In recent years, studies of composite materials have focused on the use of natural fibres as an alternative to synthetic ones. Their attractive mechanical properties, sustainability, low cost and low weight have leveraged research in this area, with the potential of a variety of applications in the engineering field. In this paper, a Full Factorial Design (2¹6¹) experiment was performed to identify the effect of silica microparticle inclusions and the stacking sequence of glass fibre cross-ply fabric and short sisal fibre layers on the apparent density, tensile and flexural strength and modulus of hybrid epoxy composites. In general, the hybrid composites with higher number of glass fibre layers achieve higher values of tensile and flexural strength (348 MPa and 663.28 MPa), tensile and flexural modulus (22 GPa and 2.50 GPa) and higher apparent density (2.02 g/cm³). It is, however, noteworthy that the incorporation of silica particles improves the mechanical performance of composites containing larger amounts of sisal fibres.
This work describes the identification of the shear modulus of open cell polyurethane thermoformed auxetic foams from 3-and 4-point bending tests. The foams are incorporated in sandwich beams with carbon fibre/epoxy face skins, and benchmarked against similar sandwich structures made with the conventional counterpart open cell foam. Three types of beams are tested: one with auxetic foams, another type related to a conventional foam core with the same thickness of the auxetic porous materials, and a third type of beam consisting in conventional foam with a thickness corresponding to an iso-weight configuration to the auxetic specimen. The auxetic foam has a shear modulus 7% lower than the one of the bulk conventional specimens, but higher shear stresses at large deformations and a smoother strain stiffening response compared to the beams with the conventional thinner core. The paper also highlights the low shear wave speed of these auxetic foams compared to other porous polymers used in helmet and head protection applications, as well as potential uses of the quasi-zero-stiffness behavior here observed for the auxetic foam sandwich beam.
RESUMO
Este trabalhou objetiva apresentar uma metodologia analítica para o cálculo dos módulos de elasticidade longitudinal (E) e transversal (G) em vigas de madeira de dimensões estruturais, segundo o emprego das teorias de vigas de Euler
Palavras-chave: madeira, teoria de vigas, módulo de elasticidade.
ABSTRACT
This paper proposed a test method to obtain the shear (G) and longitudinal (E) modulus of elasticity in timber beams with structural dimensions, based on the static threepoints bending tests and the Euler Bernoulli and Timoshenko beams theories. The woods tested were the
In the last decades the biocomposites have been widely used in the construction, automobile and aerospace industries. Not only the interface transition zone (ITZ) but also the heterogeneity of natural fibres affects the mechanical behaviour of these composites. This work focuses on the numerical and experimental analyses of a polymeric co mposite fabricated with epo xy resin and unidirectional sisal and banana fibres. A three -d imensional model was set to analyze the composites using the elastic properties of the individual phases. In addition, a two-dimensional model was set taking into account the effective composite properties obtained by micro mechanical models. A tensile testing was performed to validate the numerical analyses and evaluating the interface condition of the constitu tive phases.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.