Properties Of Blades Research Articles

Effect of Lost-Foam Casting Process on Properties of Spiral Blade

The wear failure mode of a paver spiral blade was simulated by EDEM software. High-manganese steel, medium chromium alloy steel, and high chromium alloy steel were selected as matrix materials; SiC particles and WC particles were selected as surface particle reinforcement materials; and the spiral blade was prepared by the EPC process. The performance and wear mechanism of the spiral blade prepared by EPC were analyzed by microstructure, hardness, impact, pin disk, erosion wear test, and wear morphology. Modeling with EDEM software and applying the discrete element analysis method of particle system could simulate the actual working situation of the spiral blade of the paver well. Through the simulation, it was found that the wear amount of the spiral blade of the paver from the spiral shaft to the outside of the spiral blade was increasing. SiC and WC particle-reinforced wear-resistant coatings were prepared on the surfaces of high-manganese steel, medium chromium alloy steel, and high chromium alloy steel by the EPC method. The wear-resistant coating of high-manganese steel was 5.05 mm, the coating of medium chromium alloy steel was 5.98 mm, and the coating of high chromium alloy steel was 7.02 mm. The higher the chromium content, the better the diffusion with SiC and WC particles. In the process of the wear test, the soft phase in the coating was first worn away and concaved, and the hard phase protruded to bear the wear. After wear, it was found that the sample with high chromium alloy steel as matrix and SiC and WC particles as wear-resistant coating had the best wear resistance.

Multiobjective Optimization of Composite Wind Turbine Blade.

When designing a wind turbine, the main objective is to generate maximum effective power with the lowest possible production costs. The power of a wind turbine depends primarily on the aerodynamic properties of its blades. Moreover, the cost of making a blade for a wind turbine, and therefore also for the entire wind turbine, depends on the materials used for its production. Therefore, wind turbine blades are the most studied element of a wind turbine. By selecting the optimal material and geometric properties of the wind turbine blade, it is possible to reduce the costs of making the entire wind turbine. These rationales led the authors to investigate composite wind turbine blades. A two-criteria optimization task was formulated, which allowed for the simultaneous consideration of two criteria: minimizing the mass and minimizing the vertical deflection of the wind turbine blade. Geometric properties of the blade, influencing the considered criteria, were assumed as decision variables. The weighted sum method was used. The results obtained allowed us to determine the optimal geometric and material properties of a wind turbine blade.

UV광 조사 열화 가속 실험을 통한 Polypropylene 블레이드의 사용환경 신뢰성 분석

A small wind power generator with Archimedes blades made of polypropylene has been developed for the effective generation of eco-friendly electronic energy. Despite the excellent structural characteristics of the higher performance of an Archimedes blade, its shape is complicated to manufacture, and presents difficulty in guaranteeing mechanical reliability in the outdoor operating environment. Especially, the UV-Light deterioration in a long-term of several years affects the mechanical properties of the polypropylene blade. To evaluate the change of strength depending on the amount of UV-Light irradiation in the outdoor environment, an accelerated UV-Light deterioration test is proposed and conducted using three types of blade materials, such as polypropylene with UV-Resistance material (CSUB20/SUB HSUB25/SUB N₃O) coated and mixed ones. Through the experimental tests, the UV resistant material coating on the blade showed the best properties for long-term exposure to UV light. Based on the test results of property changes, the Archimedes blade was analyzed using a finite element method to predict the reliability of the blade’s underused conditions. As a result of the analysis, the UV degradation resistance of Archimedes blades with UV coating improved by 2.4 times compared to the case without UV coating.

Comparison of lightweight and traditional figure skating blades, a prototype blade with integrated damping system and a running shoe in simulated figure skating landings and vertical countermovement jumps, and evaluation of dampening properties of the prototype blade

ABSTRACT To date, there is no empirical evidence suggesting greater jump heights or cushioned landings when using figure skating (FS) blades of different mass and design. This study examined the effect of lightweight (Gold Seal Revolution from John Wilson) and traditional (Apex Supreme from Jackson Ultima and Volant from Riedell) blades, a new prototype blade with an integrated damping system (damping blade) in two different damping configurations, and running shoes (Runfalcon from Adidas) on kinetics and kinematics during simulated on-ice landings from 0.6 m and maximal countermovement jumps on synthetic ice, and measured dampening properties of the damping blade. Seventeen participants executed trials in the six footwear conditions blinded to the different blades and acted as their own control for statistical comparison. There were no differences between the lightweight and traditional blades on the maximal vertical ground reaction force during the landing. Image analysis showed a damping effect in the damping blade that significantly decreased the landing load for all participants (mean 4.38 ± 0.68 bodyweight) (p ≤ 0.006), on average between 10.1 and 14.3% compared to lightweight and traditional blades (4.87 ± 1.01 to 5.11 ± 0.88 bodyweight). The maximal jump height achieved was the same in all FS blades.

