Journal of Mechanical Engineering, Automation and Control Systems
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Experimental analysis of running wheel for a straddle monorail vehicle
Get PDFThis article conducts in-depth research on the force analysis of the test running wheel of a certain type of straddle monorail vehicle, based on the tire six-component force test and wheel dynamic stress test. The main research objective is to accurately identify the factors affecting the wheel strength, thereby providing a solid foundation for subsequent design optimization and safety enhancement. The research commences with a meticulous calibration of the vehicle connecting rod in the laboratory, aiming to acquire the “force-strain” coefficients under both tension and compression conditions. A novel approach lies in the verification of calibration accuracy through a detailed comparison with experimental results, ensuring the reliability of subsequent data acquisition. By strategically installing displacement sensors at various positions to measure the vehicle's dynamic displacement and detecting the strain of the connecting rod, the study innovatively calculates the six-component force data of the tire, which provides a comprehensive data basis for analyzing the forces acting on the wheel hub. Then evaluating the fatigue strength of the wheel hub under AW0 and AW3 operating conditions based on the IIW standard, the research uncovers unique findings. It is revealed that, although the maximum dynamic loads of the vertical force of the running wheel, the lateral force of the guide wheel, and the lateral force of the stabilizing wheel are within the limit load range with a certain safety margin, there are 1 point and 3 points on the wheel hub under AW0 and AW3 working conditions, respectively, that fail to meet the fatigue strength criterion requirements. The maximum equivalent force amplitude at Measurement Point 3 of the inner hub reaches 51.4 MPa, while the calculated service mileage is only 31,000 kilometers. This discovery is of great significance as it precisely pinpoints the weak points of the wheel hub, which is a major contribution to the field. Moreover, during the analysis of the wheel hub's dynamic stress during emergency braking and the influence of polygonal wear on it, the research confirms that there is no abnormal change in the wheel hub’s dynamic stress during emergency braking, and the polygonal wear of the tire shoulder has a negligible impact on the wheel hub’s dynamic stress. These results not only calculate the six-component force data of the tire but also break new ground in understanding the interaction between different factors and the wheel hub’s performance
Coupling dynamics modeling and vibration characteristics analysis of TBM main drive system under complex tunnelling conditions
Get PDFIn order to ensure the reliable operation of TBM excavation process, it is particularly important to analyze the vibration characteristics in complex surrounding rock environments. The coupling dynamics model of the TBM main drive system proposed in this article considers the structural characteristics of distributed support and multi-source inputs, as well as nonlinear internal excitations such as bearing dynamic stiffness, gear meshing error, and tooth side clearance, which can more accurately calculate the dynamic characteristics of the main drive system. Based on the TBM scale test-bed, the modeling method and the vibration response of the main components were compared and verified. Based on the coupled dynamic model of the main driving system, the vibration characteristics of the driving system were analyzed under different excavation penetrations and different proportions of soft and hard surrounding rocks. The analysis results show that during the process of penetration from 5 mm to 6 mm, the average vibration increase speed is the highest, reaching 0.1493 g/mm. As the proportion of soft surrounding rock increases, the lateral unbalanced load and torque of the cutterhead significantly increase. Meanwhile, as the proportion of soft surrounding rock increases, the corresponding rate of load increase significantly increases. Within the range where the proportion of soft surrounding rock increases from 21 % to 35 %, its lateral overturning vibration RMS value increases by 13.08 %. Within the range where the proportion of soft surrounding rock increases from 35 % to 50 %, its lateral overturning vibration RMS value increases by 32.18 %. This can easily cause safety accidents such as the fracture of key load-bearing components of the system during the excavation process
Improvement of the system for reporting the state of the electrified railway contact line
Get PDFEnsuring the stable and reliable operation of electrified railways requires continuous monitoring of the overhead contact line (CL), whose mechanical displacement under wind loads can lead to interruptions in power transmission, pantograph detachment, and safety hazards. Traditional inspection and monitoring systems are limited in responsiveness and cannot provide real-time information about the dynamic state of the CL. This study presents an improved contact line deviation reporting system based on distributed Signal Processing and Transmission Modules (SPTM) and Signal Reception Modules (SRM) connected through a GSM wireless communication network. Each vibration sensor installed on the catenary wire continuously measures the displacement amplitude, converts the analog signal into digital form, and transmits it to the dispatcher or driver in real time. The developed modules were implemented using microcontrollers with embedded wireless interfaces, allowing autonomous operation powered by solar-assisted batteries and ensuring electromagnetic protection under high-voltage (25 kV) conditions. Field experiments were carried out on an electrified railway test section near the Tashkent depot to evaluate the system’s performance in real environmental conditions – including wind speeds of 5-18 m/s, ambient temperatures from –10 °C to +38 °C, and during snow and rain. The results confirmed stable data transmission up to 1 km distance with signal delay below 0.8 s and detection accuracy above 95 %. The proposed system thus enables real-time monitoring, automatic warning, and high reliability of communication even under harsh weather conditions, significantly improving the safety and efficiency of train operation. The novelty of this work lies in the practical validation of a GSM-based monitoring network for contact line deviation detection that integrates autonomous power supply, environmental robustness, and real-field reliability testing – aspects that are rarely demonstrated in previous studies
Fault diagnosis method for wind turbine rolling bearings based on adaptive deep learning
