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Документ A methodology of determining of parameter j* in discrete models of finite element method(КНУБА, 2017) Bazhenov, V. A.; Pyskunov, S. О.; Shkryl, О. О.Based on the method of reactions, a technique for determining of the parameter J * by the method of subdomain moving in discrete models of finite element method (FEM) has been developed. A number of test problems solved. The obtained results confirm the effectiveness of the technique.Документ An analysis of raft thickness in high-rise buildings - case studies(КНУБА, 2019) Nguyen Anh Tuan; Cao Van HoaThis study shows that the raft thickness is depended on foundation system, Young modulus of soil right under the raft and number of floors of superstructure, and explains very well the case of thick raft of ICC Tower, thin raft of Dubai Tower and reasonable raft thickness of Incheon Tower.Документ Analysis of the effect of the Ho Chi Minh City Tunnel settlement on the adjacent buildings(КНУБА, 2017) Nguyen Anh Tuan; Tran Duc Chinh; Nguyen Thanh DatThe paper aims to studying the effect of settlement of the Ho Chi Minh City Tunnel in soft soil condition on the nearby buildings due to tunneling by the Finite Element Method using Plaxis 3D Tunnel.Документ Application of parameter continuation method for investigation of vibroimpact systems dynamic behaviour. problem state. short survey of world scientific literature(КНУБА, 2014) Bazhenov, V. A.; Pogorelova, O. S.; Postnikova, T. G.Authors in their works study vibroimpact system dynamic behaviour by numerical parametric continuation technique combined with shooting and Newton-Raphson’s methods. The technique is adapted to two-mass two-degree-of-freedom vibroimpact system under periodic excitation. Impact is simulated by nonlinear contact interaction force based on Hertz’s contact theory. Stability or instability of obtained periodic solutions is determined by monodromy matrix eigenvalues (multipliers) based on Floquet’s theory. In the present paper we describe the state of problem of parameter continuation method using for nonlinear tasks solution. Also we give the short survey of numerous contemporary literature in English and Russian about parameter continuation method application for nonlinear problems. This method is applied for vibroimpact problem solving more rarely because of the difficulties connected with repeated impacts.Документ Application of stiffness rings for improvement of operating reliability of the tank with shape imperfections(КНУБА, 2020) Lukianchenko, O. O.An efficiency of using of two stiffness rings for improvement of operating reliability of the tank with real shape imperfection at the action of combination load was evaluated. The computer model of the tank was constructed in the form of the thin cylindrical shell by of the program complex of finite element analysis. The tank stability problem under separate and joint action of surface pressure and axial compression was solved by the Lancosh method in linear formulation and as a nonlinear static problem by the Newton-Raphson method. The region of the tank failure-free work, which has the graphical presentation, confirmed the improvement of the tank wall stability due to the use of stiffness rings, especially in the area of surface pressure action.Документ Buckling and vibrations of the shell with the hole under the action of thermomechanical loads(КНУБА, 2020) Bazhenov, V. A.; Krivenko, O. P.The paper outlines the fundamentals of the method of solving static problems of geometrically nonlinear deformation, buckling, and vibrations of thin thermoelastic inhomogeneous shells with complex-shaped midsurface, geometrical features throughout the thickness, under complex thermomechanical loading. The technique is based on the geometrically nonlinear equations of three-dimensional thermoelasticity, the finite element formulation of the problem in increments, and the use of the moment finite-element scheme. A thin shell is considered by this method as a threedimensional body. We approximate a shell by one spatial universal finite element (FE) throughout the thickness. The universal FE is based on an isoparametric spatial FE with polylinear shape functions for coordinates and displacements. The universal element has additional variable parameters introduced to expand its capabilities. The method of modal analysis of the shell is based on an approach that at each current stage of thermomechanical loading takes into account the stresses accumulated at the previous stages. The developed algorithm allows one to study geometric nonlinear deformation and buckling of elastic shells of an inhomogeneous structure with a thin and medium thickness, as well as to study small vibrations of the shells relative to the reference deformed state caused by static loading, taking into account large displacements and a prestressed state. An analysis of the stability and vibration of the spherical panel with the hole is carried out. The effect on the frequencies and mode shapes of the shell of the sequential action of thermal and mechanical loads is investigated.Документ Dynamic behaviour of nonlinear nonsmooth discontinuous vibroimpact system(КНУБА, 2015) Bazhenov, V. A.; Pogorelova, O. S.; Postnikova, T. G.Authors shortly describe the problem state about studying of discontinuous vibroimpact systems dynamical behaviour. Recently the investigations of such systems are developed rapidly. There is survey of world scientific literature about this problem. Information and description of an International Conference on Nonlinear Dynamics Complexity is given. Authors show owns the most spectacular results demonstrating the phenomena unique for nonsmooth systems describing by differential equations with discontinuous right-hand side. These results were obtained by numerical parameter continuation method.