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Abstract(s)
O estudo do comportamento dinâmico de estruturas de veículos é essencial para garantir a sua integridade em condições normais de funcionamento. Este tipo de análise envolve a determinação das suas frequências e modos naturais de vibração, bem como, das tensões instaladas devido a solicitações estáticas e dinâmicas. Embora métodos numéricos, como o Método dos Elementos Finitos, sejam amplamente utilizados na fase de desenvolvimento para analisar a resposta das estruturas, é fundamental validar os resultados com estudos
experimentais. A definição correta das condições de fronteira é uma etapa crucial para assegurar um modelo
numérico robusto. Este trabalho apresenta a construção de um modelo numérico de uma estrutura de suporte de baterias para um autocarro elétrico urbano, com foco no desenvolvimento de uma metodologia para modelar a ligação entre este suporte e a estrutura do autocarro. A metodologia adotada assenta, numa primeira etapa, na construção de um modelo numérico da estrutura isolada, recorrendo ao Método dos Elementos Finitos. As propriedades deste modelo são ajustadas para que as suas frequências e modos naturais de vibração se aproximem das obtidas experimentalmente na condição livre-livre. Na segunda etapa, são introduzidos elementos elástico de dois nós e com seis graus de liberdade, para modelar a ligação entre o
suporte de baterias e o tejadilho do autocarro. Um estudo paramétrico é conduzido para avaliar a componente da rigidez mais preponderante no comportamento dinâmico deste suporte. Segue-se a definição desta componente da rigidez que permite aproximar as frequências e modos naturais do modelo numérico às obtidas no ensaio experimental. Os resultados obtidos mostraram que a metodologia adotada é eficaz na modelação do suporte de baterias.
The study of the dynamic behaviour of vehicle structures is essential to guarantee their integrity under normal operating conditions. This type of analysis involves determining the natural frequencies, mode shapes and stresses due to static and dynamic loadings. Although numerical methods, such as the Finite Element Method, are widely used in the development phase to analyse the structures response, it is essential to validate the results with experimental studies. The correct definition of boundary conditions is a crucial step to ensure a robust numerical model. This work presents the development of a numerical model of battery support structure for an urban electric bus, focusing on a methodology for modelling the connection between this support and the bus structure. The methodology begins by creating a numerical model of the isolated structure using the Finite Element Method. The properties of this model are then adjusted to ensure its natural frequencies and mode shapes closely match those obtained experimentally for the free-free conditions. In the second stage, two-node elastic elements with six degrees of freedom are introduced to model the connection between the battery support and bus roof. A parametric study is then conducted to identify the most significant stiffness component that influences the dynamic behaviour of this support. Based on this study, the stiffness component is defined in such a way that the natural frequencies and mode shapes of the numerical model closely match those obtained in the experimental tests. The results obtained showed that the adopted methodology is effective in modelling the battery support.
The study of the dynamic behaviour of vehicle structures is essential to guarantee their integrity under normal operating conditions. This type of analysis involves determining the natural frequencies, mode shapes and stresses due to static and dynamic loadings. Although numerical methods, such as the Finite Element Method, are widely used in the development phase to analyse the structures response, it is essential to validate the results with experimental studies. The correct definition of boundary conditions is a crucial step to ensure a robust numerical model. This work presents the development of a numerical model of battery support structure for an urban electric bus, focusing on a methodology for modelling the connection between this support and the bus structure. The methodology begins by creating a numerical model of the isolated structure using the Finite Element Method. The properties of this model are then adjusted to ensure its natural frequencies and mode shapes closely match those obtained experimentally for the free-free conditions. In the second stage, two-node elastic elements with six degrees of freedom are introduced to model the connection between the battery support and bus roof. A parametric study is then conducted to identify the most significant stiffness component that influences the dynamic behaviour of this support. Based on this study, the stiffness component is defined in such a way that the natural frequencies and mode shapes of the numerical model closely match those obtained in the experimental tests. The results obtained showed that the adopted methodology is effective in modelling the battery support.
Description
Keywords
Finite element method Battery support structure Elastic supports Electric bus Experimental modal analysis Suporte de baterias Dinâmica de estruturas Vibrações Autocarros Elétricos