Investigation of Impact Induced Damage on Composite Plates by Analysing the Radiated Aerial Acoustic Signal

International audience

Effect of moisture uptake on flax-reinforced composite laminates: influence on dynamic and quasi-static properties

International audience; This study proposes to investigate the effect of moisture uptake on a wide spectrum of mechanical behaviours of unidirectional flax fibre-reinforced epoxy laminates. It includes tensile monotonic and fatigue testing. Results show that UD flax-epoxy composites, whenexposed to hygrothermal conditioning at 70°C and 85% RH, exhibit a diffusion kinetic which follows a one dimensional Fickian behaviour. The mass uptake at equilibrium is approximately 3.3 % and the diffusion coefficient 6.5 10-6 m2.s-1. Water vapour sorption is shown to induce a significant change in the shape of the tensile stress-strain curve. Contrary to all expectations, water saturation does not degrad…

MULTI AXIAL TESTING OF ADHESIVELY BONDEDJOINTS OF FIBER REINFORCED THERMOPLASTIC POLYMERS

International audience; In order to predict the mechanical behaviorof adhesively bonded joints, it is necessary to develop robust numerical models.This robustness is only reached if an extensive experimental database with tensile, shear and complex combined peel and shear loads can beestablished. The purpose of this study is to present a multi axialdevice for testing adhesively bonded joints, using KS2-type specimens traditionally utilized for spot-weld characterization. The tests were conducted on a glass fiber reinforced thermoplastic polymer(PA6-6) composite adhesively bonded with a flexible polyurethane adhesive. This adhesive/substrate combination allowsshort process times and good per…

Hydrothermal ageing of fibre metal laminates made of flax fibres

International audience; In the past two decades, fibre metal laminates (FMLs) have been widely used to manufacture aircraft and aerospace components. FMLs are hybrid composite structures based on thin sheets of metal alloys reinforced by organic matrix composites (Sinmazçelik et al., 2011). When compared to mono-material solutions, FMLs provide added functionalities such as high specific bending strength, fatigue resistance, acoustical absorption, vibration transmissibility and damping characteristics. They overcome most of the limitations of metal and polymeric reinforced composites. The first generation of FMLs was based on thermoset resins. To shorten the process cycle times, lower the p…

Experimental study of the crush efficiency of flax/epoxy and carbon/epoxy composite tubes for energy absorption systems

Influence du chargement thermohydrique sur le comportement mécanique statique, cyclique et dynamique des composites renforcés de fibres de lin

International audience; Ce travail porte sur la caractérisation de l’influence d’un chargement thermohydrique sur le comportement en traction quasi-statique, en fatigue et vibratoire d’un matériau composite lin/époxy unidirectionnel. Les résultats montrent que lorsque ces composites sont exposés à ces conditions hygrothermiques (70°C et 85% d’humidité relative), ils absorbent de l’eau suivant une loi de Fick 1D. L’absorption d’eau induit un changement de l’allure de la réponse en traction, diminue le module élastique d’environ 20% et augmente le coefficient d’amortissement d’approximativement 50%. La résistance sous chargement monotone n’est pas significativement affectée par l’absorption d…

Effects of Stacking Sequence on the Mode -I Delamination of Carbon/Epoxy Laminates

International audience

Toward Sustainable PLA-Based Multilayer Complexes with Improved Barrier Properties

Poly(lactic acid) or PLA is currently considered as one of the most promising substitutes of conventional plastics, with low environmental impact, especially for food packaging applications. Nevertheless, some drawbacks, such as high permeability to oxygen, are still limiting its industrial applications. The objective of this study was to highly increase the oxygen barrier performance of PLA without compromising its sustainable nature and following the principles of circular economy perspective. Coproducts coming from mill industries, such as wheat gluten proteins (WG), were used to produce PLA-WG-PLA multilayer complexes with improved barrier performance. Different technologies of industri…

Caractérisation mécanique de matériaux hybrides composites biosourcés/métal pour le mobilier urbain

Méthode D'essais Multiaxiaux Hors Plan Pour Des Assemblages Composites Thermoplastiques (Pa 6-6) Collés Avec Un Adhésif Hyper-Élastique

International audience; La prédiction du comportement de joints collés rend nécessaire le développement de modèles numériques robustes. Cela nécessite l’obtention d’une base de données expérimentale pour des chargements monotones multiaxiaux (traction, cisaillement et combinés). Dans cette étude, un moyen de chargement multiaxial pour la caractérisation mécanique de joints collés, utilisant des éprouvettes KS2 habituellement employées pour la caractérisation des assemblages soudés, est proposé. L’assemblage étudié est composé de substrats en matériau composite à renfort tissé en fibres de verre à résine thermoplastique polyamide 6-6 et d’un adhésif polyuréthane mono-composant à comportement…

Pla/Protein Complex Films: Multilayer Process and Properties. Matbim 2017

International audience

Tolérance À L'impact Et Au Vieillissement Hygrothermique De Composites Carbone/Époxy Et Lin/Époxy

International audience; L’effet de massification automobile qui accompagne les besoins croissants de mobilité terrestre et l’offre de nouvelles infrastructures routières qui soutient de nouvelles demandes rendent les modèles de mobilité actuels de plus en plus difficilement acceptables. En effet, les personnes souffrent de l’inconfort des villes engorgées (nuisances), de l’insécurité lors de transports du fait de défaillances techniques ou humaines, de la très grande difficulté d’optimiser ses itinéraires en fonction des horaires ou circonstances exceptionnelles (accident par exemple). Par ailleurs, la mobilité se heurte toujours aux contraintes liées aux rigidités des infrastructures compo…

The Influence of Ageing on the Impact Damage of Carbon Epoxy Composites

Abstract This study looks into the influence of ageing on the carbon epoxy composite when impact is applied. Three different stacking sequences were investigated, one sequence with the classic lay-up, whereas the other two have quasi-isotropic and quasi-homogeneous behaviour. The specimens were aged up to 2100 h (3 months) in a climatic chamber with a temperature of 70 °C and relative humidity of 85%. The mass was measured regularly during the hygrothermal ageing treatment. The mass was always measured directly after exiting the climatic chamber and it was noted that for each stacking sequence, the same regular increase in mass is observed until stabilisation. The specimens were then impact…

Effects of fiber orientation of adjacent plies on the mode I crack propagation in a carbon-epoxy laminates

Abstract The influence of ply orientation on the resistance to mode I delamination of multidirectional composite laminates can be assessed by Double Cantilever Beam (DCB) tests. However, one of the difficulties associated with such a study is the change in overall elastic parameters occurring when modifying local ply orientations. The present work uses laminates with special stacking sequences allowing for isolating the orientation parameter. Multidirectional DCB specimens were designed so as to obtain an uncoupled quasi isotropic and quasi-homogeneous elastic behavior, with the same properties for the entire laminate and the two sub laminates separated by the pre crack at mid-plane. The re…