Assessment of reactive thermoplastic composite pultrusion for continuous-fibre reinforced 3D printing

One of the new trends in additive manufacturing is the 3D printing of continuous fibre composite parts. Performance of such materials are significantly higher than for the typical 3D printed polymer materials made by filament deposition modelling (FDM) and stereolithography methods. In the frame of the project SAMIA-3D funded by the Luxembourg National Research Fund (FNR), LIST collaborates with Anisoprint to further develop its patented continuous-fibre 3D printing technology. The technology is based on a filament deposition process and involves multiphasic material. Materials currently used for the CFRP filament and the co-extruded matrix ensure the cost-effective production by printing of high performance composite material. Resulting properties present interesting mechanical properties compare to competitors and satisfy consumer’s goods requirement. But the main limitation of the current setup for structural applications is the high void volume content of the printed parts, voids both induced by the filament manufacturing process and thus the overall quality of the filament itself and also by the 3D printing process because of hot formability and multimaterial adhesion issues. One of our approach in the project is based on the improvement of the CFRP filament quality that can be achieved by using a reactive thermoplastic matrix for the filament manufacturing. The resin Elium® 595 supplied by Arkema exhibits interesting properties in terms of processability and also good mechanical properties similar to thermoset. Its reactivity and thermo-physical properties will be characterized through DSC, TGA and DMA. The manufacturing of thin filaments as well as their printability will also be assessed. A pultrusion-like process will be explored to produce filament with an expected high fiber volume ratio up to 65% whose thermo-physical and mechanical properties will be presented. In addition, the structure of the material will be investigated using a multi-scale approach, from surface aspect ratio and surface chemistry up to material morphology using SEM and micro-CT. Less than 0.5% of porosities are obtained on the filament material. Finally, printability of the reactive thermoplastic-based filament will be experimentally evaluated. Process induced defects such as multi-material interface, cracks and porosities will be characterized. Compared to existing thermoset based solution, a significant cracks and voids reduction has been observed. Please click Additional Files below to see the full abstract

Absence of Chronic Human Immunodeficiency Virus Infection without Seroconversion in Intravenous Drug Users: A Prospective and Retrospective Study

It has been reported that human immunodeficiency virus type 1 (HIV-1) infection may exist in persons without specific antibodies for years. To measure the frequency of a silent carrier state, a study was conducted in a cohort of 124 intravenous drug users (IVDUs) without anti-HIV-1 antibodies. All the participants had engaged in high-risk behavior for HIV-1 transmission for a number of years until 1987 or later. Samples were analyzed at 6-month intervals for the presence of HIV-1 provirus using DNA amplification and for the appearance of anti-HIV-1 antibodies. HIV-1 provirus and antibodies were undetectable in 122 participants, whereas seroconversion was observed in 2. In one of these, both amplified HIV-1 pol gene segment and anti-HIV-1 antibodies were detected simultaneously, and in the other, provirus was detected 1 month before seroconversion. This study suggests that long-term HIV-1 infection without anti-HIV-1 antibodies is rare and that repeated antibody testing is sufficient to determine the HIV-1 status of a person no longer at high risk for HIV-1 infectio

Caractérisation des interactions pièce-processus-ressources en mise en forme de matériaux composites en vue de la maîtrise dimensionnelle de la pièce

L'industrialisation des nouveaux procédés de mise en forme de matériaux composites à hautes performances requiert la prise en compte des interactions pièce-processus-ressources pour une meilleure maîtrise dimensionnelle. Nous proposons une méthode permettant la caractérisation des interactions résultant du transfert des contraintes pièce-outillage appliqué aux procédés de transfert de résine en vue d une optimisation du couple processus-ressources afin de minimiser ces interactions

