Authors:Glib Vatulia; Alyona Lovska, Sergiy Myamlin, Andrij Rybin, Volodymyr Nerubatskyi, Denys Hordiienko Abstract: The object of research is the processes of emergence, perception, and redistribution of loads in the body of a universal railroad gondola with a cladding of corrugated sheets. To improve the strength of the sheets of cladding, it is proposed to strengthen the most loaded area in terms of height (1/3 of the bottom tie-up) with horizontal corrugations. Determination of the geometric parameters of the corrugation is carried out by the moment of resistance of the sheet. The dynamic load of the gondola body with improved cladding was determined by mathematical modeling. The fluctuations of the jump were taken into consideration, that is, the translational movements of the body relative to the vertical axis. The results of the solution of the mathematical model have made it possible to conclude that the studied dynamics indicators are within the permissible limits while the car movement is estimated as "excellent". The calculation was performed of the strength of the body of a gondola with improved cladding. It has been established that the strength of the gondola body under the main operating load modes is ensured. According to the results of calculations of static strength, the calculation was performed of the fatigue strength of the gondola body. It must be said that the fatigue strength of the body cladding increases by 3.7 % compared to the typical one. A feature of the results obtained is that the proposed improvement of the cladding can be carried out not only at the design stage but also during repairs of cars. The scope of practical use of the results includes the engineering industry, in particular railroad transportation. At the same time, the conditions for the practical application of the research results are compliance with the requirements for loading and unloading operations of gondola cars. The results of the current research will contribute to devising recommendations for the design of modern structures of gondolas and for improving the efficiency of their operation. PubDate: Sun, 30 Apr 2023 00:00:00 +030
Authors:Ali Talib Shomran; Batool Mardan Faisal, Emad Kamil Hussein, Thiago Santos, Kies Fatima Abstract: In this investigation, the Mechanical Behavior of the composite Single-Stringer structure was subjected to numerical analysis in order to better understand its properties. As the primary material for the modeling process, the carbon-epoxy IM7/8552 with quasi-isotropic Layups has been utilized. The outcomes of the numerical analysis that were carried out on the structure while it was in its static state have been put into the structural tool that was developed by the ANSYS programme. The fundamental boundary conditions have been defined on the basis of the information that was received from the testing. Static forces with a combined magnitude of 13.7 kN are being applied to the composite Single-Stringer structure. Shear stresses, direction deformation, von mises stresses, and total deformation have all been shown to have an effect on a material's mechanical behaviour, and this effect has been demonstrated. The calculations indicate that there is a maximum amount of bending that can take place as a direct result of the load that is being applied, and that amount is equal to 0.0147. The maximum amount of bending that can take place as a direct result of the load that is being applied is equal to 0.0147. As a consequence of the application of 13.7 kN of pressure, the von Mises stress, which is also frequently referred to as comparable stresses, has reached 51.9 MPa. Shear stresses have been estimated in three distinct plans, and it was discovered that the shear stress that was applied to the XY plane achieved a maximum of 15 MPa, but the shear stress that was applied to the XZ plane reached a maximum of 9.8 MPa. This was found. Both aeroplanes were put through precisely the same amount of tension at the exact same time. At this time, the shear stress on the plane YZ has reached a level of 1.5 MPa. PubDate: Sun, 30 Apr 2023 00:00:00 +030
Authors:Serhii Nosko; Dmytro Kostiuk, Oleksandr Haletskyi, Ihor Nochnichenko Abstract: This paper investigates the influence of hydrodynamic conditions for entering the initial section of the channel located after local obstacles of various types. It is shown that the head losses in the valves and bends of pipelines and in various control elements can be several times higher than those in straight sections of the pipeline. It was established that the assumption about the rectangular shape of the velocity diagram at the entrance to the hydrodynamic initial section does not correspond to the flow pattern in real channels of technological equipment. It is proved that with the manifestation of inertia forces in the flow at the initial section of the channel, hydrodynamic energy losses usually increase, velocity and stress fields are significantly deformed. Given this, it seemed expedient to conduct a study into the processes of flow of viscous liquids in the initial section, located after local obstacles of various types. Experimental and analytical studies have confirmed that there is a significant influence of boundary conditions at the entrance to the initial section on the formation of velocity diagrams