Analysis (TSA) is proposed to investigate fatigue-induced material degradation in laminated fiber-reinforced polymer composites (FRP). The proposed model accounts for non-adiabatic conditions, the effects of the material temperature on the material properties, and the effects of stiffness material degradation due to damage. Experimental data from the literature is used to validate the part of the model that simulates the heat transfer, which results in a non-adiabatic contribution to the thermoelastic response. Specimens made from E-glass FRP representative of those used in wind turbine blade manufacture are used in the study, which make a challenging proposition for TSA. The evolution of tunneling cracks caused by cyclic loading causes stiffness degradation and changes in the thermoelastic response. The added features of the proposed model are shown to be necessary to interpret the thermoelastic response. The model improves correspondence with experimental data compared to previous TSA methods. Hence a generalized framework is proposed for incorporating the mechanisms that affect the thermoelastic response as materials degrade due to fatigue loading.

Recycling of polymer-matrix composites used in the aerospace industry-A comprehensive review

Polymer matrix composites are in high demand in many industries, including wind turbine blade manufacturing, pressure vessel manufacturing, and aerospace. In order to reduce unsustainable deconstruction that harms the environment and the potential litigation risk associated with the reintroduction of uncertified salvaged components to the aviation market, flight vehicle manufacturers have started collaborating with the recycling sector. Polymer matrix composites have strong mechanical qualities that make them appealing for a wide range of applications, but because of their heterogeneous nature, recovering composite waste is challenging. This paper compares various polymer-matrix composites (PMC) waste recycling techniques utilizing a multi-criteria decision-making approach and a literature study (MCDA). PMC waste recycling is becoming more popular, much work needs to be done to build a widespread, efficient system that is both financially sustainable and produces the highest-quality recovered materials.

Infusible thermoplastic composites for wind turbine blade manufacturing: Static characterization of thermoplastic laminates under ambient conditions

The necessity for recyclable materials in wind energy applications has fueled research in glass fiber reinforced thermoplastic composites to replace their thermoset counterparts. Toward demonstrating that infusible acrylic resins can replace epoxy based composite systems in wind blade manufacturing, comprehensive static test protocols were performed, and the resulting data are presented. Specifically, unidirectional and biaxial (±45) continuous E-glass reinforced thermoplastic and epoxy laminates were prepared in four and eight ply laminates. Physical properties were characterized including density, fiber volume fraction, and glass transition temperatures, together with mechanical properties for tensile, compression, and shear responses. Comprehensive evaluation of these data supports infusible acrylic thermoplastic resin systems as viable alternative prospects to replace epoxies in E-glass reinforced wind blades as verified by comparable results for both composite systems.

Combined effect of fiber hybridization and matrix modification on mechanical properties of polymer composites

Glass/carbon fiber reinforced hybrid composites are great candidates for wind turbine blade manufacturers to make larger blades. Variation of stacking sequences ensures design freedom to the composite engineers to optimize the composite structure's mechanical performance. On the other hand, matrix modification of polymer composites with nanoparticles is also of interest to introduce multifunctional properties. This research aims to scrutinize the influence of simultaneous fiber hybridization and matrix modification on polymer composites’ tensile, flexural, and low-velocity impact properties. Hybrid glass/carbon epoxy composites and hybrid glass/carbon/multi-walled carbon nanotube (MWCNT) multiscale polymer composites of stacking sequences [GCGCGC]S, [CGCGCG]S, and [G6C6] were manufactured. Fiber hybridization dramatically improved tensile strength between 51% and 76% compared to glass fiber composite. Depending on the stacking sequence, the flexural strength of the hybrid composites was improved between 10% and 16% concerning carbon fiber composite. With the introduction of MWCNTs, a slight increase in the tensile strength for unsymmetrical hybrid composites by around 5% and decreases by 7% for symmetrical ones were observed. Similar behavior was seen for bending characteristics. Additionally, low-velocity impact tests showed that it is achievable to bring greater impact peak forces up to 70% for hybrid composites than carbon fiber epoxy composites. MWCNTs modification of the matrix restrained the impact damage propagation, as proved by C-scan analysis.

A comprehensive investigation of drilling performance of anisotropic stacked glass‐carbon fiber reinforced hybrid laminate composites

AbstractAmong the various renewable energy sources, wind energy offers an effective solution to the energy providers. Onshore wind turbines are generally designed for sites with low wind resources, while offshore wind turbines can be more efficient in producing energy thanks to their longer blades that provide more than 10 MW of rated power. Offshore wind turbine blades are subjected to significantly higher stresses and harsh environmental conditions. Therefore, hybrid composites composed of carbon and glass fibers can offer cost‐effective and long‐lasting solutions for wind turbine blade manufacturers. Turbine blades are connected with main spars through bolted connections and high interlaminar stresses occurring during the drilling process can cause to delamination in the composites. To prevent catastrophic failure related to defective machining, the drilling process must be performed meticulously and all machining‐related results must be analyzed step by step. In this paper, dry drilling properties of hybrid glass‐carbon fiber laminate epoxy matrix composites were examined experimentally in order to contribute to the wind energy sector. The results showed that the delamination factor could be decreased with higher cutting speeds or lower feed rates. Besides, higher feed levels caused higher thrust forces on the tool body.

Fibre volume fraction screening of pultruded carbon fibre reinforced polymer panels based on analysis of anisotropic ultrasonic sound velocity

Composites have become the material of choice in a wide range of manufacturing applications. Whilst ultrasound inspection is a well-established non-destructive testing (NDT) technique, the application to composite imaging presents significant challenges stemming from the inherent anisotropy of the material. The fibre-volume fraction (FVF) of a composite plays a key role in determining the final strength and stiffness of a part as well as influencing the ultrasonic bulk velocity.In this work, a novel FVF determination technique, based on the angular dependence of the sound velocity with respect to the composite fibre direction, is presented. This method is introduced and validated by inspection of pultruded carbon fibre reinforced polymer (CFRP) panels commonly used in the manufacture of high-power wind turbine blades. Full matrix capture (FMC) data acquired from a phased array (PA) ultrasonic probe is used to generate calibration data for samples ranging in FVF from 60.5% to 69.9%. Sample velocity, as a function of propagation angle, is used to estimate the FVF of samples and ensure they fall within the desired range. Experimental results show values of 61.1, 66.1 and 68.3%, comparing favourably to the known values of 60.5, 66.3 and 69.9% respectively.The work offers significant potential in terms of factory implementation of NDT procedures to ensure final parts satisfy standards and certification by ensuring any FVF inconsistencies are identified as early in the manufacturing process as possible.