The MUJU (Multimaterial mUltiphysics Junction) project aims to develop specific multimaterial junctions with increased thermal and electrical continuity for composite materials mechanical assemblies. The proposed junctions will allow developing and exploiting the multifunctional potential of reinforcing fibers present in composite materials which offer very good multiphysical properties. Up to date, the anisotropy of composite materials, especially their bad properties in the transverse direction respect to fibers, is the reason why these potential can not be fully exploited. This constitutes the main impediment in the introduction of composite materials in thermal or electrical applications and is particularly true when an assembly is to be done. Local heating of junctions derived from heat flow or electrical current flow through the assembly can produce irreversible damage (possibly burning) on the composite elements of the junction. Currently, monolithic metallic materials are used to face those multyphysics applications. The baseline which will guide out the proposed MUJU’s developments, in terms of mass, mechanical, thermal and electrical properties will be aluminum alloys used currently in the aerospace industry. MUJU’s project proposes an original approach based on multimaterial and multiscale design to develop plates (thin shells) with their associated local junction system. The multimaterial approach is a key point because the proposed junction solutions are based on the assembly of reinforcing fibers, polymeric resins and metallic insertions. The reinforcing fibers develop optimal required physical properties (excellent thermal conduction, sufficient electrical conductivity and excellent mechanical properties). The resins are the necessary link to provide mechanical stability of the structure but they contribute with bad thermal and electrical properties performing as an isolator and producing bad macroscopic behavior in the transverse direction respect to fibers. Metallic insertions contribute with their isotropic morphology, providing good thermal and excellent electrical properties but their high density penalizes overall mass. The multiscale approach is fundamental in order to guarantee the correct behavior of the interfaces present in the multimaterial proposed for the junctions. At a sub-millimeter and micrometer range we propose to work on the architecture of the multimaterial that would better suit the set of multi-physic constraints together with the design of the geometry of the metallic insertions. The aim is to minimize the mean distance between the fibers and the metallic insertions. At a nanometric scale we propose to treat locally the fibers and the metallic insertions in order to provide continuity from the tiniest scale possible to boost overall macroscopic properties. There are several aimed applications of MUJU project. At a first stage, we focus on the mechanical elements that participate to the packaging of on-board electronic systems and that provide thermal dissipation capabilities together with electrical mass grounding, bonding and EMI protection. The methodology and solutions developed shall allow to attain 20% to 40% weight savings on on-board electronic packaging and fulfilling the above mentioned thermal, electrical, EMI and mechanical functions. At a second stage, the solutions developed shall be applied to primary or secondary structure aerospace elements providing local zones dedicated to thermal dissipation for elements such as electric power converters or batteries, or as electrical grounding zones for electric/electronic equipment. Finally, the underlying industrial need imposes to develop a rigorous design guideline that shall capitalize the advances produced through the project providing engineers a tool to apply the developed set of technologies in their products.

The OPTISOL project aims to increase the competitiveness of solar thermal power plant by increasing the solar conversion efficiency at high temperature in particular through the implementation of combined cycles. The key component of such solar processes is the solar receiver that must delivers air in the temperature range between 700 ° C and 1100 ° C. We propose a breakthrough approach by implementing a porous structures with variable optical properties that have a selective behavior in relation to solar radiation and can thus limit the radiative losses of surfaces and increase heat transfer by convection. The proposed methodology integrates all aspects of the problem since the development of materials to the testing of solar receivers on a scale basis of 5kW through the modeling of volumetric radiative properties and detailed transfer coupling. The target is to increase thermal efficiency of such receptor by 10%.

Emerging MOFs super-adsorbents present advantageous adsorption capacities, up to 60% higher than those of conventional activated carbons or zeolites. Consequently, for the two worldwide major issues of industry decarbonation and energy transition, those materials offer great perspectives such as CO2 capture and energetic gas (H2, CH4, NG) storage. Nevertheless, those enhanced storage capacities are related to equally important inhibiting thermal effects (exothermic under adsorption, endothermic under desorption). At industrial scale, those thermal effects would induce major reduction in performances (capacity, selectivity and charge/discharge kinetics) even hazard issues (hot spots). Up to date, whereas the literature on MOF for gas storage or capture is plethoric, only few research efforts were devoted to the thermal management of MOF. The project is fully devoted to it, gathering a complementary consortium of partner experts on the various multidisciplinary aspects from MOF elaboration to the targeted applications. We will especially focus our work on the development of MOF/graphite conducting composites, which will for example be of interest for isothermal-diabatic applications such as CO2 cpture in TSA processes. The 4 years research effort is shared between MOF and related composites elaborations and characterizations, comparison between raw MOF and composites, assessments of applications related performances, multi-scale modelisations (from composite material to industrial process) and lab-scale pilot tests. For all steps, from academic research to industrial concerns, environmental impacts are continuously considered.

