Análise do comportamento em fadiga axial do compósito de fibra de carbono NCF/resina epóxi com concentrador de tensão: efeitos higrotérmicos

• Autor(a) principal: Siqueira, Guilherme Silva Moraes de [UNESP]
• Data de Publicação: 2016
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/155399; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2017-05-02/000882702.pdf
• topic: Resinas compostas; Moldagem (Tecnologia quimica); Fadiga; Resistência de materiais; Composite resins

The transport sector has great interest in composite materials for their high specific mechanical properties, thus improving the autonomy and load capacity of vehicles. For these, aircraft industry has been searching for lighter materials, which may be able to replace metallic materials by keeping their original properties or even improving them. The resin transfer molding (RTM) is a promising manufacturing process of composites for structural application as it provides high mechanical strength, considering the aircraft criteria, good reproducibility and low cost. However, it is necessary to understand the behavior of composite laminates under fatigue, specifically that one obtained by RTM processing technique. Fatigue, in turn, is a phenomenon that limits the longevity of many engineering components that go under cyclic loadings. The behavior of composites, containing notch/hole with hot/wet environmental conditions, has been the goal of research for the last three decades due to the increased use of these materials. Thus, it was performed fatigue tests in specimens with open-hole under cyclic loadings with stress ratio of R=0,1 and R=-1. Prior to tests, they were conditioned to 90 % moisture and temperature 80°C and their results compared to specimen with no external effects. By stress versus number of cycles curve (SxN), it observed that fatigue tension-tension results achieved higher fatigue strength in conditioned specimens, indicating an increase in strength when exposed to hygrothermal aging effects. The opposite occurred in reverse fatigue strength curve where the curve decreased thus indicating a change in the delamination mechanism of specimens, which was assessed by images achived by Scanning Electron Microscopy (SEM)