Кафедра "Вища математика"

Постійне посилання колекціїhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/7491

Офіційний сайт кафедри http://web.kpi.kharkov.ua/vm

Напевно відомо, що в 1923 році в ХТІ вже була кафедра математики, а її першим керівником був Бржечка Володимир Фомич. Кафедра вищої математики є одним із найстаріших підрозділів нашого університету. Дисципліни вища математика та нарисна геометрія викладалися починаючи з 1885 року.

У джерел розробки методики викладання математики стояли найвидатніші вчені, академіки Олександр Михайлович Ляпунов, Володимир Андрійович Стеклов й інші. Колектив кафедри намагається на всіх етапах її становлення й розвитку зберігати традиції, закладені засновниками кафедри, продовжує наукову працю, розвиває закладені напрямки в сучасній математичній підготовці студентів університету. Щорічно навчаються математиці майже чотири тисячі студентів денного відділення.

Кафедра входить до складу Навчально-наукового інституту механічної інженерії і транспорту Національного технічного університету "Харківський політехнічний інститут .

У складі науково-педагогічного колективу кафедри працюють: доктор фізико-математичних наук, доктор педагогічних наук, 2 доктора технічних наук, 8 кандидатів наук; 4 співробітника мають звання професора, 8 – доцента.

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Research of nonlinear vibrations of orthotropic plates with a complex form
(Hindawi Publishing Corporation, 2006) Kurpa, Lidiya; Shmatko, T.; Onufrienko, O. G.
This paper deals with effects of large amplitude on the free and forced flexural vibrations of elastic orthotropic plates of arbitrary shape. R-function method (RFM) is applied to obtain the basis functions need for expansion of sought solution into Fourier series. The initial nonlinear system of differential equations with partial derivatives is reduced to system of ordinary nonlinear differential equations by Galerkin procedure. The solvingobtained system is carried out by Runge-Kutta or Galerkin methods. The numerical results for the plate of complex form and also rectangular form and different boundary conditions have been presented and compared with other known results.
Nonlinear vibration of orthotropic shallow shells of the complex shape with variable thickness
(Wydawnictwo Politechniki Łódzkiej, 2011) Awrejcewicz, Jan; Kurpa, Lidiya; Shmatko, T.
Early R-functions theory [1] combined with variational methods have been applied to linear [2] and nonlinear vibration problems [3,4] of the shallow shells theory of the constant thickness. In the present study, we first apply R-functions theory in order to investigate the geometrically nonlinear vibrations of orthotropic shallow shells of complex shape with variable thickness. Mathematical formulation is made in the framework of classical geometrically nonlinear theory of thin shallow shells. For a discretization of the original system in time, approximation of unknown functions is carried out by using a single mode approach. In order to construct a system of basic functions, the proposed algorithm includes sequence of the linear problems such as finding eigen functions of the linear vibrations of shallow shells with variable thickness and auxiliary tasks of the elasticity theory. The linear problems are solved by the R-functions method. The developed approach allows reducing the original problem to the corresponding problem of solving nonlinear ordinary differential equations (ODEs), whose coefficients are presented in analytical form. In order to solve the obtained system of ODEs the Bubnov-Galerkin method is applied. The proposed algorithm is implemented within an automated system POLE-RL [1]. Numerical examples of large-amplitude flexible vibrations of shallow orthotropic shells with complex shape and variable thickness are introduced demonstrating merits and advantages of the R-functions method. Comparison of the obtained results regarding shells with rectangular plans with the other methods confirms the reliability of the proposed method.
Large amplitude free vibration of orthotropic shallow shells of complex shapes with variable thickness
(Marcílio Alves, 2013) Awrejcewicz, Jan; Kurpa, Lidiya; Shmatko, T.
The present formulation of the analysed problem is based on Donell’s nonlinear shallow shell theory, which adopts Kirch-hoff’s hypothesis. Transverse shear deformations and rotary inertia of a shell are neglected. According to this theory, the non-linear strain-displacement relations at the shell midsurface has been proposed. The validity and reliability of the proposed approach has been illustrated and discussed, and then a few examples of either linear or non-linear dynamics of shells with variable thickness and complex shapes have been presented and discussed.
Investigation of Geometrically Nonlinear Vibrations of Laminated Shallow Shells with Layers of Variable Thickness by Meshless Approach
(Точка, 2013) Kurpa, Lidiya; Shmatko, T.
Geometrically nonlinear vibrations of laminated shallow shells with layers of variable thickness are studied. Nonlinear equations of motion for shells based on the first order shear deformation and classical shells theories are considered. In order to solve this problem we use the numerically-analytical method proposed in work [1]. Accordingly to this approach the initial problem is reduced to consequences of some linear problems including linear vibrations problem, special elasticity ones and nonlinear system of ordinary differential equations in time. The linear problems are solved by the variational Ritz’ method and Bubnov-Galerkin procedure combined with the R-functions theory [2]. To construct the basic functions that satisfy all boundary conditions in case of simply-supported shells we propose new solutions structures. The proposed method is used to solve both test problems and new ones.
