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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
Numerical modeling of reinforced concrete structures made of lightweight concrete using ANSYS
Full text linkIn this paper, extensive numerical investigations into reinforced concrete beam made of lightweight concrete are given, through the ANSYS finite element program. The main aim was to assess the load carrying capacity, stiffness and deformation characteristics of the beams of different concrete densities. There were seven beam specimens, which vary in the percentage ratio of lightweight to normal aggregates, and the material properties were duly incorporated in the model. Three-dimensional nonlinear finite element analysis was used to simulate the beams with a mesh size of 25 mm, and the results were compared with the experimental results. Results showed that when the concrete density was reduced the loadbearing capacity decreased gradually, as the concrete became normal weight (95 kN) and then fully lightweight (85.7 kN). Nevertheless, the plastic zone transition happened later in lightweight beams and this implies that the deformation resistance was more difficult than in normal-weight concrete. The load-deflection curve demonstrated the fact that lightweight concrete beams though less stiff in nature, are structurally reliable and competitive. This study highlights the possibility of the lightweight concrete to be used as a structural material in contemporary engineering practice and therefore seismic zones where minimized self-weight improves the overall safety and efficiency. The results are useful in understanding how to optimize and design the reinforced lightweight concrete members
Investigation of transient processes in auxiliary asynchronous electric motors of locomotives using differential equations
Full text linkThe aim of this research is to scientifically substantiate the operating conditions of small and medium-power auxiliary asynchronous electric motors currently in use on mainline electric locomotives of the VL60, VL80, and Ermak 3ES5K types. The goal is to draw conclusions based on scientific research, such as evaluating the operational efficiency of auxiliary asynchronous electric motors and creating the possibility to predict their service life based on the assessment results. This, in turn, will enable timely maintenance of auxiliary engines in locomotives
Die casting mold design of CH367B1 aluminum alloy throttle valve body
Full text linkAs a core component of the automotive engine intake system, the throttle valve body is subjected to long-term engine vibrations. Defects such as gas pores and shrinkage pores in the die-cast part will cause uneven stiffness of the throttle valve body, and thus lead to fatigue failure due to local stress concentration under vibration loads. In this paper, the aluminium alloy was used as the die-casting alloy to design an efficient and simple die-casting mould for CH367B1 aluminium alloy throttle valve body. After measuring the target dimensions and conducting a preliminary analysis of the UG 3D drawing of the part, the size and structure of the valve body were analysed according to the 3D model of the part to select the appropriate parting surface. In the design process, the clamping force, chamber capacity, projected area and other parameters were calculated in order to select a suitable die-casting machine. Part-related dimensions and features were analyzed. Push-out mechanisms, molded parts, guide mechanisms, etc. were designed. The whole set of molds was obtained. Suitable casting systems were designed by calculating and checking references. Mold flow analysis was carried out using ProCAST2021 software. The optimal solution was selected by observing the liquid metal filling process and the distribution of defects, and then calibrated
Numerical simulation of chloride ion transport in concrete based on a random aggregate model
Full text linkA three-dimensional stochastic aggregate model of concrete was established using the Monte Carlo method, and a numerical simulation of chloride ion diffusion at the microscopic level was conducted. The study investigated the migration behaviour of chloride ions in concrete regarding mixing proportions and temperature. The results showed that compared to the simulation results at an ambient temperature of 20 ℃, the chloride ion diffusion coefficient increased by 31 % and 70.5 % for concrete at 25 ℃ and 30 ℃ at 28 days, respectively. The chloride ion penetration depth increased by 17.3 % and 34.9 % for concrete at 25 ℃ and 30 ℃, respectively. With a slag content of 10.4 %, 20.8 %, and 27.1 %, the chloride ion diffusion coefficient at 28 days decreased by 1.4 %, 2.7 %, and 4.1 %, respectively. With a fly ash content of 8.3 %, 16.7 %, and 25 %, the chloride ion diffusion coefficient at 28 days decreased by 2.1 %, 5.4 %, and 9.2 %, respectively. Both slag and fly ash can reduce the chloride ion diffusion coefficient in concrete, with fly ash showing better effectiveness than slag. A water-to-binder ratio of 0.4, combined with 27.1 % slag and 25 % fly ash as cement replacements, can effectively improve the resistance of concrete to chloride ion attack. The micro-scale finite element model of concrete, developed through Monte Carlo simulation, offers enhanced visualization of chloride ion penetration processes under varying mix proportions and temperature conditions
Simulation of motion trajectories and kinematic characteristics of an oscillatory system with a planetary-type vibration exciter
Full text linkThe parameters of the vibration exciters significantly determine the efficiency, reliability, and durability of vibratory technological equipment. This article continues the authors’ previous research dedicated to planetary-type vibration exciters. The main objective at this stage is to substantiate the feasibility of using planetary mechanisms as drives for vibratory machinery. The methodology for conducting virtual experiments involves using the “Motion Analysis” application within the SolidWorks software to simulate the motion of an oscillatory system with a planetary-type vibration exciter. The modeling results are presented as time dependencies of displacements, velocities, and accelerations of the oscillating body (the working element of the vibratory machine), as well as its motion trajectories under different geometric parameters of the planetary mechanism. The scientific novelty of the work lies in the further development of methods for exciting oscillations of the working bodies of vibratory machines with predetermined kinematic and force parameters. The conducted research can be useful for researchers and engineers involved in the investigations and designing of vibratory equipment, aiming to ensure the technologically required motion trajectory and kinematic characteristics of the corresponding working bodies (such as conveying trays, sieves, screens, compacting plates, etc.)