and energy loss along its length. The analytical-numerical solution to the system of differential equations describing such flow is given. While solving, the system of equations, by appropriate transformations, takes the form of a nonlinear integral-differential equation. This makes it possible to obtain correct dependences for determining the length of the velocity distribution and energy loss in the investigated section of the channel. The results of calculations of velocity fields in the region of local obstacles agree well with known ideas of the flow pattern, which is observed in physical experiments and the results of analytical solutions. The quantitative difference in results ranges within 12–20 % depending on the Reynolds number. Thus, there is reason to assert that the results of studies reported here could be the basis for devising a procedure of hydrodynamic calculation aimed at structural and operational improvement of existing and designed technological equipment. PubDate: Sun, 30 Apr 2023 00:00:00 +030
Authors:Arestak Sarukhanyan; Yeghiazar Vardanyan, Pargev Baljyan, Garnik Vermishyan Abstract: The study of the patterns of change in the hydrodynamic parameters under the conditions of non-stationary flow at the entry of the cylindrical pipe and the initial arbitrary distribution of velocities in the entry section was conducted based on the boundary layer equations. A boundary problem was formed under the axisymmetric change conditions in the flow. The boundary conditions were chosen in accordance with the pattern of an arbitrary distribution of velocities in the entry section. A general solution of the approximating Navier-Stokes equations is presented depending on the initial conditions and the Reynolds number. In accordance with the type of flow, the boundary conditions of the problem are established, and the boundary-value problem is formulated. Regularities for the change in velocities lengthwise in the entrance region have been obtained for a constant and parabolic velocity distribution in the inlet cross-sections. Analytical solutions have been obtained, allowing to obtain patterns of changes in velocities and pressures toward flow at any section and at any time. For the mentioned cases, the composite graphs of velocity changes in different sections along the length of the entrance transition area were constructed by computer analysis, for different time conditions. With the obtained composite graphs, the patterns of change over the entire length of the transition area of the entrance region were constructed, enabling to obtain fluid flow velocity at any point of the section. The length of the transition zone can be estimated based on the condition of reaching a certain percentage (99%) of the maximum velocity of the flow. The proposed solutions create the conditions for correctly constructing separate units of hydromechanical equipment PubDate: Sun, 30 Apr 2023 00:00:00 +030
Authors:Ngoc-Tien Tran Abstract: Topology optimization is gaining popularity as a primary tool for engineers in the initial stages of design. Essentially, the design domain is broken down into individual pixels, with the material density of each element or mesh point serving as a design variable. The optimization problem is then tackled through mathematical programming and optimization methods that rely on analytical gradient calculation. In this study, topology optimization using honeycomb tessellation elements is explored. Hexagonal elements have the ability to flexibly connect two adjacent elements. The use of the hexagonal element limits the occurrence of the checkerboard pattern to the finite elements of the quadrilateral standard Lagrangian type. A mathematical model is developed with the objective function being the minimum compliance value of the design domain. The element stiffness matrix is constructed using the strain-displacement matrix and the constitutive matrix, assuming a unit Young's modulus. Additionally, optimal conditions are established using Lagrangian multipliers. Two sensitivity and density filtering filters are employed to increase optimization efficiency, prevent the algorithm from reaching a local optimal state, and speed up convergence. If the suggested filter is employed, the objective function achieves a value of c=173,0293 and convergence is attained after 200 iterations. In contrast, without using the filter, the objective function has a larger value (c=186,7922) and convergence occurs at the 27th iteration. The results are significant for optimizing topology to meet specific boundary condition requirements. This paper proposes a novel approach using a combination of filters to advance topology optimization using hexagonal elements in future applications. PubDate: Sun, 30 Apr 2023 00:00:00 +030
