Liquid composite moulding processes are increasingly used to manufacture composite structures. Such processes combine compression of the fibre reinforcements (in dry and/or lubricated states) and resin flow. A better modelling of the compression of fibre reinforcements would improve the accuracy of hydro-mechanical coupling modelling involved in these processes. Several models are available in the literature, but none of them consider permanent deformations (such as plasticity). This article presents a methodology to measure plasticity of fibre reinforcements in dry and impregnated states. Also a non-linear elastic-plastic model, including large deformations, is proposed for unidirectional compression. Results on glass fibre reinforcements are presented and discussed.
Composite materials reinforced with 3D layer-to-layer angle-interlock fabrics are increasingly employed due to their significant resistance to delamination and impact damage, which is not observed in classical 2D laminated composites. However, the prediction of the mechanical behavior of such composites is challenging due to the intricate fibrous architecture. The structure is intimately linked to its history of manufacturing which induces changes in the reinforcement geometry. The purpose of this work is to assess the equivalent membrane and bending elastic moduli of the shell-type structure by an asymptotic homogenization procedure on a periodic unit cell, in the framework of the Love-Kirchhoff plate theory. A specific Python program using Abaqus software package is developed, allowing for parameterized geometrical modeling and mechanical analysis in a systematic and efficient way. This modeling and simulation tool enables to consider the real composite architecture after infusion and the yarn damage during weaving. The effective properties are finally validated using numerical computations on 3D heterogeneous plates and by comparison with experimental tests.
International audienceThis paper deals with the buckling behavior of two-layer shear-deformable beams with partial interaction. The Timoshenko kinematic hypotheses are considered for both layers and the shear connection (no uplift is permitted) is represented by a continuous relationship between the interface shear flow and the corresponding slip. A set of differential equations is obtained from a general 3D bifurcation analysis, using the above assumptions. Original closed-form analytical solutions of the buckling load and mode of the composite beam under axial compression are derived for various boundary conditions. The new expressions of the critical loads are shown to be consistent with the ones corresponding to the Euler-Bernoulli beam theory, when transverse shear stiffnesses go to infinity. The proposed analytical formulae are validated using 2D finite element computations. Parametric analyses are performed, especially including the limiting cases of perfect bond and no bond. The effect of shear flexibility is particularly emphasized
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