Towards the conception of complex engineering meta-structures: Relaxed-micromorphic modelling of low-frequency mechanical diodes/high-frequency screens.

In this paper we show that an enriched continuum model of the micromorphic type (Relaxed Micromorphic Model) can be used to model metamaterials' response in view of their use for meta-structural design. We focus on the fact that the reduced model's structure, coupled with the introduction of well-posed interface conditions, allows us to easily test different combinations of metamaterials' and classical-materials bricks, so that we can eventually end-up with the conception of a meta-structure acting as a mechanical diode for low/medium frequencies and as a total screen for higher frequencies. Thanks to the reduced model's structure, we are also able to optimize this meta-structure so that the diode-behaviour is enhanced for both "pressure" and "shear" incident waves and for all possible angles of incidence. • The importance of disposing of a reduced model to enable the effective use of metamaterials in meta-structural design. • An enriched continuum model of the micromorphic type can be effectively used to model metamaterials' response, even for specimens of finite size. • The reduced model's structure, coupled with the introduction of well-posed interface conditions allows us to unveil the response of meta-structures combining metamaterials and classical-materials bricks. • The conception of a simple metamaterial/classical-material structure that acts as a mechanical diode for low/medium frequencies and as a total screen for higher frequencies. [ABSTRACT FROM AUTHOR]