The mechanical behavior of woven fibrous media is of high interest nowadays, due to their increasing use in various contexts, according to their very interersting properties: low weight, important gain of machining time for large scale productions, mighty saving of labour time, materials and energy, better distribution of efforts, important mobility of the dry fabric, increased mechanical performances, good chemical stability, resistance to corrosion. Those advantages justify the use of textiles for products with a high added value, especially in aeronautics, an area whitnessing a strong increase of the developement of composites with a thick reinforcement with a 3D architecture. SNECMA has developed a technology of gas turbine engine fan blade made of a composite material with a 3D woven reinforcement, which constitutes by itself a technological breakthrough. The orientation of fibers in the three directions of space gives this material a very good resistance to impact in comparison to solutions based on classical composites. The methodology implemented in this project aims at improving the quantitative understanding of the deformation mechanisms of 3D interlocks, in order to increase their service performances in a context of lightening of strucutres. This constitutes a major scientific and technological lock considering economic issues. Despite many attempts to model the effective behavior, there is up to now no satisfactory approach able to efficiently predict the most important aspects of the deformation of 3D wovens, and to predict the macroscopic mechanical response of the structure in a dry or preimpregnated state, from the knowledge of the behavior of fibres or complex yarns at the smaller scales. Thanks to the development of multiscale simulation techniques and imaging techniques at very fine scales such as microtomography X, it becomes possible to investigate the mechanical behavior of fibrous media at the level of fiber interactions, which opens new roads for the exploration and understanding of phenomena occurring at those scales, and especially to elaborate and identify models at intermediate scales, which is essential to predict the macroscopic behavior. The principal objecitve of the project is to build multiscale models and constitutive laws of 3D weavings, in order to solve the problems of lightening and increase of performances, leading to the search of products with low weight and optimal performances. Those models shall incorporate the fine informations related to the elementary constituents (fibres and yarns) and their muutal interactions (contact, friction), which shall be characterized by appropriate techniques. The experimental and numerical analyses shall provide criteria for the choice of the 3D architecture of weavings according to performance indicators accounting for phenomena charactérizd and modeled at the smallest scales. The identification of the principal representative phenomena, the search of relevant variables to quantify theml, are central and open questions at the interface between scales. The elaboration of predictive models will allow to evaluate the impact of the parameters of the elaborated products on their mechanical functionalities, and to optimize the criteria for the choice of 3D weavings. The principal objective at the ultimate scale is the optimization of the shape forming of 3D textiles thanks to experimental, theoretical and numerical methods.

FRAISE project intends to optimize energy conversion through falling-film absorption processes. Its main technological outcome is the development of innovative concepts for the design of efficient desorbers, which represents the bottleneck for the conception of new compact absorption machines adapted to automotive air-conditioning, and more generally to the design of efficient heat pumps, chillers and recovery systems to limit energy waste. The project focuses on the automotive application for which compactness is crucial. Yet, the investigated design solutions will benefit to the development of compact absorption machines adapted to abundant low-grade temperature sources (industrial waste, marine transports) and renewable energies (solar cooling, domestic heating). Desorbers are key elements of the absorption machines where coupled heat and mass transfer occur. The correct sizing and the compactness of these components represent the principal challenges to the aimed technical application. We propose to develop new concepts of desorbers using plate exchangers with falling films, which have the advantage to be easily operated in vacuum conditions as required whenever low-temperature heat sources are considered. In this project, we propose to optimize and control the wavy motion of a falling film in order to intensify heat and mass transfers across the film. Indeed, it is known that the mixing and surface renewal mechanisms generated by surface waves may enhance heat and mass transfer rates several folds. This project is thus devoted to the wavy regime that mostly develops at moderate Reynolds numbers. Passive control by means of wall corrugations will be considered and tested under external vibrations. The design of new strategies of transfer intensification requires (i) to understand how the wavy dynamics is affected by the coupling with the transfer due to the induced variations of physical properties at the free surface, (ii) to identify the most efficient wavy structures and their optimum dynamics (rates of creation and merging, spatial and temporal distribution etc.) to promote transfers and (iii) to propose efficient strategies to control the hydrodynamics of the flow, generate these wavy structures and their distribution in time and space and to test these strategies under external vibrations. To meet such requirements, we propose a strategy combining an advanced fundamental research effort and a latter-stage more applied study with the adaptation of a dedicated prototype of absorption machine and a test campaign on an experimental bench developed by the industrial partner. This exploratory project, oriented to fundamental research combine theoretical and numerical approaches based on direct numerical simulations (DNS), advanced shallow-water mathematical modelling and thermodynamic modelling at the component and system levels, to experimental studies using avant-garde non-intrusive optical techniques, and in particular, a two-colour Laser-Induced Fluorescence technique that will be adapted to to measure in-depth temperature gradient across the wavy film. The project will take advantage of the skills of three complementary laboratories in the field of Heat/Mass Transfer using specific non-intrusive optical techniques (LEMTA), Applied Mathematics and shallow-water approaches (LAMA/LOCIE) and Engineering with the design of absorption machines (LOCIE). The projects benefits from the involvement of the industrial partner (PSA) (two already financed test benches, one of which at PSA). The synergy between the theoretical and experimental investigations will be fostered by the proximity between two partners (LOCIE and LAMA on the same campus) and the regular meetings of the informal CNRS group GDR FILMS.

