Maintenance, Reliability and Condition Monitoring
Not a member yet
1200 research outputs found
Sort by
Comparison of different experimental methods for measuring droplet size in inkjet printing
Full text linkIn the inkjet printing process, controlling the droplet size is essential to ensure uniform thin film, a critical factor for achieving high performance of electronic devices. In this study, we evaluate the accuracy and applicability of three droplet measurement methods using inks with different properties. The first method is the laser diffraction method, which measures individual droplets based on the Fraunhofer diffraction in real time. The second is the mass measurement method, which calculates the droplet mass using a microbalance and employs evaporation compensation to minimize evaporation effects, and the third method is the shadow imaging method, a widely adopted commercial technique based on the international standard. To evaluate the accuracy of these measurement methods with three inks having various boiling points (BP), laser diffraction serves as a benchmark here to compare the results of the shadow image and mass measurement methods. Laser diffraction was selected because it shows better coefficient of variation about 1.7 % than the coefficient of variation of mass measurement and shadow imaging methods about 8.7 % and 6.4 %, respectively. The BP of the ink and measurement precision based on laser diffraction results were proportional to each other. These insights guide the selection of optimal measurement method for inkjet printing applications with printed electronic inks. When printed electronic inks with various boiling points were used, the laser diffraction method consistently demonstrated better measurement errors in droplet size than the mass measurement and the shadow imaging method
Application of GSABO-VMD-KELM in rolling bearing fault diagnosis
Full text linkTo address the difficulties in extracting fault features of rolling bearings and the low diagnostic accuracy, a fault diagnosis method for rolling bearings is proposed. This method integrates the Golden Sine Algorithm (GSA) with the Subtraction-Average-Based Optimizer (SABO) to form a Golden Sine Improved SABO Optimization Algorithm (GSABO). The GSABO algorithm is used for parameter optimization of Variational Mode Decomposition (VMD) and Kernel Extreme Learning Machine (KELM) in the fault diagnosis process. Firstly, the chaotic mapping strategy is used to optimize the population initialization of the Subtractive Clustering-Based Adaptive Optimization (SCAO) algorithm, enhancing population diversity. Secondly, the Golden Sine Algorithm (GSA) is integrated to improve the displacement algorithm, enhancing global search capability and effectively avoiding getting trapped in local optima. Then, the GSABO-VMD (Golden Sine Algorithm-Based Optimized Variational Mode Decomposition) is employed to decompose the rolling bearing fault signals, and the envelope entropy minimum criterion is used to select the effective modal components. Finally, time-frequency domain indicators of the selected modal components are computed to form a feature matrix, which is then input into GSABO-KELM (Golden Sine Algorithm-Based Optimized Kernel Extreme Learning Machine) for fault classification and recognition. Experimental analysis shows that compared to the unmodified SABO algorithm, GSABO has significant advantages in terms of escaping local optima, convergence speed, and accuracy. When compared with other traditional algorithms, GSABO-VMD-KELM achieves recognition accuracies of 99.3333 % and 99.0476 % on bearing data from Case Western Reserve University (CWRU) and Xi'an Jiao tong University (XJTU), respectively. This demonstrates the accuracy and superiority of the algorithm and provides valuable insights for engineering applications in rolling bearing fault diagnosis
Kinematic synthesis of a cam-follower mechanism of a novel internal combustion engine
Full text linkThis paper presents a kinematic synthesis of a groove-type disk cam that directly drives sliders in a novel internal-combustion engine architecture. The synthesis is formulated in an invariant (normalized) space and enforces zero acceleration at phase boundaries while embedding a quasi-constant-velocity segment in the mid-portion of the compression (retraction) phase. An arbitrary shaping function is introduced to generate a family of admissible motion laws; a constrained optimization (series truncated to four terms) minimizes the peak acceleration under a prescribed bound on velocity, yielding a PLM with a quasi-constant-velocity interval of approximately 39 % of the kinematic cycle (±5 %). The synthesized retraction law is paired with a sinusoidal approach (power) law to ensure zero endpoint accelerations for both phases. Cam profiles for the working and return strokes are constructed; maximum pressure angles remain within admissible limits across examined phase splits, including an experimental 65°/25° case. Compared with the sinusoidal baseline, the synthesized law retains a similar acceleration constant but reduces the velocity constant by approximately 31 %, indicating lower inertial loading and milder end-conditions that are favorable for mixture preparation and bearing lubrication. The results provide a compact, implementable route to motion programming for cam-driven reciprocators in internal-combustion engines and establish feasibility for multi-cylinder layouts
