SMART METACOMPOSITES FOR THE SYNTHESIS OF VIBROA-COUSTICAL PROPERTIES

Research activities in smart materials and structures represent a significant potential for technological innovation in mechanics and electronics. The necessity of controlling vibroacoustic behavior of industrial systems motivates a broad research effort for introducing active or passive technologies to control noise and vibrations. New processes are now available which allow active transducers and their driving electronics to be directly integrated into otherwise passive structures. This new approach could allow fine control of the material physical behavior for implementing new functional properties that do not exist in nature. In this sense, we can speak of ``'integrated distributed adaptive metacomposite''' that merges the notion of programmable materials with periodic structures and metamaterial. One of the main features associated to the periodic distribution of mechanical devices, the ability to design Bragg or resonant band gaps, is improved by using smart transducers and adaptive electronic circuits. Early developments of these technologies were based on analytical techniques; therefore many results are available for simple coupled systems (MDOF, beams, and plates). More recently, the combination of periodicity theories with the finite element method has allowed designers to handle complex geometries, smart materials and electronic components for optimizing waves diffusion in complex damped and coupled media. In this talk, after some reminders concerning historical aspects, the main methodologies for the design of periodic structures will be given, before showing two applications combining periodicity and smart structures (auxetic materials, semi-active and active strategies, waves in damped media) for vibroacoustic applications. All practical aspects will be discussed, from the numerical tools for design and optimization, to the practical implementation for experimental validation, together with robustness issues.