Phenolic Composition and Antioxidant, Anti-Inflammatory, Cytotoxic, and Antimicrobial Activities of Cardoon Blades at Different Growth Stages.

Simple SummaryThe rapid increase of the world population has promoted a more sustainable and efficient use of natural resources. To achieve complete and proper upcycling of plant crops, it is important to know their potential for industrial exploitation. Cardoon (Cynara cardunculus L.) is a species native to the Mediterranean basin widely used in different sectors, including food and pharmaceuticals. Despite their multiple industrial applications, not all plant tissues have been incorporated into the value chain. Therefore, this work aimed to characterize the phenolic composition and bioactive properties of cardoon blades throughout the phenological growth cycle. In addition to the structural variety of phytochemicals detected in the blade extracts, their antioxidant, anti-inflammatory, anti-proliferative, and antimicrobial properties were also highlighted. While immature material showed higher levels of phenolic compounds and greater potential to inhibit lipid peroxidation, samples at higher development stages had greater anti-proliferative, anti-inflammatory, and antimicrobial potential. These results demonstrate that the growth cycle influences the bioactive potential of cardoon blades and will be useful to establish suitable industrial applications, such as the development of ingredients for functional foods and nutraceuticals, among other products.Cardoon (Cynara cardunculus var. altilis) blades were collected at sixteen sampling dates (B1–B16) to study the influence of the phenological growth stage on the phenolic composition and biological properties. Twenty phenolic compounds were identified, among which trans 3,4-O-dicaffeoylquinic acid, 5-O-caffeoylquinic acid, and luteolin-O-hexoside (39.6, 42.6, and 101.0 mg/g extract, respectively) were the main compounds. Immature blades (B3) had a higher content of phenolic compounds (178 mg/g extract) and a greater ability to inhibit the formation of thiobarbituric acid reactive substances (IC50 of 1.61 µg/mL). Samples at more advanced growth stages revealed a greater capacity to inhibit oxidative hemolysis (B8, IC50 of 25 and 47.4 µg/mL for Δt of 60 and 120 min, respectively) and higher cytotoxic (B8–B13, GI50 between 7.1 and 17 µg/mL), anti-inflammatory (B13, IC50 of 10 µg/mL), and antibacterial activities. In turn, the antifungal activity varied depending on the tested fungi. All these results suggest that maturity influences the phenolic composition and bioactive properties of cardoon blades, which reveal great potential for the development of bioactive ingredients for food and pharmaceutical applications, among others.

Identification of torsional frequencies of a large rotor blade based on measurement and simulation data

With increasing size of wind turbines, the aerodynamic and structural properties of the rotor blades become more and more important. However, studies investigating the torsional properties using measurement data and simulation results on full-size turbines are still scarce. In this study, torsional measurements are carried out on a large wind turbine with a rotor diameter of 180 m and compared with model results. In this study, torsional measurements on a large wind turbine with a rotor diameter of 180 m are conducted and compared with model results. Torsional parameters of a rotor blade are identified using two different measurement methods, the first based on strain gauges and the second based on accelerometers. Both methods show frequencies that can be associated with the natural frequencies of the two first torsional modes of the rotor blade. To extract the natural frequencies and to reduce external effects, a manual pitching procedure is evaluated. Here, the first two natural frequencies associated with torsional modes can be identified. In a second step, the behaviour of the blade during power production is investigated and compared with the simulation results.

Wind turbine LIDAR-assisted control: Power improvement, wind coherence and loads reduction

This paper aims to firstly review various LIDAR-assisted wind turbine control methods proposed in the past ten years for improving power production in the below rated wind speed region in order to clarify their performance and quantify the potential benefits and drawbacks of LIDAR-assisted control. Secondly, a new LIDAR-assisted control algorithm based on Extremum Seeking Control (ESC) using LIDAR preview information for tracking the optimal power coefficient value is presented and compared to the traditional control strategy. The results show that the newly proposed LIDAR-assisted control strategy is beneficial in the below rated wind speed region when the aerodynamic properties of blades are changed largely compared to the original design. Lastly, the effects of the wind field coherence between the LIDAR measured points and the rotor plane on the LIDAR-assisted control for loads reduction in above rated region is discussed. An important conclusion is that the major benefit of LIDAR-assisted wind turbine control is to improve collective pitch control for reducing fatigue loads in above rated region, when the coherence bandwidth between the LIDAR measured wind speed and the rotor effective wind speed is high.

