Properties Of Blades Research Articles

Parametric Analysis and Improvement of the Johnson-Cook Model for a TC4 Titanium Alloy

Titanium alloys are widely used in the manufacture of gas turbines’ compressor blades. Elucidating their mechanical behavior and strength under damaged conditions is the key to evaluating the equipment’s reliability. However, the conventional Johnson-Cook (J-C) constitutive model has limitations in describing the dynamic response of titanium alloy materials under the impact of a high strain rate. In order to solve this problem, the mechanical behavior of a TC4 titanium alloy under high strain rate and different temperature conditions was analyzed by combining experiments and numerical simulations. In this study, the parameters of the J-C model were analyzed in detail, and an improved J-C constitutive model is proposed, based on the new mechanism of the strain rate strengthening effect and the temperature softening effect, which improves the accuracy of the description of strain sensitivity and temperature dependence. Finally, the VUMAT subroutine of ABAQUS software was used for numerical simulation, and the predictive ability of the improved model was verified. The simulation results showed that the maximum prediction error of the traditional J-C model was 23.6%, while the maximum error of the improved model was reduced to 5.6%. This indicates that the improved J-C constitutive model can more accurately predict the mechanical response of a titanium alloy under an impact load and provides a theoretical basis for the study of the mechanical properties of titanium alloy blades under subsequent conditions of foreign object damage.

Isogeometric vibration analysis of functionally graded material pre-twisted blades with three-dimensional theory

In this paper, the free vibration characteristics of a rotating functionally graded material (FGM) pre-twisted blades are investigated by the isogeometric method based on the three-dimensional (3D) theory. The effects of Coriolis force, centrifugal softening, and centrifugal rigidity of the FGM pre-twisted blades are considered in this vibration analysis model. The material properties of the FGM pre-twisted blades are assumed to change continuously along thickness direction. It is easy to satisfy the weak form requirements of the vibration control equation of the FGM pre-twisted blades by using the NURBS functions. Then, the dynamic equation of the pre-twisted rotating blades can be derived by using the Hamilton's variational principle. Finally, a standard eigenvalue equation is obtained through discretizing equations and expanding dimensions. Numerical examples showed that the current formulation has fast convergency and good accuracy. Additionally, the influence of installation angle, pre-twisted angle, variable cross-section, material properties and rotating speed on the vibration characteristics of the FGM pre-twisted blades under rotating conditions is explored in detail. The work can also shed some new lights on the vibration behaviors of pre-twisted blades composite materials.

دراسة علمية حول العزم الزاوي وعلاقته بالخصائص الميكانيكية لشفرات التوربينات

The general trend now in all countries of the world and all sectors is to achieve sustainability. One of how this sustainability can be achieved is to develop and improve the properties of raw materials, and in the field of turbine-powered power plants, sustainability must be achieved in light of the global crisis facing the energy sector, in this study, which aims to study the effect of angular torque on Mechanical properties of turbine blades, so that we can develop and improve the properties of those blades Angular torque is very important in turbine blades because it drives the turbine to rotate. Angular torque results from a force acting on a rotating body. In the case of turbine blades, the force of the gas flow produces angular torque. Turbine blades typically consist of thin, curved metal sheets. When gas passes through the blades, it exerts a force on the blades. This force forces the blades to rotate around its axis the greater the angular torque it produces. The greater the angular torque, the faster the turbine rotates. This study provides a mathematical model to calculate the angular torque resulting from turbine blades. The model was used to study the effect of various factors on the angular torque, including the gas flow speed, the shape of the blades, and their mechanical properties. Then, a simulation was run using the ANSYS program to determine the relationship between the angular torque and the mechanical properties of the turbine blades. The results indicated a large deviation of the flexible blades and unstable rotation of the rotating blade systems, due to the coupling effect of rotation and vibration, where the mechanical properties of mass/inertia distributions, damping, and stiffness are related to changes in rotational speed and local deformation in rotor blade systems, thus, the harmonic balance must occur and the mechanical properties of the blades be improved. Keywords: Angular Torque, Mechanical Properties, Raw Materials, Turbine blades, mathematical model, flow speed, ANSYS, rotation and vibration, harmonic balance.

