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Search Results (1,371)

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15 pages, 8029 KiB  
Article
Study on Length–Diameter Ratio of Axial–Radial Flux Hybrid Excitation Machine
by Mingyu Guo, Jiakuan Xia, Qimin Wu, Wenhao Gao and Hongbo Qiu
Processes 2024, 12(12), 2942; https://doi.org/10.3390/pr12122942 - 23 Dec 2024
Abstract
To improve the flux regulation range of the Axial–Radial Flux Hybrid Excitation Machine (ARFHEM) and the utilization rate of permanent magnets (PMs), the effects of different length–diameter ratios (LDRs) on the ARFHEM performance are studied. Firstly, the principle of the flux regulation of [...] Read more.
To improve the flux regulation range of the Axial–Radial Flux Hybrid Excitation Machine (ARFHEM) and the utilization rate of permanent magnets (PMs), the effects of different length–diameter ratios (LDRs) on the ARFHEM performance are studied. Firstly, the principle of the flux regulation of the ARFHEM is introduced by means of the structure and equivalent magnetic circuit method. Then, based on the principle of the bypass effect, the analytical formulas of LDRs, the number of pole-pairs, and the flux regulation ability are derived, and then the restrictive relationship between the air-gap magnetic field, LDR, and the number of pole-pairs is revealed. On this basis, the influence of an electric LDR on motor performance is studied. By comparing and analyzing the air-gap magnetic density and no-load back electromotive force (EMF) of motors with different LDRs, the variation in the magnetic flux regulation ability of motors with different LDRs is obtained and its influence mechanism is revealed. In addition, the torque regulation ability and loss of motors with different LDRs are compared and analyzed, and the influence mechanism of the LDR on torque and loss is determined. Finally, the above analysis is verified by experiments. Full article
(This article belongs to the Section Manufacturing Processes and Systems)
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Figure 1
<p>Structure of ARFHEM.</p>
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<p>The flux path and equivalent magnetic circuit of ARFHEM in different excitation current working conditions. (<b>a</b>) Only PM working state. (<b>b</b>) Negative excitation current working state. (<b>c</b>,<b>d</b>) Positive current excitation working state.</p>
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<p>Schematic diagram of bypass structure.</p>
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<p>Air-gap flux regulation characteristic curve with LDRs. (<b>a</b>) The radial air-gap flux density varies with the excitation current. (<b>b</b>) Variation of the multiple of air-gap magnetic flux regulation with LDRs.</p>
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<p>Relation between no-load back EMF and LDR. (<b>a</b>) No-load back EMF. (<b>b</b>) Total harmonic distortion.</p>
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<p>The output torque of a motor with different LDRs varies with the excitation current.</p>
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<p>Influence of different LDRs on motor loss.</p>
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<p>The ARFHEM prototypes.</p>
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<p>The test platform of prototypes.</p>
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<p>The back EMF varies with the excitation currents. (<b>a</b>) 0A. (<b>b</b>) 1A. (<b>c</b>) 3A. (<b>d</b>) 5A.</p>
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<p>The back EMF varies with the excitation currents. (<b>a</b>) 0A. (<b>b</b>) 1A. (<b>c</b>) 3A. (<b>d</b>) 5A.</p>
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19 pages, 5326 KiB  
Article
Sensitivity Analysis of Scallop Damper Seal Design Parameters for Leakage and Static Performance
by Minglong Yao, Wanfu Zhang, Qianqian Zhao, Qianlei Gu, Liyun Zhang and Jianing Yin
Aerospace 2024, 11(12), 1052; https://doi.org/10.3390/aerospace11121052 - 23 Dec 2024
Abstract
The leakage characteristics and static stiffness of scallop damper seals have a significant impact on rotor vibration and stability. A parameter sensitivity analysis model for geometrical parameters in scallop damper seals was developed using a design of experiments (DOE) approach. The method employed [...] Read more.
The leakage characteristics and static stiffness of scallop damper seals have a significant impact on rotor vibration and stability. A parameter sensitivity analysis model for geometrical parameters in scallop damper seals was developed using a design of experiments (DOE) approach. The method employed a central composite design, integrating factorial, axial, and center points to assess non-linear effects efficiently. And the effects of radial clearance, cavity depth, and length–diameter ratios on leakage performance and rotor stability were investigated. The leakage rate, flow-induced force, and static stiffness coefficient for 15 different combinations of geometric parameters at eccentricities of 0.2 and 0.4 were numerically calculated. The results show that eccentricity has little effect on leakage and its parameter sensitivity. Larger cavity depths and length–diameter ratios are beneficial for seal leakage performance. The tangential force increases with increasing eccentricity but decreases with increasing radial clearance, while it first decreases and then increases with the increase in the cavity depth and length–diameter ratios. Additionally, the radial force decreases with the increase in the length-to-diameter ratio and increases first and then decreases with the increase in radial clearance. The parameter level in this study is defined as the ratio of the actual parameter value to the maximum parameter value. Static direct stiffness reaches its maximum value at a radial clearance level of 30.2%. It remains positive within a cavity depth range of 92.3~100%, as well as a length–diameter ratio range of 0~20.3%. The static cross-coupled stiffness gradually decreases with the increase in radial clearance but first decreases and then increases with the increase in the cavity depth or length–diameter ratio levels. The research results presented in this paper can serve as a reference for the analysis of the performance and design of scallop damper seals. Full article
(This article belongs to the Section Aeronautics)
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<p>Typical damper seal.</p>
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<p>Geometry model of scallop damper seal.</p>
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<p>Mesh distribution of the scallop damper seal.</p>
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<p>Grid independence verification.</p>
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<p>Rotor eccentricity model.</p>
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<p>Comparison of experiments and CFD results.</p>
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<p>Main effect diagram of seal leakage.</p>
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<p>Main effect diagram of seal tangential force.</p>
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<p>Main effect diagram of seal radial force.</p>
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<p>Main effect diagram of seal direct static stiffness.</p>
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<p>Main effect diagram of seal static cross-coupled stiffness.</p>
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<p>Static pressure contours and response forces in the second seal cavity under different length-to-diameter ratios.</p>
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<p>Static pressure contours and response forces in the second seal cavity with different cavity depths.</p>
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<p>Mach number contour plots at the tips of the last two sealing teeth under different experimental conditions.</p>
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21 pages, 7672 KiB  
Article
Study of Cutting Forces in Drilling of Aluminum Alloy 2024-T351
by Răzvan Sebastian Crăciun, Virgil Gabriel Teodor, Nicușor Baroiu, Viorel Păunoiu and Georgiana-Alexandra Moroșanu
Machines 2024, 12(12), 937; https://doi.org/10.3390/machines12120937 - 20 Dec 2024
Viewed by 118
Abstract
Duralumin 2024-T351 is an alloy characterized by a good mechanical strength, relatively high hardness and corrosion resistance frequently used in the aeronautical, automotive, defense etc. industries. In this paper, the variation of axial forces and torques when drilling aluminum alloy 2024-T351 was investigated, [...] Read more.