Device for making a part of a composite material by resin-transfert moulding

The invention relates to a device (IO) for ma.king a part of a composite material by resin-transfer moulding, that includes a manufacturing mould (IO) in which is placed a blank (1) of the part to be impregnated with resin, characterised in that the manufacturing mould (20) is divided into a matrix (21) and one or more mobile structural members (22) to be indexed on the matrix (21), the whole defining, after assembly, an imprint corresponding to the shape of the part to be manufactured.FUI 072906222 projet CAPSAIRT

Procédés de fabrication en matériaux composites de pièces tridimensionnelles et/ou massives

L'invention concerne un procédé pour fabriquer en matériau composite une pièce brute ayant une forme massive et/ou tridimensionnelle, comprenant les étapes de : - bobiner à chaud au moins un toron de fibres renforçantes (24) imprégné de résine thermoplastique en quantité excédentaire, sur des reliefs de bobinage (17-23 ) d'un outillage de bobinage (16), pour constituer une préforme de la pièce fabriquée ; - matricer à chaud la préforme pour lui donner une forme souhaitée tout en évacuant la résine excédentaire ; - refroidir l'ensemble en maintenant sous pression l'outillage de matriçage (31) pour constituer la pièce brute. L'invention s'applique à la fabrication de pièces mécaniques structurelles telles que des pièces structurelles aéronautiques

Brownian motion: a paradigm of soft matter and biological physics

This is a pedagogical introduction to Brownian motion on the occasion of the 100th anniversary of Einstein's 1905 paper on the subject. After briefly reviewing Einstein's work in its contemporary context, we pursue some lines of further developments and applications in soft condensed matter and biology. Over the last century Brownian motion became promoted from an odd curiosity of marginal scientific interest to a guiding theme pervading all of the modern (live) sciences.Comment: 30 pages, revie

The GRAVITY+ Project: Towards All-sky, Faint-Science, High-Contrast Near-Infrared Interferometry at the VLTI

The GRAVITY instrument has been revolutionary for near-infrared interferometry by pushing sensitivity and precision to previously unknown limits. With the upgrade of GRAVITY and the Very Large Telescope Interferometer (VLTI) in GRAVITY+, these limits will be pushed even further, with vastly improved sky coverage, as well as faint-science and high-contrast capabilities. This upgrade includes the implementation of wide-field off-axis fringe-tracking, new adaptive optics systems on all Unit Telescopes, and laser guide stars in an upgraded facility. GRAVITY+ will open up the sky to the measurement of black hole masses across cosmic time in hundreds of active galactic nuclei, use the faint stars in the Galactic centre to probe General Relativity, and enable the characterisation of dozens of young exoplanets to study their formation, bearing the promise of another scientific revolution to come at the VLTI.Comment: Published in the ESO Messenge

Pre-mission InSights on the Interior of Mars

Abstract The Interior exploration using Seismic Investigations, Geodesy, and Heat Trans- port (InSight) Mission will focus on Mars’ interior structure and evolution. The basic structure of crust, mantle, and core form soon after accretion. Understanding the early differentiation process on Mars and how it relates to bulk composition is key to improving our understanding of this process on rocky bodies in our solar system, as well as in other solar systems. Current knowledge of differentiation derives largely from the layers observed via seismology on the Moon. However, the Moon’s much smaller diameter make it a poor analog with respect to interior pressure and phase changes. In this paper we review the current knowledge of the thickness of the crust, the diameter and state of the core, seismic attenuation, heat flow, and interior composition. InSight will conduct the first seismic and heat flow measurements of Mars, as well as more precise geodesy. These data reduce uncertainty in crustal thickness, core size and state, heat flow, seismic activity and meteorite impact rates by a factor of 3–10× relative to previous estimates. Based on modeling of seismic wave propagation, we can further constrain interior temperature, composition, and the location of phase changes. By combining heat flow and a well constrained value of crustal thickness, we can estimate the distribution of heat producing elements between the crust and mantle. All of these quantities are key inputs to models of interior convection and thermal evolution that predict the processes that control subsurface temperature, rates of volcanism, plume distribution and stability, and convective state. Collectively these factors offer strong controls on the overall evolution of the geology and habitability of Mars