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<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" article-type="research-article" dtd-version="1.2" xml:lang="en"><front><journal-meta><journal-id journal-id-type="publisher-id">Structural Mechanics of Engineering Constructions and Buildings</journal-id><journal-title-group><journal-title xml:lang="en">Structural Mechanics of Engineering Constructions and Buildings</journal-title><trans-title-group xml:lang="ru"><trans-title>Строительная механика инженерных конструкций и сооружений</trans-title></trans-title-group></journal-title-group><issn publication-format="print">1815-5235</issn><issn publication-format="electronic">2587-8700</issn><publisher><publisher-name xml:lang="en">Peoples’ Friendship University of Russia named after Patrice Lumumba (RUDN University)</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="publisher-id">20719</article-id><article-id pub-id-type="doi">10.22363/1815-5235-2019-15-1-62-68</article-id><article-categories><subj-group subj-group-type="toc-heading" xml:lang="en"><subject>Numerical methods of structures’  analysis</subject></subj-group><subj-group subj-group-type="toc-heading" xml:lang="ru"><subject>Численные методы расчета конструкций</subject></subj-group><subj-group subj-group-type="article-type"><subject>Research Article</subject></subj-group></article-categories><title-group><article-title xml:lang="en">Simulation of an incomplete algebraic problem of eigenvalues and vectors by the method of frequency-dynamic condensation based on FEM in the form of the classical mixed method</article-title><trans-title-group xml:lang="ru"><trans-title>Моделирование неполной алгебраической проблемы собственных значений и векторов методом частотно-динамической конденсации на основе МКЭ в форме классического смешанного метода</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author"><contrib-id contrib-id-type="spin">9405-9800</contrib-id><name-alternatives><name xml:lang="en"><surname>Ignatyev</surname><given-names>Alexander V</given-names></name><name xml:lang="ru"><surname>Игнатьев</surname><given-names>Александр Владимирович</given-names></name></name-alternatives><bio xml:lang="en"><p>PhD in Technical Sciences, Associate Professor, Department of Automated Systems Software</p></bio><bio xml:lang="ru"><p>кандидат технических наук, доцент кафедры программного обеспечения автоматизированных систем</p></bio><email>alignat@gmail.com</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><name-alternatives><name xml:lang="en"><surname>Chumakov</surname><given-names>Artem V</given-names></name><name xml:lang="ru"><surname>Чумаков</surname><given-names>Артем Владимирович</given-names></name></name-alternatives><bio xml:lang="en"><p>master student of the Department of Software of Automated Systems</p></bio><bio xml:lang="ru"><p>магистрант кафедры программного обеспечения автоматизированных систем</p></bio><email>chumakovtema@gmail.com</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><name-alternatives><name xml:lang="en"><surname>Gilka</surname><given-names>Vadim V</given-names></name><name xml:lang="ru"><surname>Гилка</surname><given-names>Вадим Викторович</given-names></name></name-alternatives><bio xml:lang="en"><p>master student of the Department of Software of Automated Systems</p></bio><bio xml:lang="ru"><p>магистрант кафедры программного обеспечения автоматизированных систем</p></bio><email>gilka_vv@mail.ru</email><xref ref-type="aff" rid="aff1"/></contrib></contrib-group><aff-alternatives id="aff1"><aff><institution xml:lang="en">Volgograd State Technical University</institution></aff><aff><institution xml:lang="ru">Волгоградский государственный технический университет</institution></aff></aff-alternatives><pub-date date-type="pub" iso-8601-date="2019-12-15" publication-format="electronic"><day>15</day><month>12</month><year>2019</year></pub-date><volume>15</volume><issue>1</issue><issue-title xml:lang="en">VOL 15, NO1 (2019)</issue-title><issue-title xml:lang="ru">ТОМ 15, №1 (2019)</issue-title><fpage>62</fpage><lpage>68</lpage><history><date date-type="received" iso-8601-date="2019-03-13"><day>13</day><month>03</month><year>2019</year></date></history><permissions><copyright-statement xml:lang="en">Copyright ©; 2019, Ignatyev A.V., Chumakov A.V., Gilka V.V.</copyright-statement><copyright-statement xml:lang="ru">Copyright ©; 2019, Игнатьев А.