Classification of non-conventional phenomena involved in meta-materials

Meta-materials have been a subject of great interest in the field of acoustic materials for several years. The term « meta » is used to emphasize that at least one non-conventional phenomenon is used. These meta-materials could also be called multiple dynamic materials. A large number of works are published every year in this field and it may be difficult to distinguish if these works present new concepts or combine several existing concepts.

This presentation attempts to synthesize the different phenomena involved in meta-materials. These non-conventional phenomena such as double porosity, multiple-scattering, acoustical resonance, permeo-elasticity will be presented and a classification of the involved effects will be drawn. In addition, it will be shown that the periodicity of the inclusions, often encountered in meta-materials, can be seen as an additional phenomenon which is not mandatory to take advantage of other phenomena. The main idea of this work is to classify the non-conventional effects in order to have a toolbox when designing an acoustical material with multiple dynamics.