Vibration analysis of Ti-SiC composite airfoil blade based on machine learning

In this study, machine learning (ML) methods are integrated with Rayleigh-Ritz method and first-order shear deformation theory (FSDT) to predict the vibration properties of Ti-SiC fiber-reinforced composite airfoil blade. The natural vibration characteristics of airfoil blade are largely determined by various geometric and material parameters, which leads to the high computational cost of numerical methods. Therefore, the low-cost ML models in conjunction with Ti-SiC fiber-reinforced composite material is developed to replace traditional numerical methods in order to predict the vibration characteristics of airfoil blade. Random Forest (RF), Gradient Boosting Decision Tree (GBDT) and Back Propagation (BP) neural network models are utilized to compare the predicted results with existing data. Among these models, the BP neural network demonstrates superior performance. Additionally, the SHapley Additive exPlanation (SHAP) method is utilized to elucidate BP neural network model, facilitating the prioritization of input features. This approach offers a feasible auxiliary solution for investigating the vibration characteristics of airfoil blade.

Analysis of Rewetting Characteristics and Mechanical Properties in Leaf Blades and Main Veins of Cured Tobacco Leaves

The moisture content and mechanical properties are crucial factors influencing the processing quality of cured tobacco leaves. Understanding the rewetting characteristics and mechanical properties of leaf blades and main veins is essential to for optimizing tobacco processing. This study measured the rewetting behavior and mechanical properties of leaf blades and main veins under varying temperature (20–40 °C) and relative humidity (RH, 50%–90%) conditions. Rewetting curves were obtained and dynamic models were constructed. Low-field nuclear magnetic resonance (LF-NMR) analysis was utilized to obtain information of relaxation time (T2), and correlation models between moisture state and mechanical properties were established. The results indicated that the rewetting rate of leaf blades and main veins decreased gradually with increasing moisture content, while higher temperature and RH enhanced the rewetting process. The rewetting time of leaf blades at 30 °C with 90% RH was reduced by 71.43% compared to that at 30 °C with 70% RH. For main veins, the rewetting time at 30 °C with 90% RH was shortened by 50.00% compared to 30 °C with 80% RH. The Peleg model was determined as the optimal dynamic model for describing the rewetting characters for leaf blades and main veins. Two moisture states were observed: strongly bound moisture and weakly bound moisture. The peak area of strongly bound moisture increased gradually, while the peak area of weakly bound moisture initially increased and then decreased. At the moisture content of 0.15 g/g, the strongly bound moisture content of leaf blades decreased by 7.75% compared to main veins, whereas the weakly bound moisture content of leaf blades increased by 3.04 times. However, the proportion of weakly bound moisture decreased despite the increasing proportion of strongly bound moisture. Furthermore, the relaxation time of leaf blades and main veins increased during rewetting. The mechanical properties analysis revealed a correlation between breaking force, strain, and elastic modulus with the content of strongly bound moisture. This study provides a theoretical basis for the development of improved rewetting processes in tobacco production.

A generalized wind turbine cross section as a reduced-order model to gain insights in blade aeroelastic challenges

In this work, we present an approach to study the aeroelastic stability of a wind turbine by focusing on the dynamics of a blade cross section. We present a methodology to obtain a reduced-order model of the blade dynamics in the form of generalized cross-sectional quantities that approximates the aerodynamic and structural properties of the full blade. The motivation for the work is to gain a physical understanding of the influence of aerodynamic models such as dynamic wake and dynamic stall on the frequency and damping of the structure using a reduced-order model with low computational cost. The model may be coupled to two-dimensional computational fluid dynamics softwares or engineering unsteady airfoil aerodynamics models accounting for dynamic wake and dynamic stall. In the latter case, we can obtain monolithic state-space forms of the aeroelastic system of equations, which simplifies the determination of the modal parameters and therefore the study of stability. The work investigates wind turbines in operation or at standstill, where vortex-induced vibrations and stall-induced vibrations, respectively, might be an issue. The implementation is made available as part of the open-source Python package WELIB and as part of the open-source unsteady aerodynamic driver of OpenFAST.

Ammonium nutrition modifies cellular calcium distribution influencing ammonium-induced growth inhibition

Proper plant growth requires balanced nutrient levels. In this study, we analyzed the relationship between ammonium (NH4+) nutrition and calcium (Ca2+) homeostasis in the leaf tissues of wild-type and mutant Arabidopsis specimens provided with different nitrogen sources (NH4+ and nitrate, NO3−). Providing plants with NH4+ as the sole nitrogen source disrupts Ca2+ homeostasis, which is essential for activating signaling pathways and maintaining the cell wall structure. The results revealed that the lower Ca2+ content in Arabidopsis leaves under NH4+ stress might result from reduced transpiration pull, which could impair root-to-shoot Ca2+ transport. Moreover, NH4+ nutrition increased the expression of genes encoding proteins responsible for exporting Ca2+ from the cytosol of leaf cells. Furthermore, overexpression of the Ca2+/H+ antiporter 1 (CAX1) gene alleviates the effects of NH4+ syndrome, including stunted growth. The oeCAX1 plants, characterized by a lower apoplastic Ca2+ level, grew better under NH4+ stress than wild-type plants. Evaluation of the mechanical properties of the leaf blades, including stiffness, strength, toughness, and extensibility, showed that the wild-type and oeCAX1 plants responded differently to the nitrogen source, highlighting the role of cell wall metabolism in inhibiting the growth of NH4+-stressed plants.

