Search results for "Flax fibre"
showing 10 items of 13 documents
Quasi-static behaviour and damage assessment of flax/epoxy composites
2015
Experimental investigations were conducted on flax and E-glass fibres reinforced epoxy matrix composites subjected to quasi-static loadings. Flax/epoxy samples having [0]12, [90]12, [0/90]3S and [±45]3S stacking sequences, with a fibre volume fraction of 43% have been tested under tension, compression and in-plane shear loadings. Overall, the compression strength of glass/epoxy was 76% greater than for the flax/epoxy composite. The damage evolution of flax/epoxy of [0/90]3S and [±45]3S samples has been evaluated in terms of transverse crack densities with respect to the load increment. The crack density exhibited a classical “S” shaped pattern for [0/90]3S and linearly for [±45]3S specimens…
Degradation mechanisms under hydro-thermo-mechanical loads of natural fibers-reinforced biocomposites : application to the development of lightweight…
2018
With the current environmental concerns, research turns to alternative solutions to synthetic fibres. Vegetal fibers appears as good candidates, with good mechanical properties. However, their low durability is a major issue, especially when the composites are exposed to hydro(hygro)thermal loadings.The purpore of this thesis is to analyse and understand the degradation mechanisms when hydro-thermo-mechanical loadings are applied, in order to implement a predictive modelisation of the composite durability.The manufacturing process wasstudied and optimised to produce reproducible and strong composites. Two materials were produced. Their only difference is their volumetric fiber contents (37.…
Properties evolution of flax/epoxy composites under fatigue loading
2014
International audience; The tension-tension fatigue behaviour of flax fibre reinforced epoxy matrix composites have been investigated for specimens having [0]12, [90]12, [0/90]3S and [±45]3S lay-ups. The Probabilized Stress-Number of cycles (P-S-N) curves have been determined for each laminate type. The measured stress and strain data allowed to quantify the evolution of the mechanical properties, i.e. stiffness, damping and permanent strain as a function of imposed cycles. Especially, the stiffening phenomenon of flax reinforcements oriented parallel to the loading direction has been confirmed. However, due to the competition between damage development and the fibre stiffening, the increas…
Impact behaviour of flax/epoxy composite plates
2015
This paper presents an experimental investigation of the impact behaviour of flax/epoxy composite plates submitted to low-velocity transverse impact. Low energy drop-weight impact tests have been performed on two types of quasi-isotropic flax/epoxy composites, rectangularly shaped with edges lengths of 142 mm × 94 mm and 2.85 mm thick. Residual properties have been assessed by compression after impact tests. A detailed description of damage development, especially the increase of the rear face crack with respect to the impact energy is given by the microscopic observation. The influence of impact damage on the residual strength is described. A loss of 15%–30% in compression resistance was n…
Durability of flax-basalt hybrid composites for marine applications
2015
The aim of the present work is to evaluate the influence of external layers of mat basalt on the durability behaviour and performances of flax/epoxy laminates. To this scope, long-term aging tests were performed to evaluate the durability of the two different laminates in critical environmental conditions. In particular, Flax composites were constituted by ten layers of bidirectional flax fabric whereas hybrid laminates (i.e. Flax-Basalt) were produced by replacing four external layers of bidirectional flax with four layers of basalt mat. Both laminates had a total average thickness equal to 3 mm. The samples were exposed to critical environmental conditions following the ASTM B 117 standar…
Thermo-Mechanical Behaviour of Flax-Fibre Reinforced Epoxy Laminates for Industrial Applications
2015
The present work describes the experimental mechanical characterisation of a natural flax fibre reinforced epoxy polymer composite. A commercial plain woven quasi-unidirectional flax fabric with spun-twisted yarns is employed in particular, as well as unidirectional composite panels manufactured with three techniques: hand-lay-up, vacuum bagging and resin infusion. The stiffness and strength behaviours are investigated under both monotonic and low-cycle fatigue loadings. The analysed material has, in particular, shown a typical bilinear behaviour under pure traction, with a knee yield point occurring at a rather low stress value, after which the material tensile stiffness is significantly r…
Mechanical Behaviour of a Green Sandwich Made of Flax Reinforced Polymer Facings and Cork Core
2015
Abstract This work investigates the flexural behavior of a composite sandwich made of flax fibers reinforced skin facings and an agglomerated cork core, to be employed as an eco-friendly solution for the making of structural components of small sailing boats. An experimental mechanical characterization of the strength and stiffness flexural behavior of the proposed sandwich is carried out, providing a comparison of performances from three implemented assembling techniques: hand-lay-up, vacuum bagging and resin infusion. Sandwich beams have been tested under three point bending (TPB) at various span lengths. A procedure is also proposed and implemented to consider the potential influence of …
IDENTIFICATION OF THE VISCOELASTIC CONSTITUTIVE EQUATIONS OF FLAX FIBREREINFORCED LAMINATESBY VIBRATION ANALYSIS
2015
International audience; Experimental and numericalapproaches to identify the viscoelastic properties of flax fibrereinforced epoxy composite laminatesare proposed in this study. The method used consisted theidentification of the evolutions of both loss factor and stiffness through the use of the frequency responses. Several free-free symmetrically guided beams were excited on the dynamic range of 10 to 4000 Hz with a swept sine excitation focused around their first’s modes. A fractional derivative Zener model was used to predict the behaviourof on-axis ply complex moduli. The modified ply constitutive law was then implemented in Classical Lamination Theory (CLT) calculation routine. The pro…
: Effects of process conditions on mechanical and physicochemical properties of unidirectional flax/epoxy composite
2017
National audience; This study focused on the development of a manufacturing process of laminated composites made from DGEBA epoxy matrix and flax fibers. The aim is to produce a material with good and low dispersed mechanical properties. Thermocompression is the chosen manufacturing method because it enables the production of composite with high fiber content. We used separated matrix and reinforcement, and not a prepreg, to fully control each component of our composites. Several curing cycle parameters have been tested in order to optimize mechanical properties and processing time. A multi-scale analyze has been carried on the produced composites in order to quantify the range of propertie…
Strength distribution of elementary flax fibres
2005
Abstract Flax fibres, along with a number of other natural fibres, are being considered as an environmentally friendly alternative of synthetic fibres in fibre-reinforced polymer composites. A common feature of natural fibres is a much higher variability of mechanical properties. This necessitates study of the flax fibre strength distribution and efficient experimental methods for its determination. Elementary flax fibres of different gauge lengths are tested by single fibre tension in order to obtain the stress–strain response and strength and failure strain distributions. The applicability of single fibre fragmentation test for flax fibre failure strain and strength characterization is co…