在具有单元细胞不对称性的弹性二元原子网格中进行切断共振放置的蓝图)
Hasan B Al Ba'ba'a1,2, Hosam Yousef2, Mostafa Nouh2,3
1Department of Mechanical Engineering, Union College, Schenectady, New York 12308, USA.
JASA express letters
|July 22, 2024
概括
弹性周期格子可以过振动,但有时会在带间隙内呈现出意想不到的共振. 这项研究揭示了单元细胞不对称性和边界条件如何控制机械波器中的这些"截断共振" (TR).
科学领域:
- 固体力学 固体力学是什么
- 材料科学 材料科学 材料科学
- 声学 声学 在声学上
背景情况:
- 弹性周期格子作为机械过器起作用,通常阻断波浪在特定频率范围内传播,称为带隙.
- 在某些条件下,这些结构可以在这些带隙内意外地表现出"截断共振" (TRs),从而导致局部振动.
研究的目的:
- 研究影响弹性周期格子中断共振 (TRs) 发生和特征的因素.
- 了解单元细胞不对称,质量/刚度对比以及TRs上的边界条件的作用.
- 提供一种设计方法来控制二元原子格子中的TRs.
主要方法:
- 在具有不对称单元细胞的弹性周期格子中理论分析波传播.
- 数字模拟以模拟不同参数下的格子的行为.
- 使用两个不同的格子示例进行实验验证,以证实理论预测.
主要成果:
- 单元细胞不对称度的程度显著影响了截断共振 (TRs) 的位置和波形状.
- 单元细胞内的质量和刚度对比是调TRs的关键参数.
- 边界条件在确定带隙内TRs的表现和频率方面发挥着至关重要的作用.
结论:
- 弹性周期格子中的截断共振 (TRs) 是可控制的现象,受结构不对称性和边界条件的影响.
- 这些发现为TRs的选择性放置提供了蓝图,使得在振动过和波操纵方面有了新的应用.
- 实验验证证证实了为设计具有定制共振行为的格子而开发的方法的预测能力.
相关概念视频
Crystal Field Theory - Tetrahedral and Square Planar Complexes
41.9K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
41.9K
X-ray Crystallography
23.8K
The size of the unit cell and the arrangement of atoms in a crystal may be determined from measurements of the diffraction of X-rays by the crystal, termed X-ray crystallography.
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...
23.8K
Resonance and Hybrid Structures
16.8K
According to the theory of resonance, if two or more Lewis structures with the same arrangement of atoms can be written for a molecule, ion, or radical, the actual distribution of electrons is an average of that shown by the various Lewis structures.
Resonance Structures and Resonance Hybrids
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N–O and N=O bonds.
Resonance Structures and Resonance Hybrids
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N–O and N=O bonds.
16.8K
VSEPR Theory and the Effect of Lone Pairs
42.0K
Effect of Lone Pairs of Electrons on Molecule Geometry
42.0K
Predicting Molecular Geometry
34.2K
VSEPR Theory for Determination of Electron Pair Geometries
34.2K
Lattice Centering and Coordination Number
9.6K
The structure of a crystalline solid, whether a metal or not, is best described by considering its simplest repeating unit, which is referred to as its unit cell. The unit cell consists of lattice points that represent the locations of atoms or ions. The entire structure then consists of this unit cell repeating in three dimensions. The three different types of unit cells present in the cubic lattice are illustrated in Figure 1.
Types of Unit Cells
Imagine taking a large number of identical...
Types of Unit Cells
Imagine taking a large number of identical...
9.6K


