Experimental and theoretical study of the efficiency of solid slag mixtures for desulfurization of 20GL steel under conditions of induction crucible melting

When producing steel, the enterprise faces difficulties in removing sulfur from the melt. In turn, an increased sulfur content in the finished product leads to a decrease in the values of some mechanical properties. This work analyzes the desulfurization process of 20GL grade steel in an induction crucible furnace. The influence of sulfur on the impact toughness of steel and the factors influencing sulfur removal are considered. Calculated data and industrial melting data were obtained, the difference between these data was explained, and recommendations were made based on this data. The parameters of steel smelting technology, which determine the chemical composition and structure, are the main factors contributing to high mechanical properties. The relevance of the work lies in the need to improve and develop the desulfurization process, which allows for the production of steel with low sulfur content and high mechanical properties

Leakage failure analysis of sewage pipe used for buried valve in natural gas station

Leakage accident occurred during the operation of a buried valve blowdown pipe in a natural gas station. After the macroscopic morphology, mechanical properties, chemical composition, metallography, scanning electron microscopy and energy spectrum analysis of the leaking blowdown pipe, it was found that the corrosion perforation was located in the outer wall of the pipe, and the damage of the corrosion layer caused the corrosion components in the saline soil to contact the steel pipe to produce oxygen corrosion. In addition, Cl– ions in the soil played a role in accelerating corrosion, which eventually led to the occurrence of perforation accidents

Correlation degree analysis of sliding bearing oil monitor data based on grey theory

Based on regular analysis of the spectrum, PQ value, precision moisture content and kinematic viscosity of a certain sliding bearing lubricating oil, this paper used grey theory to study the correlation degree within these four kinds of analysis indicators. It is hoped that it can achieve mutual verification and judgment of the state evaluation of sliding bearings. It can provides reliable basis for studying the internal operating rules of sliding bearings. It can also provide scientific basis for the management and maintenance of sliding bearings

Analysis of the crisis-deformed state and dynamic operation of reinforced concrete sleepers

Due to the vibration (dynamic) effect on the path of the load from the rolling stock, reinforced concrete sleepers cannot withstand. Hidden and obvious defects appear in them, sometimes leading to their complete destruction. The article presents the results of a computational analysis of prestressed reinforced concrete sleepers performed using finite element mechanical and mathematical modeling in the ANSYS 2021 R2 program. Comparative strength static and dynamic calculations were performed for experimental sleeper samples of “version 1 concrete grade B40” (type Sh-1) and “version 2 concrete grade B50” (type SH-2). The results of laboratory and full-scale (operational) tests of prestressed reinforced concrete sleepers after their installation on experimental sections of the railway line are presented. The purpose of this study was to identify the main causes of cracking and failure of reinforced concrete sleepers, in order to produce improved samples of prestressed concrete sleepers. The economic development of the railways of the Republic of Kazakhstan, as well as the operational safety of passengers and cargo, directly depends on this

Load transfer mechanism of flexible drill string with hinges based on dynamic relaxation method

The flexible drill string with hinges is a unique structure for drilling ultra-short radius horizontal wells. In this paper, spatial beam elements are used to simulate the flexible drill string and outer tube, universal joint connection elements are used to simulate hinge joints, and contact gap elements are used to simulate the random contact between the flexible drill string and the outer tube. A nonlinear mechanical analysis model is established for the contact of the flexible drill string with hinges in the outer tube, and the dynamic relaxation method is adopted to solve the model. The correctness of the model and method is verified by an example with analytical solutions. Numerical calculations are conducted on six types of hinge rotation limits and six different single section lengths of flexible drill strings in the inclined section. The results illustrate that the contact force between the flexible drill string and the outer tube is discontinuous and randomly distributed along the axis. The hinge rotation limit is increased from 3° to 5.5°, the axial force transmitted to the bottom of the flexible drill string is reduced from 16.7 kN to 1.5 kN, and the torque transmitted to the bottom has little changed, and its values are close to 1900N·m. When the hinge rotation limit is greater than 5 degrees, the axial force loss rate is greater than 59.5 %. When the hinge rotation limit is 4 degrees, the axial force and torque transmitted to the bottom of the well have little change for flexible drill strings of different single section lengths

Improvement of the classification of causes for the decommissioning of large-size tires