Microstructural Characteristics and Properties of Laser-Welded Diamond Saw Blade with 30CrMo Steel.

In order to enhance the quality of diamond composite materials, this work employs a Cu-Co-Fe and Ni-Cr-Cu pre-alloyed powder mixture as a transition layer, and utilizes laser-welding technology for saw blade fabrication. By adjusting the laser-welding process parameters, including welding speed and welding power, well-formed welded joints were achieved, and the microstructure and mechanical properties of the welded joints were investigated. The results demonstrate that the best welding performance was achieved at a laser power of 1600 W and a welding speed of 1400 mm/min, with a remarkable tooth engagement strength of up to 819 MPa. The fusion zone can be divided into rich Cu phase and rich Fe phase regions, characterized by coarse grains without apparent preferred orientation. The microstructure of the heat-affected zone primarily consists of high-hardness brittle quenched needle-like martensite, exhibiting a sharp increase in microhardness up to 550 HV. Fracture occurred at the boundary between the fusion zone and the heat-affected zone of the base material, where stress concentration was observed. By adjusting the welding parameters and transition layer materials, the mechanical properties of the joints were improved, thereby achieving a reliable connection between diamond composite materials and the metal substrate.

Analysis of the Aeroelastic Dynamics of Lightweight Flexible Variations of the SNL-NRT Turbine

Current trends show that wind turbines are growing in size to meet a rising demand for renewable energy generation, and their upscaled rotors have inherently become more flexible to maintain a proportionally lighter design. This is because larger rotors must be less massive relative to their diameter to minimize the levelized cost of energy (LCOE), which means that blades that are notably less stiff are produced as a result. These structural changes to blades are often reflected in their compromised aeroelastic stability and amplified deformation during operation, which has the potential to decrease the blade’s expected lifetime and the performance of the machine overall. Variations in blade flexibility are also known to influence vortex-wake structures downstream of the turbine, causing patterns of velocity deficit to evolve in ways that affect the performance of other turbines in the farm. This research explores how the increased flexibility of modern utility-scale wind turbine blades influences rotor aeroelastic behavior and interactions with farm flow. High-fidelity simulations of Sandia National Laboratories’ (SNL) National Rotor Testbed (NRT) wind turbine are presented. Flexible variations of the NRT baseline blade are simulated in a variety of realistic operational conditions typically expected at the SNL’s SWiFT facility in Lubbock, Texas. Solutions are then compared to investigate how specific changes to the structural properties of the NRT baseline blade’s design and construction can influence its aeroelastic response at the rotor and the evolution of the turbine’s wake.

3D Printing of a Tidal Turbine Blade Using Two Methods of SLS and FFF of a Reinforced PA12 Composite: A Comparative Study

This study scrutinizes the thermomechanical dynamics of 3D-printed hydrofoil blades utilizing a carbon and glass bead-reinforced thermoplastic polymer. Comparative analyses underscore the pivotal role of polymer reinforcement in augmenting mechanical strength and mitigating deformation and residual stress. The investigation elucidates the expeditious and cost-efficient manufacturing potential of low-cost Fused Filament Fabrication (FFF) printers for small-scale blades, revealing exemplary mechanical performance with nominal deflection and warping in the PA12-CB/GB printed blade. A comprehensive juxtaposition between Selective Laser Sintering (SLS) and FFF printing methods favors SLS due to its isotropic properties, notwithstanding remediable warping. Emphasizing the rigorous marine environment, the study cautions against the anisotropic properties of FFF-printed blades, despite their low mechanical warping. These discernments contribute to hydrofoil design optimization through numerical analysis, shedding light on additive manufacturing’s potential for small blades in renewable energy, while underscoring the imperative for further research to advance these techniques.