Duralumin 2024-T351 is an alloy characterized by a good mechanical strength, relatively high hardness and corrosion resistance frequently used in the aeronautical, automotive, defense etc. industries. In this paper, the variation of axial forces and torques when drilling aluminum alloy 2024-T351 was investigated, analyzing the measured values for different cutting regimes. Experimental data on the forces and moments generated during the drilling process were collected using specialized equipment, and these data were preprocessed and analyzed using MatLab R218a. The experimental plan included 27 combinations of the parameters of the cutting regime (cutting depth, cutting speed, and feed), for which energetic cutting parameters were measured, the axial force and the torsion moment, respectively Based on these data, a neural network was trained, using the Bayesian regularization algorithm, in order to predict the optimal values of the cutting energy parameters. The neural model proved to be efficient, providing predictions with a relative error below 10%, indicating a good agreement between measured and simulated values. In conclusion, neural networks offer an accurate alternative to classical analytical models, being more suitable for materials with complex behavior, such as aluminum alloys. Full article
(This article belongs to the Section Advanced Manufacturing)
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Figure 1
<p>Fixing the duralumin sample: on the numerical control machine (<b>a</b>) and on the measuring device (<b>b</b>): 1—drill; 2—sample; 3—Kistler device; 4—probe.</p>
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<p>Graphical representation of data: (<b>a</b>) measured; (<b>b</b>) selected for the analysis.</p>
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<p>Frequency distribution of measured data values (in domain selected for analysis).</p>
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<p>The used sample. (<b>a</b>) picture, (<b>b</b>) drawing.</p>
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<p>Force distribution in a helical drill.</p>
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<p>The components of the cutting forces and the analogy between the turning process and the drilling process [<a href="#B25-machines-12-00937" class="html-bibr">25</a>].</p>
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<p>Representation of the used neural network.</p>
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<p>Error histogram.</p>
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<p>Representation of the regression for the data sets: (<b>a</b>) training; (<b>b</b>) testing.</p>
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<p>Error histogram at network query.</p>
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<p>Regression function when querying the network.</p>
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<p>The variation of the axial force depending on the value of the feed, <span class="html-italic">f</span> [mm/rot.] and the depth of cut, <span class="html-italic">a</span> [mm].</p>
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<p>Variation of the torsion moment as a function of feed value, <span class="html-italic">f</span> [mm/rot.], depth of cut, <span class="html-italic">a</span> [mm] and cutting speed, <span class="html-italic">v</span> [m/min.].</p>
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19 pages, 8083 KiB  
Article
Changes of Ankle Motion and Ground Reaction Force Using Elastic Neutral AFO in Neurological Patients with Inverted Foot During Gait
by Du-Jin Park and Young-In Hwang
Actuators 2024, 13(12), 526; https://doi.org/10.3390/act13120526 - 20 Dec 2024
Viewed by 232
Abstract
Many stroke patients develop ankle deformities due to neurological or non-neurological factors, resulting in abnormal gait patterns. While Ankle-Foot Orthoses (AFOs) are commonly used to address these issues, few are specifically designed for ankle varus. The Elastic Neutral Ankle-Foot Orthosis (EN-AFO) was developed [...] Read more.
Many stroke patients develop ankle deformities due to neurological or non-neurological factors, resulting in abnormal gait patterns. While Ankle-Foot Orthoses (AFOs) are commonly used to address these issues, few are specifically designed for ankle varus. The Elastic Neutral Ankle-Foot Orthosis (EN-AFO) was developed for this purpose. This study aimed to analyze changes in kinematic and kinetic gait data in stroke patients with ankle varus, comparing those walking with and without EN-AFO in both AFO and No-AFO groups. Initially, 30 stroke patients with ankle varus were screened; after exclusions, 17 were included in the final analysis. In the No-AFO group, EN-AFO significantly improved maximal ankle inversion on the affected side during the swing phase (from 4.63 ± 13.26 to 10.56 ± 11.40, p = 0.025). Similarly, in the AFO group, EN-AFO led to a significant improvement in maximal ankle inversion on the less-affected side during the swing phase (from 7.95 ± 10.11 to 12.01 ± 8.64, p = 0.021). Additionally, ground reaction forces on the affected side of the AFO group significantly increased at both the forefoot (from 182.76 ± 61.45 to 211.55 ± 70.57, p = 0.038) and hindfoot (from 210.67 ± 107.88 to 231.85 ± 105.38, p = 0.038) with EN-AFO. Conversely, maximal and minimal thoracic axial rotation on the affected side improved significantly in the No-AFO group compared to the AFO group with EN-AFO, during both the stance and swing phases (stance phase: max improvement from −1.13 ± 1.80 to 4.83 ± 8.05, min improvement from −1.06 ± 2.45 to 5.89 ± 7.56; swing phase: max improvement from −1.33 ± 2.13 to 5.49 ± 7.82, min improvement from −1.24 ± 2.43 to 5.95 ± 7.12; max p = 0.034, min p = 0.016 during stance; max p = 0.027, min p = 0.012 during swing). Furthermore, both maximal and minimal thoracic axial rotation on the less-affected side during the swing phase improved significantly in the No-AFO group (max improvement from −2.09 ± 4.18 to 6.04 ± 6.90, min improvement from −0.47 ± 2.13 to 8.18 ± 10.45; max p = 0.027, min p = 0.012) compared with the AFO group. These findings suggest that EN-AFO may effectively improve gait in stroke patients with ankle varus in the No-AFO group. Full article
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<p>A flowchart of the study.</p>
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<p>The force plate (dark area) to analyze kinetic variables.</p>
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<p>The EN-AFO device in use. (a) Velcro straps; (b) fabric belt with elastic reinforcement; (c,d) elastic bands securing the lower leg and forefoot.</p>
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<p>The inner side of the EN-AFO. (a) Velcro strap; (b-1,b-2) joint between elastic band and fabric, (c) fabric, (d) the elastic support, (e) the elastic band wearing the lower leg and forefoot, (f-1,f-2) stiches in the shape of an overshoe in an area where thin plastic was attached. (Cited from Hwang and Park (2021) [<a href="#B10-actuators-13-00526" class="html-bibr">10</a>]).</p>
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<p>The attachments of the IMU sensors.</p>
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<p>Differentiation of kinematic data of the affected side in AFO and No-AFO groups after wearing Elastic Neutral AFO at stance phase (* <span class="html-italic">p</span> &lt; 0.05).</p>
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<p>Differentiation of kinematic data of the less-affected side in AFO and No-AFO groups after wearing Elastic Neutral AFO at stance phase (* <span class="html-italic">p</span> &lt; 0.05).</p>
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<p>Differentiation of kinematic data of the affected side after wearing Elastic Neutral AFO at swing phase (* <span class="html-italic">p</span> &lt; 0.05).</p>
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<p>Differentiation of kinematic data of the less-affected side after wearing Elastic Neutral AFO at swing phase (* <span class="html-italic">p</span> &lt; 0.05).</p>
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<p>Differentiation of kinematic data between AFO and NO-AFO groups after wearing EN-AFO at stance phase (* <span class="html-italic">p</span> &lt; 0.05).</p>
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<p>Differentiation of kinematic data between AFO and NO-AFO groups after wearing EN-AFO at swing phase (* <span class="html-italic">p</span> &lt; 0.05).</p>
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<p>Gait cycle in the AFO group: hip external rotation, ankle dorsiflexion, ankle inversion and foot external rotation.</p>
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<p>Gait cycle in the No-AFO group: hip external rotation, ankle dorsiflexion, ankle inversion, and foot external rotation.</p>
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12 pages, 3238 KiB  
Article
Air-Assisted Tribo-Electrostatic Separator for Recycling of Shredded Waste Plastics
by Fethi Miloua, Said Nemmich, Thami Zeghloul, Mohamed Miloudi, Karim Medles and Lucian Dascalescu
Sustainability 2024, 16(24), 11142; https://doi.org/10.3390/su162411142 - 19 Dec 2024
Viewed by 338
Abstract
Waste minimization is a major way to achieve sustainable development. Electrostatic separation is already used in the recycling industry for processing certain mixtures of shredded plastics originating from waste electric and electronic equipment. Standard tribo-electrostatic separators use electric forces to deflect the trajectories [...] Read more.
