Design and Characterization of an Adhesive for T-Joint Composite

• Autor(a) principal: Valente, Hugo Micael Santos
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.6/10587
• topic: Adesivo Estrutural; Cfrp; Degradação Ambiental; Juntas Em T; Modo de Falha; Propriedades Mecânicas; Spot; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Aeronáutica

With the increase in composites usage in aeronautical structures and with it, the use of Carbon-Fiber Reinforced Polymers (CFRP), there was also an increase in the use of diverse types of joints, being one of the most common the T-joints. The bonding method that has gained a lot of attention is the adhesive bonding, but its optimization requires an understanding of its behavior with different types of service conditions. In this work, the aeronautical structural adhesive film SEAL® EA451 U150 was characterized at 3-point bending using different strain-rates, stress relaxation and creep behavior. The adhesive was subjected to different temperatures while immersed in water and the degradation of properties (mechanical and viscoelastic) were evaluated. Finally, this adhesive was used in T-joints and Stiffener Pull-Off Tests (SPOT) were conducted in order to understand the effect of exposure to temperature and moisture on the failure mode. The results show that: the mechanical properties in 3-point bending of the adhesive depend on the service conditions: -it was observed that the ultimate stress strength and the elastic modulus increase with the strain-rate; - for a load of 60 % of the ultimate stress strength after 180 minutes the stress decrease is inferior to 10 %. After suffering environmental degradation, the adhesive decreases its ultimate stress strength (from 109 to 62 N) and decreases its maximum strain (from 3.4 to 1.8 %), T-joints in SPOT have a progressive failure mode (non-abrupt) and when subjected to environmental degradation present a reduction of maximum load of ~8%, but with an increase of ~18 % in deformation