Material Science, Engineering and Applications
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Alternative progressive stamping injection determination by eddy current sensors readings
Full text linkThe study discusses the accuracy of eddy current sensors in measuring material thickness, during production process with a maximum deviation of 25,3 µm. It presents a comparison table of calibrated plates and sensor readings, highlighting certain discrepancies attributed to measurement techniques, random errors and sensor positions. The experiment's findings show that by implementing sensors it is possible to monitor process in real time and adjust parameters accordingly
Analysis of the influence of flexible ring fillet length on the contact characteristics and motion stability of power roll rings
Full text linkBased on the COMSOL Multiphysics simulation platform, this paper establishes a complete finite element model of a power roll ring assembly. The model consists of inner and outer conductive rings made of H62 brass and a flexible ring made of C17200 beryllium bronze. After meshing, a rotational speed was applied to the inner conductive ring according to actual working conditions, and consistent boundary conditions and friction coefficients were set at the contact pairs for transient dynamic analysis. The study focuses on investigating the influence of the flexible ring’s fillet length (0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, 0.35 mm) on the system’s contact characteristics and motion stability. By analyzing stress nephograms, motion trajectory diagrams, and quantitatively calculating contact pressure, the results show that the maximum contact stress of the flexible ring is concentrated at the contact points with the inner and outer conductive rings and increases with the fillet length. However, the contact pressure decreases as the fillet length increases, with small fluctuation amplitude, ensuring the operational stability of the power roll ring. This research provides a theoretical basis and an effective method for the structural optimization and performance evaluation of power roll rings
Structural optimization of bus chassis frame based on proxy model
Full text linkUnder the premise of ensuring modal and strength characteristics, achieving lightweight design of the structure simultaneously has become a key issue of concern for major automobile manufacturers and research institutions. To reduce the mass redundancy of the bus chassis frame, save production costs and energy consumption, a multi-objective optimization scheme based on surrogate model technology was proposed, which could maximize weight reduction without reducing the natural frequency or increasing the peak stress. According to the working principle, load characteristics and composition of the chassis frame, a parametric coupling model for modal and strength was constructed, and the stress, deformation, natural frequency and vibration mode characteristics of the overall structure were obtained. The dimensions of H-steel were determined as design variables, and the discrete mapping data sets of maximum stress, first-order natural frequency and mass were obtained through the Latin square design scheme. Parameters such as the coefficient of determination, adjusted coefficient of determination and root mean square error were selected as the standard evaluation indicators for the accuracy of the response surface model. The reliability of different surrogate models was compared and analyzed, and finally the Kriging model was adopted as the approximation function in the construction of the mathematical model. An optimized mathematical model was constructed to convert the modal and strength objectives into boundary conditions. The design variables meeting the optimization objectives were derived through the sequential quadratic programming algorithm. The results showed that, without reducing the requirements for strength and stiffness indicators, this optimization scheme could reduce the weight of the chassis frame by 9.94 %, which has good economic benefits and engineering value
Acoustic detection of fan blade faults based on dynamic Cauchy swarm algorithm to optimize support vector machine
Full text linkFan blades operate in outdoor environments, where the detection of sound signals is susceptible to interference from background noise such as random loads, wind speed, rainwater, and other ambient noise. Therefore, this article proposes an acoustic detection method for wind turbine blade faults based on a dynamic Cauchy bee colony algorithm-optimized support vector machine. First, the signal is preprocessed using a Butterworth bandpass filter, and the full frequency band is divided into sub-bands using the octave band feature extraction method. Based on frequency domain analysis, the natural frequency offset of the blade is determined. Next, the dynamic Cauchy bee colony algorithm is applied to optimize support vector machine parameters, while moving average and bandpass filtering are used to smooth the noise power curve and extract impeller speed information. The experimental results show that the proposed method converges in fitness value after 22 iterations, with a detection time of only 6.8 seconds and small fluctuations in impeller speed amplitude. In terms of classification performance, the accuracy of detecting normal samples is 0.95, the recall rate is 0.96, and the F1 score is 0.95. The method demonstrates high prediction accuracy and stability for various types of fault samples and can be reliably applied to the acoustic detection of wind turbine blade faults
Design and verification of a new type of hydraulic vibration isolator for high-speed train floors
Full text linkWith the development of high-speed trains, the requirements for noise, vibration, and comfort are becoming increasingly stringent. The train body floor, as one of the main pathways for vibration transmission, is crucial to be treated for vibration reduction and noise attenuation. This paper, in response to this demand, has developed a new type of floor vibration isolator specifically for high-speed trains. Through finite element simulation analysis and experimental verification, it has been proven that this vibration isolator can effectively reduce the vibration of the train body floor and significantly enhance the NVH (Noise, Vibration, and Harshness) performance of the train
Dual-aggregation feature compilation network for urban traffic object detection and pedestrian pose estimation
Full text linkWith the increasing complexity of urban transportation systems, object detection and pedestrian pose estimation play a crucial role in intelligent traffic management and autonomous driving technologies. However, existing feature compilation networks are often designed for single tasks and perform poorly in small object detection and high occlusion pedestrian pose estimation tasks. To address the above issues, this paper proposes an efficient feature compilation network with Dual-aggregation, compatible with both object detection and pedestrian pose estimation. This network adopts a transfer learning-like training strategy in the feature extraction network, using a micro-complex convolution structure during training to bring the training results as close as possible to global optimization. During inference, a single simple convolution is used to inherit the training results, improving the model performance while ensuring model lightweight. The feature fusion employs a global-local dual aggregation structure, simultaneously considering multi-scale global and local features. Additionally, we use multiple public datasets to create a hybrid dataset under various scenarios to validate the robustness of the network. The experiments show that the proposed method outperforms existing mainstream methods in detection accuracy for urban object detection and pedestrian pose estimation tasks, especially demonstrating better robustness in complex urban traffic scenarios
Study on stability of shaft surrounding rock under adjacent shafts mining disturbance in underground mine
Full text linkThe stability of mine shafts is crucial for safe production in underground mining. To elucidate the impact of adjacent shaft mining disturbance on shaft structural stability in underground mines, this study takes a Manganese Mine in Guizhou, China as a case study. A refined three-dimensional model at engineering scale was established by using the Rhino-FLAC3D coupled modeling method. This model can numerically simulate the mining of ore bodies at different stages of mining. The displacement, stress distribution, and plastic zone in both strata and shaft surrounding rock were systematically analyzed to reveal the response laws of shaft surrounding rock under mining disturbance. The results showed that during the first and second mining phases, no measurable deformation occurred in the surrounding rock of the main shaft, auxiliary shaft, or ventilation shaft. During the third mining phase, the maximum displacement observed in these shafts’ surrounding rock reached 0.048 m, which remains within the stability threshold of rock masses according to evaluation criteria. Regression analysis was conducted on the monitoring displacement of three mining stages, and power function fitting curves were obtained. Plastic zones (20-30 m range) developed along the periphery of goaf areas, maintaining a safe distance of 45-55 m from adjacent shafts. A stress gradient formed around goaf areas, with tension stresses up to 1.33 MPa exceeding the ultimate tension strength of roof strata. There was potential tension failure in the roof strata of the goaf. Although mining disturbance effects on main and auxiliary shafts intensified with depth progression, no substantial structural impacts were observed. This confirms that all shaft structures can maintain stability during operational phases. The findings provide theoretical guidance for shaft stability control in deep mining operations
Design and simulation verification of differential spiral bevel gear transmission based on baja off-road vehicle
Full text linkThe differential spiral bevel gear of Baja off-road vehicle is designed and verified. Based on the competition rules and vehicle transmission parameters, the key geometric parameters of the gear pair are determined, and the three-dimensional model and finite element analysis software are established by UG for static contact analysis and modal analysis. The results show that the maximum contact stress of the tooth surface is 411.4 MPa, and the natural frequency of the gear pair is much higher than the excitation frequency of the system, which can effectively avoid the resonance risk. Through analysis and verification, it meets its application conditions
Experimental method for determining the vibrodynamic state of embankments on high-speed railways
Full text linkThe article presents modern methods for reinforcing the embankment in the zone of the interface between the coastal bridge piers and the earth bed of the high-speed railway section. It has been established that as a result of driving reinforced concrete piles into the railway embankment, the natural vibrations of the earthwork decrease by up to 15 %. A frequency equal to the frequency of vibrations arising from the speed of high-speed railways with the help of vibrators on models of the earth bed for determining the amplitude-frequency characteristics of various design points has been created and the values of this frequency have been processed by fixing them with the help of seismometric sensors SM-3 in all design points. A significant decrease of shear at the main site after driving of reinforced concrete piles and approaching of this value to microseismic value based on the values of sensors located at the main site and at a distance of 1.5 m from the foundation is determined. It has been established that by driving reinforced concrete piles into the railway embankment, the vertical settlement of the earthwork decreases by 33 % and 50 % depending on the soil type. Also, the methodology of experimentation for the study of vibrations of the earth bed piled from different soils on high-speed railroads is given
Analysis of a 10 kW mini pumped hydro storage plant with solar integration in Uzbekistan
Full text linkThis paper presents the design and performance evaluation of a 10 kW mini pumped hydro storage (PSH) system integrated with solar photovoltaic (PV) energy for rural electrification in Uzbekistan. The system stores excess solar energy during the day and generates 60 kWh electricity during evening hours at a rated power of 10 kW, with an overall efficiency of about 75 %. The optimized design includes a Cross-Flow turbine (200 mm diameter, 600 rpm), a 10 m head, and 58 solar panels of 400 W. The study demonstrates that such small PSH systems can provide a cost-effective, long-lifetime alternative to chemical batteries in rural power applications