Waste minimization is a major way to achieve sustainable development. Electrostatic separation is already used in the recycling industry for processing certain mixtures of shredded plastics originating from waste electric and electronic equipment. Standard tribo-electrostatic separators use electric forces to deflect the trajectories of triboelectrically charged particles in the electric field generated between two vertical plate electrodes connected to high voltage supplies of opposite polarities. However, the efficiency of this device is often limited by the impacts between the particles and the electrodes, which diminish the recovery and the purity of the end product. An innovative electrostatic separator was specifically designed to mitigate this risk. The innovation lies in using two rotating co-axial vertical cylindrical electrodes and assisting the movement of the particles with downward-oriented air flow to reduce their impact on the electrodes and improve the quality of the recovered products. The aim of this study was to optimize the operation of the patented electrostatic separator by using experimental design methodology to obtain quadratic polynomial models of the recovery and the purity of the products as functions of the high voltage applied to the electrode system and of the air flow through the device. The experiments were conducted with a granular mixture composed of 88% polypropylene (PP) and 12% high-impact polystyrene (HIPS) particles, extracted from the recycling process of waste electrical and electronic equipment, and triboelectrically charged in a fluidized bed device. A voltage of 50 kV combined with an air flow rate of 1700 m3/min maximized the recovery and the purity of PP and HIPS products collected at the outlet of the separator. These results open promising prospects for expanding the use of tribo-electrostatic separation for efficient recycling of granular waste plastics. Full article
(This article belongs to the Section Waste and Recycling)
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<p>Photograph of fluidized bed triboelectric charger.</p>
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<p>Schematic representation of air-assisted electrostatic separator equipped with two rotating vertical cylindrical electrodes. 1: Vibratory feeder; 2: internal cylindrical electrode; 3: high voltage supply; 4: collecting system; 5: external cylindrical electrode. (red dots: negatively-charged particles; blue dots: positively-charged particles).</p>
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<p>The shape and size of the (<b>1</b>) HIPS and (<b>2</b>) PP granules used in the experimental study of the air-assisted tribo-electrostatic separation process.</p>
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<p>The material divider for sampling the products of the electrostatic separation experiments.</p>
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<p>Photograph of recovered products: (<b>a</b>) HIPS; (<b>b</b>) PP.</p>
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<p>Goodness of fit <math display="inline"><semantics> <mrow> <msup> <mrow> <mi>R</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> </mrow> </semantics></math> and goodness of prediction <math display="inline"><semantics> <mrow> <msup> <mrow> <mi>Q</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> </mrow> </semantics></math> of model.</p>
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<p>The responses predicted by MODDE 5.0 software as a function of the air flow and the applied high voltage.</p>
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<p>MODDE 5.0—predicted variation in the collected mass values of HIPS and PP. The upper (blue) and the lower (red) curves on each graph indicate the limits of the 95% confidence interval.</p>
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19 pages, 1249 KiB  
Article
Dynamic Stiffness for a Levinson Beam Embedded Within a Pasternak Medium Subjected to Axial Load at Both Ends
by Zhijiang Chen, Qian Cheng, Xiaoqing Jin and Feodor M. Borodich
Buildings 2024, 14(12), 4008; https://doi.org/10.3390/buildings14124008 - 17 Dec 2024
Viewed by 494
Abstract
This work presents accurate values for the dynamic stiffness matrix coefficients of Levinson beams under axial loading embedded in a Winkler–Pasternak elastic foundation. Levinson’s theory accounts for greater shear deformation than the Euler–Bernoulli or Timoshenko theories. Using the dynamic stiffness approach, an explicit [...] Read more.
This work presents accurate values for the dynamic stiffness matrix coefficients of Levinson beams under axial loading embedded in a Winkler–Pasternak elastic foundation. Levinson’s theory accounts for greater shear deformation than the Euler–Bernoulli or Timoshenko theories. Using the dynamic stiffness approach, an explicit algebraic expression is derived from the homogeneous solution of the governing equations. The dynamic stiffness matrix links forces and displacements at the beam’s ends. The Wittrick–Williams algorithm solves the eigenvalue problem for the free vibration and buckling of uniform cross-section parts. Numerical results are validated against published data, and reliability is confirmed through consistency tests. Parametric studies explore the effects of aspect ratio, boundary conditions, elastic medium parameters, and axial force on beam vibration properties. The relative deviation for the fundamental frequency is almost 6.89% for a cantilever beam embedded in the Pasternak foundation, 5.16% for a fully clamped beam, and 4.79% for a clamped–hinged beam. Therefore, Levinson beam theory can be used for calculations relevant to loads with short durations that generate transient responses, such as impulsive loads from high-speed railways, using the mode superposition method. Full article
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<p>Deformation of (<b>a</b>) Winkler and (<b>b</b>) Pasternak foundation mechanical models.</p>
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<p>(<b>a</b>) Beam on Pasternak foundation. (<b>b</b>) Definition of positive forces, moments, and loads on beam element.</p>
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<p>Homogenous solution type and associated relative value of parameters <math display="inline"><semantics> <mi>δ</mi> </semantics></math> and <math display="inline"><semantics> <mi>η</mi> </semantics></math>.</p>
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<p>The dimensionless first natural frequency of the Levinson beam varies with the Winkler–Pasternak foundation parameters <math display="inline"><semantics> <msub> <mi>K</mi> <mi>W</mi> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>K</mi> <mi>P</mi> </msub> </semantics></math>, the axial force, the slenderness ratio, and different boundary conditions: (<b>a</b>) cantilever; (<b>b</b>) simple supported; (<b>c</b>) clamped; (<b>d</b>) clamped–simple supported.</p>
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<p>The first three mode shape of cantilever Levinson beam embedded in elastic base (Winkler <math display="inline"><semantics> <mrow> <msub> <mi>K</mi> <mi>W</mi> </msub> <mo>=</mo> <mn>100</mn> </mrow> </semantics></math>, Pasternak <math display="inline"><semantics> <mrow> <msub> <mi>K</mi> <mi>W</mi> </msub> <mo>=</mo> <mn>100</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>K</mi> <mi>P</mi> </msub> <mo>=</mo> <mn>0.2</mn> </mrow> </semantics></math>) with <math display="inline"><semantics> <mrow> <mi>L</mi> <mo>/</mo> <mi>h</mi> <mo>=</mo> <mn>5</mn> </mrow> </semantics></math> subjected to different axial force: (<b>a</b>) 1st mode; (<b>b</b>) 2nd mode; (<b>c</b>) 3rd mode.</p>
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17 pages, 6603 KiB  
Article
Field Test and Numerical Simulation Study on Pipe Sticking of Pipe Jacking in Composite Stratum
by Shilei Zhang, Xiaodong Xu, Feilun Luo, Tao Shi, Tianshuo Xu and Peng Zhang
Buildings 2024, 14(12), 3992; https://doi.org/10.3390/buildings14123992 - 16 Dec 2024
Viewed by 359
Abstract
In this study, the jacking force of a stuck pipe was explored under various contact conditions in long-distance composite strata. The Jiaoliu River jacking project in Yichao, Inner Mongolia, was selected for study, and the precise location of the pipe sticking was determined [...] Read more.
