Search Results (282)

Amid the global shift toward clean energy, wind power has emerged as a critical pillar of the modern energy matrix. To improve the reliability and maintainability of wind farms, this work proposes a novel hybrid fault detection approach that combines expert-driven diagnostic knowledge with data-driven modeling. The framework integrates autoencoder-based neural networks with Failure Mode and Symptoms Analysis, leveraging the strengths of both methodologies to enhance anomaly detection, feature selection, and fault localization. The methodology comprises five main stages: (i) the identification of failure modes and their observable symptoms using FMSA, (ii) the acquisition and preprocessing of SCADA monitoring data, (iii) the development of dedicated autoencoder models trained exclusively on healthy operational data, (iv) the implementation of an anomaly detection strategy based on the reconstruction error and a persistence-based rule to reduce false positives, and (v) evaluation using performance metrics. The approach adopts a fault-specific modeling strategy, in which each turbine and failure mode is associated with a customized autoencoder. The methodology was first validated using OpenFAST 3.5 simulated data with induced faults comprising normal conditions and a 1% mass imbalance fault on a blade, enabling the verification of its effectiveness under controlled conditions. Subsequently, the methodology was applied to a real-world SCADA data case study from wind turbines operated by EDP, employing historical operational data from turbines, including thermal measurements and operational variables such as wind speed and generated power. The proposed system achieved 99% classification accuracy on simulated data detect anomalies up to 60 days before reported failures in real operational conditions, successfully identifying degradations in components such as the transformer, gearbox, generator, and hydraulic group. The integration of FMSA improves feature selection and fault localization, enhancing both the interpretability and precision of the detection system. This hybrid approach demonstrates the potential to support predictive maintenance in complex industrial environments. Full article

Caragana korshinskii Kom. (CKB), widely cultivated in Inner Mongolia, China, has potential for silage feed development due to its favorable nutritional characteristics, including a crude protein content of 14.2% and a neutral detergent fiber content below 55%. However, its vascular bundle fiber structure limits the efficiency of lactic acid conversion and negatively impacts silage quality, which can be improved through mechanical crushing. Currently, conventional crushing equipment generally suffers from uneven particle size distribution, high energy consumption, and low processing efficiency. In this study, a layered aggregate model was constructed using the discrete element method (DEM), and the Hertz–Mindlin with Bonding contact model was employed to characterize the heterogeneous mechanical properties between the epidermis and the core. Model accuracy was enhanced through reverse engineering and a multi-particle-size filling strategy. Key parameters were optimized via a Box–Behnken experimental design, with a core normal stiffness of 7.37 × 10¹¹ N·m⁻¹, a core shear stiffness of 9.46 × 10¹⁰ N·m⁻¹, a core shear stress of 2.52 × 10⁸ Pa, and a skin normal stiffness of 4.01 × 10⁹ N·m⁻¹. The simulated values for bending, tensile, and compressive failure forces had relative errors of less than 10% compared to experimental results. The results showed that rectangular hammers, due to their larger contact area and more uniform stress distribution, reduced the number of residual bonded contacts by 28.9% and 26.5% compared to stepped and blade-type hammers, respectively. Optimized rotational speed improved dynamic crushing efficiency by 41.3%. The material exhibited spatial heterogeneity, with the mass proportion in the tooth plate impact area reaching 43.91%, which was 23.01% higher than that in the primary hammer crushing area. The relative error between the simulation and bench test results for the crushing rate was 6.18%, and the spatial distribution consistency reached 93.6%, verifying the reliability of the DEM parameter calibration method. This study provides a theoretical basis for the structural optimization of crushing equipment, suppression of circulation layer effects, and the realization of low-energy, high-efficiency processing. Full article

The wear failure of vertical shaft planetary mixer blades under complex working conditions directly affects the quality and productivity of concrete. Given that it is time-consuming and labor-intensive to obtain the wear characteristics of mixer blades by experimental methods, this study used numerical simulation to analyze the effects of different factors on the wear characteristics of mixer blades based on the Hertz–Mindlin with JKR cohesive contact model and the Archard wear model. The results of this study show that under the influence of different factors, the blade is subjected to tangential cumulative contact energy and contact force is significantly larger than that in the normal direction, the wear of the blade is judged to be the form of abrasive wear accompanied by impacts, and the wear on the outer middle and lower edge regions of the blade is the most serious. Specifically, for every 5 rpm increase in mixing speed, the blade wear rate increases by 24.14% on average; for every 5° increase in blade angle, the blade wear rate decreases by 2.9% on average; for every 10% increase in the mass ratio of stone aggregate, the blade wear rate increases by 5.95% on average; conical aggregates have the most serious effect on blade wear, while spherical aggregates have the most minor effect. This study provides the theoretical basis and numerical support for understanding the reasons for blade wear loss and enhancing the service life of mixer blades. Full article

The growing demand for renewable energy has underscored the importance of wind power, with wind turbines playing a pivotal role in sustainable electricity generation. However, wind turbine blades are exposed to various challenges, particularly flow-induced vibrations (FIVs), including vortex-induced vibrations, flutter, and galloping, which significantly impact the performance, efficiency, reliability, and lifespan of turbines. This review presents an in-depth analysis of wind turbine blade technology, covering the fundamental principles of operation, aerodynamic characteristics, material selection, and failure mechanisms. It examines the effects of these vibrations on blade integrity and turbine performance, highlighting the need for effective vibration suppression techniques. The paper also discusses current advancements in maintenance strategies, including active and passive vibration control methods, sensor networks, and drone-based inspections, aimed at improving turbine reliability and reducing operational costs. Furthermore, emerging technologies, such as artificial intelligence (AI)-driven prognostic assessments and novel materials for vibration damping, are explored as potential solutions to enhance turbine performance. The review emphasizes the importance of continued research in addressing the challenges posed by FIVs, particularly for offshore turbines operating in harsh environments. Full article

Background/Objectives: A material incompatibility has been established between self-etching adhesives and amine-containing dual-cure resin composite materials used for core buildups. This study aims to compare the dentin bond strength of several amine-containing and amine-free core materials using self-etching adhesives with different pHs. Methods: Extracted human molars were mounted in acrylic and ground flat with 320-grit silicon carbide paper. Next, 520 specimens (n = 10/group) were assigned to a dual-cure core buildup material group (10 amine-containing, 2 amine-free, and 1 reference light-cure only bulk fill flowable composite) and assigned to a self-etching adhesive subgroup (pH levels of approximately 1.0, 3.0, and 4.0). Within 4 h of surface preparation, the adhesive corresponding to the specimen’s subgroup was applied and light-cured. Composite buttons for the assigned dual-cure core material of each group were placed using a bonding clamp apparatus, allowed to self-cure for 2 h at 37 °C, and then unclamped. An additional group with one adhesive (pH = 3.0) was prepared in which the dual-cure core materials were light-cured. The bonded specimens were stored in water at 37 °C for 24 h. The specimens were mounted on a testing clamp and de-bonded in a universal testing machine with a load applied to a circular notched-edge blade at a crosshead speed of 1 mm/min until bond failure. The maximum load divided by the area of the button was recorded as the shear bond strength. The data was analyzed via 2-way ANOVA. Results: The analysis of bond strength via 2-way ANOVA determined statistically significant differences between the adhesives, the core materials, and their interaction (p < 0.01). There was a general trend in shear bond strength for the adhesives, where pH 4.0 > 3.0 > 1.0. The amine-free core materials consistently demonstrated higher shear bond strengths as compared to the other core materials when chemically cured only. Light-curing improved bond strength for some materials with perceived incompatibility. Conclusions: The results of this study suggest that an incompatibility can exist between self-etching adhesives and dual-cure resin composite core materials. A decrease in the pH of the utilized adhesive corresponded to a decrease in the bond strength of dual-cure core materials when self-curing. This incompatibility may be minimized with the use of core materials formulated with amine-free chemistry. Alternatively, the dual-cure core materials may be light-cured. Full article

The attenuation of bolt preload is a critical factor leading to bolt fatigue failure, whereas the study of the nonlinear attenuation behavior of preload and its mechanism during installation is an inevitable challenge in engineering practice. The attenuation of the preload of a bolt is mainly related to the stiffness of the bolt body as well as the stiffness of the connected parts. This study aimed to develop an experimental system to analyze the nonlinear attenuation behavior of preload during bolt tightening. First, a simulation system replicating the bolt installation process was constructed in a laboratory setting, incorporating blade and pitch bearing specimens identical to those used in a 10 MW wind turbine, restoring the stiffness coupling characteristics of the “composite-metal bearing” heterogeneous interface at the blade root through a 1:1 full-scale simulation system for the first time. Second, ultrasonic preload measurement equipment was employed to monitor preload variations during the bolt tightening process. Finally, the instantaneous preload decay rate of the wind turbine blade-root bolts and the over-draw coefficient were quantified. Experiments have shown that the preload decay rate of commonly used M36 leaf root bolts is 11–16%. If a more precise value is required, each bolt needs to be calibrated. These findings provide valuable insights for optimizing bolt installation procedures, enabling precise preload control to mitigate fatigue failures caused by abnormal preload attenuation. Full article

