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

2022 ◽  
Author(s):  
Jiahong Hou ◽  
Zhijun Zhang ◽  
Dong Li
Keyword(s):  
Wave Propagation ◽  
Phase Velocity ◽  
Group Velocity ◽  
Phase Structure ◽  
Single Phase ◽  
Lattice Structure ◽  
Two Dimensional ◽  
Practical Application ◽  
Dimensional Lattice ◽  
Directional Wave

Abstract 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.

Theory of 2-D complex seismic trace analysis

Geophysics ◽  
1996 ◽  
Vol 61 (1) ◽  
pp. 264-272 ◽  
Author(s):  
Arthur E. Barnes
Keyword(s):  
Phase Velocity ◽  
Group Velocity ◽  
Hilbert Transform ◽  
Instantaneous Frequency ◽  
Trace Analysis ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Two Dimensional ◽  
Instantaneous Amplitude ◽  
Dip Angle

The ideas of 1-D complex seismic trace analysis extend readily to two dimensions. Two‐dimensional instantaneous amplitude and phase are scalars, and 2-D instantaneous frequency and bandwidth are vectors perpendicular to local wavefronts, each defined by a magnitude and a dip angle. The two independent measures of instantaneous dip correspond to instantaneous apparent phase velocity and group velocity. Instantaneous phase dips are aliased for steep reflection dips following the same rule that governs the aliasing of 2-D sinusoids in f-k space. Two‐dimensional frequency and bandwidth are appropriate for migrated data, whereas 1-D frequency and bandwidth are appropriate for unmigrated data. The 2-D Hilbert transform and 2-D complex trace attributes can be efficiently computed with little more effort than their 1-D counterparts. In three dimensions, amplitude and phase remain scalars, but frequency and bandwidth are 3-D vectors with magnitude, dip angle, and azimuth.

scholarly journals Loop-TNR analysis of CP(1) model with theta term

2018 ◽  
Vol 175 ◽  
pp. 11015
Author(s):  
Hikaru Kawauchi ◽  
Shinji Takeda
Keyword(s):  
Renormalization Group ◽  
Phase Structure ◽  
Two Dimensional ◽  
Dimensional Lattice ◽  
Tensor Networks ◽  
Tensor Network ◽  
Network Methods ◽  
Renormalization Method ◽  
Future Work

The phase structure of the two dimensional lattice CP(1) model in the presence of the θ term is analyzed by tensor network methods. The tensor renormalization group, which is a standard renormalization method of tensor networks, is used for the regions θ = 0 and θ ≠ 0. Loop-TNR, which is more suitable for the analysis of near criticality, is also implemented for the region θ = 0. The application of Loop-TNR for the region θ ≠ 0 is left for future work.

scholarly journals Nonreciprocal and Directional Wave Propagation in a Two-Dimensional Lattice With Bilinear Properties

2021 ◽  
Author(s):  
Zhaocheng Lu ◽  
Andrew Norris
Keyword(s):  
Wave Propagation ◽  
Wave Motion ◽  
Signal Transmission ◽  
Two Dimensional ◽  
Direct Path ◽  
Direct Wave ◽  
Spatial Asymmetry ◽  
Starting Point ◽  
2D System ◽  
Directional Wave

Abstract A passive method of realizing nonreciprocal wave propagation in a two-dimensional (2D) lattice is proposed, using bilinear springs combined with the necessary spatial asymmetry to provide a stable and strong departure from reciprocity. The bilinear property is unique among nonlinear mechanisms in that it is independent of amplitude but sensitive to the sign of the wave motion; the 2D setup allows the flexibility of generating spatial asymmetry at both small and large scales. The starting point is a linear 2D monatomic spring-mass lattice with strong directionally dependent wave propagation. The source and receiver are aligned so that there is virtually no direct wave transmission between them. Adding a region of bilinearity combined with spatial asymmetry that is not in the direct path between the source and receiver causes signal transmission via nonreciprocal scattering. A variety of spatially asymmetric bilinear configurations are considered, ranging from compact modulations confined within the unit cell to extended ones over the whole section, to obtain different dynamic nonreciprocal effects. Simulations illustrate how the combination of bilinearity and spatial asymmetry ensures a passive amplitude-independent nonreciprocal 2D system for a variety of different excitations.

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