The development of composites based on vegetal fibers requires a good control of manufacturing process. The aim of this work is to determine the key parameters to produce high grade flax / epoxy unidirectional laminated composite by thermocompression. So, many processing parameters have been tested and ranked according to their influence on mechanical properties. Since variability can be high for this kind of materials, statistical analyses have been used to determine if properties variations were significant or not. Among all studied parameters, the three which have been identified as first rank influence on mechanical properties are: fibers conditioning, curing pressure and exit plate temperature.

This paper presents a computational homogenisation-based technique for flexural effects in textile reinforced composite planar shells. An homogenisation procedure is used for the in-plane and the out-of-plane behaviour of three-dimensional woven composite shells taking the in-plane periodicity of the material into account while relaxing any periodicity tying in the thickness direction. Several types of damage (matrix or reinforcement cracking, delamination, ...) can appear in a composite material. In this paper, material non-linear computations are used to assess the importance of bending on the risk for delamination at the reinforcement/matrix interface. The normal and tangential stresses at the interface are computed and a simplified criterion for delamination is used for this purpose. The effect of flexural loading on the stress components responsible for a potential delamination failure mode at the interface is analysed. The values of interface stresses obtained by means of flexural homogenisation are compared with 3D homogenisation results using periodicity constraints along the thickness direction, and compared qualitatively with experimental facts available from the litterature. The importance for taking flexural effects into account properly is emphasized. * Corresponding author. Tel. : +32 2 650 27 42 ; Fax : +32 2 650 27 82 On leave at

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Although the research and development in plant fibre composites is growing rapidly, these materials still require specific considerations before being adopted by industry in structural applications. One of the main issue is related to their durability. The objective of this study is to investigate the influence of hydrothermal ageing on the fatigue behaviour of an unidirectional flax-epoxy laminated composite by implementing the fatigue tests in a water bath. Results show that while the quasi-static strength and rigidity are significantly affected by the ageing, the fatigue strength is however improved. The fatigue strength coefficient is more than two times lower after ageing, indicating a lower decrease of the maximum stress with the increasing number of cycles. After ageing, the maximum stress level for an expected lifetime of 5.3 10 6 cycles is approximately 90 MPa, which is comparable to the one of unaged specimens. It is also pointed out that the remaining quasi-static tensile properties and behaviour of the aged specimen are not significantly affected after 1.3 10 6 cycles at a stress level of 90 MPa.

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Ab s t r a c tThe stabilization of organic coatings by tin dioxide resulting in glass bottle lubrication was investigated on flat glass. The anchoring function of SnO 2 was assessed for a mixture of polyethylene and polymethylmethacrylate. Friction tests in air confirm the SnO 2 anchoring property with the maintaining of the lubricant effect due to the polymer over large sliding distances. The persistence of the polymethylmethacrylate stretching band ν C=O on significant sliding distances in infrared microscopy experiments shows that the polymer coating stabilization results from the strong adhesion of the polymer on SnO 2 . The impact of roughness and surface chemistry on the stabilization of the polymer coating was tested. The 2 suppression of the lubricant effect by surface chemistry alteration or by roughness modification of SnO 2 suggests that roughness and surface chemistry of SnO 2 are both necessary for lubrication.

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