В., Чумаков А.В., Гилка В.В.</copyright-statement><copyright-year>2019</copyright-year><copyright-holder xml:lang="en">Ignatyev A.V., Chumakov A.V., Gilka V.V.</copyright-holder><copyright-holder xml:lang="ru">Игнатьев А.В., Чумаков А.В., Гилка В.В.</copyright-holder><ali:free_to_read xmlns:ali="http://www.niso.org/schemas/ali/1.0/"/><license><ali:license_ref xmlns:ali="http://www.niso.org/schemas/ali/1.0/">http://creativecommons.org/licenses/by/4.0</ali:license_ref></license></permissions><self-uri xlink:href="https://journals.rudn.ru/structural-mechanics/article/view/20719">https://journals.rudn.ru/structural-mechanics/article/view/20719</self-uri><abstract xml:lang="en"><p>Relevance . Dynamic analysis of complex structures using numerical methods leads to the solution of the algebraic problem of eigenvalues and the corresponding eigenvectors of high orders. The solution of this problem for high order matrices is performed using reduction methods. One of the most effective methods is the method of sequential frequency-dynamic condensation, which allows partial consideration of the dynamic properties of the structure in the minor degrees of freedom. This allows for more accurate results compared to static condensation. Frequency-dynamic condensation is traditionally used to reduce frequency equations derived from the finite element method in the form of the displacement method or the force method. Methods. The authors have developed an algorithm for the frequency-dynamic condensation method for the frequency equation obtained on the basis of the FEM in the form of the classical mixed method. That allows to obtain not only the spectrum of the lower vibration frequencies, but also the corresponding vibration modes and the stress-strain state of the structure. Results . This article describes the algorithm and its practical implementation in the problem of dynamic analysis of a rectangular plate. The results of the numerical analysis of the problem are presented. An assessment of the accuracy of the method and recommendations for its use are given.</p></abstract><trans-abstract xml:lang="ru"><p>Актуальность. Динамический анализ сложных конструкций при помощи численных методов приводит к решению алгебраической проблемы собственных значений и соответствующих им собственных векторов высоких порядков. Решение этой задачи для матриц высоких порядков выполняется с использованием редукционных методов. Одним из наиболее эффективных является метод последовательной частотно-динамической конденсации, позволяющий частичный учет динамических свойств конструкции во второстепенных степенях свободы. Это позволяет получить более точные результаты по сравнению со статической конденсацией. Частотно-динамическая конденсация традиционно используется для редуцирования частотных уравнений, полученных на основе метода конечных элементов в форме метода перемещений или метода сил. Методы. Авторами разработан алгоритм метода частотно-динамической конденсации для частотного уравнения, полученного на основе метода конечных элементов (МКЭ) в форме классического смешанного метода, позволяющий получить не только спектр низших частот колебаний, но и соответствующие им формы колебаний и напряженно-деформированное состояние конструкции. Результаты. В статье приведены описание алгоритма и его практическая реализация в задаче динамического расчета прямоугольной пластины. Представлены результаты численного расчета задачи. Дана оценка точности метода, и приведены рекомендации по его использованию.</p></trans-abstract><kwd-group xml:lang="en"><kwd>finite elements method in the form of the classical mixed method</kwd><kwd>algebraic eigenvalues and eigenvectors problem</kwd><kwd>frequency-dynamic condensation</kwd></kwd-group><kwd-group xml:lang="ru"><kwd>метод конечных элементов в форме классического смешанного метода</kwd><kwd>алгебраическая проблема собственных значений и собственных векторов</kwd><kwd>частотно-динамическая конденсация</kwd></kwd-group><funding-group/></article-meta></front><body></body><back><ref-list><ref id="B1"><label>1.</label><citation-alternatives><mixed-citation xml:lang="en">Choi J.H., Kim H., Cho M. (2008). Iterative method for dynamic condensation combined with substructuring scheme. Journal of Sound and Vibration, 317(1), 199–218.</mixed-citation><mixed-citation xml:lang="ru">Choi J.H., Kim H., Cho M. 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