This project is devoted to the low-frequency (LF) vibration analysis of dynamical structures having a high modal density in the LF band. The increasing complexity of dynamical structures in many industrial fields (automotive, aerospace…) induces an increase of the LF modal density and requires new predictive and efficient tools for the analysis of their complex dynamical behavior. The frequency spectrum of such structures is characterized by the presence of well separated global elastic modes which are coupled with a large number of local elastic modes in this LF band. Therefore, the classical modal analysis, which is known to be efficient for the case of well-separated resonances is no longer adapted in the investigated case. Furthermore, the global elastic modes cannot easily be separated from the local elastic modes. Indeed, due to the coupling between global elastic modes and local elastic modes, the deformations related to global elastic modes include some local contributions. In the same way, the deformations related to local elastic modes include global contributions. Thus, there are no efficient method which can be used to select the global elastic modes and the local elastic modes. In addition, although the Reduced-Order Model (ROM) must be constructed with respect to the global elastic modes, it must have the capability to predict correctly the dynamical behavior of the structure in this LF range. Since there are local elastic modes in the LF range, a part of the mechanical energy is transferred from the global elastic modes to the local elastic modes. These local modes store this energy and then induce an apparent damping at the resonances associated with the global elastic modes. There are three objectives in this project: (1) the first objective concerns the construction of a robust ROM by using a basis which is constituted of global modes and which is able to take into account the effects of the local displacements. To achieve this objective we propose to use a recent method which allows the extraction of a basis of global displacements and a basis of local displacements by solving two separated eigenvalue problems. The reduced modeling of the local contributions is the main issue for which this project aims to provide a solution. (2) The second objective is to construct ROMs in the context of slender complex dynamical structures which are characterized by a high modal density of local elastic modes in the LF band. Usually, the industry uses equivalent beam models (for which the validity is generally limited to the first resonances) to analyze this type of structure. We propose here to directly extract beam-like vectors in order to construct a ROM, which remains predictive in a large frequency domain. (3) The third objective concerns the dynamical analysis of non-linear structures (large deformations). The use of the modal analysis method to reduce the non-linear equations is prohibitive when the modal density is too high. We propose here to construct a ROM by using a global displacement basis and if needed by taking into account the effect of the local displacements. These three objectives would be achieved through: - Theoretical developments. - Experimental validations on a simple structure. - Several industrial applications. Concerning the final phase, the first industrial application concerns the construction of an efficient ROM of an automotive vehicle in collaboration with PSA Peugeot-Citroën. The second one concerns an application for the fuel assembly of a Pressurized Water Reactor in collaboration with EDF R&D. These researches aim at removing methodological locks and at providing non-intrusive methods directly usable by the involved engineers.

New constraints on energy consumption impose a strong research effort in order to develop new materials, less energy-consuming during their production, energy-saving during their use, and more efficient in recycling processes. The incorporation of air into conventional materials appears to be a simple and efficient answer to these new constraints, in every stage of the material life, from the production stage to its use as thermal insulation material in buildings. This proposal concerns issues for aerated materials known as Particulate Aerated Materials (PAM), elaborated from granular pastes, such as cementitious and plaster pastes. The potential of development of these MAP is huge, especially in the field of the thermal renovation of buildings, because contrary to the nowadays used organic foams, these materials are incombustible and can be directly produced on construction site. Nevertheless, in order to increase their thermal performance at a level comparable to that of organic foams, important research effort must be undertaken in order to increase as much as possible the fraction of incorporated air, and so increase the energy benefits which we have just recalled. So, from slightly aerated materials, they are called to become foamy materials. This transition is under way in building materials companies, but it is nowadays hindered by several major scientific challenges that must be overcome to develop this class of new materials in an optimum way. This proposal aims at overcoming a decisive stage in the understanding and the development of the existing PAM. We like to elaborate model systems for which it is possible to control finely all parameters influencing their properties. These systems will allow us to study in a parametric manner the properties of solidified and non-solidified PAM. The most ambitious objective is to develop one or several functions of industrial interest (thermal, acoustical) without degrading the mechanical resistance of the material. The morphological evolution of these systems between the instant of their generation and their hardening, which poses serious difficulties in their elaboration nowadays, will be also studied to resolve the numerous issues encountered for this class of materials. This multidisciplinary proposal gathers academic and industrial partners with supplementary competences, covering all theoretical and experimental aspects in physics and chemical physics of cellular materials, in mechanics, in heat science and in acoustics. Dedicated work will be simultaneously devoted to model systems, allowing for a complete experimental study to be undertaken on problems of industrial interest, as well as a rigorous comparison of results obtained with theoretical predictions – also developed as part of this proposal. The optimization of industrial materials, such as foamed concrete, is also planned.

