Banca de QUALIFICAÇÃO: Vilson Dalla Libera Júnior

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : Vilson Dalla Libera Júnior
DATE: 31/10/2022
TIME: 15:00
LOCAL: Via teams
TITLE:

OBTAINING HYBRID METAL FIBER LAMINATES WITH NATURAL AND SYNTHETIC FIBERS

KEY WORDS:

Fiber-Metal Laminates; Sisal fibers; Mechanical properties; Residual stresses

PAGES: 100
BIG AREA: Engenharias
AREA: Engenharia Mecânica
SUMMARY:

Fiber-Metal Laminates (FML) are hybrid composite materials manufactured from the combination between thin metal and fiber-reinforced polymeric (FRP) layers. Carbon and glass fibers are the most commonly investigated and used fibers in FMLs. However, composites based on renewable sources or biocomposites have emerged as environmentally friendly alternatives to traditional composite materials due to recent environmental and sustainability concerns. Despite their excellent mechanical properties, a limitation of FMLs is related to their processing methods, since, during the cure shrinkage, the difference between the coefficients of thermal expansion (CTE) of metal and FRP layers origins the development of residual stresses. The level of residual stresses generated after the curing/post-curing process, the manifestation of deformations, as well as the behavior of the fracture toughness in the final hybrid component are still slightly discussed in the literature. In this context, this work aims to investigate the influence of the hybridization effect on the mechanical behavior and failure mechanism of fiber-metal laminates produced with hybrid reinforcement of natural and synthetic fibers. The methodology of this work was divided into two main steps, in the first one occurs the production of prepregs, the second refers to the processing of FMLs. Initially, synthetic fiber and sisal natural fibers prepregs were produced. The impregnation was performed using an epoxy resin solution at room temperature. After reaching B-stage of curing, the prepregs were frozen at -18 °C for later use. Differential Scanning Calorimetry (DSC) of the epoxy matrix was performed to study the best curing cycle condition for FMLs. The fiber-metal laminates were produced through the hot pressing process and using a metallic layer of 2024-T3 aluminum on the external face and hybrid reinforcement alternating between natural and synthetic fiber prepregs internally. Obtaining data related to strength, modulus and deformation occurred through tensile tests coupled to the Digital Image Correlation (DIC) technique, then the results were interpreted using analysis of variance (ANOVA). According to the evaluation of the matrix extent of cure, it was possible to establish that the isotherm at 80 °C and time of 30 min define the ideal curing cycle for the processing of FMLs. The analysis of stress-strain curves indicated that the difference in elastic properties between the metallic and FRP layers directly influences the FML delamination process. In addition, this phenomenon is also associated with the presence of residual stresses existing between these layers, which are manifested in the failure mode. The effect of composites hybridization directly influenced the load capacity and deformation of the laminates. The mechanical results indicated that the sisal composite/metal layer interface can be directly affected by the nature of the fiber. Therefore, the failure modes of the material indicate that the presence of residual stresses between the constituent layers of the FMLs, and that their nature directly influences the intensity of the stresses.

BANKING MEMBERS:
Externo à Instituição - SANDRO CAMPOS AMICO - UFRGS
Externo ao Programa - 3279834 - CLAUDIO HENRIQUE SOARES DEL MENEZZI
Interno - 1722212 - EDER LIMA DE ALBUQUERQUE
Presidente - 1720225 - SANDRA MARIA DA LUZ