Towards the efficiency research of the working process of locomotives diesel under operating conditions
Full text linkA method is proposed for quantitative assessment and justification of the criterion of the rationing indicators of external and boost air temperature factors on the qualitative component of the working process of two-stroke supercharged diesel engines under various load conditions of the traction power plant of operating diesel locomotives. The results of the study were obtained in the numerical values and graphs, as well as analytical dependencies (equations) designed to substantiate the parameters under study, including their average values under different operating mode diesel and ambient temperatures. These studies are recommended to continue with the aim of studying the intensity of the dynamics of the decrease or increase in the relative filling coefficients of the 10D100 diesel cylinders with air and developing a methodology for predicting the criterion of the influence of the rationing of boost indicators and outside (external) air on the operating process of diesel locomotives diesels
Research on the influence of width-height ratio and internal friction angle of the TT mode on the trapezoidal sliding surface of backfill behind the retaining wall
Full text linkThe morphology of sliding surface is an important factor in the earth pressure analysis. To study the characteristics of the sliding surface of backfill behind a rigid wall, taking the translational mode of wall (TT model) as an example, a model test was conducted through a self-made test device, and numerical modelling and theoretical analysis were carried out. The research shows: (1) The finite sliding surface morphology starts from the heel of the wall and consists of multiple “straight lines”. The smaller the width-height ratio and the internal friction angle, the more the number of straight line segments of the finite sliding surface. (2) The “length factor” of the sliding surface is introduced and defined. Through normalisation processing, the width-height ratio, internal friction angle, and length factor are linearly fitted, showing a high degree of linear correlation. (3) The study of the width-height ratio, internal friction angle, and length factor yields a binary quadratic surface function, which shows a high degree of linear correlation. The study fills the research gap of the joint influence of the width-height ratio and internal friction angle on the folded-line type sliding surface. It proposes a quantitative calculation formula for the determination of the finite soil
Development of a flexible piezoresistive sensor prototype using resin doped with magnetically oriented nanoparticles
Full text linkHigh-performance flexible piezoresistive sensors are highly useful in areas such as biomedicine, soft robotics, and pressure change detection technology. However, they require complex designs and advanced manufacturing methods. In this study, the design and fabrication of a flexible piezoresistive sensor using a flexible resin matrix doped with magnetically oriented iron nanoparticles is presented. The sensor consists of a flexible polymer resin matrix as substrate, reinforced with iron nanoparticles in different concentrations (0.5 %, 0.7 % and 1 % by weight), oriented by a magnetic field during the manufacturing process. The nanoparticles significantly enhance the piezo-resistive properties of the sensor, increasing its sensitivity and electrical conductivity under compressive loads. The sensor demonstrated high sensitivity under loads greater than 100 N in samples with concentrations of 0.7 % and 1 % of nanoparticles, and exhibited stability during cyclic testing, demonstrating durability. Additionally, stability tests showed excellent durability in repeated load cycles. Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) confirmed the effective alignment and distribution of the nanoparticles within the matrix, enhancing conductivity. This flexible piezoresistive sensor doped with nanoparticles has great potential for future applications in technologies such as soft robotics and electronic skins, where high sensitivity and durability in pressure detection are required
Vibration damping and interfacial adhesion behavior of steel-UHMWPE composite structures
