Engenharia Mecânica

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http://repositorio.ufes.br/handle/10/17620
Programa de Pós-Graduação em Engenharia Mecânica

Centro: CT
Telefone: (27) 4009 2116
URL do programa: http://www.engenhariamecanica.ufes.br/pos-graduacao/PPGEM

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Navegando Engenharia Mecânica por Autor "Albuquerque, Éder Lima de"

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    Estudo de duas técnicas para a solução de problemas dinâmicos utilizando o método dos elementos de contorno: a superposição modal e a transformada de Laplace
    (Universidade Federal do Espírito Santo, 2024-12-20) Santos, Aquila de Jesus dos; Lara, Luciano de Oliveira Castro; Loeffler Neto, Carlos Friedrich; https://orcid.org/0000-0002-5754-6368; Saenz, Juan Sérgio Romero; Campos, Lucas Silveira; Bulcão, André; Albuquerque, Éder Lima de
    The search for a reliable and accurate method to convert domain integrals involving non-self-adjoint operators into boundary integrals, in accordance with the philosophy of the Boundary Element Method, remains a significant challenge. One of the most recent proposals to achieve this goal is the Direct Interpolation Technique of the Boundary Element Method (DIBEM). Already successfully employed in solving scalar problems governed by the Poisson, Helmholtz, and Advection-Diffusion equations, this work presents the results of using DIBEM in the analysis of wave propagation problems in homogeneous media. The main objective is to evaluate the integration of DIBEM with two distinct techniques for handling the time-dependent term: Modal Superposition and the Laplace Transform, two well-established strategies. In the first formulation, a modified modal superposition, which uses a correlated eigenvalue problem associated with the transpose of the dynamic matrix, is applied to decouple the dynamic equations. Time advancement is performed using the Houbolt algorithm, whose fictitious damping eliminates spurious modal contents, producing greater stability. In the second formulation, the Laplace transform is used to eliminate time dependence; DIBEM is used to solve the resulting stationary problem in terms of the transformation variable, and an inversion method is used to return to the time domain. Several typical wave propagation problems were solved using linear boundary elements.
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    Procedimento recursivo do método dos elementos de contorno
    (Universidade Federal do Espírito Santo, 2009-12-15) Corrêa, Humberto Barroncas; Lovatte, Enilene Regina; Loeffler Neto, Carlos Friedrich; Menandro, Fernando César Meira; Albuquerque, Éder Lima de
    This work presents a procedure based on the recursive use of the governing integral equation with the purpose to improve the accuracy of the Boundary Element Method. Usually, the recursive use of integral equation with BEM is done exclusively to determinate internal v alues of basic or primal variables, after all the nodal boundary values have been calculated. In this work, it is presented the same idea to improve the boundary results accuracy. Instead the new source points be located inside the domain, they are positioned on the boundary, with different coordinates from the nodal points. Thus, the basic variable values and their boundary spatial derivatives can be recalculated based on the boundary values calculated previously. This numerical procedure is based on the mathematical equivalence among the recursive use of the boundary integral equation and the new application of the residual weighed sentence, related to the governing equation. The procedure is here applied to Laplace´s Equation. The numerical results are compared with the analytical ones to evaluate the performance obtained with the proposed technique.