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Abstract(s)
O fabrico aditivo de componentes tem-se tornado num campo de pesquisa muito
importante, motivado pela possibilidade de criar geometrias inovadoras e de combinar diferentes
materiais. Trata-se de uma tecnologia de fabrico muito recente pelo que é escassa a informação
sobre o comportamento mecânico destes novos componentes, principalmente no que se refere ao
seu comportamento dinâmico.
O presente trabalho tem como principal objetivo a caracterização experimental do
comportamento a elevadas taxas de deformação de provetes em alumínio AlSi10Mg obtidos por
fabrico aditivo de fusão seletiva por laser (SLM), função da direção de fabrico dos provetes e da
aplicação de tratamento térmico de revenido. Os ensaios de tração foram realizados na barra de
Hopkinson existente nas instalações do Instituto de Ciência e Inovação em Engenharia Mecânica e
Engenharia Industrial (INEGI) e envolvem o registo das ondas de deformação geradas nas barras
pelo impacto e a recolha de imagens de alta-velocidade da superfície do provete. A partir do registo
das ondas incidente, transmitida e refletida são extraídas as curvas tensão-deformação. Neste
trabalho, os sinais no tempo foram filtrados com o objetivo de reduzir o ruído experimental e,
assim, melhorar a qualidade das curvas tensão-deformação. As imagens de alta-velocidade são pós processadas para a determinação do campo de deformações no provete, tendo-se, para esse efeito,
gravado previamente na superfície do provete um padrão de speckle.
Os gráficos tensão-deformação mostram que o comportamento dos provetes é fortemente
dependente da direção da deposição do material. Nos provetes submetidos a tratamento térmico
de revenido verificou-se uma ligeira redução na tensão máxima e um aumento geral na deformação
até rutura, relativamente aos provetes não tratados. A partir da energia elasto-plástica verificou-se
que os provetes fabricados na direção transversal possuem um valor mais elevado e que este
melhora com o tratamento térmico de revenido.
Additive manufacturing of components has become a very important field of research, motivated by the possibility of creating innovative geometries and combining different materials. This is a very recent manufacturing technology, so there is little information on the mechanical behavior of these new components, especially concerning their dynamic behavior. The main objective of the present work is to experimentally characterize the behavior at high deformation rates of AlSi10Mg aluminum test pieces, obtained by additive manufacturing of selective laser melting (SLM), as a function of their manufacturing direction and the application of heat tempering treatment. The tensile tests are carried out on the Hopkinson bar at the facilities of the Institute of Science and Innovation in Mechanical and Industrial Engineering (INEGI) and involve recording the deformation waves generated in the bars by the impact and collecting high-speed images of the surface specimens. From the recording of the incident, the transmitted and the reflected waves, the stress-strain curves are extracted. In this work, time signals were filtered to reduce experimental noise and, thus, improve the quality of the stress-strain curves. The high speed images are post-processed to determine the deformation field in the specimen, having, for this purpose, previously recorded a Speckle pattern on the surface of the specimen. The stress-strain curves show that the behavior of the specimens is strongly dependent on the direction of their manufacture. In specimens subjected to tempering heat treatment, there was a slight reduction in maximum stress and a general increase in deformation until failure, compared to untreated specimens. From elastoplastic energy, it was found that specimens manufactured in the transverse direction have a higher value and that this improves with the tempering heat treatment.
Additive manufacturing of components has become a very important field of research, motivated by the possibility of creating innovative geometries and combining different materials. This is a very recent manufacturing technology, so there is little information on the mechanical behavior of these new components, especially concerning their dynamic behavior. The main objective of the present work is to experimentally characterize the behavior at high deformation rates of AlSi10Mg aluminum test pieces, obtained by additive manufacturing of selective laser melting (SLM), as a function of their manufacturing direction and the application of heat tempering treatment. The tensile tests are carried out on the Hopkinson bar at the facilities of the Institute of Science and Innovation in Mechanical and Industrial Engineering (INEGI) and involve recording the deformation waves generated in the bars by the impact and collecting high-speed images of the surface specimens. From the recording of the incident, the transmitted and the reflected waves, the stress-strain curves are extracted. In this work, time signals were filtered to reduce experimental noise and, thus, improve the quality of the stress-strain curves. The high speed images are post-processed to determine the deformation field in the specimen, having, for this purpose, previously recorded a Speckle pattern on the surface of the specimen. The stress-strain curves show that the behavior of the specimens is strongly dependent on the direction of their manufacture. In specimens subjected to tempering heat treatment, there was a slight reduction in maximum stress and a general increase in deformation until failure, compared to untreated specimens. From elastoplastic energy, it was found that specimens manufactured in the transverse direction have a higher value and that this improves with the tempering heat treatment.
Description
Keywords
Additive manufacturing Hopkinson Bar Digital image correlation Stress-strain curve Deformation full field