The performance of the turbocharger nozzle ring is a key factor in the overall operation of the main engine of the ship. Minimizing failure and damage caused by high exhaust gas temperature and pressure is essential. As a first step toward improving turbocharger safety, this study performed 3D scanning of an aged nozzle ring to obtain its precise geometry and developed a corresponding numerical model. The boundary conditions of the numerical model were defined by the exhaust gas temperature and pressure at various engine output loads. Structural safety was assessed using static structural and stress-life fatigue analyses. A sharp increase in maximum equivalent stress and strain was observed at output loads of 85% and higher. At 25% load, the maximum fatigue life indicated $1.76{ \times 10}^8$ cycles, while at 100% load, the maximum damage index reached 1. A field performance test conducted at 85% of the main engine’s output load revealed severe damage under high-load conditions. Specifically, damage occurred at the contact area between the outer hoop and the tip of the blade’s trailing edge. This observed damage pattern closely aligned with the results predicted by the fatigue life analysis. The validity of the present study was confirmed through a comparative analysis of the fatigue life predictions and the field test results. Full article

Film cooling has been increasingly applied in turbine blade cooling design due to its excellent cooling performance. Although film-cooled blades demonstrate superior cooling effectiveness, the perforation design on blade surfaces compromises structural integrity, making fatigue failure prone to occur at cooling holes. Previous studies by domestic and international scholars have extensively investigated factors influencing film cooling effectiveness, including blowing ratio and hole geometry configurations. However, most research has overlooked the investigation of fatigue life in film-cooled blades. This paper systematically investigates blade fatigue life under various cooling air parameters by analyzing the relationships among cooling effectiveness, stress distribution, and fatigue life. Results indicate that maximum stress concentrations occur at cooling hole locations and near the blade root at trailing edge regions. While cooling holes effectively reduce blade surface temperature, they simultaneously create stress concentration zones around the apertures. Both excessive and insufficient cooling air pressure and temperature reduce thermal fatigue life, with optimal parameters identified as 600 K cooling temperature and 0.75 MPa pressure, achieving a maximum thermal fatigue life of 3400 cycles for this blade configuration. A thermal shock test platform was established to conduct fatigue experiments under selected cooling conditions. Initial fatigue damage traces emerged at cooling holes after 1000 cycles, with progressive damage expansion observed. By 3000 cycles, cooling holes near blade tip regions exhibited the most severe failure, demonstrating near-complete functional degradation. These findings provide critical references for cooling parameter selection in practical aeroengine applications of film-cooled blades. Full article

Vehicles exhibit complex failure modes and mechanisms because of their extreme service environments and severe external loads. The increasing level of integration in these vehicles is also driving more stringent reliability requirements, but conventional methods for reliability analysis require significant calculations, necessitating the use of surrogate models. At present, in the field of the reliability analysis of vehicle dust extraction impellers, although there are various research methods, the research on using surrogate models for relevant analysis is still not perfect. In particular, there are few studies specifically focused on dust extraction impellers. This study established a three-dimensional finite element parametric model of one such fan to simulate the impeller blade stress output for 500 parameter sets. The feedback neural network, backpropagation neural network, and quadratic polynomial response surface were subsequently used as surrogate models to learn the relationship between the parameters and output responses in these data. Comparisons of the results indicated that the feedback neural network exhibited the highest accuracy when predicting the stress responses of the dust extraction fan impeller to changes in parameter values. Through a comparative analysis of multiple surrogate models, this study determined the advantages of the feedback neural network in predicting the impeller stress response. It provides a more efficient and accurate method for reliability analysis in this field and helps to promote the development of reliability research on vehicle filtration systems. Full article

