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Abstract(s)
A incorporação de materiais poliméricos em componentes da estrutura automóvel, com o decorrer dos anos, tem vindo a desempenhar um papel primordial no setor automóvel, permitindo a produção de veículos mais eficientes e ecológicos. De entre muitas opções para a fixação destes componentes, encontram-se os clips e os snapfits, que não só facilitam a montagem e desmontagem, como também contribuem para a redução da massa total do automóvel. A presente dissertação de mestrado foi desenvolvida em âmbito industrial, na empresa Simoldes Plásticos, e surge da necessidade de haver um controlo mais rigoroso a envolver algumas fixações normalizadas internas, incorporadas nos componentes desenvolvidos pela Simoldes, a fim de cumprir com as especificações dos clientes. Numa fase inicial, e após a seleção das fixações normalizadas a serem alvo de estudo, realizaram-se ensaios experimentais segundo as direções que os cadernos de encargos das marcas automóveis estipulam para a resistência das fixações a serem incorporadas nos seus componentes. Com recurso ao Método de Elementos Finitos (MEF), efetuaram-se simulações numéricas no software Abaqus®, onde se replicaram as condições dos ensaios físicos a fim de correlacionar ambos os testes. Numa fase final, tendo em conta a diferença relativa dos resultados numéricos em relação aos resultados reais, procedeu-se à respetiva validação geométrica, realizando modificações nas zonas que se identificaram como críticas, nos casos em que os resultados obtidos das simulações assim o ditem. Com a elaboração do presente trabalho foi possível estudar diferentes abordagens de cálculo numérico e perceber qual delas se adequa melhor ao problema em questão, entre as quais a utilização de elementos de casca para fazer a aproximação dos modelos de ensaio ou a utilização de elementos sólidos tetraédricos, realização de simulações estáticas ou dinâmicas e perceber qual aquela que fornece melhores resultados, e ainda estudar o influência que o mass scaling possui nas análises dinâmicas realizadas. A partir do trabalho realizado foi possível validar a geometria das fixações de estudo.
The incorporation of polymeric materials in car structure components, over the years, has been playing a key role in the automotive sector, enabling the production of more efficient and ecological vehicles. Among the many options for fixing these components, there are clips and snap-fits, which not only facilitate assembly and disassembly, but also contribute to reduce the total mass of the car. This master's dissertation was developed in an industrial environment, at the company Simoldes Plastics, and arises from the need for a more rigorous control involving some internal standardized fixings, incorporated in the components developed by Simoldes, to comply with customer specifications. In an initial phase, and after the selection of the standardized fastenings to be studied, experimental tests were carried out according to the directions that the specifications of the automotive brands stipulate for the strength of the fastenings to be incorporated into their components. Using the Finite Element Method (FEM), numerical simulations were performed in the Abaqus® software, where the conditions of the physical tests were replicated to correlate both tests. In a final phase, considering the relative difference of the numerical results in relation to the real results, the respective geometric validation was carried out, making changes in the areas that were identified as critical, in cases where the results obtained from the simulations so dictate. With the elaboration of the present work, it was possible to study different approaches to numerical calculation and to understand which one is best suited to the problem in question, including the use of shell elements to approximate the test models or the use of tetrahedral solid elements, performing static or dynamic simulations and realizing which one provides better results, and also studying the influence that mass scaling has on the dynamic analyzes performed. From the work carried out, it was possible to validate the geometry of the study fixtures.
The incorporation of polymeric materials in car structure components, over the years, has been playing a key role in the automotive sector, enabling the production of more efficient and ecological vehicles. Among the many options for fixing these components, there are clips and snap-fits, which not only facilitate assembly and disassembly, but also contribute to reduce the total mass of the car. This master's dissertation was developed in an industrial environment, at the company Simoldes Plastics, and arises from the need for a more rigorous control involving some internal standardized fixings, incorporated in the components developed by Simoldes, to comply with customer specifications. In an initial phase, and after the selection of the standardized fastenings to be studied, experimental tests were carried out according to the directions that the specifications of the automotive brands stipulate for the strength of the fastenings to be incorporated into their components. Using the Finite Element Method (FEM), numerical simulations were performed in the Abaqus® software, where the conditions of the physical tests were replicated to correlate both tests. In a final phase, considering the relative difference of the numerical results in relation to the real results, the respective geometric validation was carried out, making changes in the areas that were identified as critical, in cases where the results obtained from the simulations so dictate. With the elaboration of the present work, it was possible to study different approaches to numerical calculation and to understand which one is best suited to the problem in question, including the use of shell elements to approximate the test models or the use of tetrahedral solid elements, performing static or dynamic simulations and realizing which one provides better results, and also studying the influence that mass scaling has on the dynamic analyzes performed. From the work carried out, it was possible to validate the geometry of the study fixtures.
Description
Keywords
Snap-fits Clips Componentes poliméricos Indústria Automóvel Método dos elementos finitos Correlações Ensaios físicos Polymeric Components Automotive Industry Finite element method Correlations Physical tests