Papers by Keyword: Dynamics

Abstract: The research presented in this scientific paper focuses on modeling the dynamics of multicomponent systems with particles of different geometries using the GROMACS software package. Three main types of particles were analyzed in the study: spheres, ellipsoids, and plates, each of which has its own unique geometric characteristics that affect their behavior in the environment. The modeling allowed us to investigate the influence of particle shape on their diffusion, self-organization, and interaction between particles of different shapes. In particular, spherical particles, having an isotropic geometry, show the highest diffusion coefficient, since their symmetrical structure minimizes the resistance of the environment. This, in turn, makes them ideal for modeling simple interactions in liquids or colloids. Ellipsoidal particles, due to their anisotropy, have a slightly reduced diffusion coefficient, since their orientation in space affects the motion. Plates, which have a significant surface area relative to the volume, demonstrate the lowest diffusion rate, which is associated with a large interaction with the environment and the resistance created by their geometry. The results of the study also showed that the diffusion coefficient decreases with increasing particle size for all types. At the same time, spheres demonstrated the highest diffusion coefficient at the same size compared to other geometries, while plates have the lowest values ​​of this indicator. Analysis of the trajectories of particle motion in space using the GROMACS software allowed us to assess the influence of geometry on particle mobility. It was found that spheres exhibit the largest displacement amplitude, which indicates their high mobility and chaotic nature of the motion. Ellipsoids have a more stable motion with smaller displacements, which is associated with their geometric anisotropy. Plates, due to the large resistance of the environment, have the smallest displacements, which indicates limited mobility. It should be noted that the obtained research results open up opportunities for a deeper understanding of interactions in complex multicomponent systems and can be useful for further research in various fields. It is also worth noting that the comparison of different types of particles with different geometries and their influence on diffusion processes allowed us to obtain valuable information for improving models and practical applications in relevant fields of science and technology.

Abstract: In an open or unbounded system, when a solid sphere freely falls into a liquid, it accelerates until it reaches a terminal velocity. At this point, the gravitational force, buoyant force, and viscous drag acting on the sphere are balanced. Stokes' law describes that in a laminar flow state, the viscous drag on the sphere is proportional to its radius, velocity, and viscosity coefficient. In this paper, an experimental system was constructed and the vertical and horizontal positions of spheres were measured with different sizes and densities in liquids of different diameters and viscosities, and the vertical and horizontal positions, velocities, and accelerations of spheres were analyzed. The data analysis shows that the sphere is not only subjected to the viscous drag and but also the boundary forces from the system. This work will have a significance in modeling and computer simulation of accurate measurement of liquid viscosity.

Abstract: In this paper, the boundary element method (BEM) is investigated and computer simulations are conducted to study the patterns of structure formation of non-isometric elements. The modeling of this study covered various aspects, including shape, radius, angle from the stable radius, porosity, average coordination number, simulation time, component falling force, and electrostatic constant. The simulation results provided important information about the properties and interaction of non-isometric components under different conditions. It was found that the obtained parameters can be effectively predicted for further research. It should also be noted that important processes, such as deformation and material behavior, colloidal aspects, dynamic modeling of the movement of components with complex shapes, and features of nanotechnology, were observed in parallel with computer simulation.

Abstract: The result of the research aims to provide a foundation structure that reduces the amplitude of oscillation of machines and equipment from various technical causes and natural phenomena, preventing resonant phenomena and economical use of foundation material. The proposed foundation, compared to existing foundations, provides a decrease in amplitude and prevents the phenomenon of resonance of vibrations of foundations for machines and equipment creating savings in the use of cement-concrete material. There is considered mathematical, structural, and practical modeling of anti-vibration foundations of mechanical installations in this article. The purpose of the study is to create a foundation design that reduces the amplitude of oscillation of structures from various technical reasons and natural phenomena, prevents resonant phenomena, and economical use of foundation-reinforced concrete material. The research results can be used in the design of foundations of piston machines and equipment used in the oil and gas industry.