Additive manufacturing processes have opened the doors for the conception of high temperature energy systems (volumetric solar receivers, gas-to-gas heat exchangers, radiant tube inserts) based on highly porous ceramics with 3D tailored geometries. New architectures are now accessible (triply periodic minimal surfaces, hierarchical structures) but their thermal and mechanical performances remain questionable especially when they are used under harsh environment (T>1300 K, high-temperature gradient ? 500 K, high heat flux ? MW/m2). The fine control of the 3D spatial distribution of both radiative heat and fluid flows is crucial here to push back the current limitations. To make a decisive breakthrough in this topic, ORCHESTRA will gather a multidisciplinary consortium (LTeN, GeM, IFPEN, IRCER) whose objective will be to print SiC-based ceramics whose 3D architectures will be settled through advanced topology optimisation approaches, taking into account radiative transfers and all the coupled physics. A fast 3D numerical image-based pore-scale methodology under HPC environment based on voxel finite element methods will be then developed in order to finely reproduce the thermo-mechanical behaviours of the 3D architectures up to failure at high temperatures. Then the selected architectures will be elaborated by coupling the robocasting process and the polymer-derived ceramics route. In addition, new experimental (energy conversion, thermal shocks) facilities will be also implemented to determine both the thermal efficiencies and mechanical performances of the as-grown architectures. Finely, the confrontation of the numerical results with those obtained through the experimental part of OCHESTRA will allow us to define a robust methodology to design improved high temperature energy systems.

Performances achievable through the use of continuous reinforced composites are today typically acquired and demonstrated. Among these composite materials, it is generally accepted that the use of thermoplastic matrices represents a major advantage because of their low environmental impact (no solvents and no VOCs) and their good behaviour in crash stress (intrinsic ductility). However, the inability to produce parts of complex geometry at controlled cost prevents the use of composite materials for applications in medium to large series. The Project objective is to develop new materials / new processing ways for the production of composite parts based on thermoplastic polymer for the automotive market, in order to meet the demand about lighter structures which become necessary because of new environmental regulations and energy dependence problems. This weight reduction requires the development of high performances parts or component modules, compatible with the requirements of cost and mass production rate. Composite fiber thermoplastics (CFRT) is a technological response to this need, but several problems have to be solved in order to consider the use of such materials. Thus, there are currently no available materials that meet the requirements of processability / performance / cost. Among the different manufacturing processes of composite structures, the consolidation in mold at low pressure (Liquid Composite Molding) present a major interest in the production of parts with complex geometry (non-developable surfaces) with the possibility of integrated functions. The recent development of new thermoplastic polymers with low melt viscosity (based on polyamide chemistry) enables access to these new processing routes, but a number of drawbacks about both the consolidated material and the final part have to be solved. This is the case of thermal transfer, the impregnation at high rate of a given reinforcing structure (deformable perform, with variable permeability), and the control of the polymer crystallization and induced residual stresses (thermal and crystallization volumic variation). The objective of the Project is fully consistent with this approach, and its complexity and character of technological breakthrough requires the use of close collaboration between industrial skills (major Groups and SMEs) and academic experts in their field. We will focus together to : - develop base materials (compatible polymers and reinforcements, polymer viscosity, wettability, crystallinity ...); - optimize the processing conditions (LCM) at lab via an instrumented mold of simple geometry (plate) in a first time; - develop a database modeling and simulation; - validate the models on a real functional piece (3D geometry) to be simulated and processed using a LCM system design; - optimize the technical and economic performance of the developed processing way (positive cost, life cycle analysis, recycling aspect ...). The complementarity of the partners in this consortium must help to realize the breaking science and technology needed to strengthen the position of France in the field of composites by opening the way to medium / large series market.