This proposal is concerned with the development of novel methodologies (including identification and validation strategies), stochastic representations and numerical methods in stochastic micromechanical modeling of nonlinear microstructures and imperfect interfaces. For the sake of feasibility, the applications will specifically focus on the modeling of hyperelastic microstructures and materials exhibiting surface effects and containing nano-inhomogeneities (such as nanoreinforcements and nanopores). For the case of nonlinear microstructures, the project aims at developing relevant probabilistic models for quantities of interests at both the microscale and mesoscale. The consideration of the latter turns out to be especially suitable for random nonlinear microstructures (such as living tissues) for which the scale separation, which is usually assumed in nonlinear homogenization, cannot be stated. Random variable and random field models for strain-energy functions will be constructed by invoking the maximum entropy principle and propagated through stochastic nonlinear homogenization techniques. A complete methodology for identifying the proposed representations will be further introduced and validated on a simulated database. Concerning the imperfect interface modeling, one may note that surface effects are usually taken into account by retaining an interface model (such as the widely used membrane-type model) involving several assumptions such as those related to the mechanical description of the membrane. Such arbitrary choices certainly generate model uncertainties which may be critical while propagated to coarsest scales and which may therefore penalize the predictive capabilities of the associated multiscale approaches. In this project, we propose to tackle the issue of model uncertainties in multiscale analysis of random microstructures with nano-heterogeneities by constructing nonparametric probabilistic representations for the homogenized properties. A complementary aspect is the construction of robust random generators, able to simulate random variables taking their values in given subspaces defined by inequality constraints and non-Gaussian random fields. Whereas such random fields can typically be generated making use of point-wise polynomial chaos expansions, the preservation of the statistical dependence is hardly achievable with the currently available techniques. In this proposal, we will subsequently address the construction of new random generators relying on the definition of families of Itô stochastic differential equations. Such generators are intended to depend on a limited number of parameters (independent of the probabilistic dimension), for which tuning guidelines will be provided. The proposed models will clearly go a step beyond what is currently done in deterministic mechanics for such materials and the expected results are in the forefront of the ongoing developments within the scopes of uncertainty quantification and material science. In addition, it worth pointing out that such theoretical derivations are absolutely required in order to support the current new developments of 3D-fields measurements and image processing at the microscale of complex materials.

The increases of population lifetime and of the accidents are the two main reasons explaining the growing interest of the scientific community in studying the osteoarticular system. Although implant and osteoarticular prostheses have been widely used in clinical routine since more than 30 year and have allowed considerable therapeutic and esthetic improvements, a lot of optimizations and developments of their performances remain to be done. In particular, dental implants are widely used for maxillofacial rehabilitation purposes, with more than 400 000 implant surgery per year in France. Many cases of failure still happen due to a bad timing in the implant loading with the prosthesis. This is due to the fact that a reliable tool capable of verifying the quality of osseointegration is still missing. Such failures induce pain, degraded mastication conditions for patients and increased costs for dental surgeons. It still remains difficult to assess the stability of a dental implant and in particular the biomechanical properties of newly formed bone tissue around the implant. OsseoWave aims at developing an evaluation tool to assess the implant stability and to follow the implant osseointegration in the osteoarticular system. The first application to be transferred will be dental implants. The MSME laboratory of University Paris-Est has developed a new method for the follow-up of implants, which is sensitive to the bone-implant interface quality, the only accurate criteria for the implant surgical success. The system uses quantitative ultrasound analysis, which is a non invasive, non radiating and relatively cheap approach. A proof of concept has been demonstrated ex vivo and in vivo, which has allowed a French and PCT patent application and a new statement of invention. We intend to keep on working on in vivo validation experiments in rabbits and to start new ones in dogs in conditions closer to the clinical situation. Moreover, the development of numerical simulation tools will