Journal of Engineering and Thermal Sciences
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Finite element analysis and vibration simulation of electromagnetic imaging sensor housing based on ANSYS
Full text linkMining sensors work in harsh environments and are subject to complex vibrations. Its internal structure is prone to strength failure or fatigue damage. This paper focuses on the structural design of the front discharge and receiver housing inside the electromagnetic imaging sensor for coal-rock demarcation detection. Static analysis, modal analysis, and random vibration simulation were performed using ANSYS Workbench software to verify its reliability and strength in mining. In the static analysis, the thickness of the designed housing is 2 mm. The maximum equivalent elastic strain after applying a pressure of 0.5 MPa to the housing is 0.133 %, much less than the criterion of material fracture strain. This proves that it has excellent strength properties and will not experience strength failure. Modal analysis shows that the first-order intrinsic frequency of the housing is 3298.7 Hz. It is much higher than the vibration frequency in the actual working environment, which can effectively avoid resonance and improve the reliability of the structure. Random vibration simulation results show that the housing's maximum equivalent force and displacement are within the safe range, and the impact on the structural performance is negligible. These results provide a theoretical basis for the optimal design of the sensor housing and its application in complex vibration environments
Effect of vibration on the calculated resistance of sandy soils
Full text linkIn the territories of the Republic of Uzbekistan, where sandy soils are widespread, it is important to forecast and eliminate the consequences of possible accidents that may arise under the influence of oscillatory movements, taking into account engineering-geological and hydrogeological conditions, during the period of their use as a foundation for the construction of buildings and structures. Therefore, a number of scientists have studied and expressed their opinions on the change in resistance of sandy soils when exposed to vibration. One of the main objectives of the article was to determine the quantitative values of the design resistance R of sandy soils under the influence of vibration movements in natural conditions. To solve this problem, a DU-62 vibratory roller was used to vibrate sandy soils at a test site located in the Termez and Jarkurgan districts of the Surkhandarya region. Before and after the application of vibration using a vibratory roller, vibration behavior data were obtained using a UNI-T UT315A portable vibration meter and the measurement results were processed. As a result, it became clear that when designing buildings and structures in areas with widespread sandy soils, it is necessary to take into account that the calculated resistance of sand under the action of vibration forces decreases by 1.18 times compared to the absence of vibration movements. In this case, if the earthquake results in ground movement, then when designing buildings and structures, the calculated resistance of sandy soils should be increased by 1.18 times
Reinforcement of the embankment with reinforced concrete piles in the transition zone from the railway embankment to the bridge
Full text linkThe article presents the design of the transition section to be used in different conditions in the region of junction of roadbed and the bridge, establishment and reasons of vertical shifts under the action of vibro-dynamic forces which appear when trains are driven along transition section. Likewise, in the sections of the foundation of the roadbed and the bridge, the types and types of a variety of defects caused by this fact, such as when the pressure of the weight of constant and temporary forces dropped on the rolling stock passes the active pressure of the ground (Ea), which acts on the support of the bridge shore at the point of the passage, are provided. In order to minimize the active effort at the junction formed by soil, reinforce and make the junction location defect-free, reinforced concrete piles are driven into the embankment to act as bases of junction location between the roadbed of the railway and the bridge location and a formula of computing the spacing of the piles has been contributed taking into consideration outer influences
Analysis of the structural performance of reinforced concrete under fire loading
Full text linkThis study examined the behavior of reinforced concrete structures when exposed to high temperatures resulting from fire. Deterioration in material strength due to fire exposure alters a reinforced concrete structureβs load-bearing capacity and overall behavior. Elevated temperatures negatively affect key material properties of reinforced concrete, including density, coefficient of thermal expansion, thermal conductivity, and elastic modulus. As a result, if a structure experiences fire either concurrently with or prior to an earthquake, these changes in material properties will significantly influence its dynamic performance. For the numerical simulation, the selected structure was designed with a formwork plan and load-bearing system in accordance with earthquake-resistant design principles. Based on this design, fixed and variable loads acting on the beams were assigned. By promoting resilient infrastructure capable of withstanding severe environmental conditions such as earthquakes and fires, this study contributes to the achievement of sustainable development goals. It underscores the necessity of integrating fire resistance into earthquake-resistant design to foster disaster-resilient urban development. The findings may encourage more flexible and sustainable construction practices aligned with SDGs 9 (Industry, Innovation and Infrastructure), 11 (Sustainable Cities and Communities), and 13 (Climate Action)
