Figure 3.

Dispersion relations ω=ω(k) for the transverse waves of the relaxed micromorphic model with gradient micro-inertia ${\overline{\eta }}_2=(0,2\times {10}^{-3},\hspace{0.17em}2\times {10}^{-2})$ kg m⁻¹ and η=0. Black dots indicate the dispersion relations for a first gradient model with Lamé parameters μ_macro and λ_macro and the same inertiae ρ and ${\overline{\eta }}_t$. (Online version in colour.)