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Advisor(s)
Abstract(s)
Ao longo dos últimos anos as juntas coladas têm aumentado significativamente o seu
campo de aplicação. Apesar de tudo, a resposta ao impacto não tem sido alvo de tanto estudo
como o do carregamento estático. Neste contexto, revela-se do maior interesse a
compreensão dos mecanismos de falha em ambos os casos. O presente trabalho pretende,
assim, estudar a resistência estática e a resistência ao impacto transversal de juntas coladas
sobrepostas simples com diferentes aderentes (aço/aço, aço/compósito e
compósito/compósito). O efeito da humidade na resistência estática e no impacto também é
avaliado através de água destilada (à temperatura ambiente e a 40 ºC) e água do mar (à
temperatura ambiente), considerando diferentes tempos de imersão (1, 2, 4 e 8 semanas).
Verificou-se que as juntas coladas com aderentes em aço mostraram-se mais sensíveis ao
meio ambiente estudado e ao tempo de exposição. Relativamente às juntas coladas com
aderentes em materiais compósitos, a água (destilada ou salgada) mostrou um efeito
marginal. No entanto, o efeito higrotérmico foi marcante na resistência à tração em todas as
juntas independentemente dos aderentes envolvidos. Finalmente, a imersão nas soluções
estudadas apresentaram um efeito na resistência ao impacto muito semelhante ao observado
nos ensaios de tração, mas com uma maior severidade, independentemente dos mecanismos
de dano serem semelhantes aos observados nos ensaios de tração para todas as juntas coladas
estudadas.
Over the last years, adhesive joints have significantly increased their applications. However, the impact response has received limited attention compared to quasi-static loading. In this context, it is very important to understand their failure mechanisms in both cases. Therefore, the main goal of the present work is to study the tensile strength and the transverse impact strength of single lap joints with different adherends (steel/steel, steel/composite and composite/composite). The moisture effect on the tensile and impact strength will be also studied and, for this purpose, distilled water (at room temperature and at 40 ºC) and sea water (at room temperature) will be used with different exposure time (1, 2, 4 e 8 weeks). It was possible to conclude that the adhesive joints with steel adherends are very sensitive to the environment and exposure time. Relatively to the adhesive joints with composite adherends, the water showed a marginal effect. However, a marked hygrothermal effect was observed for all joints. Finally, the moisture presents a similar effect on the impact strength, but much more severe than that observed in tensile tests, independently of the damages mechanisms are similar to those observed for the tensile tests.
Over the last years, adhesive joints have significantly increased their applications. However, the impact response has received limited attention compared to quasi-static loading. In this context, it is very important to understand their failure mechanisms in both cases. Therefore, the main goal of the present work is to study the tensile strength and the transverse impact strength of single lap joints with different adherends (steel/steel, steel/composite and composite/composite). The moisture effect on the tensile and impact strength will be also studied and, for this purpose, distilled water (at room temperature and at 40 ºC) and sea water (at room temperature) will be used with different exposure time (1, 2, 4 e 8 weeks). It was possible to conclude that the adhesive joints with steel adherends are very sensitive to the environment and exposure time. Relatively to the adhesive joints with composite adherends, the water showed a marginal effect. However, a marked hygrothermal effect was observed for all joints. Finally, the moisture presents a similar effect on the impact strength, but much more severe than that observed in tensile tests, independently of the damages mechanisms are similar to those observed for the tensile tests.
Description
Keywords
Juntas Coladas Meio Ambiente Resistência Ao Impacto Transversal Resistência Estática