Journal of Engineering and Thermal Sciences
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Establishing the natural frequency of oscillations of a continuous system with a concentrated mass in aviation and manufacturing engineering
Full text linkThe 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
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
Fatigue performance of corroded fatigue detail of weathering steel
Full text linkThis study evaluates the fatigue properties of corroded weathering steels to assess their long-term structural safety, durability, and economic feasibility. The fatigue life of two groups of weathering steel is measured by experiment. The first group consists of non-corroded specimens, while the second group is subjected to atmospheric corrosion for a duration of one year. The fatigue life of weathering steel is predicted by numerical calculation. It is found that the fatigue life of numerical simulation can accurately predict the fatigue life of butt weld specimens and provide a certain safety margin. The difference between the two is 2.5 %, which is a strong validation of the method. Then, Utilizing the ABAQUS and FRANC3D interactive platforms, the study achieves numerical computations for initial crack insertion and crack propagation under fatigue loading, and the influence of stress amplitude, initial crack size, initial crack shape, initial crack position, and welding dislocation on fatigue life is analyzed. Nine different stress amplitudes are simulated, and the fatigue life difference between the stress amplitudes of 117 MPa and 189 MPa being 31.72 %. Six different initial crack sizes are simulated. The initial crack sizes are 0.075 and 0.5 mm, and the difference in fatigue life between the two is 48.58 %. Four different initial crack shapes are simulated, and the fatigue life difference between the short axis and the long axis ratio of 1/4 and 1/1 of the initial crack is 30.70 %. Three initial crack positions are simulated, and the difference in fatigue life at different positions is less than 10 %. The effects of four different sets of angular dislocations on fatigue life are simulated. Angular misalignment in butt weld specimens has a minimal effect on fatigue performance, approximately 1 %, provided that the flatness requirements of the specifications are met. However, when the flatness requirements exceeded the specification, the effect on the specimen was greater than 30 %, and its effect cannot be ignored. Based on fatigue detail tests of corroded weathering steel, this paper proposes and validates a method for evaluating the fatigue life of weathering steel after corrosion, and clarifies the factors influencing the fatigue life of weathering steel structures, the proposed method can provide support for the design of fatigue details of weathering steel bridges
Stodola-Vianello iteration method for the free flexural vibration frequencies of Shimpi’s single variable shear deformable beams
Full text linkThe natural vibration frequency analysis of beams is vital for their design against resonance failures because such failures occur when the excitation load frequencies of vibration coincide with such natural frequencies. This work presents a single variable shear deformable beam equation formulated using Shimpi’s displacement field assumptions. This results in a quadratic shear stress profile over the depth and a satisfaction of the transverse shear stress-free boundary conditions. The governing equation is obtained using a first principles consideration and equilibrium method as a partial differential equation (PDE) which is non-homogenous for forced vibrations and homogeneous for free vibrations. The study then used the Stodola-Vianello iteration method to solve the resulting homogeneous PDE for simply supported boundary conditions and harmonic response. The problem reduced to an iterative problem of algebra involving the computation of an (n+1)th vibratory modal shape function from an nth shape function that satisfies the boundary conditions. This work used a sinusoidal shape function which is exact for the simply supported boundary condition investigated. The use of boundary conditions solved the integration constants involved. Application of the convergence rule led to the eigenequation from which the eigenvalues were found. The eigenvalues were presented for the first four modes of vibration and for a rectangular beam. It was found that for l/h varying from 5 to 100, the natural vibration frequencies were identical with the ωn values obtained using Navier method for other thick beam vibration problems. It was also found that ωnwas close to the exact values for all vibration modes and for all values of l/h between 5 and 100. For all vibration modes and all considered l/h values negligible differences, were observed between the ωn obtained using SVIM and the exact values obtained by previous researchers
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
Analysis and synthesis of a controllable crank-slider mechanism with parallel springs for frame saws
