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Author : C. Baley
Results 1 - 4 of 4
Long Term Immersion in Natural Seawater of Flax / Biocomposite
The present article gives information on 2 years seawater aging effect on injected flax/PLA biocomposite. Biocomposite suffer from relatively high moisture absorption which is controlled by vegetal fibre. Simple rule of mixture allows for
flax fibre the determination of a weight gain at saturation around 12% which is close to already published values. Bundles of fibres and especially middle lamellae influence water uptake. Water alters biocomposites, and flax fibres since their mechanical properties are reduced (Young modulus and tensile strength) with aging. Linear relationship is observed between water uptake and loss of mechanical properties. Load-unload cycles highlight damage occuring earlier as biocomposite undergo aging. These damages can be induced by fibre degradation and washing out of soluble components especially the fibre bundles cement, by debonding of fibre bundles linked to their swelling.
Study of the Influence of Singularities Created by Automated Fiber Placement on the Performance of Composite Materials for Naval Structures
The Automated Fiber Placement (AFP) process shows great potential for efficient production of large composite materials structures, in the construction of racing yachts. However, during the manufacturing of complex shapes, unavoidable singularities are induced on the entire structure manufactured. The lack of knowledge concerning the influence of these defects on the performance of composite materials led us to study the effects of two main singularities, the overlap and the gap. Ultrasound inspection and Scanning Electronic Microscopy have been performed to compare the microstructures of a plate without defects with plates containing these singularities. This study also compared the mechanical properties of a plate made by manual layup with those of a plate made by automated layup, by tensile tests on carbon / epoxy specimens.
Glass fibre reinforced thermoset composites are widely used in marine applications, even though they raise a number of
health and environmental questions (e.g. emission of volatile organic compounds VOC), and offer very few solutions at
the end of their life. One alternative is natural fibre reinforced biopolymer composites called biocomposites. Indeed
these are subject to increasing attention because of their good mechanical properties and total biodegradability. The aim
of this study is to investigate the influence of processing on the properties of biocomposites and then to examine their
durability in the marine environment. Unreinforced PLLA (Poly(L-Lactic acid)), and injected and film stacked flax
composites with the same PLLA matrix have been studied. All the samples were aged in seawater at different
temperatures in order to accelerate hygrothermal aging. The evolution of physico-chemical behaviour has been followed
by weight measurements, GPC and tensile testing, completed by SEM analysis of fractured specimens.
Influence of Epoxy Curing Cycle on Microdamage. Comparison Between Glass/Epoxy and Carbon/Epoxy Using Multiscale Tests.
The need to improve performance of marine composites requires a better understanding of the multi scale
phenomena. The influence of the cure cycle on the bulk and surface properties of the matrix resin, and of
composites based on epoxy resins reinforced with glass fibres has been already studied. It was shown that the
increase in interfacial shear strength and interlaminar shear strength increased with cure temperature. The aim of
the present study is to continue this work by comparing the influence of curing cycle on glass/epoxy with
carbon/epoxy. The relation between micro and macro properties is studied by:
• microbond test for the interfacial shear strength.
• Off axis tensile test (±45°) for the intralaminar and interlaminar shear stress