Banca de DEFESA: Linconl Araujo Teixeira

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Linconl Araujo Teixeira
DATE: 23/11/2023
TIME: 13:30
LOCAL: Microsoft TEAMS
TITLE:

THE EFFECT OF DIFFERENT CURING CONDITIONS ON THE CREEP BEHAVIOR OF UNIDIRECTIONAL SISAL/EPOXY COMPOSITES.

KEY WORDS:

Epoxy; sisal; unidirectional composites; mathematical modeling; creep test.

PAGES: 106
BIG AREA: Engenharias
AREA: Engenharia Mecânica
SUMMARY:

Curing is a critical stage in the manufacture of epoxy resin-based composites, and the proper selection of curing conditions can significantly impact the mechanical properties of the material during creep testing. Creep is essential for evaluating the behavior of the composite material under constant load and/or elevated temperatures, replicating long-term service conditions. Although understanding the different curing conditions' effect on the material's creep response is essential for optimizing composite performance, and even though the scientific literature addresses the general effects of curing conditions on composites, the appropriate selection of curing conditions is a rarely discussed topic for natural fiber-reinforced composites. Thus, this study aimed to investigate the effect of different curing conditions on the creep properties of unidirectional sisal/epoxy fiber-reinforced composites. Experimentally, composites with fibers oriented at 0°, 45°, and cross-ply [0°/45°/45°/0°] were prepared and subjected to the following curing conditions: composites cured at room temperature with a post-curing process, composites cured at 100°C/4h in an oven, and composites cured with an accelerator. The various curing conditions investigated in this study demonstrated a significant effect on the epoxy resin's chemical structure, resulting in variations in the degree of curing, thermal stability, and level of cross-linking. These changes in resin properties played a crucial role in mechanical tests, highlighting the critical importance of curing conditions in understanding the epoxy resin's mechanical behavior and the composite manufacturing process. Regarding the composites, those cured with an accelerator exhibited greater thermal stability, while a higher degree of curing was found for the composites cured at room temperature and post-cured. Regarding mechanical properties, it was observed that all composites with fibers oriented at 0° exhibited superior performance in terms of tensile strength and modulus of elasticity compared to other fiber orientations. Concerning curing conditions, composites cured at room temperature and post-cured showed better mechanical performance in tension. Regarding creep analysis, the results showed that both the resin and the composites cured with an accelerator demonstrated greater resistance to creep deformation. Furthermore, the Findley and Burger mathematical models fit well with the experimental results, suggesting that they are useful tools for predicting and analyzing the creep behavior of these materials under long-term service conditions.

COMMITTEE MEMBERS:
Interno - 1722212 - EDER LIMA DE ALBUQUERQUE
Interno - 1249764 - JORGE LUIZ DE ALMEIDA FERREIRA
Presidente - 1720225 - SANDRA MARIA DA LUZ
Externo à Instituição - SANDRO CAMPOS AMICO - UFRGS
Externo à Instituição - SÉRGIO HENRIQUE PEZZIN - UDESC