Get PDFIn response to the problem of difficulty in extracting fault features of rolling bearings in wind turbine transmission systems under complex working conditions, which limits the accuracy of fault diagnosis. This article proposes an Adaptive Deep Learning based Rolling Bearing Fault Diagnosis Method (ADLM). Introducing dynamic convolution into Convolutional Neural Networks (CNNs) can adaptively capture data features; At the same time, the fishing optimization algorithm (CFOA) was used to optimize the hyperparameters of the bidirectional long short-term memory network (BiLSTM), and the CFOA-BiLSTM network was constructed to fully leverage its advantages in time series analysis. The specific implementation steps are as follows: first, preprocess the collected vibration signals and divide the processed dataset into a training set and a testing set; Then, parallel adaptive convolutional neural networks (ACNN) are used to process the training set and extract spatial domain local features from the vibration signal; Then, the features extracted from the two branches are weighted and fused through a dynamic weight adjustment mechanism, and the fused features are input into the CFOA-BiLSTM network to further capture the time-dependent features of the signal; Finally, the extracted features are input into the classifier to complete model training, and the model performance is evaluated using a test set. Experimental verification shows that on the dataset of Southeast University, the diagnostic accuracy of the ADLM model reached 98.52 %, demonstrating good reliability, robustness, and superiority in the diagnosis of rolling bearing faults
Establishing the natural frequency of oscillations of a continuous system with a concentrated mass in aviation and manufacturing engineering
Get PDFThe uneven transportation of products in the working bodies (trays) of one-mass vibrating conveyors with inertial exciters prompted the conduct of a study aimed at establishing the natural frequency of oscillations of a continuous system, namely, a long-dimensional body with distributed parameters in the form of a beam with a rigidly fixed concentrated mass. Using the Krylov-Duncan functions, the differential equation of movement of the beam was solved, taking into account the concentrated mass and the boundary conditions at its ends. The system of equations made it possible to analytically establish the natural frequency of such a continuous system. This approach was tested to establish the natural oscillation frequency of a glider, demonstrating its versatility for use in various industries. An analysis of the obtained results was carried out, and conclusions were drawn
An integrative review of control strategies in robotics
Get PDFThis paper presents an integrative review of control strategies in robotics, covering classical control methods (linear quadratic regulator, proportional-integral-derivative), modern methods (adaptive, sliding mode, model predictive, and H-infinity), intelligent control methods (neural network, fuzzy logic, and machine learning), and hybrid control methods (integration of classical, modern, and intelligent control methods) to identify the advantages, limitations and gaps for future. A brief comparison of control methods between the types of control strategies is conducted with respect to robustness, stability, and complexity of implementation on 3 different levels of evaluation criteria: high, average, and low; advantages; limitations; and robotic applications, including examples. This paper discusses the theoretical and practical advancements and the classification of control strategies according to controller types (linear, nonlinear, and learning-based), approaches (model-based and model-free), and classifications (centralized, decentralized, and modal control). The review highlights the strengths, limitations, and potential research directions in bridging classical, modern, intelligent, and hybrid control paradigms to achieve safe, efficient, and adaptive robotic behavior in complex, uncertain environments. We discuss the future direction: autonomy, human-robot collaboration, and enhanced learning and challenges: cost, reliability, safety of control strategies, concluding with recommendations for future research
Machining parameters optimization in high-speed milling of titanium alloy chips
Get PDFHigh-speed cutting of titanium alloy has the advantages of high processing efficiency, reducing tool wear, and obtaining good surface quality, but there is a lack of research on the influence of chip shape on machining parameter selection mechanism in the cutting process, which hinders the development of high-speed milling quality of titanium alloy. In this paper, the shape of titanium alloy (Ti6Al4V) chips at different speeds and different temperatures were simulated. With the increase of cutting speed, the tool squeezes the workpiece material, causing it to undergo elastic deformation and thereby forming a cutting layer. As the cutting process progresses, the chip gradually takes on a serrated shape, the degree of sawtooth sharpening of chips was analyzed. The formation mechanism of chips and the formation process of sawtooth chips during right-angle cutting were analyzed. The locust optimization algorithm was used to optimize the multi-objective parameters, and it was found that high performance machining effect could be achieved by using large feed speed, radial cutting depth and spindle speed
Study on stability of shaft surrounding rock under adjacent shafts mining disturbance in underground mine
Get PDFThe 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
Study of a two-stage wood chip hydrolysis process and the kinetics of monosaccharide formation
Get PDFThis article studies the sulfuric acid hydrolysis of paulownia and poplar wood chips using a two-stage approach. The research analyzes the temperature-dependent kinetics of the hydrolysis process, nothing a peak yield of reducing agents at 170 °C. An increased likelihood of reducing agent decomposition is observed as temperature rises, especially at 180 °C. Using liquid chromatography, the amounts of glucose, fructose, and arabinose in the hydrolysates were measured, with the largest glucose yield obtained at 170 °C. In addition, High-performance liquid chromatography (HPLC) and Fourier-transform infrared (FTIR) spectroscopy showed the emergence of new functional groups in the hydrolyzed wood structure. Based on mathematical modeling and experimental validation, the two-stage hydrolysis method is regarded as a good technique. This method helps raise the of hydrolysates, which are employed as raw materials in biopolymer manufacture
Construction of a mathematical model of the motion of a vibrating separator with pneumatic suspension
Get PDFThe mathematical model of the movement of an arbitrary point of the container of a vibrating separator with a pneumatic suspension is built in the article. For modeling, a vibrating separator with two independently driven unbalances and a pneumatic suspension was chosen, which has a number of advantages over other separators, is characterized by simplicity of construction and maintenance, and low sensitivity to the properties of the medium being separated. The developed unified parameterized model of a vibrating separator can be used by changing its parameters or zeroing them for a wide range of designs of vibrating separators. The use of data from ready-made unified mathematical models allows you to reduce the duration of research and design of vibrating separators, and reduce material costs in general