The objective of this academic proposal is to initiate a technological breakthrough by developing a new class of locally-resonant passive acoustic materials for stealth and discretion in underwater acoustics. These metamaterials are synthesized from polymer engineering and involve strong resonant multiple-scattering phenomena within the medium. The main focus of this project is the engineering of sound/noise control in marine environment for the military and civilian areas. The potentialities of these new materials are: increasing sound absorption levels; the possible reduction of thickness of anechoic or masking coatings; a good compatibility with the industrial constraints of manufacture and use. This proposal is a strongly multidisciplinary project between three CNRS laboratories from the Bordeaux campus (experts in wave-physics, soft-matter and microfluidics techniques) and a major industrial group specialized in naval defence. The academic partners have more than 7 years of joint research on the topic of metamaterials (design and manufacturing) and DCNS has recently had a CIFRE/DGA action with one of them. This long collaboration coupled with a geographical proximity and a complementarity of skills up to the industrial level, is a key point to meet the materials and acoustics challenges of the project. The materials challenge. These inclusion-type materials will incorporate sub-millimetric porous micro-resonators (made by emulsions or microfluidics) dispersed in an elastomer matrix adapted to the marine environment. Using "dense" and "resonant" inclusions must make it possible to address two major challenges for better performance of the boat-hull coverings: resistance to hydrostatic pressures during immersion; higher absorption properties due to the resonant multiple scattering. The wave physics challenge concerns the modeling and the experimental proof of the functions and characteristics sought for the synthesized subwavelength materials/structures. An important phase for ultrasonic characterization under mechanical loading of the laboratory samples will indicate the performance of the latter, in particular in terms of absorption. Contextualized experiments will be conducted to predict the anechoic/masking power of the laboratory materials, as well as acoustic measurements on metric panels placed in a pressurized tank. The industrial challenge seeks to take into account at the project outset, a number of manufacturing and use constraints that cannot be avoided by the industrial over the medium to long terms. This is why the soft-matter techniques that are easily-to-be-industrialized techniques, and the account for the hydrostatic pressure are two key elements at the heart of this exploratory-research project for naval engineering. The synoptic operational overview of PANAMA is as follows. 1. Definition of the resonant inclusion media (acoustic design) according to the targeted specifications (absorption level, frequency range, static/dynamic impedance, static loading). 2. Chemistry and synthesis of porous micro-resonators according to certain criteria: size, shape, calibration, controlled polydispersity, mass production. Incorporation of the objects in an elastomer matrix. 3. Acoustic experiments/tests (in laboratory: under loading in open air; in a conventional acoustic water-tank at atmospheric pressure; in a specialized laboratory: in a pressurized tank).

In Additive Manufacturing, Directed Energy Deposition (DED) is a promising technology that gains a growing interest in industry. An essential feature of this process its rapid fabrication capability, even for large-size parts. However, generating good material deposition trajectories remain a huge challenge that CAM software often fail to correctly deal with. The KAM4AM project aims at developing a software for DED manufacturing, based on the proven Artificial Intelligence technology of Reinforced Learning, to get a learning and adaptive CAM solution. A list of study cases from industry will help to collect the typologies of parts as well as technical and scientific issues related to DED technology. This data, combined with research cases, will enable to define the objectives and the functions of the learning environment that needs to be created. The main research challenges are (1) to design a problem-independent reward system, based on expert rules of the DED domain, (2) to develop a phenomenological model of the DED process, fast enough for allowing the numerous iterations required for the learning process. A last step consists in a thorough test of the generated trajectories, followed by the integration of these trajectories into Esprit Additive software.

The French territory presents many old historical constructions classified as building open to the public (ERP). However, this architectural heritage in masonry is fragile regarding the fire risk as the disaster that occurred on April 15 at Notre-Dame Cathedral in Paris. After a fire, the heritage value of these ERP implies that, if a doubt of structural stability exists, the question of their demolition is generally ruled out, unlike contemporary constructions without architectural value. Moreover, when these buildings are classified as Historic Monuments (HM), they must be restored and, or at least be rebuilt as it was. In any case, the question of the structure stability subjected to fire remains. However, today, knowledge and tools to assess the post-fire structural stability of a masonry building are still missing. The DEMMEFI project proposes to respond to this problem by carrying out a post-fire structural assessment methodology for complex 3D masonry structures. This methodology will first be applied to a common span of the nave of Notre-Dame cathedral and then generalized to similar masonry historic buildings with high heritage value. The methodology developed will be based on the combined and optimized use of the two main existing numerical methods: the finite element method (FEM) and the discrete element method (DEM). A so-called hybrid FEM-DEM method will be proposed in order to combine the advantages of the FEM and DEM methods in order to simulate the mechanical behavior of masonry material. The problem of mechanical stability subjected to fire action (during fire and post-fire) will be provided by a thermo-mechanical characterization of equivalent materials (limestone and lime mortar) and assemblies. Moreover, an estimation of the spatio-temporal fire action on the vault extrados will be studied. The modeling strategy will be based on a multi-scale approach using the hybrid method from the material to the structure. Finally, the relevance of stability indicators in terms of limit thrusts, limit displacements or limit stresses will be studied for each type of sub-structure of the cathedral in order to propose practical verification methods contributing to the structural assessment of these complex heterogeneous structures.

The VIVAE project focuses on power electronics (PE) systems to increase their lifetime or to preserve the functional, environmental and economic high value of their subsystems with respect to industry constraints. These considerations often delayed or even not studied due to the conservatism of industrial actors, despite the high repair potential or preservation of residual values inherent in PE systems (components or materials based on the evaluation of different end-of-life scenarios). VIVAE will propose an integrated modular re-design method for the circular economy of these products until standards proposal. It will also propose method and indicators to evaluate the residual values of the system and its subparts and components, in order to assess the best repair / recovery scenarios. Ecodesign of these new generations of EPs is coupled with the development of a proof of concept of a robot-cobot dis-assembly cell interacting with an augmented operator.

New innovative and advanced materials are needed to develop robust, safe and cost-effective infrastructures for hydrogen distribution or storage. BYRON will focus on the fabrication of multilayered structures composed of two semi-crystalline polymers that can serve as innovative materials for polymer liners (or membranes) in high-pressure gaseous systems (tubes or type IV/type V pressure vessel). The use of an innovative layer-multiplying coextrusion process, specially designed for annular geometries like tubes, will allow the creation of a high number of alternating thin layers. The impact of this nanolayering on the crystalline structure will be characterized and correlated with hydrogen permeability and mechanical properties. The behavior of the multi-nanolayered structures will be investigated in conditions close to the actual working conditions of the hydrogen storage tank (effect of hydrogen exposure and high-pressures), using specific permeation equipment and mechanical tests. In particular, failure modes and sensitivity to blistering will be thoroughly studied. Finally, a numerical diffusion model will be developed in order to assess the impact of the geometrical parameters on the permeation and used as a predictive tool for guiding the development of optimized multilayered architectures.