Maintenance, Reliability and Condition Monitoring
Not a member yet
1200 research outputs found
Sort by
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
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
Predictive vibration diagnostics of helicopter rotating units in field conditions
Full text linkCurrent 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
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
Full text linkShaft 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
Experimental study on dynamic load compensation of risers under ultra-low frequency vibration
Full text linkIn the event that a floating drilling platform is struck suddenly by a typhoon, preventing the complete retrieval of the riser, a compensation system is required to alleviate the considerable dynamic loads on the riser resulting from platform movement, thus keeping the riser tension within safe limits. Evaluation of the mathematical model for the conventional vibration isolation system indicated unsatisfactory performance under conditions of large displacement and ultra-low-frequency vibration. To address this, a new dynamic load compensation system for the riser has been developed, along with a dedicated experimental platform. In this setup, platform heave is simulated via the extension and retraction of a hydraulic cylinder, while the riser load is represented using multiple mass blocks. The experimental platform supports both manual and automatic control modes. Utilizing Visual Basic (VB) programming integrated with an Access database, the monitoring and control software provides capabilities for parameter configuration, data monitoring, and data archiving. Experiments performed on this platform, including heavy simulation and dynamic load compensation, demonstrated a compensation effect of 27.4 %. The successful mitigation of dynamic loads on the riser presents a novel approach for drilling platforms to cope with typhoon emergencies and suggests valuable applications for vibration isolation technology in other domains
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
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
Research on the dynamics of a permanent magnet direct-drive bogie with consideration of electromechanical coupling
Full text linkA 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
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