POPCOM platform: Composites Advanced Manufacturing

National audiencePOPCOM Composites Advanced Manufacturing Platform @ IMT LIlle Douai : Original facilities for development and industrialization of structural composites and reinforced polymers, embracing the whole chain of product life cycle … the ‘’Swiss Army Knife’’ of composites

Fabrication par imprégnation directe et assemblage par soudage de composites thermoplastiques structuraux à renfort textile en fibres végétales

National audience* Développement d’une technique originale d'imprégnation directe de renforts continus de lin par des thermoplastiques totalement ou partiellement bio-sourcés, par injection dans un moule fermé* Étude multi-échelles des mécanismes d'imprégnation / gonflement sous contraintes thermo-hydromécaniques des fibres végétales. Déduction des évolutions de propriétés physiques et mécaniques* Étude des mécanismes d’imprégnation de composites moulés à haute cadence avec des thermoplastiques mono- ou bi-composants de haute fluidité* Assemblage de pièces composites renforcées de fibres végétales par soudage laser* Qualification de la résistance des joints de soudure des composites thermoplastiques bio-sourcé

Influence of resin curing cycle on the characterization of the tensile properties of flax fibers by impregnated fiber bundle test

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Analysis of impregnation mechanism of weft-knitted commingled yarn composites by staged consolidation and laboratory X-ray computed tomography

International audienceAbsorption-based microcomputed tomography (μCT) scans using polychromatic X-ray sources are frequently used to analyse the microstructure of polymer-matrix composites. Assuming the proportionality between linear X-ray attenuation coefficients and gray levels in the reconstructed μCT images, segmentation techniques can be used to conduct qualitative and quantitative analyses. Nevertheless, the reliability of such analyses islimited in partially consolidated composites formed of commingled yarns due to low contrast induced by beam hardening and partial volume effect. This paper aims at investigating the possibility of using low-contrast μCT images to analyse fiber bed deformation and impregnation mechanism by staged consolidation of a weft-knitted fabric of commingled thermoplastic/glass yarns. The experimental work is focused on the effect of the compaction ratio of the consolidation cycle. Absorption-based μCT analyses are conducted for representative samples using a voxel size of 10μm and a constant energy-level of the X-rays source. Preliminary qualitative analyses of the raw reconstructed images indicate that beam hardening is the most significant in the case of the non-consolidated sample and that partial volume effect makes it difficult to visually distinguish between dry and impregnated zones inside the yarns at a compaction ratio of 63%. Thus, two image-quality descriptors, viz. contrast and signal-to-noise ratio are evaluated based on the K-means clustering method to follow their variation for four consolidation levels. The corresponding volume fractions of glass fibers, thermoplastic matrix, and voids are compared with the results of a second weight-controlled thresholding method. Considering that the weight-controlled thresholding method is less sensitive to beam hardening, it is confirmed that obtaining reliable segmentation results based on the K-means method requires a contrast around 0.5 and signal-to-noise ratio lower than 3. The results from the comparison with the classical consolidation scenario of commingled yarns confirm the potential of using μCT images of different qualities to characterize partially consolidated weft-knitted fabrics

POPCOM platform: Composites Advanced Manufacturing

National audiencePOPCOM Composites Advanced Manufacturing Platform @ IMT LIlle Douai : Original facilities for development and industrialization of structural composites and reinforced polymers, embracing the whole chain of product life cycle … the ‘’Swiss Army Knife’’ of composites

POPCOM platform: Composites Advanced Manufacturing

National audiencePOPCOM Composites Advanced Manufacturing Platform @ IMT LIlle Douai : Original facilities for development and industrialization of structural composites and reinforced polymers, embracing the whole chain of product life cycle … the ‘’Swiss Army Knife’’ of composites

Preform permeability measurement and 3D resin flow simulation for dry AFP

International audienceAn efficient experimental method is proposed to measure very low permeability of composite laminated preform fabricated by automated dry fiber tape placement. A new computer program is also presented for the numerical simulation of three dimensional resin flow which is generally impossible by conventional commercial packages due to an extremely heavy computing cost

Fabrication par imprégnation directe et assemblage par soudage de composites thermoplastiques structuraux à renfort textile en fibres végétales

National audience* Développement d’une technique originale d'imprégnation directe de renforts continus de lin par des thermoplastiques totalement ou partiellement bio-sourcés, par injection dans un moule fermé* Étude multi-échelles des mécanismes d'imprégnation / gonflement sous contraintes thermo-hydromécaniques des fibres végétales. Déduction des évolutions de propriétés physiques et mécaniques* Étude des mécanismes d’imprégnation de composites moulés à haute cadence avec des thermoplastiques mono- ou bi-composants de haute fluidité* Assemblage de pièces composites renforcées de fibres végétales par soudage laser* Qualification de la résistance des joints de soudure des composites thermoplastiques bio-sourcé