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Abstract(s)
Os materiais compósitos são cada vez mais implementados em várias aplicações e soluções na Engenharia, desde aplicações mais convencionais, como o imobiliário, até às mais avançadas tecnologicamente, como componentes aeroespaciais. Esta crescente aplicação baseia-se nas excelentes propriedades mecânicas que estes possuem, como a elevada resistência mecânica e o baixo peso. No entanto, há aplicações em que estes são acoplados a outros. Estas ligações podem ser através de juntas adesivas, por fusão ou aparafusadas. Dependendo da situação, as aparafusadas são as mais versáteis porque não são permanentes. Para concretizar este tipo de ligação, são utilizados diversos processos de maquinagem, com a furação a ser o mais utilizado. A furação provoca danos irreversíveis no material e por isso surge a necessidade de estudar o
efeito deste tipo de maquinagem nas propriedades do material. É nesta necessidade que se baseia a presente dissertação. Neste documento será apresentado um estudo efetuado a 48 placas de laminado tipo carbono/epóxido, nas quais foram efetuados dois furos em cada. Para as furações foram considerados três fatores de controlo: o tipo de broca, a velocidade de corte e o avanço. O desgaste das brocas nas furações foi considerado com um fator não controlável ou de ruído. Posteriormente, estes provetes foram submetidos a uma análise por radiografia com o objetivo de quantificar o dano. Foram também sujeitos a um ensaio Bearing para registar a tensão máxima de rotura. Estes dados foram analisados e comparados entre si. Recorreu-se ao método de Taguchi para delinear o planeamento experimental e para comprovar estatisticamente os
resultados obtidos. Dos resultados, foi possível concluir que um avanço reduzido e uma velocidade de corte elevada é a configuração de furação que imprime menos danos no material.
Composite materials are increasingly being implemented in various applications and solutions in Engineering, ranging from more conventional applications, such as furniture, to more technologically advanced ones, such as aerospace components. This increasing application is based on the excellent mechanical properties that these materials possess, such as high mechanical strength and low weight. However, there are applications in which these materials are coupled with others. These connections can be made through adhesive joints, fusion, or bolting. Depending on the situation, bolted connections are the most versatile because they are not permanent. To achieve this type of connection, various machining processes are used, with drilling being the most common. Drilling causes irreversible damage to the material, which necessitates studying the effect of this type of machining on the material's properties. This necessity forms the basis of the present dissertation. This document presents a study conducted on 48 carbon/epoxy laminate plates, each with two holes drilled in them. Three control factors were considered for the drilling: drill bit type, cutting speed, and feed rate. Drill bit wear during drilling was considered an uncontrollable or noise factor. Subsequently, these specimens were subjected to an X-ray analysis to quantify the damage. They were also subjected to a bearing test to record the maximum breaking stress. These data were analyzed and compared. The Taguchi method was used to design the experimental plan and to statistically validate the obtained results. From the results, it was possible to conclude that a low feed rate and a high cutting speed is the drilling configuration that inflicts the least damage on the material.
Composite materials are increasingly being implemented in various applications and solutions in Engineering, ranging from more conventional applications, such as furniture, to more technologically advanced ones, such as aerospace components. This increasing application is based on the excellent mechanical properties that these materials possess, such as high mechanical strength and low weight. However, there are applications in which these materials are coupled with others. These connections can be made through adhesive joints, fusion, or bolting. Depending on the situation, bolted connections are the most versatile because they are not permanent. To achieve this type of connection, various machining processes are used, with drilling being the most common. Drilling causes irreversible damage to the material, which necessitates studying the effect of this type of machining on the material's properties. This necessity forms the basis of the present dissertation. This document presents a study conducted on 48 carbon/epoxy laminate plates, each with two holes drilled in them. Three control factors were considered for the drilling: drill bit type, cutting speed, and feed rate. Drill bit wear during drilling was considered an uncontrollable or noise factor. Subsequently, these specimens were subjected to an X-ray analysis to quantify the damage. They were also subjected to a bearing test to record the maximum breaking stress. These data were analyzed and compared. The Taguchi method was used to design the experimental plan and to statistically validate the obtained results. From the results, it was possible to conclude that a low feed rate and a high cutting speed is the drilling configuration that inflicts the least damage on the material.
Description
Keywords
Composite materials Carbon-epoxy Drilling Radiography Bearing test Taguchi method Materiais compósitos Carbono/epóxido Furação Radiografia Ensaio Bearing Método de Taguchi