Microcracking of composites reinforced by stitched multiaxials subjected to cyclical hygrothermal loadings

International audienceMicrocracking of polymer matrix composites reinforced by multiaxial multi-ply stitched carbon preforms submitted to cyclical purely hygrothermal loading is analyzed. The laminates are manufactured by liquid resin infusion (LRI). The stitching induces deviations in fibre layout and creates openings which become resin-rich regions after the resin infusion. The interaction between resin-rich regions and microcracks induced by the hygrothermal cycles was investigated by 2D metallographic micrography and X-ray microtomography. Specific microcracking process was found to occur in this type of material. The occurrence of cracks was quantified and the morphology of the 3D crack network studied. The nature of the stitching yarn and the size of the diamond-shaped resin-rich regions were identified as having a major influence on laminate microcracking after ageing. (C) 2011 Elsevier Ltd. All rights reserved

Introduction à la durabilité des matériaux composites renforcés par nappes unidirectionnelles cousues.

National audienc

Role of interface formation versus fibres properties in the mechanical behaviour of bio-based composites manufactured by Liquid Composite Molding processes

The aim of this work was to study the effect of free surface energy modification of flax fibres by a thermal treatment on the mechanical behaviour of bio-based composites. It has been proved that this modification enhances the wettability of flax fibres by liquid epoxy resin and results in a lower porosity amount in composites. Tests to evaluate mechanical properties of elementary fibres, yarns and composites have been performed. The main outcome of this multiscale study, even if elementary fibres and yarns have been embrittled and interface properties have been lowered after thermal treatment, is that the mechanical behaviour of composites manufactured by Liquid Composite Molding (LCM) is better with treated fibres

Fluoration de fibres de lin pour la fabrication d’éco-composites.

International audienc

In-plane permeability characterization of engineering textiles based on radial flow experiments: A benchmark exercise

© 2019 Elsevier Ltd Although good progress was made by two international benchmark exercises on in-plane permeability, existing methods have not yet been standardized. This paper presents the results of a third benchmark exercise using in-plane permeability measurement, based on systems applying the radial unsaturated injection method. 19 participants using 20 systems characterized a non-crimp and a woven fabric at three different fiber volume contents, using a commercially available silicone oil as impregnating fluid. They followed a detailed characterization procedure and also completed a questionnaire on their set-up and analysis methods. Excluding outliers (2 of 20), the average coefficient of variation (c v ) between the participant's results was 32% and 44% (non-crimp and woven fabric), while the average c v for individual participants was 8% and 12%, respectively. This indicates statistically significant variations between the measurement systems. Cavity deformation was identified as a major influence, besides fluid pressure/viscosity measurement, textile variations, and data analysis.status: publishe

In-plane permeability characterization of engineering textiles based on radial flow experiments: A benchmark exercise

International audienceAlthough good progress was made by two international benchmark exercises on in-plane permeability, existing methods have not yet been standardized. This paper presents the results of a third benchmark exercise using in-plane permeability measurement, based on systems applying the radial unsaturated injection method. 19 participants using 20 systems characterized a non-crimp and a woven fabric at three different fiber volume contents, using a commercially available silicone oil as impregnating fluid. They followed a detailed characterization procedure and also completed a questionnaire on their set-up and analysis methods. Excluding outliers (2 of 20), the average coefficient of variation (cv) between the participant’s results was 32% and 44% (non-crimp and woven fabric), while the average cv for individual participants was 8% and 12%, respectively. This indicates statistically significant variations between the measurement systems. Cavity deformation was identified as a major influence, besides fluid pressure/viscosity measurement, textile variations, and data analysis

Trabecular bone remodelling under pathological conditions based on biochemical and mechanical processes involved in BMU activity

International audienc