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Innovative design of a gear belt transmission for technological machines
Full text linkThe article presents the types of belt transmission designs, as well as the advantages of their use in mechanical engineering. Belt drives create loads as a result of excessive vibrations due to a flexible element (belt). A new design of an innovative toothed belt drive is proposed, which contains two paired driving and driven gear pulleys with different diameters and two belts with teeth covering them, while the gear ratios of each pair of gears are equal to each other. The simulation demonstrates a 25-38 % reduction in velocity fluctuation compared to conventional drives, confirming the effectiveness of the proposed design
Stress analysis and seismic performance testing of surrounding rock in coal mine roadway
Full text linkThis study focuses on the stability control of surrounding rock in coal mine roadway. The finite difference method combined with FLAC3D software was adopted to establish numerical simulation model of the roadway roof, so as to analyze the influence of roof cutting height and roof cutting angle on the surrounding rock stress field. Through field tests, the bidirectional blasting excavation technology with energy-gathering pipes was used, combined with resistance-controllable support equipment. Differentiated monitoring point scheme was designed to monitor the changes in anchor cable tension and roof subsidence. The research results show that when the roof cutting height increases from 3 m to 6 m, the maximum stress of the roadway decreases by approximately 17 %, and the high-stress area shifts to the deep stable rock formation. When the roof cutting angle is adjusted from 0° to 10°, the maximum stress decreases by about 19.4 %, and the area of the high-stress zone is reduced to 11 % of the total cross-sectional area. When the distance behind the working face exceeds 100 m, the roof reaches a stable state under the action of support
Analysis of progressive collapse of low-rise concrete frame structure under double earthquake in Türkiye
Full text linkThe double earthquake that struck Türkiye on February 6, 2023 killed over 50,000 people. It also caused the collapse of thousands of low-rise reinforced concrete structures in the seismic area, resulting in incredible damage. To study the reasons for the progressive collapse of numerous buildings, a nine-story concrete frame structure was established in this study, and the elastic-plastic time-history analysis under the double earthquake was performed. The element failure criterion was defined using the max equivalent compressive strain, refining the damage initiation point and transmission path of the proposed structure. The results showed that: 1. The natural period of vibration of the low-rise concrete frame structure in the seismic area is in the peak spectral acceleration region of the first earthquake, which maximizes the earthquake damage force. 2. The first strong earthquake disabled the main load-bearing columns on the ground floor of the structure, resulting in collapse within a few seconds of the second earthquake. 3. The seismic damage investigation showed that the low-rise frame structure had insufficient longitudinal reinforcement laps, insufficient transverse reinforcement and stirrups, and weak embeddedness between longitudinal bars and concrete. These issues have amplified the damage degree. 4. Despite the comprehensive building seismic regulations in Türkiye, the most pressing problem may be the long-term regulatory failure of the authorities
Equations of motion for the rigid and elastic double pendulum using Lagrange’s equations
Full text linkThe double pendulum is a well-known system exhibiting nonlinear dynamics and chaotic behavior. This study extends the conventional rigid double pendulum by introducing elastic extensions in the links, leading to a system known as the elastic double pendulum. The mathematical model incorporates both rotational and translational motion, accounting for elastic deformations using Hooke’s Law. The governing equations are derived using Lagrangian mechanics, considering both gravitational and spring potential energy contributions. Numerical simulations are performed to compare the motion of the elastic and rigid double pendulums, highlighting differences in phase-space trajectories, energy transfer, and stability characteristics. Results demonstrate that elasticity introduces additional oscillatory components, increases system nonlinearity, and affects the overall predictability of motion. These findings provide insights into elastic multi-body dynamics and have potential applications in flexible robotic arms, soft mechanisms, and bio-inspired locomotion
Improved iterative reweighted L1 norm minimization method for sound source identification
Full text linkSparse reconstruction algorithm is one of the main research topics in compressed sensing. To address the shortcomings of existing iteratively reweighted l1-norm minimization methods, which exhibit poor performance in low-frequency sound source identification and weak anti-interference capability, this paper proposes an improved iteratively reweighted l1-norm minimization method. Unlike traditional methods, this method introduces a log-sum penalty function and constructs a surrogate function, transforming the problem into an effective form for solving the source strength distribution vector. Through numerical simulations comparing the two methods under different frequencies and signal-to-noise ratios (SNR), the results demonstrate that the proposed method enhances both the sound source identification accuracy and anti-interference capability of the algorithm, while also being able to adapt to lower frequency ranges
Experimental evaluation of residual deflection and structural stiffness of the UzTE16M locomotive frame under static loading conditions