Документ Effectiveness of semi-analytical finite element method in the numeric analysis of deformation of non-homogeneous 3d constructions subject to initial deviation of form(КНУБА, 2015) Solodei, I. I.; Vabishchevych, M. O.; Sіzevych, B. I.; Chepurna, O. O.Static and dynamic numeric models to analyze stress-strain state of 3D uncanonical form bodies are considered in the range of semi-analytical finite element method. Effectiveness and simulation veracity analysis are provided on the base of specific test cases.Документ Impact a circular cylinder with a flat on an elastic layer(Lira-K, 2018-01-02) Bogdanov, VladislavIn the work the comparison of the results of solving two plane problems is performed: the impact of a circular cylinder with a plane platform parallel to the cylinder axle (the flat) with an elastic layer and a second − plane strain state of nonstationary interaction of a circular cylinder with a flat with an elastic layer in a purely elastic and elastic-plastic mathematical formulation corresponding. The first contact occurs along the plane of the flat. A good coincidence of the results of the second problem at an elastic stage with the results of the first problem is shown. In the author's works a new approach was developed to solve plane and tree dimension problems of impact and non-stationary interaction in an elastoplastic formulation. The crack growing was simulated using an elastoplastic mathematical model. The numerical solution was obtained using the finite difference method scheme.The use of an elastic-plastic formulation makes it possible: 1) determine the stress-strain state at the points determined by the partitioning grid of the computational domain, not only on the surface; 2) to give a reliable description of the development of plastic deformations − the stage corresponding to plasticity is a continuation of the elastic stage; 3) reliably determine the destruction toughness. A method has been developed for calculating plastic strain fields and destruction toughness of the material using the solutions of dynamic plane problems of the stress-strain state in an elastoplastic formulation taking into account possible material unloading; 4) to verify and calibrate the solution of problems in an elastoplastic formulation for the first steps by time when the deformation process is elastic, it is convenient to use the solution of the corresponding elastic problem.Документ Influence of system stiffness parameters at contact softness in vibroimpact system(КНУБА, 2014) Bazhenov, V. A.; Pogorelova, O. S.; Postnikova, T. G.The possibility of contact character changing by system parameters changing is researching. It is investigated the contact between two bodies in two-degree-of-freedom vibroimpact system. We show which parameters changing can transform the rigid impact in system into the soft one. In the main these parameters are the Young’s modulus and geometrical characteristics of the contact zone for both bodies.Документ Invariant torus break-down in vibroimpact system – route to crisis ?(КНУБА, 2018) Bazhenov, V. A.; Pogorelova, O. S.; Postnikova, T. G.Chaotic vibrations of dynamical systems and their routes to chaos are interesting and investigated subjects in nonlinear dynamics. Particularly the routes to chaos in non-smooth dynamical systems are of the special scientists’ interest. In this paper we study quasiperiodic route to chaos in nonlinear non-smooth discontinuous 2-DOF vibroimpact system. The break-down of invariant torus or of the closed curve occurs just under the quasiperiodic route to chaos. Is it route to crisis? In narrow frequency range different oscillatory regimes have succeeded each other many times under very small control parameter varying. There were periodic subharmonic regimes − chatters, quasiperiodic, and chaotic regimes, the zones of prechaotic and postchaotic motion. The hysteresis effects (jump phenomena) occurred for increasing and decreasing frequencies. The observed chaos was the transient one.The chaoticity of obtained regime has been confirmed by typical views of Poincaré map and Fourier spectrum, by the positive value of the largest Lyapunov exponent, and by the fractal structure of Poincaré map. These investigations confirm the theory by Newhouse, Ruelle, and Takens who suggested a new bifurcation scenario where a periodic solution produces subsequently a torus and then a strange attractor.Документ Lyapunov exponents estimation for strongly nonlinear nonsmooth discontinuous vibroimpact system(КНУБА, 2017) Bazhenov, V. A.; Pogorelova, O. S.; Postnikova, T. G.Lyapunov exponents are ones of the most important characteristics for the definition of the dynamical system state. Their estimation for nonsmooth discontinuous system that is vibroimpact system has got certain difficulties. We study their calculation by following the evolution of two nearby orbits in phase space and use three formulas for such estimation. We check this calculation for three different oscillatory regimes: periodic, quasi-periodic and chaotic. We also define the largest Lyapunov exponent by Benettin’s algorithm and compare obtained results.Документ Modeling of nonlinear deformation and buckling of elastic inhomogeneous shells(КНУБА, 2014) Bazhenov, V. A.; Solovei, N. A.; Krivenko, O. P.The paper outlines the fundamentals of the method of solving static problems of geometrically nonlinear deformation, buckling, and postbuckling behavior of thin thermoelastic inhomogeneous shells with complex-shaped mid-surface, geometrical features throughout the thickness, and multilayer structure under complex thermomechanical loading. The method is based on the geometrically nonlinear equations of three-dimensional thermoelasticity and the moment finiteelement scheme. The method is justified numerically. Comparing solutions with those obtained by other authors and by software LIRA and SCAD is conducted.