Full text linkHybrid structures combining steel and polymer layers are widely used in engineering systems where vibration reduction and mechanical durability are required. In this study, a composite structure consisting of a low-carbon steel substrate and an ultrahigh molecular weight polyethylene (UHMWPE) coating was investigated in terms of vibration damping capacity, adhesion strength, and thermal behavior. The UHMWPE coating was applied to the steel surface through a thermal pressing technique under optimized temperature and pressure conditions. The vibration damping performance was analyzed using a modal analysis method and accelerometer-based measurements within the frequency range of 100-1000 Hz. Interfacial adhesion was evaluated via shear and peel tests according to ASTM D1002 standards. Results show that the steel-UHMWPE composite exhibits up to 35-40 % improvement in damping ratio compared to bare steel specimens. The optimal adhesion strength was achieved at a processing temperature of 190 ℃, where the interfacial energy balance between the polymer and steel substrate minimizes delamination. Thermal stability analysis using DSC and TGA confirmed the material’s operational range up to 120 ℃, making it suitable for automotive and mechanical vibration isolation applications. These findings demonstrate that the combination of steel’s stiffness and UHMWPE’s viscoelastic damping behavior offers a promising approach to lightweight vibration control components. Further optimization of interface modification and filler reinforcement is planned to enhance tribological and thermal resistance properties
Development of methodology for monitoring of metalworking fluids quality
Full text linkEfficient monitoring of metal-working fluids (MWFs) is crucial to maintaining optimal machining performance and ensuring the safety and health of workers in the metalworking industries. Knowledge of the performance of cutting fluids in the machining of various workpiece materials is very important to improve the efficiency of any machining process. Metal machining companies using MWS have the opportunity to choose the best product from the wide range offered, which can differ in physical parameters as it is designed to be best for the selected process. The unique adaptation to the manufacturing process poses certain challenges in monitoring MWS quality during machining. The importance of MWS quality is crucial, which can lead to costly defects and loss of workpieces. The monitoring only by the quality lab sometimes is insufficient. This article presents the development of a sensor for the indirect monitoring of MWFs, aiming to provide a cost-effective and nonintrusive solution to assess the quality and condition of these fluids. The measurement results are compared with those of other emulsion quality control protocols. Its implementation can significantly enhance the efficiency of MWF management, leading to improved machining performance, reduced downtime, and enhanced worker safety. The sensor's nonintrusive nature eliminates the need for frequent manual sampling, reducing costs and minimizing the environmental impact associated with traditional monitoring practices. Overall, the sensor described in this article offers a viable solution for indirect monitoring of MWFs, contributing to the advancement of smart manufacturing and the optimization of metalworking processes
Experimental study on vibration isolation performance of mining dump truck suspensions for improving ride comfort
Full text linkThis study addresses the challenge of reducing the transmission of low-frequency road excitation vibrations to the cab of mining dump trucks to enhance ride comfort. Given the harsh working conditions of these vehicles, a novel methodology combining experimental data collection and advanced signal processing techniques was developed. The research established a comprehensive vibration testing program aligned with earth-moving machinery standards, collecting vibration acceleration data under both idling and full-load operation at 35 km/h. To improve data accuracy, Singular Value Decomposition (SVD) was employed to denoise the experimental vibration data, effectively mitigating environmental interference. Subsequent Fourier transform analysis revealed the vibration energy transfer patterns of the vehicle suspension system in the frequency domain. The results indicated a significant vibration isolation rate of 89 % for the frame suspension system, contrasting with only 7 % for the cab suspension system. Notably, the cab seat suspension system was found to amplify low-frequency road excitations. Compared to previous methods, this study innovatively integrates SVD and Fourier transform techniques to provide a more accurate and detailed understanding of vibration transmission. The key result of achieving an 89 % vibration isolation rate for the frame suspension system demonstrates the effectiveness of the proposed methodology. This study offers practical optimization directions for improving suspension system performance and ride comfort in mining dump trucks, outperforming traditional approaches by providing a more comprehensive analysis and actionable insights for vibration isolation. The findings also serve as valuable references for addressing similar engineering challenges in heavy machinery
Analysis on the influence of blade pitch angle on dynamic characteristics of the rotor system
Full text linkAt present, few studies focus on variable-pitch fans for small-to-medium turbofan engines, with most relying on hydraulic actuation that fails to meet strict environmental and efficiency demands. This paper analyzes an electrically actuated lead-screw servo-motor-driven variable-pitch fan rotor: at 1×10⁷ N/m support stiffness, the first critical speed exceeds the operational range and pitch angle’s influence is negligible, peak unbalance response is 1.22×10⁻⁶ m linearly decreasing with pitch angle, and vibration analysis avoids resonance. Results confirm the electric pitch-change concept’s feasibility