Influência do condicionamento higrotérmico no comportamento mecânico de compósitos soldados de PEI/fibras de carbono
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Data
2016-08-02
Autores
Reis, Jonas Frank [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Apesar da grande utilização dos compósitos termoplásticos na indústria aeronáutica, ainda existem diversos desafios relacionados à integração das partes constituintes de uma aeronave. Como alternativa para união destas peças, dentre os principais métodos de união disponíveis em compósitos termoplásticos, a soldagem vem sendo considerada a mais vantajosa. A soldagem por resistência elétrica aplicada a compósitos termoplásticos apresenta como principal característica um tempo menor de processamento em relação às outras técnicas de soldagem. No entanto, componentes que requerem exigências estruturais, quando expostos a ambientes agressivos como a umidade associada à temperatura, podem ter suas propriedades mecânicas reduzidas. Desta forma, este trabalho tem como principal objetivo avaliar a influência do condicionamento higrotérmico em amostras de compósito polimérico PEI/fibras de carbono soldados. Os parâmetros de soldagem (corrente, tempo e pressão) foram determinados realizando-se ensaios baseados na literatura. Para o desenvolvimento deste trabalho foi também empregado um método de soldagem por partes, cujo objetivo foi produzir juntas soldadas que pudessem se adequar aos ensaios realizados no estudo. A análise do processo de soldagem foi realizada a partir dos ensaios Double Cantilever Beam (DCB), Análise Termomecânica (TMA), Lap Shear e End-Notched Flexure (ENF), sendo realizada a análise da fratura após a realização dos ensaios mecânicos. Amostras soldadas foram também condicionadas em câmara higrotérmica. A partir deste condicionamento, foi observado que a absorção de umidade, tanto para amostras não soldadas como para as soldadas, apresenta o comportamento Fickiano. Quando considerados os resultados mecânicos obtidos das amostras condicionadas, como esperado, foi observada uma diminuição de algumas propriedades em até 40% devido, provavelmente, ao efeito da plasticização da matriz polimérica. Ainda, de acordo com os resultados de DCB, a adesão da malha metálica na região soldada é satisfatória, não havendo defeitos ou delaminações na junta soldada realizada pelo método de soldagem por partes.
Despite widespread use of thermoplastic composite materials in the aerospace industry, there is a constant concern about the integration of the constituent parts of an aircraft. As an alternative to joining these parts, among the main union methods in thermoplastic composites, welding has been considered the most advantageous. The electrical resistance welding applied to thermoplastic composites has as its main characteristic a shorter processing time compared to other welding techniques. However, components requiring structural requirements, when exposed to aggressive environments such as moisture associated with temperature can have their reduced mechanical properties. Thus, this study has as main objective to evaluate the influence of hygrothermal conditioning in PEI/carbon fiber welded composite welded samples. Welding parameters (current, time and pressure) were determined by performing assays based on the literature. For the development of this work was also employed a welding method by parts, whose aim was to produce welded joints that could fit the tests performed in the study. The analysis of the welding process was performed from the Double Cantilever Beam (DCB), Thermomechanical Analysis (TMA), Lap Shear and End-Notched Flexure (ENF) tests, the analysis of the fracture being performed after completion of the mechanical tests. Welded samples were also conditioned on hygrothermal chamber. From this conditioning, it was observed that the moisture absorption, of welded and not welded samples, presented Fickian. When considering the mechanical results obtained from the conditioned samples, as expected, was observed a decrease in some properties by up to 40% due probably to the plasticizing effect of the polymer matrix. Also, according to the results of DCB, adhesion of the metal mesh in the welded area is satisfactory, with no defects or delamination in the welded joint welding method performed by parts.
Despite widespread use of thermoplastic composite materials in the aerospace industry, there is a constant concern about the integration of the constituent parts of an aircraft. As an alternative to joining these parts, among the main union methods in thermoplastic composites, welding has been considered the most advantageous. The electrical resistance welding applied to thermoplastic composites has as its main characteristic a shorter processing time compared to other welding techniques. However, components requiring structural requirements, when exposed to aggressive environments such as moisture associated with temperature can have their reduced mechanical properties. Thus, this study has as main objective to evaluate the influence of hygrothermal conditioning in PEI/carbon fiber welded composite welded samples. Welding parameters (current, time and pressure) were determined by performing assays based on the literature. For the development of this work was also employed a welding method by parts, whose aim was to produce welded joints that could fit the tests performed in the study. The analysis of the welding process was performed from the Double Cantilever Beam (DCB), Thermomechanical Analysis (TMA), Lap Shear and End-Notched Flexure (ENF) tests, the analysis of the fracture being performed after completion of the mechanical tests. Welded samples were also conditioned on hygrothermal chamber. From this conditioning, it was observed that the moisture absorption, of welded and not welded samples, presented Fickian. When considering the mechanical results obtained from the conditioned samples, as expected, was observed a decrease in some properties by up to 40% due probably to the plasticizing effect of the polymer matrix. Also, according to the results of DCB, adhesion of the metal mesh in the welded area is satisfactory, with no defects or delamination in the welded joint welding method performed by parts.
Descrição
Palavras-chave
Compósitos, PEI/fibra de carbono, Condicionamento higrotérmico, Soldagem, Composites, PEI/carbon fiber, Hygrothermal conditioning, Welding