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Abstract(s)
Nas últimas décadas, os materiais compósitos têm vindo a ganhar predominância nas nossas vidas, devidos às suas características, tornando a sua aplicação desejável nas mais diversas áreas. Devido ao seu processo de fabrico, as peças produzidas a partir destes materiais têm uma geometria quase final ou mesmo terminada, não sendo necessário aplicar tão extensivamente os processos de maquinagem como na produção de peças em materiais convencionais. Um dos processos de maquinagem mais utilizados é a furação. Este processo permite a utilização de ligações mecânicas de forma a unir peças de modo mais seguro, podendo estas ligações serem permanentes ou não, ao contrário, das ligações adesivas que são ligações permanentes. Assim, surge a necessidade de uma avaliação extensiva sobre o dano que a furação provoca sobre o material. Esta avaliação é efetuada sobre a área afetada, que pode variar com os parâmetros do processo de maquinagem. Esta dissertação irá apresentar um estudo efetuado a 42 placas de laminado do tipo carbono/epóxi, às quais foram efetuados furos utilizando 2 parâmetros diferentes, 2 avanços mas a mesma rotação da ferramenta, e 3 geometrias de brocas distintas. Posteriormente, os provetes foram submetidos a ensaios não destrutivos (radiografia com contraste) e destrutivos (ensaio de tração, bearing e pin-bearing). Os resultados foram analisados e comparados. Durante o procedimento de maquinagem foram registadas as forças e binários exercidos pelas ferramentas. Quando analisados os resultados verificou-se que os parâmetros de maquinagem e as brocas escolhidas não afetaram de forma significativa a resistência do material, apesar de ter afetado a força axial durante o processo de maquinagem, bem como a área danificada e os fatores de dano.
In the last decades, composite materials have been gaining predominance in our lives, due to their characteristics, making their application desirable in the most diverse areas. Due to their manufacturing process, parts produced from these materials have an almost final or even finished geometry and it is not necessary to apply the machining processes as extensively as in conventional materials. Despite this, one of the most used processes is drilling, to be able to use these parts in conjunction with mechanical connection, this allows a more secure connection and can either a be permanent or not, contrary to adhesive connection that are permanent. Thus, the need arises for an extensive assessment of the damage that drilling causes to the material. This assessment is carried out on the affected area, which can vary with the parameters of the machining process. This dissertation will present a study carried out on 42 laminated plates of carbon/epoxy, to which holes were drilled using 2 different parameters, 2 feed rates and a single rotating speed, and 3 different drill geometries, afterwards the test pieces were tested in non-destructive (enhanced radiography) and destructive (bearing, pin-bearing and tensile) tests. The results were analysed and compared. During the machining procedure, the forces and torques exerted by the tools were recorded. When the results were analysed, it was found that the machining parameters and the drills chosen did not significantly affect the material resistance, despite having affected the axial force during the machining process as well as the damaged area and the damage factors.
In the last decades, composite materials have been gaining predominance in our lives, due to their characteristics, making their application desirable in the most diverse areas. Due to their manufacturing process, parts produced from these materials have an almost final or even finished geometry and it is not necessary to apply the machining processes as extensively as in conventional materials. Despite this, one of the most used processes is drilling, to be able to use these parts in conjunction with mechanical connection, this allows a more secure connection and can either a be permanent or not, contrary to adhesive connection that are permanent. Thus, the need arises for an extensive assessment of the damage that drilling causes to the material. This assessment is carried out on the affected area, which can vary with the parameters of the machining process. This dissertation will present a study carried out on 42 laminated plates of carbon/epoxy, to which holes were drilled using 2 different parameters, 2 feed rates and a single rotating speed, and 3 different drill geometries, afterwards the test pieces were tested in non-destructive (enhanced radiography) and destructive (bearing, pin-bearing and tensile) tests. The results were analysed and compared. During the machining procedure, the forces and torques exerted by the tools were recorded. When the results were analysed, it was found that the machining parameters and the drills chosen did not significantly affect the material resistance, despite having affected the axial force during the machining process as well as the damaged area and the damage factors.
Description
Keywords
Materiais Compósitos Polímero Reforçado com Fibras de Carbono Furação de Compósito Forças de Furação Delaminação Ensaios não Destrutivos Radiografia Processamento de Imagem Ensaios Destrutivos Ensaio Bearing Ensaio Pin-Bearing Tração Composite materials Carbon fiber reinforced polymer Composite drilling Drilling forces Delamination Non destructive testing Radiography Image Processing Destructive testing Bearing Test Pin-Bearing Test Tensile Testing