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International audience; Wood is a complex cellular material because of its heterogeneity and variability. The first level of variability is that of the species, which controls the organization of the woody plane, which is specific to it. But within the same species, with the same genetic baggage, each tree has its own mode of growth, of wood formation, which are then strongly dependent on the region, the plot, in which it develops but also on the local environment of the individual. Finally, each year, each season imposes its own environmental conditions of growth which will modulate the biological processes. In addition, there are the local specificities of the wood linked to particular developments such as knots, the presence of reaction wood, etc.But, finally, even among those who work with wood on a daily basis, few have the opportunity to spend hours under a microscope to appreciate all this complexity and diversity of structures. And yet, many teachers, in high school, university or in a wood science engineering school, wish to have their students observe these fascinating structures.There is now a theoretically simple solution, a little more complex to implement, which makes it possible to put in the hands of all, an object, exact copy of an anatomical structure of wood in 3D.; Le bois est un matériau cellulaire complexe par son hétérogénéité et sa variabilité. Le premier niveau de variabilité est celui de l’espèce, laquelle pilote l’organisation du plan ligneux, qui lui est spécifique. Mais au sein d’une même espèce, au même bagage génétique, chaque arbre a son propre mode de croissance, de formation du bois, lesquels sont alors fortement dépendant de la région, de la placette, dans laquelle il se développe mais aussi de l’environnement local de l’individu. Enfin, chaque année, chaque saison impose ses conditions environnementales de croissance qui vont moduler les processus biologiques. A cela se rajoutent les spécificités locales du bois liées à des développements particuliers tels que les noeuds, la présence de bois de réaction, etc.Mais, finalement, même parmi ceux qui travaillent le bois quotidiennement, peu sont ceux qui ont l’occasion de passer des heures sous un microscope pour apprécier toute cette complexité et cette diversité de structures. Et nombreux sont pourtant les enseignants, en lycée, à l’université, dans une école d’ingénieur de sciences du bois, qui souhaitent faire observer ces fascinantes structures à leurs élèves.Il existe maintenant une solution théoriquement simple, un peu plus complexe à mettre en oeuvre, qui permet de mettre dans les mains de tous, un objet, copie conforme d’une structure anatomique de bois en 3D.

This paper presents a monolithic bistable micro-actuator with stroke reducing structure. A single pre-shaped beam was chosen as the bistable element. To constraint the rotation of the central point of the beam and get more precise output, two kinds of stroke reducing structures were designed and monolithically integrated into the actuator. The first design is purely based on flexible hinges. To decrease the dimension of the stroke reducing structure and maintain the output at the same order, a second hybrid stroke reducing structure integrated micro-actuator using flexible hinges and deflected beams was designed. Both devices were fabricated by laser machining of medium density fiberboard material. Outputs of the bistable micro-actuator before and after the reducing structure were measured by fiber optic distance sensor. The bistability was experimentally characterized. The output stroke before and after reduction for the first reducing structure are 2.38mm and 0.79μm. The outputs stroke before and after reduction for the second hybrid reducing structure are 2.38mm and 0.99μm.Copyright © 2014 by ASME

In vitro experimental simulations of blood fluid in carotid artery require ideal phantoms that are as precise as possible. The purpose of this work is to demonstrate a method for carotid phantom fabrication by rapid prototyping technique (RP). By using 3D reconstructed projection of the 3D time-of-flight (TOF) Magnetic Resonance Imaging (MRI) sequence, a 12.5 cm multi-dimensional spatial structure of a carotid artery has been set up. Y-shaped and patient specific models have been generated respectively using silicone elastomer, which has a high resilience and a good tensile strength. The final patient specific model has internal carotid artery (ICA) with a highly spiraling siphon and an external carotid artery (ECA). Elastic properties of carotid walls have also been evaluated by Young's elastic modulus test and dynamic behaviors in optical and echography simulation experiments.