The article presents the results of the analysis of the causes of failure of large-size tyres operated in the conditions of Navoi MMC. On the basis of generalisation of the accumulated data the classification of the main factors leading to tyre failure is proposed. All causes are grouped into three key categories: wear, mechanical damage and thermal damage. Wear includes the processes of natural and accelerated tread abrasion, as well as various forms of uneven wear arising from deviations from the recommended operating conditions. Mechanical damage is considered as a result of short-term or long-term external impacts, including punctures, cuts, cord breaks and frame deformations. In 2024, the plant used more than 19 thousand car tires with a total value of about 1.4 trillion soums. These quarry dump trucks use tires manufactured by Bridgestone, Goodyear, Luan, Michelin, Techking, Advance, Aeolus, Maxam and Noble. For transport enterprises, the task of rational use of tire resources by improving the condition of quarry roads and reducing premature tire failure is relevant. The results obtained can be used to improve tyre maintenance and condition monitoring systems at mining enterprises

Improved iterative reweighted L1 norm minimization method for sound source identification

Sparse reconstruction algorithm is one of the main research topics in compressed sensing. To address the shortcomings of existing iteratively reweighted l1-norm minimization methods, which exhibit poor performance in low-frequency sound source identification and weak anti-interference capability, this paper proposes an improved iteratively reweighted l1-norm minimization method. Unlike traditional methods, this method introduces a log-sum penalty function and constructs a surrogate function, transforming the problem into an effective form for solving the source strength distribution vector. Through numerical simulations comparing the two methods under different frequencies and signal-to-noise ratios (SNR), the results demonstrate that the proposed method enhances both the sound source identification accuracy and anti-interference capability of the algorithm, while also being able to adapt to lower frequency ranges

Equations of motion for the rigid and elastic double pendulum using Lagrange’s equations

The double pendulum is a well-known system exhibiting nonlinear dynamics and chaotic behavior. This study extends the conventional rigid double pendulum by introducing elastic extensions in the links, leading to a system known as the elastic double pendulum. The mathematical model incorporates both rotational and translational motion, accounting for elastic deformations using Hooke’s Law. The governing equations are derived using Lagrangian mechanics, considering both gravitational and spring potential energy contributions. Numerical simulations are performed to compare the motion of the elastic and rigid double pendulums, highlighting differences in phase-space trajectories, energy transfer, and stability characteristics. Results demonstrate that elasticity introduces additional oscillatory components, increases system nonlinearity, and affects the overall predictability of motion. These findings provide insights into elastic multi-body dynamics and have potential applications in flexible robotic arms, soft mechanisms, and bio-inspired locomotion

Analysis of shimming performance and clearance influence under manipulation state

During the roll control process of an aircraft, shimmy often occurs, usually manifested as high-frequency and low amplitude vibrations. In order to better analyze the essential causes of landing gear shimmy, this paper establishes a flexible shimmy dynamics model for the nose landing gear and analyzes the influence of the hydraulic stiffness of the control actuator. The analysis shows that a decrease in stiffness will reduce the stability of the system, and the shimmy frequency will decrease, but the frequency will be higher than the reduced shimmy state. Finally, the system damping ratio is compared to evaluate the stability of the system. Based on the above model and combined with clearance theory, a set of shimmy dynamics model considering the influence of clearance was established. The results show that radial clearance has almost no effect on shimmy; The presence of axial clearance can cause equal amplitude vibration in the system, and increasing the clearance value can cause an increase in amplitude; When the initial swing angle of the system is different, the system will gradually swing to the same amplitude of vibration; There is a coupling effect between system stiffness and clearance values, and as the system stiffness decreases, its amplitude will increase nonlinearly

Data-driven modeling and experimental validation of heat-resistant concrete for industrial furnace lining

The purpose of this study is to extend the service life of liquid-layer furnaces through experimental evaluation of their performance. Instead of using conventional large and small aggregates, this research investigates the use of secondary refractory materials to reduce the cost of the concrete mixture. To address this problem, it was proposed to replace the traditional method of lining the furnace floor with SHB-brand fireclay bricks by a monolithic concrete structure. Considering the operational characteristics of the furnace - high temperatures up to 1000 °C and an aggressive environment producing SO3 gaseous sulfur -sodium-infused liquid glass concrete was selected as the base. Instead of cement, liquid glass with low thermal conductivity, including amorphous-phase materials and glass-layered composite viscous substances, is recommended. A novel aspect of this research is the integration of machine learning techniques with experimental data to predict the thermal performance of concrete under high-temperature conditions. Furthermore, the study introduces the use of secondary refractory materials as a cost-effective aggregate alternative, offering a unique combination of sustainability and performance in industrial furnace applications