Parameter varying control of wind turbine smart rotor for structural load mitigation

This study investigates the Linear Parameter Varying (LPV) control of a Horizontal Axis Wind Turbine (HAWT) smart rotor in order to alleviate the structural loads. The smart rotor blades are equipped with actuators called Deformable Trailing Edge Flap (DTEF). These flaps benefit from a continuous airfoil deformation on the trailing edge in order to change the aerodynamic properties of blades. The objective of using a flap is to reduce the amplitude of load fluctuations in high wind speeds to decrease the fatigue loads on the wind turbine components and increase their working life. Here, the aerodynamic behavior of NACA 64-418 airfoil in the presence of DTEF deflection is studied numerically. The airfoil with 10% chord deformation is mounted on 5 MW NREL reference wind turbine blades in 67% to 95% of its length relative to the blade root. The nonlinear aeroelastic FAST code is used to determine the effects of DTEFs on structural load mitigation. Consequently, the modeling of nonlinear wind turbine system using LPV approach is discussed including the angle of DTEFs as a control input. A robust LPV controller has been designed using Linear Matrix Inequality (LMI) solution along the operating trajectory to guarantee the internal stability and H∞ robust performance of the closed-loop system in the presence of modeling uncertainties as well as wind turbulence. In sum, the idea of this study is the aerodynamic modeling of the wind turbine equipped with a smart rotor, designing an LPV controller and comparing the results with the conventional PI gain-scheduled controller. The principal objective is to reduce the amplitude of blade root flapwise bending moment oscillations about its mean values along the operating trajectory. As a summary of the results, a reduction in blade root flapwise bending moment fatigue load has been observed by 33% based on Damage Equivalent Load (DEL) calculation.

Aerodynamics and Control of Next Generation Electric Rotorcraft

Innovative design of helicopters promises great benefitsover conventional aircraft but there are a number oftechnical challenges. Hyper Q Aerospace brought a project tothe 2020 Mathematics-in-Industry Study Group to consider ahelicopter design with a counter-rotating, coaxial, doublerotor. Specific considerations were the vibration andharmonic properties of the rotor blades, the noise from theaircraft and the aerodynamic characteristics.Euler--Bernoulli beam theory and classical airfoil theorywere implemented to consider the vibration and aerodynamicfeatures of the aircraft and the rotor system. Thefundamental lengthwise and lateral harmonics of the bladeswere obtained and compared with typical rotational forcingfrequencies. The modification to the lift generated by thecounter-rotating blades and noise mitigation strategies werediscussed. Improved design strategies were presented.

Analytical Solution for Forced Vibration Characteristics of Rotating Functionally Graded Blades under Rub-Impact and Base Excitation.

This paper presents an analytical investigation on the forced vibration characteristics of a rotating functionally graded material (FGM) blade subjected to rub-impact and base excitation. Based on the Kirchhoff plate theory, the rotating blade is modelled theoretically. The material properties of the FGM blade are considered to vary continuously and smoothly along the thickness direction according to a volume fraction power-law distribution. By employing Hamilton’s principle, the equations of motion are derived. Then, the Galerkin method and the small parameter perturbation method are utilized to obtain the analytical solution for the composite blade under a combined action of radial force, tangential force and displacement load. Finally, special attention is given to the effects of power-law index, rub-impact location, friction coefficient, base excitation amplitude and blade aspect ratio on the vibration characteristics of the FGM structure. The obtained results can play a role in the design of rotating FGM blades to achieve significantly improved structural performance.

Structural modeling and modal analysis of rotor blade during ice accretion

The icing phenomenon of rotor presents strong couplings among multi-physical fields, which is highly affected by the instantaneous flowfield, physical environment and flight conditions, leading to potential distinct structural properties. To address this issue, the CLORNS-ICE algorithm is introduced to simulate the icing phenomenon of rotor, and whereby the features of ice profile are extracted to obtain the sectional coefficients of iced blade. The structural model of rotor is developed to consider the non-classical nonlinearities due to ice accretion by virtue of finite element method. The influence mechanisms of environmental factors, inflow state and structural parameters on the structural characteristics of rotor are revealed by means of parametric analyses, in which the modal properties of iced blade are analyzed through comparative analyses. The developed method also provides guidance for the comprehensive dynamic analysis of rotating blade during ice accretion.