In this study, the jacking force of a stuck pipe was explored under various contact conditions in long-distance composite strata. The Jiaoliu River jacking project in Yichao, Inner Mongolia, was selected for study, and the precise location of the pipe sticking was determined by laying strain gauges on the surface of the pipe and via integration with the measured data. Corresponding technical measures for releasing the pipe sticking were also put forward. Finally, ABAQUS 2022 software was used to establish a finite element analysis model of jacking force considering full contact conditions, and the maximum friction coefficient of the pipe that can be jacked forward in the pipe sticking state was calculated, providing a reference for related engineering cases. The results show that the position of the pipe sticking can be accurately identified through strain gauges on the surface of the pipe. The axial jacking force is transmitted more effectively in the upper section of the pipe than in the lower section, and as the jacking force increases, the length of the pipe becomes longer according to this rule. Measures were taken to adequately lubricate the pipe affected by sticking to ameliorate this condition. Full article
(This article belongs to the Special Issue Building Foundation Analysis: Soil–Structure Interaction)
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<p>Pipe jacking trajectory diagram.</p>
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<p>Pipe structure diagram.</p>
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<p>Geological conditions of pipe jacking cross-section of Jiaoliu River.</p>
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<p>Monitoring of pipe surface strain after pipe sticking.</p>
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<p>The strain difference measured with a surface strain gauge.</p>
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<p>Encryption fixed-point measurement of strain difference.</p>
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<p>Stratigraphic parameter diagram.</p>
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<p>Model grid division.</p>
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<p>Soil stress diagram after in situ stress balance.</p>
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<p>The overall settings of the boundary conditions of the model.</p>
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<p>The full-contact state of pipe sticking.</p>
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<p>Axial displacement of pipe under full-contact condition when jacking force reaches 3500 t.</p>
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<p>Axial stress distribution of pipe under full-contact condition when jacking force reaches 3500 t.</p>
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<p>Contact pressure around the pipe.</p>
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<p>In-tube flushing method.</p>
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17 pages, 23136 KiB  
Article
Analysis of an Axial Field Hybrid Excitation Synchronous Generator
by Junyue Yu, Shushu Zhu and Chuang Liu
Energies 2024, 17(24), 6329; https://doi.org/10.3390/en17246329 - 16 Dec 2024
Viewed by 280
Abstract
An axial field hybrid excitation synchronous generator (AF-HESG) is proposed for an independent power supply system, and its electromagnetic performance is studied in this paper. The distinguishing feature of the proposed generator is the addition of static magnetic bridges at both ends to [...] Read more.
An axial field hybrid excitation synchronous generator (AF-HESG) is proposed for an independent power supply system, and its electromagnetic performance is studied in this paper. The distinguishing feature of the proposed generator is the addition of static magnetic bridges at both ends to place the field windings and the use of a sloping surface to increase the additional air-gap cross-sectional area. The advantage of the structure is that it achieves brushless excitation and improves the flux-regulation range. The structure and magnetic circuit characteristics are introduced in detail. Theoretical analysis of the flux-regulation principle is conducted by studying the relationship between field magnetomotive force, rotor reluctance, and air-gap flux density. Quantitative calculation is performed using a magnetomotive force (MMF)-specific permeance model, and the influence of the main parameters on the air-gap flux density and flux-regulation range is analyzed. Subsequently, magnetic field, no-load, and load characteristics are investigated through three-dimensional finite element analysis. The loss distribution is analyzed, and the temperature of the generator under rated conditions is simulated. Finally, a 30 kW, 1500 r/min prototype is developed and tested. The test results show good flux-regulation capability and stable voltage output performance of the proposed generator. Full article
(This article belongs to the Section F: Electrical Engineering)
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<p>Sectional view of the AF-HESG.</p>
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<p>Diagram of various components of the AF-HESG.</p>
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<p>Schematic of the AF-HESG system.</p>
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<p>Magnetic circuit of AF-HESG.</p>
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<p>Equivalent magnetic circuit and electrical circuit of the AF-HESG.</p>
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<p>Relationship between armature flux direction and field flux. (<b>a</b>) Case 1. (<b>b</b>) Case 2. (<b>c</b>) Case 3.</p>
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<p>MEC of the AF-HESG. (<b>a</b>) Case 1. (<b>b</b>) Case 3.</p>
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<p>Ideal air-gap MMF waveform.</p>
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<p>Calculation results of the MMF-specific permeance model. (<b>a</b>) Air-gap MMF. (<b>b</b>) Air-gap permeance. (<b>c</b>) Air-gap flux density.</p>
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<p>Relationship of the air-gap flux density and field current.</p>
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<p>The influence of main parameters on air gap. (<b>a</b>) Air-gap MMF generated by PM <span class="html-italic">F</span><sub>g_PM</sub>. (<b>b</b>) Air-gap MMF generated by FW <span class="html-italic">F</span><sub>g_<span class="html-italic">f</span></sub>. (<b>c</b>) Air-gap flux density <span class="html-italic">B</span><sub>g</sub>. (<b>d</b>) Flux-regulation range <span class="html-italic">k<sub>f</sub></span>.</p>
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<p>The influence of main air-gap length on air-gap flux density, MMF, and permeance.</p>
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<p>Magnetic field distributions with different <span class="html-italic">I<sub>f</sub></span>. (<b>a</b>) <span class="html-italic">I<sub>f</sub></span> = 0 A. (<b>b</b>) <span class="html-italic">I<sub>f</sub></span> = 2 A. (<b>c</b>) <span class="html-italic">I<sub>f</sub></span> = 6 A.</p>
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<p>The air-gap flux density distribution under different <span class="html-italic">I<sub>f</sub></span>.</p>
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<p>Output voltage under different <span class="html-italic">I<sub>f</sub></span>. (<b>a</b>) No-load voltage. (<b>b</b>) Load voltage.</p>
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<p>Harmonic of no-load and load output voltage.</p>
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<p>No-load characteristics.</p>
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<p>External characteristics under different field currents.</p>
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<p>Regulation characteristics (<span class="html-italic">U</span><sub>out</sub> = 220 V).</p>
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<p>Component of loss on the rated conditions.</p>
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<p>Steady-state temperature field of each component.</p>
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<p>Prototype and test platform.</p>
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<p>Measured no-load output voltage waveform.</p>
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<p>Measured load output voltage waveform.</p>
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<p>Comparison of no-load characteristics at different speeds.</p>
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<p>Comparison of external characteristics.</p>
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<p>Comparison of regulation characteristics.</p>
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18 pages, 6621 KiB  
Article
The Buckling Behavior and Reliability Evaluation of a Cable-Stayed Bridge with Unique-Shaped Towers
by Yaoxiang Jia, Rujin Ma, Xiaoyu Zhou and Benjin Wang
Materials 2024, 17(24), 6124; https://doi.org/10.3390/ma17246124 - 14 Dec 2024
Viewed by 391
Abstract
Buckling is a significant concern for cable-stayed bridges that incorporate a large number of steel components, particularly those featuring unique-shaped towers that require further examination due to the intricate internal force and stress distribution. This paper investigates the buckling behavior of a cable-stayed [...] Read more.