When analyzing the dynamics of wind turbines under the action of wind and ground motion, mass–point models cannot accurately predict the dynamic response of the structure. Additionally, the coupling effect between the pile foundation and the soil affects the vibration characteristics of the wind turbine. In this paper, the dynamic response of a DTU 10 MW wind turbine under the coupling effect of wind and an earthquake is numerically studied through the combined simulation of finite-element software ABAQUS 6.14-4 and OpenFAST v3.0.0. A multi-pile foundation is used as the foundation of the wind turbine structure, and the interaction between the soil and the structure is simulated by using p-y curves in the numerical model. Considering the coupling effect between the blade and the tower as well as the soil–structure coupling effect, this paper systematically investigates the vibration response of the blade–tower coupled structure under dynamic loads. The study shows that: (1) the blade vibration has a significant impact on the tower’s vibration characteristics; (2) the ground motion has varying effects on blades in different positions and will increase the out-of-plane vibration of the blades; (3) the SSI effect has a substantial impact on the out-of-plane vibration of the blade, which may cause the blade to collide with the tower, thus resulting in the failure and damage of the wind turbine structure. Full article

Inconel 600 alloy has gained consideration as a favourable material for heat and power applications, particularly in turbine blades, due to its superior mechanical behaviour encompassing strength, toughness, oxidation resistance, and ductility. Tungsten Inert Gas (TIG) welding is one of the preferred techniques for joining these alloys. Therefore, the investigation of the mechanical behaviour after the welding process is crucial for selecting the appropriate technique for joining Inconel 600 sheets. This research focuses on investigating the microstructure and mechanical behaviour of TIG-welded Inconel 600 through a series of tests, such as tensile, fatigue, creep, and hardness evaluations. In addition, microstructural analysis is combined with these mechanical evaluations to simulate the operating conditions experienced by turbine blades. Key parameters such as yield strength, tensile strength, and elongation have been evaluated through these analyses. The Ramberg–Osgood relationship has been investigated using the engineering and true stress–strain curves obtained from the welded specimens. The results of the fatigue test illustrate the relationship between strain amplitude and the number of cycles to failure for single and double-edge notched specimens. The test was performed at two different loads including 400 MPa and 250 MPa at a constant temperature of 650 °C, and the corresponding strain-time curves were recorded. The results showed rapid creep failure at 650 °C, suggesting that TIG welding may need to be optimized for high temperature applications. Full article

Compared with powder metallurgy, centrifugal casting, jet molding, and other technologies, Laser Melting Deposition (LMD) stands out as an advanced additive manufacturing technology that provides substantial advantages in the melt forming of functional gradient materials and composites. However, when high-temperature and high-speed laser energy is applied, the resulting materials are susceptible to porosity, which restricts their extensive use in fatigue-sensitive applications such as turbine engine blades, engine connecting rods, gears, and suspension system components. Since fatigue cracks generally originate near pore defects or at stress concentration points, it is crucial to investigate evaluation methods for pore defects and stress concentration in LMD applications. This study examines the effect of pore defects on stress concentration in LMD-manufactured AlSi10Mg using the crystal plasticity finite element method and proposes a stress concentration coefficient characterization approach that considers pore size, morphology, and location. The simulation results indicate a competitive mechanism between pores and grains, where the larger entity dominates. Regarding the influence of aspect ratio on stress concentration, as the aspect ratio decreases along the stress direction, the stress concentration increases significantly. When pores are just emerging from the surface (s/r = 1), the stress concentration caused by the pore reaches its maximum, posing the highest risk of material failure. To assess the extent to which the aspect ratio, position, and size of pores affect stress concentration, a statistical correlation analysis of these variables was conducted. Full article

