Hygrothermal Effect on Composites Under In-Plane Fatigue at Stress Ratios of R=-1 and R=0.1: An Analysis of Quasi-Isotropic Stitched Carbon Fibers

Autor(es)

Shiino, Marcos Yutaka ^{[1, 2]} ; Moraes de Siqueira, Guilherme Silva ^[3] ; Hilario Cioffi, Maria Odila ^{[1, 3]} ; Montoro, Sergio Roberto ^[4] ; Donadon, Mauricio Vicente ^[5]

Afiliação do(s) autor(es)

^[1] UNESP, IEAMar, Inst Estudos Avancados Mar, Sao Jose Dos Campos, SP - Brazil

^[2] Univ Estadual Paulista Unesp, Inst Ciencia & Tecnol, Sao Jose Dos Campos - Brazil

^[3] Univ Estadual Paulista Unesp, Fac Engn, Fatigue & Aeronaut Mat Res Grp, Dept Mat & Tecnol, Guaratingueta - Brazil

^[4] Fatec Fac Tecnol Pindamonhangaba, Caixa Postal 1, BR-12445010 Pindamonhangaba, SP - Brazil

^[5] ITA, Div Engn Aeronaut, Praca Marechal Ar Eduardo Gomes, Vila Acacias, BR-12228900 Sao Jose Dos Campos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Materials Engineering and Performance; v. 27, n. 11, p. 5964-5972, NOV 2018.
• Citações Web of Science: 0

Resumo

The aeronautic structures normally operate under high levels of hygroscopic moisture from the surrounding environment at different temperature ranges while in service. Under such conditions, the behavior of laminate composite submitted to cyclic or static loadings can change drastically. In order to understand those effects in stitched fabrics, fatigue tests with open-hole specimens were carried out with a stress ratio of R=-1 and R=0.1. The specimens were fatigue-tested as provided (environmental conditions) and after exposed to hygrothermal weathering conditions. Based on evidences from recent studies available in the open literature, e.g., effect of water diffusion on epoxy matrix, the overall results indicated a significant reduction in stiffness after the specimens are exposed to hygrothermal effects. The reduction in matrix stiffness, in this case, enhanced the fatigue strength in tension-tension load (R=0.1) when compared to the specimens in normal conditions. The opposite occurs for the specimens loaded with stress ratio of R=-1, in which the delamination mechanisms changed during the loading reversion from tension to compression that promoted early delamination. Therefore, this process reduced the fatigue life of the specimens under hygrothermal condition. Then, by fractographic investigation, it was verified fracture patterns that regard to mode II damage in R=-1, in which mode II fracture toughness is known to decrease in the presence of water molecules. (AU)

• Processo FAPESP: 11/01937-0 - Taxa de delaminação em compósitos 5HS carbono/epóxi processado via RTM: relação do carregamento axial tração-tração como modos I e II puros
• Beneficiário: Marcos Yutaka Shiino
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 12/07646-0 - Avaliação do efeito do gradiente de pressão no processamento RTM em laminado 5HS por DCB no modo i em fadiga
• Beneficiário: Marcos Yutaka Shiino
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado