Christophe Poilâne

Bio: Christophe Poilâne is an academic researcher from University of Caen Lower Normandy. The author has contributed to research in topics: Epoxy & Ultimate tensile strength. The author has an hindex of 13, co-authored 36 publications receiving 1039 citations. Previous affiliations of Christophe Poilâne include Centre national de la recherche scientifique & École nationale supérieure d'ingénieurs du Mans.

Influence of hygrothermal ageing on the damage mechanisms of flax-fibre reinforced epoxy composite

Abstract: This paper describes the influence of hygrothermal ageing on mechanical properties and damage behaviour of quasi-unidirectional flax-fibre reinforced epoxy (FFRE) composite. The evolution of water absorption for FFRE composite appears to be Fickian and the kinetics parameters are influenced by the temperature variation. Young’s modulus and tensile strength are clearly affected by the hygrothermal ageing because a significant reduction in Young’s modulus is shown while tensile strength decreases much less for water-saturated composites. The decrease of both properties could be explained by a reorientation of flax microfibrils and the plasticiser effect of water on the matrix, which are both stimulated by moisture absorption. Acoustic emissions analysis combined with scanning electron microscopy enabled investigating the effects of hygrothermal ageing on the process of degradation of flax-fibre composite.

Assessment of Digital Image Correlation Measurement Accuracy in the Ultimate Error Regime: Main Results of a Collaborative Benchmark

Abstract: We report on the main results of a collaborative work devoted to the study of the uncertainties associated with Digital image correlation techniques (DIC). More specifically, the dependence of displacement measurement uncertainties with both image characteristics and DIC parameters is emphasised. A previous work [Bornert et al. (2009) Assessment of digital image correlation measurement errors: methodology and results. Exp. Mech. 49, 353-370] dedicated to situations with spatially fluctuating displacement fields demonstrated the existence of an 'ultimate error' regime, insensitive to the mismatch between the shape function and the real displacement field. The present work is focused on this ultimate error. To ensure that there is no mismatch error, synthetic images of in-plane rigid body translation have been analysed. Several DIC softwares developed by or in use in the French community have been used to explore the effects of a large number of settings. The discrepancies between DIC evaluated displacements and prescribed ones have been statistically analysed in terms of random errors and systematic bias, in correlation with the fractional part τ of the displacement component expressed in pixels. Main results are as follows: (i) bias amplitude is almost always insensitive to subset size, (ii) standard deviation of random error increases with noise level and decreases with subset size and (iii) DIC formulations can be split up into two main families regarding bias sensitivity to noise. For the first one, bias amplitude increases with noise while it remains nearly constant for the second one. In addition, for the first family, a strong dependence of random error with τ is observed for noisy images.

Flax fibre and its composites – A review

Abstract: In recent years, the use of flax fibres as reinforcement in composites has gained popularity due to an increasing requirement for developing sustainable materials. Flax fibres are cost-effective and offer specific mechanical properties comparable to those of glass fibres. Composites made of flax fibres with thermoplastic, thermoset, and biodegradable matrices have exhibited good mechanical properties. This review presents a summary of recent developments of flax fibre and its composites. Firstly, the fibre structure, mechanical properties, cost, the effect of various parameters (i.e. relative humidity, various physical/chemical treatments, gauge length, fibre diameter, fibre location in a stem, oleaginous, mechanical defects such as kink bands) on tensile properties of flax fibre have been reviewed. Secondly, the effect of fibre configuration (i.e. in forms of fabric, mat, yarn, roving and monofilament), manufacturing processes, fibre volume, and fibre/matrix interface parameters on the mechanical properties of flax fibre reinforced composites have been reviewed. Next, the studies of life cycle assessment and durability investigation of flax fibre reinforced composites have been reviewed.

Carbon nanotube-based hierarchical composites: a review

Abstract: The introduction of carbon nanotubes (CNTs) into conventional fibre-reinforced polymer composites creates a hierarchical reinforcement structure and can significantly improve composite performance. This paper reviews the progress to date towards the creation of fibre reinforced (hierarchical) nanocomposites and assesses the potential for a new generation of advanced multifunctional materials. Two alternative strategies for forming CNT-based hierarchical composites are contrasted, the dispersion of CNTs into the composite matrix and their direct attachment onto the primary fibre surface. The implications of each approach for composite processing and performance are discussed, along with a summary of the measured improvements in the mechanical, electrical and thermal properties of the resulting hierarchical composites.