An investigation into ways of substructuring for a vibratory system with rubber isolators
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Data
2017-12-12
Autores
Marques, Viviane Cassol
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Universidade Estadual Paulista (Unesp)
Resumo
Grandes estruturas, como aviões, navios e até mesmo sistemas de refrigeração, que possuem muitos componentes podem ser substruturados, com o intuito de agilizar e facilitar o cálculo da transmissão vibratória entre seus componentes. Existem diversas formas e domínios em que esta substruração pode ser realizada, sendo a utilizada nesta tese a substruturação no domínio da frequência utilizando para o cálculo as mobilidades medidas nos pontos de acoplamento dos componentes. Esta tese se concentra na substruturação de sistemas dinâmicos que possuem áreas flexíveis de contato como o que ocorre no acoplamento de amortecedores de borracha em sistemas vibratórios, sendo que para estes casos foi verificado que os métodos de substruturação mais usuais não apresentaram bons resultados para frequências superiores a primeira frequência natural do sistema completo, mesmo quando utilizados vários pontos de acoplamento no amortecedor de borracha. Utilizando o cálculo do comprimento de onda em diferentes materiais, neste caso o aço e a borracha, foi possível determinar uma relação entre a distância dos pontos de acoplamento e o comprimento de onda em que a metodologia de substruturação apresenta resultados acurados. Devido a estas limitações dos métodos de substruração, quando acoplamentos flexíveis existem nos subsistemas considerados, uma nova forma de substruração foi apresentada a qual mostrou resultados muito melhores, especialmente quando comparados com os resultados do sistema completo quando substruturado no acoplamento flexível.
Large structures, such as airplanes, ships and even refrigeration systems, which have many components, can be substructured in order to speed up and facilitate the process of calculating the vibratory transmission between the system components. There are several methods and domains in which the substructuring can be done. In this thesis the substructuring method in the frequency domain is chosen to do the calculations, with the mobilities measured at the coupling points of the components. This thesis focuses on the substructuring of dynamic systems that have flexible distributed connections, such as those which occur in the coupling with rubber isolators in vibratory systems. For these cases, the most usual substructuring methods are shown not to give good results for frequencies higher than the first natural frequency of the complete system, even when several coupling points are used for the rubber isolator. Using the calculation of the flexural wavelength in different materials, in this case steel and rubber, it is possible to determine a relationship between the distance of the coupling points within the isolator and the wavelengths of the component materials, at which the substructuring methodology gives accurate results. Due to these limitations of current substructuring methods, when soft flexible couplings exist in the subsystems, a new substructuring approach is presented, and is shown to really improve the results, especially when compared to the when the complete system is substructured at the flexible coupling.
Large structures, such as airplanes, ships and even refrigeration systems, which have many components, can be substructured in order to speed up and facilitate the process of calculating the vibratory transmission between the system components. There are several methods and domains in which the substructuring can be done. In this thesis the substructuring method in the frequency domain is chosen to do the calculations, with the mobilities measured at the coupling points of the components. This thesis focuses on the substructuring of dynamic systems that have flexible distributed connections, such as those which occur in the coupling with rubber isolators in vibratory systems. For these cases, the most usual substructuring methods are shown not to give good results for frequencies higher than the first natural frequency of the complete system, even when several coupling points are used for the rubber isolator. Using the calculation of the flexural wavelength in different materials, in this case steel and rubber, it is possible to determine a relationship between the distance of the coupling points within the isolator and the wavelengths of the component materials, at which the substructuring methodology gives accurate results. Due to these limitations of current substructuring methods, when soft flexible couplings exist in the subsystems, a new substructuring approach is presented, and is shown to really improve the results, especially when compared to the when the complete system is substructured at the flexible coupling.
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Palavras-chave
Substruração, Amortecedor de borracha, Mobilidades, Substructuring, Rubber isolator, Mobilities