Impact of Process Technology on Properties of Large-Scale Wind Turbine Blade Composite Spar Cap

As wind turbine blade length increases, reconciling lightweight design with strength necessitates continuous advancements in process technology. The impact of three different process technologies–vacuum-assisted resin transfer moulding (VARTM), prepreg, and pultrusion–on the properties of wind turbine blade composite spar caps was investigated using scanning electron microscopy, dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, and static and fatigue testing. The results demonstrated that the fibre weight content and 0° tensile modulus of the VARTM and pultrusion composites increased as compared to those of the prepreg samples. Subsequently, the properties of a 94-m blade were analysed using the Ansys Composite PrepPost (ACP) and static structure modules in Ansys simulations, and the weights of the spar cap were compared with test data of materials under different process technologies. The results showed that the masses of the spar cap of a 94-m blade in the pultrusion, VARTM, and prepreg processes were 7965, 9170, and 9942 kg, respectively. The quantitative influence rules on the weight of the wind turbine blade spar cap prepared through different process technologies were formulated. The findings of this study are promising and are expected to aid the development of wind turbine blade process technologies.

The Icing Characteristics of a 1.5 MW Wind Turbine Blade and Its Influence on the Blade Mechanical Properties

Ice accumulation significantly impacts the mechanical properties of wind turbine blades, affecting power output and reducing unit lifespan. This study explores the icing characteristics and their effects on a 1.5 megawatt (MW) wind turbine blade’s mechanical properties under various conditions, including wind speeds of 5 m per second (m/s) and 10 m per second, temperatures of −5 degrees centigrade (°C) and −10 degrees centigrade, and different liquid water contents, by using icing wind tunnel tests and structural statics analysis. The research reveals that ice predominantly forms in an irregular pattern on the leading edge of the blade. It is easy to produce corner ice and ice skating when the icing temperature and wind speed are higher, and the icing surface is rougher. When the other conditions remain unchanged, the decrease in temperature, an increase in wind speed, or a rise in liquid water content all lead to an increase in the average thickness of icing and the volume of icing at the leading edge, with the effect of the wind speed on the two being 147.8% and 147.9%, the effect of the liquid water content on the two being 39.9% and 53.5%, and the effect of the temperature on the two being 24.6% and 13.2%. The study finds that the blade tip experiences the maximum displacement in both iced and non-iced states, although the positions of peak equivalent stress and strain vary. The above study will also provide references for the design of new wind turbine blades and the anti-icing maintenance of wind turbine generator sets.

Vibration characteristics of pre-twisted rotating Ti-SiC composite airfoil blade

In this paper, a pre-twisted blade model is established based on the FSDT (first-order shear deformation theory), where the Ti-SiC fiber reinforced composite and NACA 4-digit airfoil are innovatively proposed. Rayleigh-Ritz method is utilized to deduce the pre-twisted blade natural frequencies and mode shapes where the exponential polynomials satisfying the cantilever boundary conditions are taken as admissible functions. Comparing with the existing literature, the precision of the model and the method is verified. The material properties of Ti-SiC fiber reinforced composites are calculated by the M-T (Mori-Tanaka) method and FE (Finite Element) method to guarantee the reliability of the calculation method. In addition, the parameters affecting blade vibration, such as rotating speed and aspect ratio, are studied in detail. The research findings indicate that the addition of SiC fibers enhances the properties of the composite blade, and then improves the frequency of the rotating blade. Additionally, the pre-twisted angle, rotating speed, aspect ratio and blade shape significantly affect the natural frequency of Ti-SiC composite airfoil blade. The well-established model accurately predicts the dynamic behaviors of the rotating blade, which has certain guiding value for the optimization of blade material and geometric size.

Assessment of performance properties of compressor blades made of EI961-Sh steel with nickel-cadmium and titanium-nitride coatings

Comparative tests of compressor blades made of EI961-SH steel were carried out for resistance to fatigue, abrasive wear and corrosion damage to the surface when applying electrolytic nickel-cadmium and vacuum plasma coating of titanium nitride.

RESEARCH ON TESTING A GENUINE DAMASCUS STEEL. A CASE STUDY

Based on the fascinating legends and excellent properties of Damascene blades, the study of Damascus steel provided the opportunity to observe in detail the laborious process of manufacturing this material, which involves forging and welding different layers of steel to obtain a particularly strong and durable final product. To carry out this research, high-quality materials were selected from a catalog of steels, with a particular focus on achieving the best results. In this case, two types of steel were chosen to create genuine Damascus steel: AISI 1095 and 15N20 steel. Both materials have been selected for their individual properties, such as strength and durability, which contribute to the ultimate quality of Damascus steel. This rigorous selection of materials ensured a high-quality and authentic product. Additional studies, such as finite element analysis and strength of materials, were conducted to understand and evaluate the behaviour of Damascus steel under various scenarios and loadings. Processing and laboratory tests were carried out on the obtained Damascus steel to evaluate its mechanical properties, including the processing of the results using Autodesk Inventor Professional 2023 and simulation in Ansys 2023.

