Journal of Mechanical Engineering, Automation and Control Systems
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Multi-scale rheological properties of municipal solid waste fly ash-asphalt mastic materials
Full text linkIn order to promote the resource utilization of the byproducts of municipal solid waste incineration in asphalt pavement materials, this study selected different types of waste incineration fly ash as fillers and prepared waste fly ash-asphalt mastic materials. The Brookfield viscosity test was used to investigate the variation in apparent viscosity of the waste fly ash-asphalt mastic at different temperatures. The dynamic shear rheological test was employed to study the effects of fly ash content on the viscoelastic properties of asphalt under different frequencies. The low-temperature bending beam rheological test was used to analyze the changes in creep stiffness and creep rate of the waste fly ash-asphalt mastic. Based on this, the rotating film oven aging test was conducted to investigate the mass loss and softening point increment of the waste fly ash-asphalt mastic. The results indicated that the small particle size and developed pore structure of fly ash contributed to the adsorption of asphalt components, enhancing the volume of the mastic. As the fly ash content increased, its specific surface area also increased, further promoting the increase in the viscosity of the asphalt mastic. Under low-temperature conditions, the asphalt mastic became more prone to hardening and brittleness, which resulted in poorer low-temperature cracking resistance, consistent with the ductility results
Research on the relationship between shaft vibration and bearing vibration under complex fault conditions using full vector spectrum
No full textShaft vibration and bearing vibration are key indicators for measuring the dynamic characteristics of the rotor and support bearing system, which play crucial role in reflecting the operation performance of the equipment. However, collecting shaft vibration and bearing vibration signals simultaneously often encounters multiple challenges in practical applications, mainly due to limitations in measurement technology, interference from faults, and variability in operating environments. Conducting in-depth research to explore the interrelationship between shaft vibration and bearing vibration is of great significance, which not only could achieve data complementarity and enhance information integrity, but also provide more accurate references for fault analysis and status monitoring. Therefore, this study proposes a method to investigate the relationship between the two under support loose fault state based on integrating homologous information. The study first constructs a dynamic model under support loose fault condition. Then the homologous information is integrated using full vector spectrum technology, which could enhance the accuracy in reflecting the relationship between the shaft vibration and bearing vibration at different speeds. The simulation results reveal that by mastering this complementary relationship, the operating health status of equipment can be inferred based on the trend of some other key parameters even if in the absence of a certain measured signal, and corresponding maintenance and management measures can be formulated accordingly
Research on the dynamics of a permanent magnet direct-drive bogie with consideration of electromechanical coupling
No full textA vehicle–motor coupled dynamic model for a permanent magnet direct-drive (PMDD) axlebox-built-in bogie operating at 120-200 km/h is developed in this study. The model integrates a multibody vehicle system and a PMSM traction system under an SVPWM vector-control strategy to investigate electromechanical coupling effects. The influence of current-loop and speed-loop control parameters on motor output characteristics and vibration transmission is analyzed. Simulation results show that the dominant frequencies of vehicle lateral and vertical vibrations are mainly concentrated in 3-15 Hz, and the vehicle maintains stable dynamic performance during traction. The speed-loop parameters significantly affect the coupled vibration between the motor and the bogie frame and may induce vertical resonance, while the current-loop parameters have minimal impact. Furthermore, the analysis of motor-suspension stiffness indicates that higher stiffness improves high-speed running stability. The proposed model provides guidance for PMDD traction system control optimization and bogie design for 120-200 km/h urban rail trains
Numerical evaluation of horn geometry influence on VHCF ultrasonic test parameters
Full text linkThe study presents a numerical investigation of the influence of horn geometry on the performance of a 20 kHz ultrasonic testing system used for Very High Cycle Fatigue (VHCF) applications. The system, comprising an aluminium horn and duplex 2205 steel specimen, was evaluated using COMSOL Multiphysics. Four horn geometries – conical, stepped-conical, exponential, and stepped-cylindrical – were analysed to compare their ability to amplify displacement and stress under varying input voltages. Findings indicate the importance of horn geometry in achieving optimal resonance and mechanical amplification, offering valuable insight for the design of efficient ultrasonic fatigue testing systems
Development of a tool centre point tracker for performance monitoring of industrial robots
Full text linkAccurate monitoring of robotic Tool Centre Point (TCP) trajectories is essential for ensuring precision, repeatability, and quality in industrial processes such as welding, milling, and assembly. The proposed framework integrates computer vision techniques with trajectory analysis to facilitate the monitoring of robotic operations. The system integrates an industrial robot with an HD camera and Python-based OpenCV processing to visualize and evaluate deviations in real time. The methodology is structured into three stages: (i) contour detection and preprocessing of visual data, (ii) trajectory tracking and visualization, and (iii) accuracy evaluation through nearest-neighbor point cloud analysis and Euclidean distance metrics. The findings demonstrate the system's capacity to reliably detect pointer motion, remove irrelevant background information and compute deviations with millimeter-scale precision. A comparative investigation was conducted to determine the accuracy, consistency, and robustness of automated monitoring in comparison to manual observation