Full text linkThe structural reliability of locomotive frames is essential for ensuring the safety and durability of railway operations. This study presents a full-scale experimental assessment of the residual deflection and stiffness of the UzTE16M locomotive frame under static loading, supported by finite element method (FEM) validation. Tests were performed on three locomotives (Nos. 005, 010, and 019) at “O‘ztemiryo‘lmashta’mir” JSC under loads of 15, 30, and 40 tons, with deflections measured at three control points. The load–deflection response was nearly linear up to 30 tons, confirming elastic behavior, while at 40 tons a slight deviation appeared, with a maximum deflection of 11.2 mm. Residual deflections of 2-6 mm remained within regulatory limits. FEM analysis reproduced identical boundary conditions, showing a maximum von Mises stress of 127 MPa – below the 235 MPa yield strength – and a deviation of less than 5 % from test results. The integrated experimental-numerical approach effectively evaluates stiffness degradation and residual deflection, offering a reliable framework for fatigue diagnostics, condition-based maintenance, and extending the service life of modernized locomotive frames
Vibration characteristics testing and vibration reduction optimization design of four-wheel-drive micro-tiller handlebar assembly
Full text linkMicro-tillers are essential for agricultural operations in hilly and mountainous regions, yet their severe vibrations pose significant health risks to operators, including hand-arm vibration syndrome. This study presents an innovative vibration reduction solution through the installation of a damping spring isolator at the handle-frame connection point. Comprehensive vibration testing revealed that the vertical vibration under tillage conditions reached 2.15 m/s2 RMS, with spectral analysis identifying critical excitation frequencies at 39 Hz, 78 Hz, and 156 Hz. Constrained modal analysis demonstrated that the handle frame's third-order natural frequency of 41.02 Hz risked resonance with the engine’s 39 Hz excitation. The optimized isolator system, designed with a damping ratio of ξ= 0.2, successfully reduced this critical frequency to 34.87 Hz (15 % reduction), effectively avoiding resonance. Field validation showed significant vibration attenuation, with RMS values decreasing by 14.17 % (idle), 17.61 % (no-load), and 23.26 % (tillage), while achieving 19.3 % vibration energy absorption during operation. This research represents the first successful integration of isolation and damping mechanisms for micro-tiller handle frames, providing a cost-effective solution (< 1.5 % of machine cost) that significantly improves operator comfort and addresses long-standing ergonomic challenges in small-scale agricultural machinery. The solution's simple implementation without structural modifications makes it particularly suitable for widespread adoption in developing regions
Small sample fault diagnosis method based on dual convolutional kernel feature fusion and channel attention weighted temporal convolutional network (DCK-CAM-TCN)
Full text linkIn actual industrial environments, equipment failures often occur sporadically during operation, resulting in insufficient labeled data for training. To address the issues of difficult feature extraction and poor generalization caused by insufficient data in small-sample fault diagnosis, a small sample fault diagnosis method based on dual convolutional kernel feature fusion and channel attention weighted temporal convolutional network (DCK-CAM-TCN) is proposed. Firstly, dual convolution kernels are employed to extract signal features, with the large kernel capturing low-frequency components and the small kernel extracting additional features to enhance the network's expressiveness. Secondly, the channel attention mechanism adaptively adjusts the feature responses of each channel, enabling the network to focus on the most informative and relevant features while suppressing unimportant ones. Finally, the Temporal Convolutional Network (TCN) is utilized to capture dependency features within long time series, further improving the model's ability to process sequential data. Experimental results demonstrate that the DCK-CAM-TCN model significantly outperforms traditional Convolutional Neural Networks (CNNs) and other comparison models in small-sample scenarios. The results indicate the significant advantages of the DCK-CAM-TCN model in small-sample fault diagnosis
Graphical analytical modeling of the kinematic scheme of a rock-piston pump
Full text linkTwo kinematic diagrams are presented, consisting of two combined toggle mechanisms and a piston pump. Kinematic calculations of the moving link parameters for both kinematic diagrams resulted in the determination of the displacement of the working and idle stroke lengths S of the piston as a function of the toggle mechanism swing angle φ and the change in the toggle length and crank radius of the piston pump. The numerical value of the coefficient K of the average toggle mechanism slider velocity, K= 2, and the displacement of the piston stroke S were obtained: for a toggle-piston pump, S= 1.25, and for a crank-toggle mechanism, SK= 0.7 m. Various asymmetric phase angles were calculated for the working φp and idle φx strokes of the slider during rotation of the toggle mechanism crank for both kinematic diagrams. The relationship between the center distance α and the position of the fixed support point O1 of the crank axis of rotation to the support point O2 of the rocker arm is obtained. The numerical values of the stroke displacement SD, linear velocity VD, and acceleration αD of the pump piston for both kinematic diagrams of the rocker-piston pump mechanism are presented in tabular form by numerical values and in kinematic diagrams
A new self-adaptive anti-galloping device in suppressing conductor galloping in transmission lines
Full text linkConductor galloping is a serious threat to transmission line integrity, inducing excessive conductor tension that may lead to catastrophic failures including conductor breakage and tower collapse. This study proposes a novel self-adaptive anti-galloping device (SAGD) to mitigate galloping amplitudes and reduce associated risks. In this paper a novel self-adaptive anti-galloping device (SAGD) to mitigate galloping amplitudes and reduce associated risks was proposed. The structural design scheme of the device is provided, and its operation sequence was verified through static loading experiments. Conductor free-falling experiments validated the SAGD's vibration control performance, with test results demonstrating its practical applicability for transmission line protection. A finite element model for the conductor-SAGD system was developed, enabling numerical simulation of galloping displacement time history and analysis of endpoint support reaction dynamics. The device's galloping suppression effectiveness is systematically evaluated under varying stroke lengths and threshold conditions