Buckling is a significant concern for cable-stayed bridges that incorporate a large number of steel components, particularly those featuring unique-shaped towers that require further examination due to the intricate internal force and stress distribution. This paper investigates the buckling behavior of a cable-stayed bridge with inverted V-shaped towers. The cable tower is characterized by its unique design that consists of diagonal bracings and columns in a compression-bending state. A finite element model is established for the nonlinear buckling analysis of the bridge, revealing that the buckling failure mode of the bridge mainly concerns the tower columns that bear large bending moments and axial compressions. The buckling safety factors are analyzed under different loading conditions and design parameters, including the stiffening rib thickness, the width-to-thickness ratio, and the initial cable forces. It indicates that the design optimization can be achieved by using smaller and thinner ribs while maintaining the buckling safety factor above the required level in design specifications. Furthermore, the reliability evaluation of buckling safety is considered using Monte Carlo simulations, which incorporates the long-term effects of corrosion on steel components. Based on the identified buckling failure modes and safety factors, it suggests that the buckling resistance of the bridge is sufficient, though it can be further enhanced by using high-strength weathering steel on critical parts. Additionally, maintenance interventions are shown to be highly beneficial in improving the life-cycle performance of the structure. Full article
(This article belongs to the Section Construction and Building Materials)
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<p>The details of the bridge structure (units: mm).</p>
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<p>Full and local model of FEM: (<b>a</b>) Global model and sub-model; (<b>b</b>) Mesh of the sub-model; (<b>c</b>) Boundary conditions.</p>
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<p>Ideal elastic–plastic constitutive model of Q345 steel.</p>
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<p>The dead load and live load on the bridge.</p>
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<p>Eigenvalue buckling deformation.</p>
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<p>(<b>a</b>) The displacement of the buckling point on the tower column of Case 1; (<b>b</b>) The displacement of the buckling point on the tower column of Case 2.</p>
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<p>Von Mises stresses of the bridge tower under dead loads.</p>
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<p>Von Mises stresses on the sub-model during the buckling (Case 1): (<b>a</b>) Load factor 5.75; (<b>b</b>) Load factor 8.25; (<b>c</b>) Load factor 14.19; (<b>d</b>) Load factor 20.13.</p>
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<p>The displacement of the buckling point on the sub-model (Case 1).</p>
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<p>Von Mises stresses on the sub-model during the buckling (Case 2): (<b>a</b>) Load factor 0.2; (<b>b</b>) Load factor 1.825; (<b>c</b>) Load factor 2.837; (<b>d</b>) Load factor 3.69.</p>
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<p>Displacement of the buckling point on the sub-model (Case 2).</p>
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<p>The effect of stiffening rib thickness with respect to load factor: (<b>a</b>) the load factor of Case 1; (<b>b</b>) the load factor of Case 2.</p>
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<p>The effect of the width–thickness ratio of stiffening ribs with respect to load factor: (<b>a</b>) the load factor of Case 1; (<b>b</b>) the load factor of Case 2.</p>
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<p>Effect of initial cable forces on load factor.</p>
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<p>Buckling safety factors by Monte Carlo simulations (<math display="inline"><semantics> <mrow> <msub> <mrow> <mi>t</mi> </mrow> <mrow> <mn>1</mn> </mrow> </msub> </mrow> </semantics></math> = 10 mm at 10 years).</p>
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<p>Critical load factors for different service periods for Case 1.</p>
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<p>Buckling safety factor for different service periods for Case 2.</p>
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15 pages, 5903 KiB  
Article
Leaf Pruning End-Effector for Adaptive Positioning at the Branch–Stem Junction of Tomato Plants
by Yuhuan Sun, Wenqiao Lu, Qingchun Feng, Liang He, Hongda Diao, Yuhang Ma and Liping Chen
Agriculture 2024, 14(12), 2281; https://doi.org/10.3390/agriculture14122281 - 12 Dec 2024
Viewed by 576
Abstract
To address the needs of mechanized tomato leaf pruning, this paper presents the design of an end-effector capable of adaptive positioning at the base of the branch. This design effectively prevents infection at the cut sites of a residual branch and protects the [...] Read more.
To address the needs of mechanized tomato leaf pruning, this paper presents the design of an end-effector capable of adaptive positioning at the base of the branch. This design effectively prevents infection at the cut sites of a residual branch and protects the rest of the plant from damage. The design objectives for the pruning actuator were established through the measurement of key parameters related to the morphology and mechanical properties of the lateral branch. Based on this foundation, we developed an innovative gripper featuring a spiral guide groove, enabling simultaneous axial traction and radial cutting of the branch. This design ensures that the branch–stem junction conforms to the cutting blade under shear stress, achieving the required adaptive positioning. By analyzing the mechanical properties of the lateral branch, we modeled the actuator’s traction and cutting forces to determine the key geometric parameters of the spiral fingers and the necessary driving torque. We validated the actuator’s operational effectiveness through discrete element simulation and practical application tests. The experimental results indicate that when removing the branch, a traction force of 32.5 N and a cutting force of 66.3 N are generated. Harvesting effectiveness tests conducted in the tomato field achieved a success rate of 85%. This research offers technical support for the development of handheld pruning devices and pruning robots. Full article
(This article belongs to the Section Agricultural Technology)
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<p>Branch pruning principle. (<b>a</b>) Tomato plants in greenhouse. (<b>b</b>) Branch on main stem.</p>
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<p>Branch compressive mechanics experiment. (<b>a</b>) Branch compression testing device. (<b>b</b>) Branch compression force curve of various diameter.</p>
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<p>Branch cutting mechanics experiment. (<b>a</b>) Branch cutting testing device. (<b>b</b>) Branch cutting force curve of various diameters.</p>
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<p>Branch frictional force mechanics experiment.</p>
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<p>Leaf pruning end-effector.</p>
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<p>The gripping force of the branch from the roller finger.</p>
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<p>Squeeze contact area.</p>
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<p>The traction force of the branch from the roller finger.</p>
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<p>Branch clamping process simulation. (<b>a</b>) Normal stress distribution. (<b>b</b>) Different diameter branch normal stress variation curve.</p>
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<p>Branch cutting process simulation. (<b>a</b>) Cutting stress distribution. (<b>b</b>) Different diameter branch cutting stress variation curve.</p>
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<p>Simulation and force analysis of the gripping process of the end-effector.</p>
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<p>Pruning end-effector test.</p>
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<p>The force on a branch from the end-effector.</p>
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18 pages, 10536 KiB  
Article
Bearing Characteristics and Negative Skin Friction Preventive Measures for Highway Bridge Pile Foundations in Collapsible Loess Areas Under Water Immersion
by Haiding Bian and Jin Wei
Water 2024, 16(24), 3587; https://doi.org/10.3390/w16243587 - 12 Dec 2024
Viewed by 482
Abstract
In collapsible loess sites, large-scale collapsible settlement may occur after water immersion, which will reduce the bearing capacity of existing highway bridge pile foundations and pose serious potential safety hazards. Given this, a large-scale field pile foundation immersion–loading test was conducted in a [...] Read more.
