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Reinforcement/matrix interaction is recognized as a key issue in polymeric composite materials. From the mechanical point of view, being the link between the fibres and the polymer, a proper load transfer is ensured only if a good enough interphase exists. This is particularly critical in carbon fibre (CF) composites since, due to the non-polar characteristics and chemical inertness of carbon, sometimes they exhibit weak interfacial adhesion. In this sense, various surface treatments for CFs are currently being investigated, in order to improve their interaction with the polymeric matrices: wet chemical or electrochemical methods, chemically or physically activated oxidation procedures, application of thin coatings and plasma treatments. This is precisely one of the challenges addressed in the MODCOMP project. This paper describes part of the work carried out within the mentioned project in order to estimate the improvement of properties that can be achieved through enhancements of the CF/epoxy interphases. The study covers both elastic engineering constants and strengths predictions, and it has been performed using finite element models of RVEs of UD fibres and introducing cohesive elements to take into account the interfacial failure mode. The results obtained allow identifying which range of CF/epoxy interphase properties enhancement should be achieved in order to get significant effects in the composites mechanical response.

International audience; This paper reports the results of an international benchmark exercise on the measurement of fibre bed compaction behaviour. The aim was to identify aspects of the test method critical to obtain reliable results and to arrive at a recommended test procedure for fibre bed compaction measurements. A glass fibre 2/2 twill weave and a biaxial (±45°) glass fibre non-crimp fabric (NCF) were tested in dry and wet conditions. All participants used the same testing procedure but were allowed to use the testing frame, the fixture and sample geometry of their choice. The results showed a large scatter in the maximum compaction stress between participants at the given target thickness, with coefficients of variation ranging from 38 % to 58 %. Statistical analysis of data indicated that wetting of the specimen significantly affected the scatter in results for the woven fabric, but not for the NCF. This is related to the fibre mobility in the architectures in both fabrics. As isolating the effect of other test parameters on the results was not possible, no statistically significant effect of other test parameters could be proven. The high sensitivity of the recorded compaction pressure near the minimum specimen thickness to changes in specimen thickness suggests that small uncertainties in thickness can result in large variations in the maximum value of the compaction stress. Hence, it is suspected that the thickness measurement technique used may have an effect on the scatter.

Although good progress was made by two international benchmark exercises on in-plane permeability, existing methods have not yet been standardized. This paper presents the results of a third benchmark exercise using in-plane permeability measurement, based on systems applying the radial unsaturated injection method. 19 participants using 20 systems characterized a non-crimp and a woven fabric at three different fiber volume contents, using a commercially available silicone oil as impregnating fluid. They followed a detailed characterization procedure and also completed a questionnaire on their set-up and analysis methods. Excluding outliers (2 of 20), the average coefficient of variation (c v ) between the participant´s results was 32% and 44% (non-crimp and woven fabric), while the average c v for individual participants was 8% and 12%, respectively. This indicates statistically significant variations between the measurement systems. Cavity deformation was identified as a major influence, besides fluid pressure/viscosity measurement, textile variations, and data analysis. Fil: May, D.. Institut Für Verbundwerkstoffe Gmbh; Alemania Fil: Aktas, A.. National Physical Laboratory; Reino Unido Fil: Advani, S.G.. University Of Delaware; Estados Unidos Fil: Berg, D. C.. Technische Universität Clausthal; Alemania Fil: Endruweit, A.. University of Nottingham; Estados Unidos. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino Unido Fil: Fauster, E.. Montanuniversitat Leoben; Austria Fil: Lomov, S. V.. Katholikie Universiteit Leuven; Bélgica Fil: Long, A.. University of Nottingham; Estados Unidos. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino Unido Fil: Mitschang, P.. Institut Für Verbundwerkstoffe Gmbh; Alemania Fil: Abaimov, S.. Skolkovo Institute Of Science And Technology; Rusia Fil: Abliz, D.. Technische Universität Clausthal; Alemania Fil: Akhatov, I.. Skolkovo Institute Of Science And Technology; Rusia Fil: Ali, M. A.. Khalifa University Of Science And Technology; Emiratos Arabes Unidos Fil: Allen, T. D.. University of Auckland; Nueva Zelanda Fil: Bickerton, S.. University of Auckland; Nueva Zelanda Fil: Bodaghi, M.. Institute Of Science And Innovation In Mechanical And Industrial; Portugal Fil: Caglar, B.. Koç Üniversitesi; Turquía Fil: Caglar, H.. Koç Üniversitesi; Turquía Fil: Chiminelli, A.. Instituto Tecnologico de Aragon; España Fil: Correia, N.. Institute Of Science And Innovation In Mechanical And Industrial; Portugal Fil: Cosson, B.. Imt Lille Douai; Francia Fil: Danzi, M.. Eth Zürich; Suiza Fil: Dittmann, J.. Universität Stuttgart; Alemania Fil: Ermanni, P.. Eth Zürich; Suiza Fil: Francucci, Gaston Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina Fil: George, A.. University Brigham Young; Estados Unidos Fil: Grishaev, V.. Skolkovo Institute Of Science And Technology; Rusia Fil: Hancioglu, M.. Koç Üniversitesi; Turquía Fil: Kabachi, M. A.. Eth Zürich; Suiza Fil: Kind, K.. Universitat Technical Zu Munich; Alemania Fil: Deléglise Lagardère, M.. Imt Lille Douai; Francia Fil: Laspalas, M.. Instituto Tecnologico de Aragon; España Fil: Lebedev, O. V.. Skolkovo Institute Of Science And Technology; Rusia Fil: Lizaranzu, M.. Instituto Tecnologico de Aragon; España Fil: Liotier, P. J.. Université de Lyon; Francia Fil: Middendorf, P.. Universität Stuttgart; Alemania Fil: Morán, J.. Universidad Nacional de Mar del Plata; Argentina Fil: Park, C. H.. Imt Lille Douai; Francia Fil: Pipes, R. B.. Purdue University; Estados Unidos Fil: Pucci, M. F.. Université de Montpellier; Austria Fil: Raynal, J.. Groupe Institut de Soudure; Francia Fil: Rodriguez, E. S.. Universidad Nacional de Mar del Plata; Argentina Fil: Schledjewski, R.. Montanuniversitat Leoben; Austria Fil: Schubnel, R.. Groupe Institut de Soudure; Francia Fil: Sharp, N.. Purdue University; Estados Unidos Fil: Sims, G.. National Physical Laboratory; Reino Unido Fil: Sozer, E. M.. Koç Üniversitesi; Turquía Fil: Sousa, P.. Katholikie Universiteit Leuven; Bélgica Fil: Thomas, J.. Khalifa University Of Science And Technology; Emiratos Arabes Unidos Fil: Umer, R.. Khalifa University Of Science And Technology; Emiratos Arabes Unidos Fil: Wijaya, W.. University of Auckland; Nueva Zelanda Fil: Willenbacher, B.. Institut Für Verbundwerkstoffe Gmbh; Alemania Fil: Yong, A.. National Physical Laboratory; Reino Unido Fil: Zaremba, S.. Universitat Technical Zu Munich; Alemania Fil: Ziegmann, G.. Technische Universität Clausthal; Alemania