The objective of this project is to propose a set of tools for the design and implementation of composite structures with periodic inclusions to absorb vibration and acoustic waves. The originality of the project lies in the integrated approach that will be implemented to ensure technical feasibility and reliability of devices that will be designed. Target applications are mainly absorbing walls, with higher efficiency than conventional devices thanks to the inclusions. The structures will be developed on the basis of polymers (PU or silicone) that will be used as composite matrices in which the inclusions, potentially resonant, will create band gaps by wave interference effects. The devices will then couple the effects of band gaps to the effects of intrinsic dissipation of the materials. The materials will be used either in bulk, or porous state for applications where acoustic phenomena are predominant. For the latter category, there will be a partial controlled degassing to keep air bubbles in the material in order to generate open pores. A part of the project will be dedicated to process control development and shaping of structures based polymer, and the determination of the relationship between process parameters and mechanical properties (particularly in terms of dissipation) of the material.

The design of these structures makes use of advanced techniques for finite element modeling, including multiphysics phenomena, dissipative effects and taking into account periodicity in multidimensional space. An important part of the work will be dedicated to the elaboration and validation of these models in order to have efficient computational tools for the design, optimization and reliability analyses.

The optimization of the structures will be carried out taking into account the constraints related to manufacturing and expected performances of the system. In particular, the inclusions may be rigid (metal structure such as balls or rollers), or resonant, in order to obtain physical properties typically observed in metamaterials. The difference here concerns the fact that we are dealing with macro structures, including mechanical couplings between materials, some of them being highly damped, and multiphysical couplings. So we use the generic term metacomposites in this project.

To give a very general adaptability to the devices designed in the project, one of the tasks will be dedicated to the development of techniques that could render the system tunable or adaptive, based on shape memory polymers and electroactive polymers. The analysis of sensitivity and reliability of complex systems such as metacomposites are essential steps for their development on a large scale. It is proposed to carry out these analyses to ensure, firstly, the control of the various parameters and their impact on features of interest (vibroacoustic performances), and secondly, the quantification of reliability associated with failure modes previously identified. These tests, as the entire project, will be carried out for completeness on the various parameters involved in the design of the metacomposites, from the manufacturing issues to the final integration and in situ vibroacoustic validation.