In collapsible loess sites, large-scale collapsible settlement may occur after water immersion, which will reduce the bearing capacity of existing highway bridge pile foundations and pose serious potential safety hazards. Given this, a large-scale field pile foundation immersion–loading test was conducted in a collapsible loess site. The settlement law of collapsible loess during the immersion was obtained, the bearing characteristics of pile foundations under the loading and immersion–loading conditions were compared and analyzed, and the formation mechanism of negative skin friction was discussed. The results show that the degree of collapsible deformation is related to the duration of immersion, external load, boundary conditions, and soil layer depth. Whether the collapsible loess site is immersed or not can only change the value and transfer rate of the axial force of the pile foundation but cannot change its transfer law. The collapsible deformation will increase the utilization rate of the pile tip resistance. During the collapsible settlement process, part of the gravity of the soil around the pile will be transferred to the pile, generating negative skin friction on the pile shaft. On this basis, eight preventive measures for reducing the negative skin friction of pile foundations in collapsible loess sites were proposed. The research findings can serve as a valuable reference for the design and construction of highway bridge pile foundations in collapsible loess areas. Full article
(This article belongs to the Section Soil and Water)
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<p>Location of test site [<a href="#B3-water-16-03587" class="html-bibr">3</a>].</p>
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<p>Arrangement of instruments on reinforcement cage.</p>
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<p>Reaction frame equipment.</p>
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<p>Water immersion pit and settlement monitoring points.</p>
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<p>Settlement of soil around S1 test pile during immersion: (<b>a</b>) north-south direction; (<b>b</b>) northwest-southeast direction; (<b>c</b>) east-west direction; (<b>d</b>) southwest-northeast direction.</p>
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<p>Relationship between settlement and load of test piles.</p>
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<p>Axial force of test piles: (<b>a</b>) S1; (<b>b</b>) S2.</p>
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<p>Tip resistance of test piles.</p>
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<p>Shaft resistance of test piles: (<b>a</b>) S1; (<b>b</b>) S2.</p>
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<p>Formation mechanism of negative skin friction.</p>
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<p>New type of pile foundations.</p>
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<p>Post-grouting method.</p>
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<p>Coating method.</p>
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<p>Drilling pre-immersion method.</p>
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<p>Pneumatic-vibratory probe compaction method.</p>
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<p>Dynamic compaction method.</p>
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<p>Replacement method.</p>
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22 pages, 11198 KiB  
Article
Theoretical and Experimental Vibration Generation in a Coaxial Pulse-Tube Cryocooler
by Hongyan Wei, Yulan Li, Yuqiang Xun and Huaqiang Zhong
Vibration 2024, 7(4), 1226-1247; https://doi.org/10.3390/vibration7040063 - 11 Dec 2024
Viewed by 448
Abstract
The microphonic noise induced by the vibration from cryocoolers has been found to cause energy resolution degradation in vibration-sensitive instruments. In this paper, theoretical and experimental research on the vibration generation mechanism of an aerospace-grade coaxial pulse-tube cryocooler (CPTC) is presented. Accordingly, suggestions [...] Read more.
The microphonic noise induced by the vibration from cryocoolers has been found to cause energy resolution degradation in vibration-sensitive instruments. In this paper, theoretical and experimental research on the vibration generation mechanism of an aerospace-grade coaxial pulse-tube cryocooler (CPTC) is presented. Accordingly, suggestions for suppressing the vibration of the pulse-tube cryocooler are provided. A vibration model for the Oxford-type dual-opposed linear compressor is established, and the mechanism of vibration induced by the compressor is theoretically analyzed. A numerical simulation indicates that deviations in the compressor’s inductance coefficient, electromagnetic force coefficient, and flexure spring stiffness coefficient significantly affect the axial vibration of the compressor. The theoretical and experimental studies show that the high-order harmonic vibrations of the compressor are determined by both the resonance of the flexure springs and the high-order harmonics of the driving power supply. Through experiments and simulations, it is revealed that the dynamic gas pressure only induces vibration axially at the cold tip, while the radial vibration at the cold tip is determined by the heat head ‘s vibration and the structural response characteristics of the cold finger. Full article
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<p>Schematic of the Oxford-style dual-opposed moving-coil linear compressor.</p>
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<p>Schematic of a single-degree-of-freedom mechanical force system in a compressor.</p>
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<p>Equivalent circuit diagram in a compressor.</p>
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<p>Diagram of the Simulink model for the dual-opposed compressor’s vibration analysis.</p>
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<p>Schematic diagram of the cold finger vibration model.</p>
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<p>Schematic diagram of gas micro cluster flow inside the cold finger.</p>
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<p>Stress distribution diagrams of the cold finger on the transverse and longitudinal sections under radial pressure (<b>a</b>) and axial pressure (<b>b</b>).</p>
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<p>Schematic diagram of axial strain displacement under the action of axial pressure waves (<b>a</b>) and radial pressure (<b>b</b>) at the cold tip.</p>
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<p>Strain displacement generated by pressure waves at the cold tip.</p>
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<p>Variation in cold tip axial vibration acceleration with pressure amplitude.</p>
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<p>Test system of the drive power supply’s harmonic distortion.</p>
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<p>NF (<b>a</b>) and ITM 7383 (<b>b</b>) power voltage quality.</p>
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<p>Test system of compressor drive power distortion vs. vibration force.</p>
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<p>Characterization of compressor operating current (<b>a</b>) and compressor vibration force (<b>b</b>) under different drive powers.</p>
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<p>Compressor vibration force under different drive powers.</p>
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<p>Illustration of the flexure spring configuration.</p>
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<p>The test platform of flexure springs’ resonance impact (<b>a</b>) and laser displacement monitoring points (<b>b</b>).</p>
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<p>Flexure springs’ axial displacement with varying frequency.</p>
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<p>Flexure springs’ axial displacement on the left (<b>a</b>) and right (<b>b</b>) with varying frequency.</p>
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<p>Axial vibration force spectrum of compressor during flexure spring resonance.</p>
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<p>Flexure spring driving displacement at 108.8 Hz (resonance) (<b>a</b>) and compressor’s vibration force FFT spectrum (<b>b</b>).</p>
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<p>Flexure spring driving displacement at 77.2 Hz (resonance) (<b>a</b>) and compressor vibration force FFT spectrum (<b>b</b>).</p>
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<p>Flexure spring driving displacement at 136.8 Hz (resonance) (<b>a</b>) and compressor’s vibration force FFT spectrum (<b>b</b>).</p>
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<p>System for testing the cold finger’s vibration acceleration.</p>
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<p>FFT spectral distribution of vibration acceleration in cold finger radial (<b>a</b>), vertical (<b>b</b>) and axial (<b>c</b>) directions under a charge pressure 0 MPa.</p>
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<p>Cold tip’s radial vibration acceleration gains factor (<b>a</b>) and FFT spectra of radial vibration acceleration at heat head 2 (<b>b</b>) and cold tip (<b>c</b>) under different charge pressures.</p>
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<p>Cold tip’s axial vibration acceleration gain factor: (<b>a</b>) FFT spectra of axial vibration acceleration at heat head 2 (<b>b</b>) and cold tip (<b>c</b>) under different charge pressures.</p>
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<p>Cold tip’s vertical vibration acceleration gains factor (<b>a</b>) and FFT spectra of vertical vibration acceleration at heat head 2 (<b>b</b>) and cold tip (<b>c</b>) under different charge pressures.</p>
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<p>Axial vibration acceleration at the cold tip under different driving powers.</p>
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26 pages, 19954 KiB  
Article
Guidelines for Nonlinear Finite Element Analysis of Reinforced Concrete Columns with Various Types of Degradation Subjected to Seismic Loading
by Seyed Sasan Khedmatgozar Dolati, Adolfo Matamoros and Wassim Ghannoum
Infrastructures 2024, 9(12), 227; https://doi.org/10.3390/infrastructures9120227 - 10 Dec 2024
Viewed by 931
Abstract
Concrete columns are considered critical elements with respect to the stability of buildings during earthquakes. To improve the accuracy of column damage and collapse risk estimates using numerical simulations, it is important to develop a methodology to quantify the effect of displacement history [...] Read more.