Документ “Nonlinear Dynamics - 2016” Conference(КНУБА, 2016) Bazhenov, V. A.; Pogorelova, O. S.; Postnikova, T. G.There is short description of problem state on nonlinear dynamics in this paper. Information about some contemporary journals and recent Conferences on this subject is given. Information about 5th International Conference on Nonlinear Dynamics which was holding in National Technical University “Kharkov Polytechnic Institute” in September 2016 and impression about it are presented.Документ Numerical solution of the problem of porous solids vibration(КНУБА, 2017) Каrа, І. D.In this paper vibration of fluid-saturated porous solids under the equal distribution load is studied using two different approaches. One of them is analytical way. Biot’s equations in terms of displacement, pore pressure, porosity and effective densities are used for one-dimensional column. Using boundary conditions analytical expressions for parameters of stress-strain state: the solid and fluid displacements and stresses are obtained. Another way is Boundary Integral Equation Method. Equilibrium equations for 3-D linear dynamic poroelasticity are presented. Also required components of fundamental solution tensors as weighting displacement fields are obtained and analyzed with the help of the analogy between poroelastisity and thermoelastisity. The solution of the porous solid vibration problem for two types of boundary conditions is presented in the figures. Graphs present the comparison of the normalized solid displacement u3 at the top and normalized pressure σ33 in elastic region and in porous solid of poroelastic region depending on frequency ω that are computed using Boundary Integral Equation and analytical methods. Figures show that graphs of the displacements and pressure in poroelastic and elastic region have the same character but different values. The numerical solution of this problem was calculated using material properties which are corresponding to the Barea Sandstone. It shows that massive porous bodies cannot be modeling as homogeneous elastic media but it is necessary to use two phase model and equations of poroelasticity. Since the agreement between the BEM results and the analytical solution is good so such an approach can be used for development and testing of numerical techniques for analyzing of 3-D porous solids vibration.Документ Simulation of forming a spatial thin rod located in a continuous deformable solid(КНУБА, 2016) Khromov, V. G.; Khromov, I. V.; Khromov, O. V.Authors describe the derivation of equations to determine the deformation parameters of the longitudinal axis of a thin rod for a given strain tensor continuum. A single wire of a steel rope is subject to complex deformation when machining, its form and internal stresses are changing as a result. Application of an equations which reflect the most general laws describing form changing of a thin rod requires sophisticated analytical transformations and engaging visual picture of spatial displacements of single points of a rod. It making difficult to conclude calculation formulas. The problem is solved in the framework of a small displacement and deformation hypothesis using tensor analysis. Formulas derived from the new equations coincide with the known results previously obtained on the basis of Clebsch equations and principle of kinematic analogy. On one hand, it confirms the validity of the proposed method and on the other hand it is an additional verification of known formulas. Some examples have been given to illustrate the efficiency of the general equations in tensor form: analyzing the sinusoid forming on a deformable plane, as well as for calculating the deformations of thin helical elements while stretching and twisting helical wire rope. Now there is no need to use a visual picture to describe the displacement of the spatially curved axis of a wire, and all the analysis is carried out by a uniform algorithm. The proposed method to calculate small deformations of a thin rod for a given strain tensor of continuum might be further applied when improving the existing and developing new software for the design of production processes in manufacturing of wire rope and cable.Документ The formulation of nonlinear deformation and fracture of heterogeneous 3d bodies subject to the emergence and spread of cracks under dynamic loading(КНУБА, 2014) Solodey, I. I.; Vabishchevych, М. О.Describes the main output parameters of the problems of fracture mechanics and existing calculation methods for inhomogeneous spatial bodies with cracks in terms of nonlinear dynamic effects.Документ Адаптивные кэ-модели в основе систем мониторинга несущих конструкций уникальных зданий(КНУБА, 2015) Белостоцкий, А. М.; Каличава, Д. К.; Островский, К. И.; Новиков, П. И.Предложена и теоретически обоснована расчетно-экспериментальная методика мониторинга несущих конструкций уникальных (высотных и большепролетных) зданий и сооружений. Методика базируется на деталь- ных большеразмерных пространственных динамических КЭ-моделях, ко- торые параметризуются для всех значимых стадий «жизненного цикла» объекта и адаптируются по данным инструментальных наблюдений.Документ Алгоритм розв'язування просторової задачі термов'язкопружнопластичності призматичних тіл з урахуванням пошкодженості(КНУБА, 2006) Баженов, В. А.; Гуляр, О. І.; Пискунов, С. О.; Андрієвський, В. П.Розроблено алгоритм з екстраполяцією переміщень для розв’язання просторових задач термов’язкопружнопластичності призматичних тіл з урахуванням пошкодженості матеріалу на основі напіваналітичного методу скінчених елементів (НМСЕ) і проведено дослідження його достовірності і ефективності на тестових прикладах.Документ Алгоритм розв’язання задач нелінійного деформування та стійкості пружнопластичних вісесиметричних оболонок середньої товщини(КНУБА, 2014) Максим’юк, Ю. В.Розроблена методика, яка базується на розрахункових співвідношеннях моментної схеми скінчених елементів (МССЕ), і запропонований алгоритм розв’язання систем нелінійних рівнянь пружнопластичного деформування і втрати стійкості вісесиметричних оболонок середньої товщини неканонічної форми, який дозволяє отримувати достовірні результати для широкого класу тонкостінних об’єктів.