Full text linkFrame saws suffer from large unbalanced inertia forces, limiting operating speed and requiring heavy construction. This study aims to overcome these limitations by synthesizing a dynamically balanced main drive mechanism using a novel approach based on prescribed motion laws. The methodology involves proposing a crank-slider mechanism featuring a cam-actuated variable-length crank. The mechanism configuration with parallel spring is analyzed allowing for balancing inertia forces, achieved using a prescribed cosine slider motion law. For the considered configuration, the required variable crank length function (cam profile) and associated mechanism parameters (connecting rod length, spring stiffness) are analytically synthesized. The results of the carried-out numerical modeling demonstrate successful synthesis of a near-circular cam profile and very low pressure angles for the case studied. These findings show that synthesizing the saw drive kinematics based on force balancing requirements can theoretically eliminate inertial loads, offering the potential for higher speeds of saw frames and reduced loads. The synthesized near-circular cam profile suggests a pathway towards simpler manufacturing. The implications of successfully implementing such dynamically balanced frame saw mechanisms are potentially transformative for the sawmilling industry. Eliminating the primary inertial forces removes the major obstacle to increasing operating speeds. This could allow frame saws to operate closer to the optimal cutting speeds for wood (e.g., 40-50 m/s), leading to significant gains in productivity
Influence of dynamic behavior of excavator steel structure on correction of human vibrations: operator cabin case study
Full text linkIn this paper, the investigation and the influence of the dynamic behavior of the structure of the structural part on the correction of human vibrations of the cabin of the unloading boom of a bucket wheel excavator are performed. Diagnostic analysis using the finite element method influenced the reconstruction of the local part of the structure to increase the first natural frequency of the given structure, i.e. to reduce the human vibrations of the unloading boom booth. This way, the lifespan of structural parts is extended, but also the health of the operator and better working conditions are affected. By monitoring the state of human vibrations in a certain time interval, before and after the reconstruction, this correct approach was prove
Coupling dynamics modeling and vibration characteristics analysis of TBM main drive system under complex tunnelling conditions
Full text linkIn 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
Acoustic detection of fan blade faults based on dynamic Cauchy swarm algorithm to optimize support vector machine
Full text linkFan blades operate in outdoor environments, where the detection of sound signals is susceptible to interference from background noise such as random loads, wind speed, rainwater, and other ambient noise. Therefore, this article proposes an acoustic detection method for wind turbine blade faults based on a dynamic Cauchy bee colony algorithm-optimized support vector machine. First, the signal is preprocessed using a Butterworth bandpass filter, and the full frequency band is divided into sub-bands using the octave band feature extraction method. Based on frequency domain analysis, the natural frequency offset of the blade is determined. Next, the dynamic Cauchy bee colony algorithm is applied to optimize support vector machine parameters, while moving average and bandpass filtering are used to smooth the noise power curve and extract impeller speed information. The experimental results show that the proposed method converges in fitness value after 22 iterations, with a detection time of only 6.8 seconds and small fluctuations in impeller speed amplitude. In terms of classification performance, the accuracy of detecting normal samples is 0.95, the recall rate is 0.96, and the F1 score is 0.95. The method demonstrates high prediction accuracy and stability for various types of fault samples and can be reliably applied to the acoustic detection of wind turbine blade faults
A vision-based deep learning approach for non-contact vibration measurement using (2+1)D CNN and optical flow
Full text linkThis paper introduces a proof-of-concept vision-based deep learning approach for vibration measurement, proposing a factorized (2+1)D Convolutional Neural Network (CNN) model to predict four vibration metrics: acceleration, velocity, displacement, and frequency, with a focus on rigid body motion. Unlike conventional neural network models that primarily focus on frequency prediction alone, this approach uniquely enables the simultaneous estimation of four critical vibration metrics, offering a comprehensive and cost-effective alternative to traditional contact-based sensors such as accelerometers. The framework relies on the visibility of a training fiducial marker, eliminates the need for calibration in controlled settings, enhancing scalability across specific environments. A curated dataset was generated using a controlled experimental setup comprising a single object in a lab-scale environment, augmented synthetically to enhance frequency diversity. An optical flow-based preprocessing algorithm synchronized motion features in recorded video inputs with measured vibration labels, improving measurement accuracy. The proposed model achieved an average Mean Absolute Percentage Error (MAPE) of 7.51 %, with acceleration predictions exhibiting the lowest error at 4.84 % and displacement the highest at 8.80 % across varying brightness levels and object-camera distances. Techniques such as Region of Interest (ROI) cropping and multi-section frame extraction were implemented to reduce computational complexity while further enhancing accuracy. These results highlight the framework’s potential for non-invasive vibration analysis, though its generalizability is limited by the single-object dataset. Future work will expand the dataset, integrate multi-sensor inputs, explore marker-less tracking methods, and enable real-time deployment for predictive maintenance and structural health monitoring