Abstract: On the basis of theoretical and experimental studies, the prerequisites and the method of calculation of bent and compressed-curved reinforced concrete structures with zone reinforcement made of steel fiber, working under static and short-term dynamic loads, are formulated. In the developed method for calculating the strength of normal and inclined sections, a nonlinear deformation model is implemented, which is based on the actual deformation diagrams of materials. The developed calculation method is brought to the program of calculation of reinforced concrete structures with zone reinforcement of steel fiber under short-term dynamic loading, taking into account the inelastic properties of materials. The numerical studies made it possible to determine the influence of various parameters of steel-fiber reinforcement on the strength of reinforced concrete elements. To confirm the main results of the developed calculation method, experimental studies of reinforced concrete beam structures reinforced with conventional reinforcement and a zone steel-fiber layer are planned and carried out. Experimental studies were carried out under static and short-term dynamic loads. As a result of the conducted experiments, data were obtained that characterize the process of destruction, deformation and cracking of steel-reinforced concrete elements under such types of loading. The dependences of changes in the energy intensity of reinforced concrete structures with zone reinforcement made of steel fiber in the compressed and stretched cross-section zones under dynamic loading are obtained. The effectiveness of the use of fiber reinforcement of normal and inclined sections of bent and compressed-curved elements to improve the strength and deformative.

Abstract: The current accelerated developments within the automotive sector have triggered a series of performance, comfort, safety and design-related issues. Hence, oftentimes manufacturers are challenged to combine various elements so as to achieve an attractive design, without diminishing the vehicle’s dynamic performance. In order to determine the vehicle dynamic performances we carried out an analysis by two methods. In the first part of the paper, we have used the analytical method to establish the dynamic performances of a vehicle. The second part of our study addresses another method to determine the star performances of the vehicle by means of computerized simulations. The first test aimed to determine vehicle starting performances for two vehicle models, with similar technical configuration, but with the same initial data. In the second test, we aimed at determining the start performance for the same car model, with the same initial data, but for different adhesion coefficients

Abstract: Test structure development is critical for single wafer pattern collapse evaluations. A good test vehicle not only allows optimization and benchmarking of different processes, but also facilitates understanding of the underlying mechanism. For high aspect ratio silicon nanopillar arrays, by increasing the gap distance in one direction while keeping the other direction constant, an unexpected higher collapse rate is found. This preliminary finding is contradictory to the prevalent models that are based on equilibrium force balance between capillary and mechanical interactions. It is postulated that the asymmetric arrangement of pillars facilitates the formation of liquid bridge and thus more pattern collapse. Such test structures can bring useful insights to understand the dynamic mechanism of pattern collapse.

Abstract: According to recent research, quite a large part of the buses have exceeded the loading standards, which causes road damage. In order to reduce weight, the use of lighter materials such as aluminum was used. Moreover, the cost of maintenance decreases and the fuel consumption is reduced. In this paper we summarize the study of the dynamic and vibrational behavior of the chassis, including the rolling system. In the paper [2], several models have been elaborated necessary for this study. In the present paper we proposed the integration and, implicitly, the finding of the dynamic response, as a result of the behavior of the chassis in operation, in the form of time functions that we represented graphically according to a real numerical application, these representations better suggesting this behavior.

Abstract: This paper describes some features and analogies of the mathematical models for the elastic elements with movable load and for the elastic elements of changeable length. In these systems two forms of own oscillations - the own component and the accompanying one, displaced in phase to the right angle correspond to every frequency of the system. The accompanying component is caused by the mobile inertia load or by the changeable length and they are not trivial only when this factor exists. As for objects with time-varying length, these problems lie in outside of the scope classical problems of mathematical physics due to that the eigenfrequencies and eigenforms become time-dependent functions. This non-classical section of the mathematical physics is waiting for its development, new researches and generalizations.

Abstract: The paper deals with design, modeling, and dynamic analysis of an integral (4-wheel) steering system for 2-axle cars. The study is focused on the steering box of the rear wheels, which is based on cam - follower mechanism. In the proposed concept, the integral steering intends to improve the stability and handling of the vehicle by considering the integral steering law, which is formulated in terms of correlation between the steering angles of the front and rear wheels. In this regard, a double-profiled cam is designed, whose profile dictates the translational movement of the follower, which is connected to the rear left and right steering tie-rods. The dynamic modeling and simulation of the 4-wheel steering vehicle was performed by using the MBS software package ADAMS. The results of the dynamic tests demonstrate the handling and stability performances of the proposed system, in relation with a classical 2-wheel steering vehicle.