The meshing characteristics of planetary gear transmission system considering the effects of load and system parameters
Full text linkIn order to investigate the effects of load and system parameters on the planetary gear system, this paper develops a nonlinear time-varying dynamic model of a 12-degree-of-freedom planetary gear system. The model is employed to analyze the influence of load and system parameter variations on the meshing force, kinetic energy, strain energy, and load-sharing coefficient. The results demonstrate that the unbalance exacerbates tooth collision and increase the peak meshing force. Increasing the load will reduce the tooth collision and enhances the load sharing coefficient of the system. Decreasing the tooth side clearance, the unilateral tooth collision will be transformed into bilateral collision and mitigates the fluctuation of the meshing force. Additionally, increasing the transmission error amplifies the magnitude and fluctuation of the strain energy but reduces the systemβs load-sharing coefficient
Dynamic response characteristics of shallow-buried biased small clearance tunnel subjected to various ground shaking
Full text linkThe axial force and bending moment of tunnel lining are crucial for lining stability. To investigate the response patterns of axial force and bending moment in shallow-buried biased small clearance tunnels under various conditions β including different adjacent slope angles, loading wave types, peak loads, and loading directions β extensive numerical simulations were conducted. The numerical results were subsequently verified through large-scale vibration table physical model experiments. The findings reveal that the variation patterns of lining axial force and bending moment under bidirectional coupled seismic waves demonstrate similarity to those under vertical seismic waves. Vertical seismic motion exerts a more pronounced influence on lining axial force response. Seismic wave peak intensity significantly affects lining axial force and bending moment, with both parameters showing gradual increases corresponding to peak load escalation. The arch shoulder of the slope-side right tunnel lining exhibits particularly strong axial force and bending moment responses. While Darui wave, Wenchuan wave, and Kobe wave produce essentially consistent axial force and bending moment response patterns in tunnel linings, their magnitudes differ substantially. Seismic wave type primarily influences response magnitude rather than characteristic patterns of axial force distribution. Increasing slope angles adjacent to tunnels correlate with heightened axial force and bending moment responses in linings. A logarithmic functional relationship exists between slope angle and response values at the lining arch shoulder. These findings provide valuable references for seismic design of shallow-buried biased small clearance tunnels
Dynamic response behaviors of buried pipelines subjected to the impact of spherical falling objects in cold regions
Full text linkImpact from falling objects can easily cause the local deformation of pipeline, which threatens the safe and stable operation of pipeline. In order to study the dynamic response behavior of impacted buried pipelines in cold regions, the buried pipelines, frozen soil and falling objects are taken as the object. Considering the nonlinearity of pipeline material, the contact nonlinearity between pipeline, falling objects and frozen soil, a double nonlinear dynamic analysis model of buried pipeline in cold regions is established by explicit dynamic analysis method. The rationality of the model method is verified by comparing the curves in this paper with those from the experiment. Furthermore, the changing laws of dynamic response of pipeline influenced by different factors are discussed. The results show that: when the buried depth of pipeline is 2 m, the deformation and residual stress of pipeline increase with the increase of pipelineβs diameter-to-thickness ratio, the impact velocity of falling object and the water content of frozen soil, and the impact velocity of falling objects influences the dynamic response behavior of pipelines most significantly, followed by the diameter-thickness ratio of pipelines and the water content of frozen soil; When the diameter-thickness ratio of the pipeline is 58, the deformation and residual stress of pipeline decrease with the increase of buried depth by 75 % and 88 % respectively. Among the four influencing factors, when the impact velocity of falling objects is 10 m/s and the buried depth of pipeline is 3 m, the deformation amplitude of pipelines caused by falling objects is the smallest. It is suggested that in the high-risk regions of falling objects, the diameter-thickness ratio, buried depth and the water content of frozen soil can be reasonably controlled under the condition of predicting the maximum potential impact velocity of falling objects, so as to improve the ability of the pipeline to resist external impact damage, which provides theoretical basis and quantitative control standards for the impact design of pipeline engineering in cold regions