Direct borohydride fuel cells (DBFC) are a promising alternative to PEMFCs for mobile applications. They benefit from the advantages of the NaBH4 fuel (NaBH4 is easy to store and transport as a dry material, is dense in energy and can easily be fed as a stable fuel in alkaline anolyte solutions), but also from the fact it can use non-noble catalysts (cheaper and more abundant than platinum, the classical catalyst in low-temperature fuel cells). However, the anodic reaction in a DBFC (the borohydride oxidation reaction: BOR) is complex and still insufficiently mastered. In particular, the knowledge derived from lab-scale experiments (in model conditions, dilute anolyte solutions, low temperature) is insufficient to predict the behavior of DBFC systems. The MobiDiC project will provide further insights into the fundamentals of the electrochemical BOR and of the chemical BH4- catalytic decomposition in real DBFC conditions of small generators for portable applications (concentrated electrolytes, T = 10-40°C, three-dimensional porous electrodes); we will particularly focus on model surfaces of increasing complexity, mostly based on non-Pt electrocatalysts (e.g. Pd, Co, Ni), and increase our understanding of the processes involved in DBFC anodes by coupling classical electrochemical techniques and state-of-the-art in situ physico-chemical techniques. This knowledge will be strengthened by the modelling of the mechanisms of (electro)chemical reactions, the model and experiments being looped to optimize the (electro)catalysts developed in the project. Then, we will elaborate and characterize model DBFC anodes of increasing complexity using segmented fuel cells. Our strategy to optimize the fuel consumption and maximize the energy output is highly innovative. It consists of building heterogeneous electrodes, e.g. multifunctional gradient anodes, for the optimized and combined heterogeneous hydrolysis and electrooxidation of the BH4-, including by promoting the desired catalytic decomposition of BH4- into BH3OH- (the latter compound being much easier to oxidize at low potential than the former) at the inlet on one catalyst, and the valorization at low potential of this compound (and of the unavoidable molecular H2) on relevant electrocatalysts throughout the outlet. As such, the anode will bear different regions across its thickness and/or along the gas channel to complete the fuel oxidation. The unique methodology that consists in using various surfaces of increasing complexity in experimental conditions that are characteristic of real DBFC operation will enable us to bridge the fundamental and engineering approaches that are complementary, but often opposed in the literature. From this, we will propose a model of the processes at stake in 3D (practical) electrodes for the complex BOR, model that will take into account the interplay of mass-transfer of reactants and intermediates, their adsorption/desorption, as well as chemical and electrochemical reactions. The third objective of the project is to capitalize on these fundamental outcomes to build optimized electrodes for a portable DBFC demonstrator (using the relevant (electro)catalyst materials and electrode structures determined in the project), and to test their long-term operation to assess their durability, understand their degradation mechanisms and propose mitigation strategies. Lastly, a mobile DBFC demonstrator will be built and field-tests will be carried out.