Concrete columns are considered critical elements with respect to the stability of buildings during earthquakes. To improve the accuracy of column damage and collapse risk estimates using numerical simulations, it is important to develop a methodology to quantify the effect of displacement history on column force–deformation modeling parameters. Addressing this knowledge gap systematically and comprehensively through experimentation is difficult due to the prohibitive cost. The primary objective of this study was to develop guidelines to simulate the lateral cyclic behavior and axial collapse of concrete columns with different modes of failure using continuum finite element (FE) models, such that wider parametric studies can be conducted numerically to improve the accuracy of assessment methodologies for critical columns. This study expands on existing FEM research by addressing the complex behavior of columns that experience multiple failure modes, including axial collapse following flexure–shear, shear, and flexure degradation, a topic which has been underexplored in previous works. Nonlinear FE models were constructed and calibrated to experimental tests for 21 columns that sustained flexure, flexure–shear, and shear failures, followed by axial failure, when subjected to cyclic and monotonic lateral displacement protocols. The selected columns represented a range of axial loads, shear stresses, transverse reinforcement ratios, longitudinal reinforcement ratios, and shear span-to-depth ratios. Recommendations on optimal material model parameters obtained from a parametric study are presented. Metrics used for optimization include crack widths, damage in concrete and reinforcement, drift at initiation of axial and lateral strength degradation, and peak lateral strength. The capacities of shear–critical columns calculated with the optimized numerical models are compared with experimental results and standard equations from ASCE 41-17 and ACI 318-19. The optimized finite element models were found to reliably predict peak strength and deformation at the onset of both lateral and axial strength failure, independent of the mode of lateral strength degradation. Also, current standard shear capacity provisions were found to be conservative in most cases, while the FE models estimated shear strength with greater accuracy. Full article
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<p>Test setup by [<a href="#B19-infrastructures-09-00227" class="html-bibr">19</a>], and FEA specimen rendering in ATENA.</p>
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<p>Specimen_1 finite element model. (<b>a</b>) Model macro-elements. (<b>b</b>) Steel plates. (<b>c</b>) Constraint surfaces. (<b>d</b>) Lateral load. (<b>e</b>) Axial load.</p>
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<p>Brick finite elements. Linear and quadratic [<a href="#B34-infrastructures-09-00227" class="html-bibr">34</a>]. (<b>a</b>) Linear: 8 nodes and 8 integration points. (<b>b</b>) Quadratic: 20 nodes and 27 integration points.</p>
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<p>Uniaxial stress–strain law for concrete, adapted from [<a href="#B34-infrastructures-09-00227" class="html-bibr">34</a>].</p>
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<p>Concrete uniaxial compression stress–strain relations. (<b>a</b>) ATENA concrete compression model [<a href="#B34-infrastructures-09-00227" class="html-bibr">34</a>]. (<b>b</b>) Kent–Park model, adapted from [<a href="#B58-infrastructures-09-00227" class="html-bibr">58</a>].</p>
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<p>Tensile behavior of concrete in ATENA. (<b>a</b>) Stages of crack opening [<a href="#B34-infrastructures-09-00227" class="html-bibr">34</a>]. (<b>b</b>) Exponential crack-opening law [<a href="#B59-infrastructures-09-00227" class="html-bibr">59</a>].</p>
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<p>Comparison of unloading factor for SC-2.4-0.2 (SC) (low axial load).</p>
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<p>Comparison of unloading factor for SC-2.4-0.5 (SC) (high axial load).</p>
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<p>Comparison of unloading factor for Specimen_1 (FSC) (low axial load).</p>
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<p>Comparison of unloading factor for Specimen_2 (FSC) (low axial load).</p>
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<p>Comparison of <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>w</mi> </mrow> <mrow> <mi>d</mi> </mrow> </msub> </mrow> </semantics></math> for 3CLH18 (SC) (low axial load).</p>
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<p>Comparison of <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>w</mi> </mrow> <mrow> <mi>d</mi> </mrow> </msub> </mrow> </semantics></math> for 3CMH18 (SC) (high axial load).</p>
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<p>Comparison of <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>w</mi> </mrow> <mrow> <mi>d</mi> </mrow> </msub> </mrow> </semantics></math> for Specimen_1 (FSC) (low axial load).</p>
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<p>Comparison of <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>w</mi> </mrow> <mrow> <mi>d</mi> </mrow> </msub> </mrow> </semantics></math> for Specimen_2 (FSC) (high axial load).</p>
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<p>Comparison of β for SC-2.4-0.2 (SC) (low axial load).</p>
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<p>Comparison of β for SC-2.4-0.5 (SC) (high axial load).</p>
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<p>Comparison of Beta for Specimen_1 (FSC) (low axial load).</p>
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<p>Comparison of Beta for Specimen_2 (FSC) (high axial load).</p>
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<p>Comparative analysis of responses for two distinct mesh sizes in SC-2.4-0.2 (SC).</p>
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<p>Comparative analysis of responses for two distinct mesh sizes in Specimen_1 (FSC).</p>
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<p>Reinforcement stress–strain relationship using a multi-linear model for reinforcement’s cyclic performance (Menegotto 1973 [<a href="#B63-infrastructures-09-00227" class="html-bibr">63</a>]).</p>
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<p>Effects of bond stress–slip relation on behavior of SC-2.4-0.2. (<b>a</b>) Default vs. proposed bond model. (<b>b</b>) Experiment vs. default bond model. (<b>c</b>) Experiment vs. proposed bond model.</p>
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<p>Modeling parameters versus column properties for SC columns.</p>
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<p>Modeling parameters versus column properties for FC and FSC columns.</p>
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<p>Regression fits for <math display="inline"><semantics> <mrow> <mi>β</mi> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mrow> <mo> </mo> <mi>f</mi> </mrow> <mrow> <mi>u</mi> </mrow> </msub> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>w</mi> </mrow> <mrow> <mi>d</mi> </mrow> </msub> </mrow> </semantics></math> for FC and FSC columns with respect to errors in drift at axial degradation.</p>
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<p>Regression fits for <math display="inline"><semantics> <mrow> <mi>β</mi> </mrow> </semantics></math>,<math display="inline"><semantics> <mrow> <msub> <mrow> <mo> </mo> <mi>f</mi> </mrow> <mrow> <mi>u</mi> </mrow> </msub> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>w</mi> </mrow> <mrow> <mi>d</mi> </mrow> </msub> </mrow> </semantics></math> for FC and FSC columns with respect to errors in drift at capping point.</p>
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<p>Regression fits for <math display="inline"><semantics> <mrow> <mi>β</mi> </mrow> </semantics></math>,<math display="inline"><semantics> <mrow> <msub> <mrow> <mo> </mo> <mi>f</mi> </mrow> <mrow> <mi>u</mi> </mrow> </msub> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>w</mi> </mrow> <mrow> <mi>d</mi> </mrow> </msub> </mrow> </semantics></math> for SC columns with respect to errors in drift at axial degradation.</p>
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<p>Regression fits for <math display="inline"><semantics> <mrow> <mi>β</mi> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mrow> <mo> </mo> <mi>f</mi> </mrow> <mrow> <mi>u</mi> </mrow> </msub> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>w</mi> </mrow> <mrow> <mi>d</mi> </mrow> </msub> </mrow> </semantics></math> for SC columns with respect to errors in drift at capping point.</p>
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<p>Simulation versus experiment for Specimen#1 and Specimen#2 (SC).</p>
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<p>Simulation versus experiment for CS60 and CS80 (FSC).</p>
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<p>Simulation versus experiment for CH60 and CH100 (FC).</p>
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<p>Patterns of damage and cracking observed between computational and physical models of SC column at initiation of axial degradation.</p>
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<p>Patterns of damage and cracking observed between computational and physical models for FSC columns at initiation of axial degradation.</p>
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17 pages, 4716 KiB  
Article
Research on the Simplified Calculation Model and Parameter Analysis of Large-Size PBL-Stiffened Steel–Concrete Joints
by Haolin Liu, Baisong Du and Heying Zhou
Buildings 2024, 14(12), 3926; https://doi.org/10.3390/buildings14123926 - 9 Dec 2024
Viewed by 400
Abstract
To investigate the design principles and simplified calculation model of large-size PBL-stiffened steel–concrete joints, this study uses a Y-shaped rigid frame-tied arch composite bridge as an engineering background. Based on deformation coordination theory, a combination of theoretical analysis and numerical simulation was employed [...] Read more.
