Study on bandgap and directional wave propagation of a two-dimensional lattice with nested core

This paper proposed a two-dimensional lattice structure with a nested core. The bandgap distribution and the anisotropy of phase velocity and group velocity were studied based on Bloch’s theorem and finite element method. The effects of eccentric ratio (e) and rotation angle (θ) of dual-phase structure on the bandgap distribution were investigated, and the anisotropy was studied via phase velocity and group velocity. The structure of (e) = 0.3 displayed the maximum total bandgap width. With (θ) increasing, the total bandgap widths of structures of different (e) all increased apparently and the low-frequency bandgap properties were improved. The phase velocity and group velocity of (e) = 0 displayed strong anisotropy, and the anisotropy was tuned by tuning (θ). Furthermore, the group velocity of the eighth mode displayed high directional wave propagation. For practical application, a single-phase structure was proposed and analyzed. Through additive manufacturing technology, the single-phase structure was prepared and tested by a low amplitude test setup. The experimental results displayed a good agreement with numerical results which demonstrated high directional propagation. This finding may pave the way for the practical application of the proposed lattice metamaterial in terms of wave filtering.

Surface phase structure evolution of the fcc MoC (001) surface in steam reforming atmosphere: systematic kinetic and thermodynamic investigations

The kinetic and thermodynamic aspects of the surface phase structure evolution on a fcc MoC (001) surface under H2O/H2-rich atmosphere typical in steam reforming processes were systematically studied by periodic...

Магнитные взаимодействия в структуре фазы Ауривиллиуса Bi-=SUB=-5-=/SUB=-FeTi-=SUB=-3-=/SUB=-O-=SUB=-15-=/SUB=-

This paper analysis the temperature dependence of FC and ZFC magnetization for Bi5FeTi3O15 multiferroic. It has Aurivillius four-layer phase structure. The analysis evidence on the influence of the grains of this material on its overall magnetic properties. The lack of a dramatic temperature threshold in the FC(ZFC) dependences may result in spin canting induced by the Dzyaloshinskii-Moriya interaction.