Results of numerical investigation of dynamic behavior of deformed wing aircraft in a gas flow are presented in the paper. Vibrations with respect to deflections are described by a system of integro-differential equations in partial derivatives. Using the Bubnov-Galerkin method, the problem is reduced to a system of ordinary integro-differential equations, where time is an independent variable. The solutions of integro-differential equations are determined by a numerical method based on the use of quadrature formulas. Computational algorithms and a package of applied programs have been created to solve problems on nonlinear flutter of viscoelastic elements of an aircraft. The reliability of the solution of the problem is confirmed by comparison with known numerical and analytical results. The effect of different boundary conditions on critical flutter velocity is studied. Critical velocity and critical flutter time of viscoelastic plates are determined. It is shown that the singularity parameter α affects not only the vibrations of viscoelastic systems, but also critical time and critical flutter velocity. It is stated that consideration of viscoelastic properties of plate material leads to 40 60% decrease in critical flutter velocity.
Research on the problems of creating effective control and diagnostic systems allows us to single out the following areas: the development of the theory and methods for diagnosing and predicting the strength and reliability of structures, theoretical and experimental studies of fracture processes, and the corresponding changes in characteristics and parameters, i.e., carriers of information about the processes occurring in the material during destruction; creation of information-measuring systems designed to register and analyze the information necessary to resolve the issue of the state of the structure; development of software for measuring equipment, including not only the main programs for generating and processing incoming information but auxiliary subroutines that provide information compression, increase the reliability of measurement results, defect recognition, decision making. The article is devoted to the methods of acoustic-emission control of metal structures and developing a computerized system for its implementation. The basics of organizing a software-algorithmic system for locating and processing acoustic emission signals are considered, including methods for discretizing models of sensors and acoustic emission signals, which make it possible to obtain computational schemes such as a digital filter that provide effective algorithmic implementation; description of fragments of an experimental software-algorithmic system for processing acoustic emission signals, illustrating the principle of constructing software tools in an arbitrarily chosen computing area, the structure of the software organization of computational processes for locating an acoustic emission signal, which ensures the construction of the corresponding subsystem of a computer complex for acoustic-emission control, both in single-antenna and in a multi-antenna version.
Численно исследован колебательный процесс вязкоупругого трубопровода, лежащего на упругом основании, описываемом моделью Винклера. На основе теории балки Тимошенко разработана математическая модель вибрации вязкоупругого трубопровода, транспортирующего жидкость. Для описания процессов деформирования вязкоупругих материалов использована интегральная модель Больцмана-Вольтерра. Решение интегродифференциальных уравнений определяется численным методом, основанным на исключении особенности в ядре релаксации интегрального оператора. Ключевые слова: математическая модель; вычислительный алгоритм; вязкоупругость; трубопровод; теория Тимошенко.
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