CT-Scan-Based Approach for Turbine Blade Geometry Extraction

Abstract This paper presents a method for the assessment of the geometrical properties of the turbine blade after a long running time. This method uses a medical imaging device (CT-Scan) to provide segmentation images of the turbine blade. Image processing technique was employed to produce the cross-sectional properties such as area, centroid, minimum moment of inertia, maximum moment of inertia, and the angle of twist of the principal axes along the blade span. This geometrical information was produced using MATLAB code and validated against Image-J software data. This method can be used as a nondestructive method to evaluate the geometry of the turbine.

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.

Study on heat transfer and flow resistance characteristics of cracking furnace tube by axial width of opening combination rotor blade

Based on the passive enhanced heat transfer mechanism, this paper proposes the new opening combination rotor blade, which aims to improve heat and mass transfer performance by changing internal structure of cracking furnace tube, thus achieving efficient production of ethylene. Through mathematical modeling and simulation of heat transfer properties of opening combination rotor blade, heat transfer performance and fluid flow characteristics of ordinary rotor blade tubes and opening combination rotor blade with axial widths of W (W = 0.25 R, 0.5 R, 0.75 R) are analyzed using field synergy principle and comprehensive heat transfer evaluation coefficient (PEC).The results demonstrate that the Nusselt number of opening combination rotor blade is 19%-23% lower than that of ordinary rotor blade. The resistance coefficient of opening combination rotor blade with axial width of 0.25 R is significantly lower by 33%-43%. Opening combination rotor blade with axial width of 0.25 R has a significantly lower resistance coefficient of 72%-78%. Its PEC value is between 1.23–1.28 with significantly improved overall heat transfer performance. In summary, opening combination rotor blade with axial width of 0.25 R has the most significant heat transfer effect and has a high reference significance for engineering design.

Methodology for developing a prediction model for the remaining fatigue life and residual strength of tidal turbine blades

As tidal energy nears commercial viability, the reliability and safety of a tidal energy device becomes more prevalent. A key aspect for determining their reliability and safety, along with reducing risk during operational deployment, is the structural integrity of tidal turbine blades. Therefore, a validated model for predicting the structural integrity of tidal turbine blades will aid in de-risking tidal energy technologies. In this study, a three-phase approach was used to formulate a strategy to predict the remaining fatigue life and residual strength of tidal turbine blades, over their operational lifespan. In Phase 1, the parameters influencing the structural properties of tidal turbine blades were identified based on the literature review, and the expertise in the field. Then, parameters were extensively studied and classified into four main impact groups, which include load conditions, design and manufacturing, degradation, and unexpected situations. Loading conditions on the blade are directly linked to hydrodynamic forces, maintenance, operating conditions, and corrosion effects. At the same time, these scenarios can vary with fluid-structure interactions, climate conditions, local site conditions, and maintenance and inspection schedules of the blades. The design and manufacturing category mainly represents the impact of the properties of composite materials, the geometry of the blade, and manufacturing process parameters. Similar to the other structures, tidal turbine blades are subject to deterioration and unexpected accidents during their service life, which significantly compromises the structural integrity of the blade. In Phase 2, a data management strategy was formulated related to identified four impact categories and investigated the possible methods of analysing the data. In this context, finite element analysis of composite tidal turbine blades was identified as the most appropriate tool to comprehensively examine collected data, prior to comparing the results to the field and laboratory-based test data. Mesh properties of the numerical models, test standards, instrumentation, and equipment used for field and laboratory-based structural testing of tidal turbine blades, as well as the accuracy of data acquisition systems, influence the comparison of these results. Finally, with the information gathered, as well as knowledge and experience in the field, a method for estimating the residual strength and remaining fatigue life of tidal turbines at each stage of their operation was formulated. The model will undergo a series of extensive validation processes using experimental testing datasets and will be used in the future to develop vulnerability curves related to the remaining structural life of the tidal turbine blades.

The Effect of Pulling Speed on the Structure and Properties of DZ22B Superalloy Blades

DZ22B alloy is commonly used as a blade material for aircraft engines and gas turbines, and its preparation process is an important factor affecting its performance. In the present work, a reliable numerical model is established through ProCAST numerical simulation and auxiliary experimental verification methods, based on which the effect of casting speed on the grain and dendrite growth of DZ22B superalloy blades is studied. The results indicate that increasing the pulling speed can reduce the spacing between secondary dendrites, which is beneficial for the growth of dendrites. Based on numerical simulation and experimental verification, it is suggested that the pulling rate of the directional solidification DZ22B superalloy blade should be 6-2mm/min variable speed pulling to improve the production success rate.