The airflow behavior of light particulate materials during free fall and their impact dynamics on screening surfaces
No full textTo optimize the efficiency and noise performance of high-frequency vibrating screens, this study investigates the airflow behavior of lightweight materials during free fall and their impact dynamics on the screening surface. Based on the energy conservation theorem and the characteristics of tobacco screening, a computational model for the air resistance coefficient was derived. KT board specimens were employed as experimental substitutes for tobacco leaves to examine the effects of porosity and geometric dimensions on descent velocity and air resistance. The results indicated that materials with higher porosity exhibited greater descent velocities and lower air resistance, whereas larger geometric dimensions lead to increased aerodynamic drag and higher resistance coefficients. Furthermore, field operational modal analysis revealed that the sieve plate exhibited subharmonic resonances within the 9.9-10 Hz and 20-30 Hz frequency bands under nonlinear excitation. These findings could provide theoretical and data support for structural optimization aimed at noise reduction and screening efficiency enhancement
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
Predictive vibration diagnostics of helicopter rotating units in field conditions
No full textCurrent helicopter onboard monitoring systems are not effective enough, and most helicopters do not even have them. As helicopter unit state is not clearly known, it is subject of preventive maintenance. To maintain helicopters predictively reducing repair costs and time, the techniques are required that allow diagnosing the operating units in field conditions for all helicopters. This work is aimed to practically check the Vibropassport techniques allowing the predictive maintenance on the operating helicopter. The Vibropassport using high-order models considers the spatial vibrations in a wide frequency range, applies diagnostic parameters at the normalized scale, and allows diagnostics using a single field inspection. The main finding of the work is that the Vibropassport-based system adapted to a specific helicopter type allows the detailed diagnostics of the engines, gearboxes and transmissions based on the data of a single test in field conditions. Applicability of the Vibropassport system in field conditions was demonstrated on an operating helicopter, and the vibration-based diagnostics estimates whether the unit state complies with the thresholds common for a wide range of similar units. The Vibropassport-based system makes the predictive maintenance possible, reducing costs of maintenance and repair for helicopters, including those without onboard monitoring systems
Study on craniocerebral dynamic response and helmet protection performance under accompanying shock wave
No full textTo systematically investigate the protective effects of helmets against human head injuries under various shock wave conditions, a finite element head-helmet coupling model was developed. This model analyzed how helmets influence biomechanical response parameters, such as intracranial and cranial pressure, when subjected to a single blast wave and its accompanying shock wave. While extensive research exists on single blast scenarios, studies on the more complex and militarily relevant accompanying shock waves, which pose a greater threat due to prolonged loading and multiple reflections, remain scarce. Several impact scenarios were considered, including single frontal impact, positive continuous impacts, successive sidewall impacts, and simultaneous frontal and lateral impacts. The study examined the dynamic changes in brain tissue within a blast environment to assess the efficacy of helmets in protecting the human head. In single frontal impact scenarios, helmets effectively reduced intracranial pressures in the frontal, occipital, and parietal lobes by 32 %, 38 %, and 19 %, respectively, while significantly decreasing the stress peak at the back of the skull. During positive continuous impacts, helmets decreased intracranial pressure in the parietal and occipital lobes by 36 % and 21 %, respectively, although their effectiveness in reducing frontal lobe pressure was limited due to inadequate facial protection. For successive sidewall impacts, helmet protection delayed the blast wave, reducing intracranial pressure in the frontal lobe by 60 kPa but increasing pressure in the parietal lobe by 80 kPa. This alleviated stress on the skull’s rear while increasing stress on the opposite side. In scenarios involving simultaneous frontal and lateral impacts, lateral blasts increased parietal intracranial pressure by 20 kPa, with the right hemisphere experiencing more pressure than the left due to the mitigating effect of reflective side blasts on skull stress. The study found that, compared to single blast waves, accompanying shock waves present a greater risk of cranial injuries due to their prolonged impact. These findings address a critical gap in blast neurotrauma research and provide valuable insights into the biomechanics of head injuries under realistic multi-blast conditions, which can directly inform the design of improved helmets with enhanced protection in complex blast environments. However, because shock waves may originate from multiple directions and elevations, the protective capability of conventional helmets for the facial region remains limited
Evaluation of the ride smoothness of railway rolling stock with a pneumatic suspension system
Full text linkThe object of the study is multiple-unit rolling stock with a pneumatic suspension system. To evaluate the dynamic safety indicators of train operation, namely ride smoothness, full-scale experimental dynamic tests of the multiple-unit rolling stock were conducted under actual operating conditions. The tests involved attaching analog acceleration sensors to the upper mounting plate of the pneumatic spring. Using modern ADXL-335 analog accelerometers combined with an ESP-32 microcontroller, acceleration records of the car body in vertical and horizontal directions were obtained. It was established that the root mean square acceleration in the vertical direction is 0.278-0.312 m/s2, in the horizontal direction – 0.206-0.251 m/s2, while the ride smoothness index W lies within the following ranges: for the vertical direction – 2.96-3.06; for the horizontal – 2.91-3.09. The obtained results can further be used to verify the adequacy of the outcomes derived from theoretical mathematical models