To investigate the design principles and simplified calculation model of large-size PBL-stiffened steel–concrete joints, this study uses a Y-shaped rigid frame-tied arch composite bridge as an engineering background. Based on deformation coordination theory, a combination of theoretical analysis and numerical simulation was employed to derive a simplified calculation model that accounts for boundary conditions such as the stiffness of steel beam end restraints and the local bearing effect of the bearing plate. Parametric analysis of the steel–concrete joint was conducted. The results indicate that the derived simplified calculation model exhibits good accuracy and is suitable for calculating force transfer in various components of the steel–concrete joint under different boundary conditions. Using the simplified model, the effects of parameters such as steel–concrete joint length, connector stiffness, and structural axial stiffness on the axial force transfer in primary force-bearing components (connectors and bearing plates) were studied. The findings reveal that an excessively long steel–concrete joint does not effectively reduce maximum shear force; variations in connector stiffness primarily affect connectors farther from the bearing plate without changing the shear force distribution. Increasing the axial stiffness of the steel structure within a certain range can improve the maximum shear force in connectors, whereas increasing the axial stiffness of the concrete structure has the opposite effect. Full article
(This article belongs to the Special Issue UHPC Materials: Structural and Mechanical Analysis in Buildings)
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<p>The SCJ of a Y-shaped rigid frame-tied arch composite bridge (unit: mm): (<b>a</b>) a schematic diagram of the SCJ; (<b>b</b>) a schematic diagram of the steel cabin; (<b>c</b>) a detailed construction diagram of the steel cabin.</p>
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<p>Simplified mechanical calculation model for SCJS.</p>
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<p>An internal force and displacement diagram for the <span class="html-italic">i</span>-th segment in the mechanical model of the SCJS.</p>
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<p>Structure of specimen J-1 (unit: mm).</p>
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<p>Schematic diagram of force transfer components in SCJS: (<b>a</b>) PBL; (<b>b</b>) Bearing plate; (<b>c</b>) Entire end of the steel beam; (<b>d</b>) End of perforated steel plate.</p>
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<p>The finite element model of the steel cabin in the SCJS.</p>
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<p>Impact of variation in SCJS length (L) on load transfer: (<b>a</b>) load transferred by PBL connectors under different SCJS lengths (L); (<b>b</b>) load transferred by bearing plates under different SCJS lengths (L).</p>
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<p>Effect of PBL connector stiffness (K) variation on load transfer: (<b>a</b>) PBL connector load transfer under different stiffnesses (K); (<b>b</b>) bearing plate load transfer under different stiffnesses (K).</p>
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<p>The effect of axial stiffness variation on load transfer: (<b>a</b>) the maximum load transfer ratio of the connectors under different axial stiffnesses; (<b>b</b>) the load transfer ratio of the bearing plates under different axial stiffnesses.</p>
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16 pages, 3898 KiB  
Article
The Influence of Changing Belt Loading Conditions on the Operational Condition of the Belt Transmission
by Jozef Mascenik and Tomas Coranic
Actuators 2024, 13(12), 506; https://doi.org/10.3390/act13120506 - 8 Dec 2024
Viewed by 460
Abstract
Given the fact that belt drives are used to transmit power to a fairly large extent, it is natural to devote scientific attention to their transmission with an effort to contribute to the constant technical and technological progress in the field of belt [...] Read more.
Given the fact that belt drives are used to transmit power to a fairly large extent, it is natural to devote scientific attention to their transmission with an effort to contribute to the constant technical and technological progress in the field of belt production and use. For testing and monitoring belt drives, a measuring system was designed and manufactured, which allowed the installation of various types of belt drives and, under a controlled load, to monitor selected parameters and the behavior of individual transmission elements. The presented contribution presents both the measuring system itself and experimental measurements on three V-belts of the same size manufactured by three different manufacturers. During the experimental measurements, parameters such as belt tension were changed by changing the axial distances of the pulley axes; by connecting electric motors through frequency converters, it was possible to control the change in the input speed of the transmission and, at the same time, the load on the output pulley. On the proposed specific design solution for testing belt drives, the actual speed of the input and output pulleys was measured by sensors to determine the belt slip, and the belt’s floating in one plane was monitored using high-precision distance measurement sensors. The analysis of the belt drives also included an assessment of their impact on other parts of the machine or equipment (for example, when transmitting large forces, this can have a negative impact on bearings and gearbox components) on which they are installed; therefore, vibration measurements were also performed. The results of the experimental measurements can contribute to designers choosing a belt drive, for example, even under boundary load parameters and extreme conditions. Full article
(This article belongs to the Section Control Systems)
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<p>Control panel of the new measuring system.</p>
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<p>Monitoring the tension of the belt (<b>a</b>) using a tensometric sensor (<b>b</b>) that detects the compressive (tensioning) force.</p>
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<p>Mechanism used to tension the belt in the mechanism.</p>
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<p>Three-dimensional model and real measuring and monitoring equipment.</p>
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<p>Transmission part of the device intended for testing belt transmissions.</p>
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<p>Dependence of the coefficient of elastic slip on the input speed and the load at the output of the belt transmission when the belt was tensioned at 50 N.</p>
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<p>Dependence of the coefficient of the elastic slip on the input speed and the load at the output of the belt transmission with a belt tension of 250 N.</p>
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<p>Dependence of the coefficient of elastic slip on the input speed and the load at the output of the belt transmission when the belt was tensioned at 450 N.</p>
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<p>Dependence of the belt floating in the lightened branch on the input speed and the load at the output of the belt transmission when the belt was tensioned at 250 N.</p>
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<p>Dependence of the belt float in the traction branch on the input speed and the load at the output of the belt transmission when the belt was tensioned at 250 N.</p>
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<p>Dependence of vibrations on the input speed and the load at the output of the belt transmission when the belt is tensioned at 250 N.</p>
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