Determination of dynamic properties of flax fibres reinforced laminate using vibration measurements

International audienceExperimental and numerical methods to identify the linear viscoelastic properties of flax fibre reinforced polymer (FFRP) composite are presented in this study. The method relies on the evolution of storage modulus and loss factor as observed through the frequency response. Free-free symmetrically guided beams were excited in the dynamic range of 10 Hz to 4 kHz with a swept sine excitation focused around their first modes. A fractional derivative Zener model has been identified to predict the complex moduli. A modified ply constitutive law has been then implemented in a classical laminates theory calculation (CLT) routine. Overall, the Zener model fitted the experimental results well. The storage modulus was not frequency dependant, while the loss factor increased with frequency and reached a maximum value for a fibre orientation of 70 degrees. The damping of FFRP was, respectively, 5 and 2 times higher than for equivalent carbon and glass fibres reinforced epoxy composites. (C) 2016 Elsevier Ltd. All rights reserved

Multi-scale modelling of heterogeneous shell structures

This paper reviews multi-scale computational homogenisation frameworks for the non-linear behaviour of heterogeneous thin planar shells. Based on a review of some of the currently available methods, a computational homogenisation scheme for shells is applied on to representative volume elements for plain weave composites. The effect of flexural loading on the potential failure modes of such materials is analysed, focusing on the reinforcement-matrix delamination mechanism. The attention is next shifted toward failure localisation in masonry unit cells. Subsequently, a recently developed computational FE 2 solution scheme accounting for damage localisation at structural scales based on RVE computations is applied. Copyright © 2011 by Institute of Fundamental Technological Research, Polish Academy of Sciences

Multi-axial testing of thick adhesive bonded joints of fibre reinforced thermoplastic polymers

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The pattern of LH secretion and the ovarian response to the 'ram effect' in the anoestrous ewe is influenced by body condition but not by short-term nutritional supplementation

Remerciements : Laboratoire Phénotypage - Endocrinologie INRA, UMR Physiologie de la Reproduction et des Comportements, Centre Val de LoireIn sheep, the ‘ram effect’ induces out-of-season fertility and good nutrition increases prolificacy. This experiment determined if fatness or short-term nutritional supplementation modified the response to the ‘ram effect’. A group of 48 Île-de-France ewes were fed diets that produced groups with body-condition scores (BCS) of >3.0 and <2.0. Within each BCS group animals were supplemented daily with 500 g of lupins from Day –5 to Day 0 (ram introduction) resulting in four groups: low BCS, supplemented (n = 7) and non-supplemented (n = 8) and high BCS, supplemented (n = 12) and non-supplemented (n = 11). The blood concentrations of glucose and insulin and the LH response to gonadotrophin-releasing hormone (GnRH) were determined. After the ‘ram effect’ the pattern of LH pulsatility, the LH surge and ovarian responses were analysed. Low BCS ewes had lower glucose and insulin (P < 0.001) and supplementation increased both (P ≤ 0.001). The increase in LH induced by GnRH was reduced in low BCS ewes (P = 0.015) but it was not affected by supplementation. Similarly, LH pulsatility was reduced in low BCS ewes (P < 0.05). The LH surge and ovarian cyclicity were not affected but the follow-up cycle was delayed (P = 0.034) and progesterone was reduced (P = 0.029) in low BCS ewes. There was an effect of BCS on ovulation rate (P < 0.05). These results show that the BCS can modify the response to the ‘ram effect’ and that supplementation has little effect on this response

Cosmic ray detectors for high schools in France

Sciences ACO is a non-profit association based in Orsay (France). It manages a "Museum of Light and Matter" visited by more than 1,000 people each year. In this unique place, scientists and cultural mediators preserve, exhibit and explain pieces of the history of science & technology, to pass on the knowledge of this heritage to the audience. The museum is located at the centre of the "LAL-LURE accelerator complex", which was awarded the "Historic Site" label by the European Physical Society last September. The main piece of Sciences ACO is indeed the "Anneau de Collisions d'Orsay" (ACO), a lepton storage ring whose operation started in 1965 and ended in 1988. ACO was first used as an electron-positron collider. It lead to important discoveries in accelerator physics and to many pioneering measurements of vector meson properties. In 1973, ACO became the first storage ring in Europe available to synchrotron light users. Ten years later, a free-electron laser was successfully operated at ACO - the second in the world, it was the first one in the visible bandwidth and the first at a storage ring. Rather than being decommissioned and disassembled like almost all accelerators in the world once they are turned off, ACO was carefully preserved by the very people who worked on it. The machine was later recognized as a French "historic monument" and the association, still very active, is now bringing three generations of scientists together. Sciences ACO visitors - among them there are many high school students and teachers - come to learn about the progress of science and the evolution of the technologies over more than four decades. As an example, a new room was recently opened in the museum to display the control room of the former LAL linear accelerator. This record of the seventies allows our guides not only to explain how this machine was operated and what its performances were, but also to shed light on the extraordinary advances of electronics and computing. Therefore, Sciences ACO is more than just a historical museum: it is a driving force for the development of outreach and pedagogical activities on the Paris Sud University campus and in the neighboring towns Moreover, real demonstration apparatuses - like the "Electrons' ronde", probably the world's smallest interactive electron storage ring model - are being designed by engineering experts from the association, while virtual visits are being developed to enrich the visitors experience. All of this has been obtained by a small group of dedicated individuals, within the limited financial resources of the association. The history, the present activity and the prospects of Sciences ACO will be presented in the talk proposed in the "Education and Outreach" ICHEP 2014 parallel session

Bending effect on the risk for delamination at the reinforcement/matrix interface of 3D woven fabric composite using a shell-like RVE

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 literature. The importance for taking flexural effects into account properly is emphasised.SCOPUS: ar.jinfo:eu-repo/semantics/publishe