Microstructure of a Damascene sabre after annealing

Abstract X-ray phase analysis combined with high-resolution electron microscopy of samples taken from a genuine Damascus sabre after annealing for 24 hat 400 °C and 800 °C followed by slow cooling down to room temperature has led to a better insight into the nature of cementite nanowires, which have been discovered recently. According to the present study, nanowires remained after 400 °C annealing, but disappeared after heat treatment at 800 °C and subsequent cooling down. On the other hand, perlitic cementite has been retained qualitatively after the same treatment. Knowing that the exceptional mechanical properties of Damascene blades disappear after annealing, the present results suggest a significant influence of the nanowires upon these features.

Variability and specificity of bone cutting mark properties in cases involving stabbing with knives.

Sharp force traumas are frequently encountered in stabbing crime victims. During an examination, the properties of cutting marks in bones are compared with the properties of suspect tools, particularly knives. Therefore, the variation and specificity of knife and cutting mark properties must be known. This article provides the variability and specificity of a set of knife blade and cutting mark properties. Plain and serrated knives are used to create experimental cutting marks in porcine ribs, knife properties are derived from surface acquisitions of the blades and mark properties from Micro-CT data. We consider two conditions, automated stabbing using a motorized stage and manual stabbing. In addition, we study the influence of maceration on marks. For knives, the blade edge angle, blade thickness, and bevel height, and for cutting marks, the shape, the wall angle, the width, and the bevel height are determined and compared. The results show that the relationship between corresponding properties of blades and marks depends on the knife type. For plain knives, the width and wall angle of the marks are dependent on the mark depth and are significantly smaller than the blade properties edge angle and width. For serrated knives, this is not the case. The mark shape only provides slight support for a knife type for marks deeper than the blade bevel height. In conclusion, mark properties are only specific for a particular knife brand and model if the blade properties differ significantly and assuming a specific knife type.

Effects of Heat Treatment on Microstructure and Properties of Inconel625 Alloy Blades Prepared by Selective Laser Melting

Effects of Heat Treatment on Microstructure and Properties of Inconel625 Alloy Blades Prepared by Selective Laser Melting

Aerodynamic and aeroacoustic properties of axial fan blades with slitted leading edges

A detailed experimental analysis of the aerodynamic and aeroacoustic properties of flat-plate axial fans with slitted leading edges is performed. The sound emissions of five slitted leading edge designs are measured at a constant rotational speed and at a constant total-to-static pressure rise of the fans. For both cases, the fan blades with slitted leading edges reduce the turbulence interaction noise and lead to a reduction of the overall sound pressure level for volume flow rates above 0.6 m3 s−1 compared to an axial fan with solid leading edges. The far-field noise analysis shows that the slits result in a noise reduction for frequencies below 2 kHz and a noise increase above 2 kHz. In addition, sound source localization is conducted with a microphone array and rotating beamforming methods are applied. The identified sound source distributions prove that slitted leading edges reduce turbulence interaction noise, but generate broadband noise in the fan blades’ trailing edge regions. The maximum sound reduction due to the slits could be detected at a dimensionless frequency of $ fh/\bar{w}\approx 0.5$, where f is the frequency, h is the height of the slit and $ \bar{w}$ is the mean relative inflow velocity. The noise reduction mechanism on axial fan blades corresponds well to previous investigations on flat-plate airfoils with slits.

Estimation of blade forces in wind turbines using blade root strain measurements with OpenFAST verification

This paper introduces an inference method for computing the forces and bending moments on operating wind turbine blades using strain measurements and supervisory control and data acquisition (SCADA) data. Operational data from four months of a Clipper Liberty C96 2.5 MW turbine instrumented with interferometric strain sensors at the blade roots as well as SCADA data such as wind speed, rotor hub speed, and blade pitch angle allow for accurate calculation of blade forces and moments. To perform such calculations, certain structural properties of the turbine blades must be inferred in the absence of detailed, proprietary information. This is done by inferring missing information from the National Renewable Energy Laboratory (NREL) 3 MW WindPACT reference wind turbine specifications. The derived forces and moments computed on the blades of the Clipper turbine are compared with the behavior of the NREL 3 MW reference turbine according to OpenFAST simulation outputs. Comparison of blade root reaction forces to OpenFAST outputs match closely, demonstrating that this inference method can be used to successfully estimate the internal forces and bending moments acting on the blades. These methods are useful on turbines for which all the structural information is not available.

