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Les systèmes de tenségrité sont des structures spatiales formées de barres comprimées en équilibre dans un réseau de câbles tendus. Leur rigidité dépend à la fois des propriétés mécaniques des éléments et de leurs efforts internes introduits durant l'assemblage. Grâce à leurs propriétés structurales, nous répondons à la problématique de l'accessibilité à la mer en offrant une solution légère, permettant un montage/démontage aisé et respectant la loi littoral. Des plateformes de configurations variables et capables d'épouser d'une manière écologique le milieu marin sont désormais réalisables grâce à des structures de tenségrité à double nappe. Cette étude, aussi bien numérique qu'expérimentale, dévoile les différents aspects structurels et conceptuels de cette solution qui permettent de valider ses capacités mécaniques ainsi que sa faisabilité, notamment à travers la modulabilité, le pliage/déploiement et l'implantation. De l'optimisation structurale des éléments sous contrainte de légèreté et résistance, nous aborderons la conception des noeuds, composants complexes indispensables assurant la géométrie et le pliage de la structure mais aussi son interaction avec son environnement.

Tensegrity structures,which emerged in the mid-20th century in the form of sculptures,are a class of reticulated space structures composed of compressed bars maintained in equilibrium by a network of tensioned cables. Their stiffness depends both on the mechanical properties of the elements and their internal stress introduced during assembly,which is called self-stress state.They have been increasingly studied during the last few decades for civil engineering applications.Taking advantage of their promising structural properties, we respond to the challenge of accessibility to the sea with modular lightweight and transparent platforms. Variable configurations are developed to fit ecologically into the marine environment thanks to double layer tensegrity structures. Moreover, allowing easy assembly /disassembly we respect also the coastal law in France.This study, both numerical and experimental, sheds light on the different structural and conceptual aspects of this solution, thus validating its mechanical capabilities as well as its feasibility, particularly through the aspects of modularity, folding/deployment and setup.After the structural and design optimization of elements constrained by weight and stiffness, we detail the design of the nodes, which are the key components to ensure the geometry and foldability of the structure but also the interaction with the supports on the seabed and the deck.

Variable-geometry structures are useful in aerospace applications because they are deployable, from a compact configuration (launch phase) to a spread geometry (operational phase). They may also benefit from the use of flexible joints, which store elastic energy for automatic deployment. Following the development of a self-deploying antenna frame structure with scissors, the geometrical configuration of a new kind of structure, simpler, lighter, and minimizing mechanical joints between elements, is proposed in this article. This topology can form a three-dimensional structure when partially opened or a planar structure when fully deployed. The applications concern autotensioning structures such as meshed space antenna, deorbiting sails, and also solar panel support structures.

This paper presents a numerical technique to model soft particle materials in which the particles can undergo large deformations. It combines an implicit finite strain formalism of the Material Point Method and the Contact Dynamics method. In this framework, the large deformations of individual particles as well as their collective interactions are treated consistently. In order to reduce the computational cost, this method is parallelised using the Message Passing Interface (MPI) strategy. Using this approach, we investigate the uniaxial compaction of 2D packings composed of particles governed by a Neo-Hookean material behaviour. We consider compressibility rates ranging from fully compressible to incompressible particles. The packing deformation mechanism is a combination of both particle rearrangements and large deformations, and leads to high packing fractions beyond the jamming state. We show that the packing strength declines when the particle compressibility decreases, and the packing can deform considerably. We also discuss the evolution of the connectivity of the particles and particle deformation distributions in the packing.