Investigating geometrically nonlinear vibrations of laminated shallow shells with layers of variable thickness via the R-functions theory
(Elsevier Inc., 2015) Awrejcewicz, Jan; Kurpa, Lidiya; Shmatko, T.
A novel numerical/analytical approach to study geometrically nonlinear vibrations of shells with variable thickness of layers is proposed. It enables investigation of shallow shells with complex forms and different boundary conditions. The proposed method combines application of the R-functions theory, variational Ritz’s method, as well as hybrid Bubnov–Galerkin method and the fourth-order Runge–Kutta method. Mainly two approaches, classical and first-order shear deformation theories of shells are used. An original scheme of discretization regarding time reduces the initial problem to the solution of a sequence of linear problems including those related to linear vibrations with a special type of elasticity, as well as problems governed by non-linear system of ordinary differential equations. The proposed method is validated by the investigation of test problems for shallow shells with rectangular planform and applied to new vibration problems for shallow shells with complex planforms and variable thickness of layers.
Vibration of functionally graded shallow shells with complex shape
(Department of Automation, Biomechanics and Mechatronics, 2015) Awrejcewicz, Jan; Kurpa, Lidiya; Shmatko, T.
The method for studying the geometrically nonlinear vibrations of functionally graded shallow shells with a complex planform is proposed. Сomposite shallow shells made from a mixture of ceramic and metal are considered. In order to take into account varying of the volume fraction of ceramic the power law is accepted. Formulation of the problem is carried out using the refined geometrically nonlinear theory of shallow shells of the first order (Timoshenko’s type). The R-functions theory, variational Ritz’s method, procedure by Bubnov Galerkin and Runge-Kytta method are used in the developed approach. A distinctive feature of the proposed approach is the method of reducing the initial nonlinear system of equations of motion for partial derivatives to a nonlinear system of ordinary differential equations. According to the developed approach first it is necessary to solve linear vibration problem. Further to solve elasticity problems for inhomogeneous differential equations with right hand side, containing eigen functions. Obtained solutions of these problems are applied for representation of unknown functions of the nonlinear problem. Application of the theory of R-functions on every step allows us to extend the proposed approach to the shell with arbitrary shape of plan and different kinds of boundary condition. The proposed method is validated by investigation of test problems for shallow shells with rectangular and elliptical planform and applied to new vibration problems for shallow shells with complex planform.
Analysis of Geometrically Nonlinear Vibrations of Functionally Graded Shallow Shells of a Complex Shape
(Marcílio Alves, 2017) Awrejcewicz, Jan; Kurpa, Lidiya; Shmatko, T.
Geometrically nonlinear vibrations of functionally graded shallow shells of complex planform are studied. The paper deals with a power-law distribution of the volume fraction of ceramics and metal through the thickness. The analysis is performed with the use of the R-functions theory and variational Ritz method. Moreover, the Bubnov-Galerkin and the Runge-Kutta methods are employed. A novel approach of discretization of the equation of motion with respect to time is proposed. According to the developed approach, the eigenfunctions of the linear vibration problem and some auxiliary functions are appropriately matched to fit unknown functions of the input nonlinear problem. Application of the R-functions theory on every step has allowed the extension of the proposed approach to study shallow shells with an arbitrary shape and different kinds of boundary conditions. Numerical realization of the proposed method is performed only for one-mode approximation with respect to time. Simultaneously, the developed method is validated by investigating test problems for shallow shells with rectangular and elliptical planforms, and then applied to new kinds of dynamic problems for shallow shells having complex planforms.
Geometrical analysis of vibrations of functionally graded shell panels using the R-functions theory
(London Calling, 2017) Shmatko, T.; Kurpa, Lidiya; Bhaskar, Atul
An approach for investigation of geometrically nonlinear vibrations of functionally graded shallow shells and plates with complex planform is proposed. It combines the application of the R-functions theory (RFM), variational Ritz’s method, the procedure by Bubnov-Galerkin and Runge-Kutta method. The presented method is developed in the framework of the first–order shear deformation shallow shell theory (FSDT). Shell panels under consideration are made from a mixture of ceramics and metal. Power law of volume fraction distribution of materials through thickness is chosen. Investigation of nonlinear vibrations of functionally graded shallow shells and plates with arbitrary planform and different types of boundary conditions is carried out. Test problems and numerical results have been presented for one-mode approximation in time. Effect of volume fraction exponent, geometry of a shape and boundary conditions on the natural frequencies is brought out.