X-ray Computed Tomography Method for Macroscopic Structural Property Evaluation of Active Twist Composite Blades

This paper describes an evaluation of the structural properties of the next-generation active twist blade using X-ray computed tomography (CT) combined with digital image processing. This non-destructive testing technique avoids the costly demolition of the blade structure. The CT scan covers the whole blade region, including the root, transition, and tip regions, as well as the airfoil blade regions, in which there are spanwise variations in the interior structural layout due to the existence of heavy instrumentation. The three-dimensional digital image data are processed at selected radial stations, and finite element beam cross-section analyses are conducted to evaluate the structural properties of the blade at the macroscopic level. The fidelity of the digital blade model is first assessed by correlating the estimated blade mass with the measured data. A separate mechanical measurement is then carried out to determine the representative elastic properties of the blade and to verify the predicted results. The agreement is found to be good to excellent for the mass, elastic axis, flap bending, and torsional rigidity. The discrepancies are less than 2.0% for the mass and elastic axis locations, and about 8.1% for the blade stiffness properties, as compared with the measured data. Finally, a sensitivity analysis is conducted to clarify the impact of modeling the sensor and actuator cables, nose weight, and manufacturing imperfections on the structural properties of the blade.

Imprinted Glass Fiber-Reinforced Polymer Vascular Networks for Creating Self-Healing Wind Turbine Blades

Abstract Self-healing wind turbine blades can reduce costs associated with maintenance, repair, and energy compensation. Self-healing is the ability to sustain and recover from damage autonomously. We discuss the efforts made to optimize the self-healing properties of wind turbine blades and provide a new system to maximize this offset. This system utilizes vacuum-assisted resin transfer molding (VARTM), and 3D printed templates to imprint a vascular network onto a single glass fiber-reinforced polymer (FRP) sheet. This imprinted layer is infused with Grubbs first-generation catalyst and filled with dicyclopentadiene (DCPD) which is then sealed using plastic sheeting. The sealed imprint layer is embedded into a larger multilayer FRP prior to VARTM. After VARTM, the completed multilayer FRP is fully capable of self-healing microcracks. Three-dimensional printed templates with square grid and hexagonal patterns were used to evaluate how differences in DCPD distribution affect overall recovery. Three-point bending tests were performed to obtain the maximum flexural strengths of the FRP samples before and after self-healing to evaluate recovery. Overall, with the imprint layer method, the catalyst was focused in one area of the complete FRP, reducing the amount of unused catalyst present in the FRP. Also, the samples created using the imprint method were able to achieve a maximum average recovery of over 200% and a storage efficiency of 100%.

블레이드와 로터의 결합 조건에 의한 Mistuning 효과

In this study, the assembling conditions of blades and rotors are investigated by the FEM model of a blade with the different boundary conditions. It is assumed that the modal properties of blades are identical and the blade modal frequencies are changed by the assembling condition only. It is shown that the change in modal frequency by the assembling condition is approximately 0.25 % in normal operating conditions. However, the variance of blade response can be increased by more than 30 % under narrow-band random excitations.

Study on creep properties of nickel-based superalloy blades based on microstructure characteristics

Creep experiments were performed on miniature K480 nickel-based superalloy specimens at 835 °C and 400 MPa. These specimens were cut from turbine blades processed with different casting processes and pouring temperatures. The microstructure analysis, fracture morphology analysis, and grain size analysis were carried out by scanning electron microscopy (SEM), indicating that the influence of the moulding process and pouring temperature on the microstructure of the alloy is mainly reflected in the difference in the size of crystal grains, grain boundary precipitates and casting defects, which in turn affects the high temperature creep properties of the alloy. Based on crystal plasticity theory, a polycrystalline alloy viscoplastic constitutive equation considering the moulding process and pouring temperature parameters is established, meanwhile, the geometric models of the K480 alloy were established based on the observations of its microscopic structure under SEM. The study revealed the relationship between the casting process of the blade, the microstructure of the material, and the creep property of the specimen. The established plastic constitutive model can predict blade stress rupture life under different casting processes.