lead to the optimization of the signal processing methods used in the software of the device, which will improve the overall performances of the device. An industrialization study aim at conceiving and manufacturing the final version of the device. Then, the device will be validated in the framework of a preliminary clinical study and the results will be protected through new patent applications. The present project will bring the technology to the CE certification, which is necessary in order to carry out a clinical investigation at a larger scale in the framework of a PHRC funding. The present project will pave the way towards for other applications (ankle, hip and spine among others). The team is constituted by members with complementary skills (dental surgeons experts in oral biology of bone remodeling and researchers specialized in quantitative ultrasound imaging). The project has won the concours national de Création d’entreprise in Emergence and was founded through an Aima project by the Centre Francilien pour l’Innovation and through the ANR project WaveImplant (end: September 2013). These funding have been used to realize an intellectual property study which has shown the freedom to operate of the device and a first in vivo validation. Moreover, the laboratory has been contacted by two leading companies of the dental field (Septodont and Zimmer Dental) for the realization of a dedicated study. The developed technology has been under industrial transfer since mid-2009 which will be concretized through a grant of patent and know-how license to a company to be created and already incubated. The developed technology has the potential to justify a start-up creation because of: - An important, international and growing market with no effective competitors - Multiple possible applications of the technology - Need for a technical expertise but also for a strong industrial and marketing environment

The goal of BIO ART is to develop new bio-epoxy resins from renewable resources without bisphenol A, which is toxic to humans and the environment. BIO ART’s originality comes from the synergy between green chemistry and emerging technologies (multiscale modeling and artificial neural network) and sustainable application in industry. In contrast to purely experimental or exclusively numerical approaches, BIO ART integrates simulations and experiments at length and time scales ranging from the atomistic level to the engineering scale. The proposed project will contribute to close the four knowledge gaps: i) use of exclusively bio-sourced molecules from abundant resources and natural fillers with competitive mechanical properties, ii) multiscale modeling of epoxy including its macromolecular network topology, iii) optimization of the resin formulation by an artificial neural network framework linking the chemical nature of the molecules to the mechanical properties, and iv) advanced mechanical characterization and processing of fiber-reinforced bio-composites. BIO ART’s consortium consists of four complementary Franco-German partners with recognized skills in the synthesis of bio-polymers and physicochemical characterization (ICMPE/FR), in microstructure generation and surrogate models based on artificial neural networks (MSME/FR) as well as in multiscale modeling of polymers and discrete-to-continuum coupling methods (FAU/DE), and in composite processing and advanced mechanical characterization (UBT/DE). The scientific program is divided into 5 work packages: WP1: Synthesis of bio-sourced epoxy, WP2: Characterization of bio-sourced epoxy, WP3: Multiscale modeling, WP4: Optimization of bio-sourced epoxy formulation by artificial neural network, and WP5: Composite processing and mechanical characterization. The work packages are defined in a way that they can be completed in 3 years by 3 collaborating doctoral researchers, one for experimental part and two for the numerical part. A technician will support the experimental PhD candidate as regards the processing and characterization of the obtained materials. Beyond them, BIO ART’s consortium, which is a well-balanced composition of early career and senior scientists, will actively contribute to achieve the project’s milestones. BIO ART’s methods are up-to-date, are based on recently published results, and benefit from the strong synergies with current projects of the project partners. In particular, the experimental and numerical methods will range from the atomistic scale (molecular structure, synthesis of constituents, molecular dynamics simulations), to the mesoscale (curing process, network characterization, network model), and to the macroscale (fracture properties, continuum mechanical simulations). This methodology will focus on the investigation of the relationship between the structure and the multiscale properties of the obtained materials. This approach will synergistically combine modelling with experimental characterizations, which will allow to address the scientific issues of this project. This multidisciplinary scientific approach will allow BIO ART to respond to a current crucial societal issue, i.e. biosourced polymer materials from circular bio-economy, aimed for sustainable development applications