Improving summer outdoor comfort in metropolitan park: a data-driven approach using AI, experimental and design analysis
Full text linkThis study aims to address the growing urban heat challenges by exploring the application of AI-driven simulations to improve outdoor thermal comfort and air quality in urban parks. The primary goal was to optimize park designs using advanced AI technologies and data analysis, improving the quality of public green spaces. A highly accurate AI model was employed, with performance metrics including RMSE (3.68 Β°C), MAPE (6.50 %), and a Pearson Correlation Coefficient of 0.982, to evaluate key environmental parameters such as temperature, wind speed, and thermal radiation. These assessments served as the foundation for design optimization through the integration of AI and Computational Fluid Dynamics (CFD) modeling. Innovative design improvements, such as enhanced shading structures, strategic vegetation placement, and refined material selection, resulted in a 15 % reduction in thermal radiation, a 1 m/s increase in wind speed, and a decrease in PM2.5 and PM10 concentrations by 12 % and 15 %, respectively. These changes led to increased pedestrian comfort, improved health outcomes, and a 20 % rise in park usage. Post-optimization analysis further demonstrated a 25 % reduction in thermal radiation and a 10 % improvement in the Air Quality Index (AQI). Furthermore, resilience testing for short-term climate changes indicated that these design improvements would remain effective for at least three years, confirming the robustness and long-term sustainability of the AI-enhanced strategies. This research highlights the potential of integrating AI technologies in urban park design, offering valuable insights into creating sustainable, user-centered green spaces. By combining real-world environmental data with AI-driven optimization, the study emphasizes the importance of interdisciplinary approaches in enhancing the livability and resilience of urban environments
Signal Sampling criteria and application of structural monitoring based on amplitude analysis
Full text linkThe research explores the influence of sampling frequency on the amplitude analysis error for signals with diverse functional forms, and delineates the approach for ascertaining the optimal sampling frequency for amplitude analysis of signals under dynamic monitoring. A method for determining the sampling frequency of amplitude analysis based on the maximum error criterion is proposed through theoretical derivation of sine function and its composite forms. The correctness of the proposed method is further verified through numerical simulation analysis using MATLAB software. The results indicate that the Nyquist sampling criterion does not meet the precision requirements for amplitude analysis; the impact of odd multiples and even multiples `sampling frequencies on the accuracy of signal amplitude analysis is different; the maximum amplitude error is closely related to the order of the signal; and the even multiples sampling frequency is more reasonable for amplitude analysis. The proposed sampling frequency determination method was applied to the construction of dust removal impact testing system and the fatigue damage analysis of a four-section boom pump truck structure, demonstrating the feasibility of this method in engineering applications. The research in this paper provides theoretical and methodological support for the economic collection and efficient processing of massive condition monitoring signals in engineering practice
Experimental studies of dynamic properties of soils of railroad embankments
Full text linkThe safety and stability of train traffic directly depend on the reliable operation of railroads and the condition of the subgrade. The main purpose of the research was to study the influence of vibration effects on the deformation characteristics of cohesive soils used in the subgrade of railroad embankments. The paper presents the results of compression tests, as well as deformability parameters of the studied soils under static and vibrodynamic loads. The values of deformation modulus (E) for soils of natural origin and with disturbed structure are discussed. It is confirmed that the change in the modulus of deformation of non-water saturated cohesive soils under the influence of vibration depends on changes in the stress state. The modulus of deformation of non-water-saturated clayey soils under static and vibrodynamic loads is determined by the type and nature of interactions between soil particles, as well as possible changes in the process of testing. Soil humidity is one of the key factors influencing the nature of water-colloidal bonds and deformation properties of the soil sample under both static and vibrodynamic loading conditions