This review investigates interlayer hybrid fiber composites for wind turbine blades (WTBs), focusing on their potential to enhance blade damage tolerance and maintain structural integrity. The objectives of this review are: (I) to assess the effect of different hybrid lay-up configurations on the damage tolerance and failure analysis of interlayer hybrid fiber composites and (II) to identify potential fiber combinations for WTBs to supplement or replace existing glass fibers. Our method involves comprehensive qualitative and quantitative analyses of the existing literature. Qualitatively, we assess the damage tolerance—with an emphasis on impact load—and failure analysis under blades operational load of six distinct hybrid lay-up configurations. Quantitatively, we compare tensile and flexural properties—essential for WTBs structural integrity—of hybrid and glass composites. The qualitative review reveals that placing high elongation (HE)-low stiffness (LS) fibers, e.g., glass, on the impacted side reduces damage size and improves residual properties of hybrid composites. Placing low elongation (LE)-high stiffness (HS) fibers, e.g., carbon, in middle layers, protects them during impact load and equips hybrid composites with mechanisms that delay failure under various load conditions. A sandwich lay-up with HE-LS fibers on the outermost and LE-HS fibers in the innermost layers provides the best balance between structural integrity and post-impact residual properties. This lay-up benefits from synergistic effects, including fiber bridging, enhanced buckling resistance, and the mitigation of LE-HS fiber breakage. Quantitatively, hybrid synthetic/natural composites demonstrate nearly a twofold improvement in mechanical properties compared to natural fiber composites. Negligible enhancement (typically 10%) is observed for hybrid synthetic/synthetic composites relative to synthetic fiber composites. Additionally, glass/carbon, glass/flax, and carbon/flax composites are potential alternatives to present glass laminates in WTBs. This review is novel as it is the first attempt to identify suitable interlayer hybrid fiber composites for WTBs. Full article

Stiffened panels are extensively used in aerospace applications, particularly in wing and fuselage sections, due to their favorable strength-to-weight ratio under in-plane loading conditions. This research employs the commercial finite element software Ansys-19 to analysis the critical buckling and ultimate collapse load of an aluminum stiffened panel having a dimension of 1244 mm (Length) × 957 mm (width) × 3.5 mm (thickness), with three stiffener blades located 280 mm away from each other. Both the critical buckling load and post-buckling ultimate failure load of the panel are validated against the experimental data found in the available literature, where the edges towards the length are clamped and simply supported, and the other two edges are free. For nonlinear buckling analysis, a plasticity power law is adopted with a small geometric imperfection of 0.4% at the middle of the panel. After the numerical validation, the investigation is further carried out considering four different lateral pressures, specifically 0.013 MPa, 0.065 MPa, 0.085 MPa, and 0.13 MPa, along with the compressive loading boundary conditions. It was found that even though the pressure application of 0.013 MPa did not significantly impact the critical buckling load of the panel, the ultimate collapse load was reduced by 18.5%. In general, the ultimate collapse load of the panel was severely affected by the presence of lateral pressure while edge compressing. Three opening shapes—namely, square, circular, and rectangular/hemispherical—were also investigated to understand the behavior of the panel with openings. It was found that the openings significantly affected the critical buckling load and ultimate collapse load of the stiffened panel, with the lateral pressure also contributing to this effect. Finally, in critical areas with higher lateral pressure load, a titanium panel can be a good alternative to the aluminum panel since it can provide almost twice to thrice better buckling stability and ultimate collapse load to the panels with a weight nearly 1.6 times higher than aluminum. These findings highlight the significance of precision manufacturing, particularly in improving and optimizing the structural efficiency of stiffened panels in aerospace industries. Full article

The periodic unsteady flow induced by rotor–stator interaction (RSI) is the primary cause of blade forced vibration and fatigue failure. Therefore, analyzing the excitation characteristics of RSI flow fields under multi-parameter conditions is essential for vibration analysis and optimization in fluid–structure interaction. This study derives the Toeplitz structure of the correlation matrix in proper orthogonal decomposition (POD) for strictly periodic flow fields and reveals that the POD spatial modes appear in pairs with a 90° spatial phase difference, which originates from the cosine and sine form of the eigenvectors of the Toeplitz matrix. Taking a 1.5-stage compressor cascade as an example, the POD method is employed to effectively extract the main spatiotemporal characteristics of the RSI flow field, and the spatial symmetry and phase difference of the POD modes are further interpreted from a physical perspective. To address the high computational cost and resource demands arising from large-scale similar cases in multi-parameter excitation optimization and analysis, a reduced-order modeling (ROM) method based on time–space and parameter decoupling is proposed using multi-parameter POD. Spatial bases are extracted through the first-level POD, and a second-level POD is applied to the first-level coefficients to obtain temporal bases and coefficients that are solely parameter-dependent. A radial basis function (RBF) interpolation is used to establish the mapping between parameters and the second-level coefficients, enabling efficient multi-parameter ROM construction. The resulting ROM achieves a relative prediction error of less than 1.4% under typical operating conditions and less than 2.9% near the choke boundary, improving computational efficiency by four orders of magnitude while maintaining accuracy, thereby providing an effective approach for aerodynamic excitation acquisition. Full article