Authors:Duaa Talib Hashim; Ali Wathiq Abdulaghani, Hasan Mohammed Ahmed Albegmprli Abstract: The study aimed to explore the possibility of strengthening RC corbels with many strengthening techniques. The research analyzed the RC corbels behavior under a wide range of variables. The theoretical study consisted of twelve models reinforced with GFRP bars with strengthening by steel plate. Finite element analysis with ANSYS APDL was used to verify five specimens. This research deals with a static nonlinear FE simulation to investigate the behavior of RC Corbels reinforced internally and externally. The verification with experimental work demonstrated a satisfactory agreement in the load-displacement relationship, ultimate load and displacement, and failure mode. The parametric study was implemented which included strengthening the four concrete corbels externally and four corbels internally by a steel plate in many configurations while the remaining three were modeled with varied compressive strength (30, 40, and 50) MPa. The external strengthening included the placing of steel plate externally around the corbel in a U-shaped form and partial strengthening by strips and bottom plate. The models with internal strengthening involved placing the steel plate internally instead of stirrups. The results discovered that the strengthening provided enrichments in the stiffness, ductility, and energy absorption by 37 %, 4 %, and 26 %. In addition, in the case of full external strengthening more than internal retrofitting, there is a maximum improvement in the cracking and ultimate load carrying capacity. The external strengthening was better than internal one due to the confinement effect of the concrete. The stress distribution and crack pattern were affected by the strengthening techniques and more cracks appeared in the corbels with external steel plates. PubDate: Sun, 30 Apr 2023 00:00:00 +030
Authors:Andrii Kozhushko; Yevhen Pelypenko, Serhii Kravchenko, Vitalii Danylenko Abstract: This paper considers the influence of hydrodynamic processes in the movement of the free surface of liquid in partially filled tractor tanks. Splashing liquid in partially filled containers is a significant problem in the study of functional stability of movement in the marine, aerospace, rail, and automotive industries. After all, it affects productivity and traffic safety. The same effect was observed when performing transportation work while delivering liquid cargoes in the agricultural sector. That was due to increasing the transportation speeds of wheeled tractors. In the procedure, using the Rayleigh theory of surface waves, a linearized problem of motion of the free surface of a liquid is obtained. Based on Helmholtz's theorem, the components of scalar and Laplace field vector potentials of fluid velocity vector are separated. The potential problem for translational motion of fluid, in which vortex component of the field is absent, is considered. Instead of the fluid velocity potential, a scalar fluid displacement potential in Rayleigh surface waves was introduced. Comparing the results of calculating fluid splashing with the work of other scientists, a high convergence of natural frequencies of partial oscillators in 3D space was found. This is noticeable in the last quarter of the filling of the tank, in which significant displacements of the deep liquid occur. A feature of the results is the introduction, instead of the real shape of the container, an equivalent form of a parallelepiped, the final shape of which depends on the level of fullness. The frequency properties of movement of the free surface of liquid based on the standard size of tanks used in agriculture are separated. The proposed improved methodology could be used to increase stability, controllability, and smoothness when operating tanks with a wheeled tractor. PubDate: Sun, 30 Apr 2023 00:00:00 +030
Authors:Oleksandr Lazarenko; Taras Hembara, Vitalii Pospolitak, Dmytro Voytovych Abstract: This paper considers the deformation properties of the body of the lithium-ion power cell (LIPC) Panasonic NCR18650B (LiNi0.8Co0.15Al0.05O2) exposed to the action of static load at various techniques of fixing the cell. Determining the properties of LIPCs under appropriate conditions makes it possible to fill the gap in existing studies, which will further ensure the safety of their use. Based on the results of experimental studies, the LIPC rigidity and temperature indicators were determined in accordance with the applied load. The most dangerous variant, from the point of view of fire danger, of applying a static load on the cell has been established. It was experimentally established that, on average, the Panasonic NCR18650B LIPC housing can withstand a load of about 80 kg·s/cm2 (or 7.84 MPa) without further ignition. An increase in pressure force in the range exceeding 85–90 kg·s/cm2 leads to an irreversible chain thermochemical reaction, which, within 2–3 seconds, leads to LIPC ignition. Compressing the LIPC evenly along its lateral surface showed the occurrence of combustion at the load on the cell equal to 150 kg·s/cm2. The average temperature of the cell during combustion caused by the deformation of the housing is 350–450 °C, and the maximum value is registered in the range of 580–680 °C. The mathematical model built on the basis of the mathematical theory of thin shells adequately describes the stressed-strained state of the cylindrical body of cells under the action of a force concentrated and distributed load. The estimation model is satisfactorily verified by experimental results, making it possible to improve the strength and rigidity of LIPC housing by choosing the appropriate steel grade for its body, the geometric dimensions, and the structural technique of its fastening. PubDate: Sun, 30 Apr 2023 00:00:00 +030
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