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A metamaterial with five-mode material characteristics and its determination method

A metamaterial and axial direction technology, applied in the field of acoustic metamaterials, can solve the problems of unsatisfactory configuration characteristic index, weak anisotropy degree, and insufficient wide adjustment range of effective properties, etc., and achieve wide equivalent density adjustment range, The effect of wide modulus adjustment range and wide frequency application range

Active Publication Date: 2016-09-14
BEIJING INSTITUTE OF TECHNOLOGYGY
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0009] In view of the defects that the existing five-mode materials have unsatisfactory configuration characteristics, the degree of anisotropy is not strong, and the effective property adjustment range is not wide enough, one of the purposes of the present invention is to provide a metamaterial with the characteristics of five-mode materials. The acoustic characteristics of metamaterials are closer to ideal five-mode materials, which is conducive to precise control of acoustic wave propagation, and at the same time has a greater degree of anisotropy adjustment and a wider range of macroscopically effective properties (modulus and density)

Method used

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  • A metamaterial with five-mode material characteristics and its determination method
  • A metamaterial with five-mode material characteristics and its determination method
  • A metamaterial with five-mode material characteristics and its determination method

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Embodiment 1

[0039] A metamaterial with five-mode material characteristics, the microstructure unit cell of the metamaterial includes a Y-shaped rod for adjusting equivalent stiffness and a counterweight 3 for adjusting equivalent density; the Cartesian coordinate system xoy of the unit cell is established, In the Cartesian coordinate system xoy, the x-axis direction is to the right in the plane, and the y-axis direction is vertically upward in the plane. The Cartesian coordinate system xoy is the coordinate of the main axis of the unit cell; the unit cell configuration is a hexagon, and the opposite side of the hexagon Keep parallel and equal length, one group of opposite sides is vertical direction; starting from the vertex with the smallest y-coordinate of the unit cell, name the six vertices of the unit cell as vertex No. 1 to vertex No. 6 respectively in the counterclockwise direction; The above-mentioned Y-shaped bar is composed of one end of a vertical bar 1 and one end of two obliqu...

Embodiment 2

[0046] Metal aluminum is used as the matrix material of the three metamaterial unit cells described in Example 1, and the geometric parameters of each component of the unit cell are adjusted through COMSOLMultiphysics numerical simulation, and a super material with five-mode material characteristics that matches the acoustic characteristics of the water can be designed. Material, that is, "metal water" material.

[0047] The density of aluminum is 2700kg / m 3 , the modulus is 69GPa, and Poisson's ratio is 0.33. for figure 1 The geometrical parameters obtained by simulation of the first unit cell configuration are as follows: l=m=10mm, β=60°, t=0.61mm, w=6.93mm, h=2.84mm, the equivalent density of the unit cell ρ and elastic matrix C are shown in formula (3):

[0048] ρ = 1.000 ρ 0 , C = 1.009 0.996 ...

Embodiment 3

[0056] Figure 5 It is a schematic diagram of a quarter part of the microstructure of the circular sound wave stealth cover layer metamaterial, which has the function of guiding the sound waves incident on the cover layer to bypass the central area and transmit from the rear, which can realize the target object in the central area External detection sonic stealth. The base material of the covering layer is aluminum metal, the inner radius R is 300 mm, and the total thickness of the covering layer is 71.63 mm. The covering layer is composed of three layers of microstructure, and the unit cell configuration of the microstructure is figure 1 The unit cell configuration shown in ; the innermost microstructure is composed of two unit cells arranged in the direction of the inner radius R and copied 100 times in the circumferential direction, and the middle layer is composed of a unit cell rotated and copied 100 times in the circumferential direction , the outermost layer is compose...

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Abstract

The invention relates to a metamaterial having the characteristics of a pentamode material, and a determination method thereof, and belongs to the field of sound wave regulation. The metamaterial has good characteristics of the pentamode material, is a honeycomb microstructure formed by unit cells, and each of the unit cells comprises a Y-shaped rod, balancing weights and a cavity; the rectangular coordinates of each of the unit cells is xoy and is a principal axis coordinate; each of the unit cells is a hexagon with parallel opposite sides with a same length, and one group of the opposite edges is vertical in direction; 6 vertexes of each of the unit cells from the smallest vertex of a y-axial coordinate along an anticlockwise direction are named as No.1-6 vertexes; the Y-shaped rod is formed through intersecting a vertical rod and bilaterally symmetrically distributed oblique rods in the unit cell, the intersection point of the three rods is No.0 vertex in the vertical symmetric axis of the unit cell, and the other ends of the vertical rods and the oblique rods are respectively positioned in the No.1, No.3 and No.5 vertexes; and the balancing weights are bilaterally symmetrically fixedly arranged on the oblique rods and are not in contact with the No.0 vertex. Whether the metamaterial has obvious pentamode characteristics or not is determined according to the unit cell configuration parameters pi and mu through the method, so the method fills the gap in quantitative determination methods of current pentamode material characteristics.

Description

technical field [0001] The invention relates to a metamaterial with five-mode material characteristics and a determination method, in particular to an acoustic metamaterial with wide and low frequency applicability, and belongs to the field of sound wave regulation. Background technique [0002] It is known from the natural phenomenon that light will bend when propagating in inhomogeneous materials that by designing the gradient distribution of material properties in space, it is possible to achieve precise control of the wave propagation trajectory. This typical inverse problem was first solved by the transformation theory proposed in the field of electromagnetic waves, and then extended to the fields of elastic waves and sound waves. This method is collectively called the transformation theory. According to this transformation theory, the gradient distribution of material properties can be designed to achieve various special functions, the most valuable of which is to desi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N33/00G10K11/18
Inventor 刘晓宁陈毅胡更开
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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