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Composite materials with complex internal microstructures, such as the flax nonwoven bio-composite studied in this work, require advanced numerical models in order to predict their mechanical performance. Otherwise, the micro-structural interactions that take place between their components makes very difficult to obtain their mechanical properties and failure mechanisms. This paper presents a novel methodology that couples two homogenization formulations: a phenomenological one, the serial-parallel mixing theory; and a numerical multiscale procedure. The resulting methodology has a minimal computational cost, while it is capable to account for the different interactions that take place among the composite constituents. With the proposed approach, it is possible to characterize the mechanical response of nonwoven composites and to predict their structural failure. The methodology developed is applied to a flax nonwoven biocomposite manufactured and tested by the German Aerospace Center (DLR). The good results obtained from the simulation, when compared with the experimental values, allow considering the proposed procedure an excellent approach for the analysis of large structures made with complex microstructures, such as nonwoven biocomposites.

The chief panel of the decorated cave of Mayenne-Sciences is often mentioned in scientific literature, but il is generally truncated : only the horse and mammoth couple facing each other is considerated. In fact, there are no less than seven representations on this panel (five figures : four horses, a mammoth, and two signs : an ovaliezd triangle and an angular sign) as well as one red palmar print-all of them placed by the Paleolithic man in order to fit in with the reliefs and volumes of the wall. A thorough study with assorted experimentation shows that we have here an authentic pyramidal composition probably realized in a very short lapse of time. Moreover, the position of the panel at the entrance of Roger Bouillon's hall in relation with the other decorated panels in the same sector reveals the ostentatious intention of the paleolithics to give this panel a spectacular caracter wich is to put in relation with the parietal apparatus and the symbolical constructions of the cave; Le panneau principal de la grotte ornée Mayenne-Sciences (Thorigné en Charnie, Mayenne) est souvent cité dans la littérature scientifique, mais sous la forme tronquée du couple Cheval-Mammouth affrontés. Or, ce ne sont pas moins de sept représentations (cinq figures : quatre équidés, un Mammouth, et deux signes : un triangle ovalisé et un signe angulaire) ainsi qu'une empreinte palmaire rouge qui ont été apposées sur cette paroi par les Paléolithiques et cadrées précisément sur les reliefs et les volumes naturels. Une étude approfondie assortie d'expérimentations démontre qu'il s'agit d'une véritable composition pyramidale, réalisée sans doute en très peu de temps. Par ailleurs, la position du panneau juste devant l'entrée de la salle Roger Bouillon, et ses rapports avec les autres parois ornées du même secteur trahissent la volonté affichée par les Paléolithiques de lui donner un caractère spectaculaire, à mettre en rapport avec le dispositif pariétal et les constructions symboliques de la cavité.