Correlação entre modelos de micromecânica e ensaios experimentais para um compósito de fibras de sisal produzido por infusão a vácuo

Abstract

Fiber-reinforced composite materials exhibit highly advantageous mechanical properties for a wide range of engineering applications. However, due to the use of synthetic components, such as resins and fibers, these materials generate significant environmental impacts during their manufacturing process and especially at the end of the life cycle of the products in which they are used. In this context, the use of natural fibers, such as plant-based fibers, emerges as a sustainable alternative that reduces environmental harm without compromising the beneficial properties of composites. Among natural fibers, sisal has attracted interest in recent studies due to its good mechanical properties; however, its application remains underexplored. To help bridge this gap, this work aims to analyze design tools such as micromechanical models and finite element analysis applied to sisal fiber-reinforced composites. Materials and methods were also adopted with the goal of integrating this composite material into engineering applications. The following models were used: (i) Rule of Mixtures, (ii) Halpin-Tsai, and (iii) numerical simulation of a representative volume element (RVE) to estimate material properties, which were used in finite element simulations of tensile and bending tests. In addition, the sisal fiber composite, manufactured via vacuum infusion using polyester resin as the matrix, had its tensile and flexural properties evaluated through standardized tests. The mechanical properties and stress-strain curves obtained experimentally were compared with the results from micromechanical models and simulations. The micromechanical models and RVE simulation showed variations in the elastic modulus between 3% and 5.5% compared to the experimental results. However, the comparison between the simulated and experimental stressstrain curves for the tensile and bending tests showed a notable divergence. This discrepancy can be attributed to factors such as fiber anisotropy, waviness, the presence of defects, and adhesion failures, which are not considered in micromechanical models. Nevertheless, the correlation can serve as a useful reference for future studies involving micromechanics, finite element simulations, and engineering applications of sisal fiber-reinforced composites.