The subject of this project is the 3D printing (SLS) of PA12/glass beads composite for applications in aerospace industry. The SLS process uses laser sintering of composite powder with polymer matrix containing glass beads. One of the limiting points of polymers composites for their use in aerospace systems is their durability, and more specifically their resistance to failure due to fatigue cracking. The objective of this project will focus on the study of finished products obtained by SLS of composites powders and their resistance to cracking. The objectives of this work are to understand failure mechanisms in these highly heterogeneous materials at two scales, the scale of the microsctructure and the scale of the workpiece, by combining experimental characterization of cracks networks by mechanical testing, 3D imaging by X-rays laboratory microtomography image analysis, and numerical simulations. The identified microstructural damage models will be used to construct a crack propagation model at the scale of the workpieces, and will account for specificities related to the material and the process: the highly heterogeneous nature of the microstructure and its strong anisotropy due to the layered structure obtained by SLS. Then, it will be used to optimize the process parameters and the shapes of products in the design step. Up to now, the damage mechanisms in compounds obtained by SLS 3D printing are not very well understood, even less for products obtained from composite powders. The objectives imply several challenges related to the numerical simulation of complex crack networks in highly heterogeneous materials, the detection of micro cracks by 3D imagery imaging within combined with in situ mechanical testing, the modelling of damage and its identification at both micro and macro scales. The mechanical parameters, including the damage ones, will be characterized at the micro and macro scales by approaches combining tomography within microstructures (damage at the interfaces, damage related to the layered structure of the material) or at the scale of the workpiece, and numerical simulations through inverse approaches. The studied material is obtained from composite powder made of a polymer matrix of PA12 and containing glass beads. The powder is then sintered by laser to obtain 3D workpieces by PRISMADD. This project will allow optimizing the process parameters of the 3D process and the geometries of the workpieces with respect to failure criteria and lightweight. A numerical simulation code working able to capture damage mechanisms at both microscopic and macroscopic scales will be developed, based on the phase field method. This technique allows modelling initiation, propagation and merging of complex 3D crack networks in heterogeneous media. The method will be extended to the behaviour related to the material, characterized by a strongly nonlinear anisotropic behaviour. The tasks will consist into: (a) developing an efficient modeling numerical framework for simulating complex networks of cracks in highly heterogeneous microstructures from voxel models such as those arising from X-rays computed micro tomography imaging (XRµCT) and at the scale of the workpieces; (b) manufacturing by SLS 3D printing samples for a set of controlled process parameters; (c) characterize the strength properties of the new manufactured materials, with both macroscopic experimental mechanical testing and imaging at microscale, based on in situ mechanical testing in imaging devices and full-field kinematic measurement techniques, in 2D (optical observation) and in full 3D (XRµCT) ; (d) proposing microstructural and macroscopic damage models, identifying them by the mentioned experiments, and developing simplified multiscale damage models for bridging micro and macro damage; (e) optimizing the process parameters and the geometries of the produced workpieces with respect to the strength resistance of the produced products.

With the rapid economic and social development in the industrialised and developing countries, these communities are increasingly at the forefront of most pressing challenges. Along with the many social and economic benefits of urbanisation comes a plethora of construction and environmental problems, some of staggering proportion. One of these problems results from the evolution of the development strategies of urban areas. Indeed, contrary to what has been done for decades, there is a tendency to increase housing density in urban areas and in certain neighbourhoods. This would led to a reduction of car travel, a better use of public transportation, and thus to a reduction of pollution. In this context, one strategy is to use former industrial areas abandoned during the last 20 years to develop new housings / commercial zones. Most of these abandoned areas are situated at the edges of existing cities. Nevertheless, there are a number of issues that need to be addressed. These soils can be considered as problematic soils from a geotechnical point of view (clay, organic soils, and sediments). There is also a major environmental issue related to the quality of the subsurface environment that is being adversely affected by former industrial, municipal, mining and agricultural activities. Therefore, there is a need to develop innovative integrated and collective multidisciplinary approaches to deal with these issues at the European level, from geotechnical and geoenvironmental points of view. This will then permit a more efficient management of problematic areas both from the geoenvironmental and geotechnical points of view. The proposed research program will bring together expertise in civil engineering, geochemistry and geoenvironmental engineering to achieve these objectives. The combination of these approaches may decrease material inputs, reduce energy consumption and emissions, recover valuable by-products and minimise wastes. Therefore, there is a need to develop innovative integrated and collective multidisciplinary approaches to deal with these issues at the European level, from geotechnical and geoenvironmental points of view. The proposed research network GeoStab will bring together expertise in civil engineering, geochemistry and geoenvironmental engineering to achieve these objectives. The main objective associated to this ANR project is to foster the creation of the GeoStab network. The present members of the network established some research priorities and actions to be undertaken. To carry out its research program, the network will apply for funding at the EU level. The network will apply for an “Innovative Training Network” program (Marie Curie Action) for the call of 2015 under the coordination of Université de Lorraine. The intended form of the ITN will be a European Training Network (ETN). The creation of this research network is in line with the first societal challenges identified within the call for proposal Strategic Agenda “Efficient resource management and adaptation to climate change” and within the European Research Programme “Horizon 2020” challenge “Climate action, resource efficiency and raw materials”. This project will contribute to development of solutions for better use of raw materials from construction and demolition waste. The research will promote a network of partners in the area of soil stabilisation / solidification with a focus on sustainable methods. It would also foster the protection and sustainable management of natural resources for construction. The involvement of private partners reflects their will to increase competitiveness of soil-construction-waste treatment-related industries.