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A finite strain fibre-reinforced viscoelasto-viscoplastic model implemented in a finite element (FE) analysis is presented to study the expansive growth of plant cell walls. Three components of the deformation of growing cell wall, i.e. elasticity, viscoelasticity and viscoplasticity-like growth, are modelled within a consistent framework aiming to present an integrative growth model. The two aspects of growth-turgor-driven creep and new material deposition-and the interplay between them are considered by presenting a yield function, flow rule and hardening law. A fibre-reinforcement formulation is used to account for the role of cellulose microfibrils in the anisotropic growth. Mechanisms in in vivo growth are taken into account to represent the corresponding biology-controlled behaviour of a cell wall. A viscoelastic formulation is proposed to capture the viscoelastic response in the cell wall. The proposed constitutive model provides a unique framework for modelling both the in vivo growth of cell wall dominated by viscoplasticity-like behaviour and in vitro deformation dominated by elastic or viscoelastic responses. A numerical scheme is devised, and FE case studies are reported and compared with experimental data. [ABSTRACT FROM AUTHOR]

This paper reports on the development of braided reinforced composite rods as a substitute for the steel reinforcement in concrete. The research work aims at understanding the mechanical behaviour of core-reinforced braided fabrics and braided reinforced composite rods, namely concerning the influence of the braiding angle, the type of core reinforcement fibre, and preloading and postloading conditions. The core-reinforced braided fabrics were made from polyester fibres for producing braided structures, and E-glass, carbon, HT polyethylene, and sisal fibres were used for the core reinforcement. The braided reinforced composite rods were obtained by impregnating the core-reinforced braided fabric with a vinyl ester resin. The preloading of the core-reinforced braided fabrics and the postloading of the braided reinforced composite rods were performed in three and two stages, respectively. The results of tensile tests carried out on different samples of core-reinforced braided fabrics are presented and discussed. The tensile and bending properties of the braided reinforced composite rods have been evaluated, and the results obtained are presented, discussed, and compared with those of conventional materials, such as steel. [ABSTRACT FROM AUTHOR]

This paper demonstrates the effect of non-local interactions in an edge-cracked body made of composite material, in the case that the scale of the body is not large in comparison with the scale of the microstructure, as can occur, for example, in laboratory testing of concrete specimens. Not only are there significant boundary layers in the vicinity of all of the specimen boundaries, but the small size of the body permits their interaction, to alter the value of the mean field globally relative to the value that would be predicted by the use of “ordinary” homogenization, under conditions of “displacement control”. Such an effect would be present even for an uncracked body but the presence of the crack induces strong gradients in the mean field which significantly enhance this effect. The mean strain component $$\langle {e_{22}}\rangle$$ tends to become concentrated around the line ahead of the crack in comparison with the prediction of homogenization; there is, in addition, an enhancement of the stress and strain concentrations in the harder phase. The method of analysis is a finite-element implementation of a variational formulation related to the Hashin–Shtrikman variational principle, developed in the context of non-local effective response by the present authors. The present calculations are considered to be more accurate than some previously reported (Luciano and Willis, Journal of the Mechanics and Physics of Solids 53, 1505–1522, 2005) and the conclusions differ correspondingly. [ABSTRACT FROM AUTHOR]