Analysis on the influence of blade pitch angle on dynamic characteristics of the rotor system
Full text linkAt present, few studies focus on variable-pitch fans for small-to-medium turbofan engines, with most relying on hydraulic actuation that fails to meet strict environmental and efficiency demands. This paper analyzes an electrically actuated lead-screw servo-motor-driven variable-pitch fan rotor: at 1×10⁷ N/m support stiffness, the first critical speed exceeds the operational range and pitch angle’s influence is negligible, peak unbalance response is 1.22×10⁻⁶ m linearly decreasing with pitch angle, and vibration analysis avoids resonance. Results confirm the electric pitch-change concept’s feasibility
Challenges to properly accounting for cyclic response in transversely isotropic elastic soil idealizations
Full text linkThe way natural soils are deposited gravitationally inherently leads to an anisotropic microfabric. The elasticity of such anisotropic soils has typically been idealized as being transversely isotropic (or “cross anisotropic”). The importance of elastic anisotropy in geotechnical engineering applications has particularly been invoked in conjunction with predicting ground deformations associated with underground structures such as deep excavations and tunnels. The development of elastic constitutive relations for transversely isotropic geomaterials is complicated by the fact that the elastic material parameters are usually not constant. This paper briefly reviews the issue of elasticity in soils. Following a short overview of isotropic elastic idealizations, the more relevant topic of transversely isotropic idealizations is discussed, with emphasis not only on monotonic but also on cyclic response
Anomaly detection method of traction motor bearing based on multi-scale sub-band fuzzy entropy manifold fusion index
Full text linkDetecting early faults in traction motor bearings poses significant challenges due to weak signals and difficulties in identifying fault initiation points with sufficient sensitivity. This paper introduces a novel anomaly detection method based on a multi-scale sub-band fuzzy entropy manifold fusion index (MFMI). The proposed method decomposes vibration signals across multiple scales to capture local features of bearing health, calculates sub-band fuzzy entropy to quantify fault characteristics, and uses locality preserving projection to retain nonlinear structural features while reducing dimensionality. Validation experiments using full-cycle acceleration life vibration signals demonstrate the superior performance of the proposed method. For instance, in the traction motor case, the proposed index detected early damage at the 189th time point, outperforming other indicators that detected damage after the 200th time point. The proposed method also shows higher sensitivity to early degradation trends while maintaining stability during normal operation. These results highlight the practical applicability of the method for early anomaly detection in traction motor bearings, offering earlier and more reliable fault detection compared to traditional methods
A rolling bearing fault diagnosis method under insufficient samples condition based on MSLSTM transfer learning
Full text linkIt usually affects the accuracy and reliability of deep learning based intelligent diagnosis methods under the condition of insufficient samples. Existing methods for handling insufficient samples often have problems such as requiring rich expert experience or consuming a lot of time. To solve the above problems, a rolling bearing fault diagnosis method under insufficient samples condition based on multi-scale long-term and short-term memory network (MSLSTM) transfer learning is proposed, which mainly consists of an improved long-term and short-term memory network named as MSLSTM and transfer learning. By introducing multi-scale convolution operation into the traditional LSTM to improve its drawback that only extracts single type of fault feature information, which leads to poor diagnostic performance in noisy environments. Besides, the pooling layer and global average pooling layer in traditional LSTM are replaced with convolution operation to avoid the problem of information loss. Subsequently, the MSLSTM is combined with transfer learning, and a rolling bearing fault diagnosis method under insufficient samples condition based on MSLSTM transfer learning is proposed, which fine tunes the model parameters using a small amount of target domain data. Feasibility of the proposed method is verified through two kinds of experiments. The proposed method has stronger feature extraction ability and training efficiency compared with other models