CN104118151A - Low-frequency wideband nacreous layer bionic vibration isolation material - Google Patents

Abstract

The invention discloses a low-frequency wideband nacreous layer bionic vibration isolation material. The low-frequency wideband nacreous layer bionic vibration isolation material is provided with a periodic structure consisting of a plurality of basic structure units, wherein each basic structure unit comprises a structure layer I, a connecting layer and a structure layer II which are sequentially connected along the height direction of the periodic structure; the connecting layer comprises four secondary connecting layers which are ranked in a 2*2 matrix and are ranked at equal intervals; each secondary connecting layer comprises a structure layer III as well as a connecting layer I and a connecting layer II which are respectively positioned on the upper and lower surfaces of the structure layer III; the structure layer I, the structure layer II and the structure layer III are made of a material I; the connecting layer I and the connecting layer II are made of a material II; the density of the material I is ymat, wherein ymat is greater than or equal to 1*10<3>kg/m<3> and smaller than or equal to 20*10<3>kg/m<3>; the elasticity modulus of the material II is xmat, wherein xmat is greater than or equal to 0.1Mpa and smaller than or equal to 100Mpa. The basic structure units have the characteristics of quite wide low-frequency band clearance and band clearance designability.

Description

A kind of bionical vibration isolation material of nacre of broad band low frequency

Technical field

The present invention relates to a kind of vibration isolation material, specifically the bionical vibration isolation material of a kind of nacre of broad band low frequency.

Background technology

Traditional damping technology core is to adopt damping vibration attenuation material, as rubber, the materials such as resin, the macromolecular material that these materials are normally single-phase or the mixture of several macromolecular materials, macromolecular material is by growing, the soft curling and molecular composition that tangles mutually, intermolecular chemical bond coupling in addition once in a while, and there is very high damped coefficient.Damping is to change the energy of system vibration in vibration processes into other forms of energy and the process that dissipates, can be by the interior friction between its inner macromolecule, and other forms of energy comprises heat energy, electric energy, magnetic energy etc.Damping can reduce vibratory output, the amount of being hit and the noise level of system.When free vibration, damping constantly decays amplitude.When forced vibration, damping consumes excitation to system work, reduces the amplitude of system.

Viscoelastic damping damping material has the characteristic of viscous liquid loss of energy under flow regime and the characteristic of elastic solid material stored energy concurrently, can by sticky note structurally, form large composite damping structure, to reach the object of vibration damping.

Tradition damping vibration attenuation material based on interior friction energy-dissipating mechanism, not remarkable for low frequency vibration damping effect, and there is the not programmable problem of object tape broadband, different types of material need to be designed in field for different bandwidth frequency, and vibration damping scope can not cover vibration and wider acoustics frequency range.For special dimension, require effectiveness in vibration suppression remarkable, can shield the elastic wave in particular frequency range, such as the friction processing environment that high-accuracy system of processing needs, the sound shielding environment in particular frequency range, traditional damping vibration attenuation material can not be competent at.

Summary of the invention

Not remarkable to low frequency vibration damping effect according to traditional damping vibration attenuation material of above-mentioned proposition, and there is the not programmable technical problem of object tape broadband, and a kind of bionical vibration isolation material of nacre of broad band low frequency is provided.

The technological means that the present invention adopts is as follows:

The bionical vibration isolation material of nacre of broad band low frequency, has a periodic structure, and described periodic structure is made up of multiple basic structural units;

Described basic structural unit comprises the structure sheaf one connecting successively along described periodic structure short transverse, articulamentum and structure sheaf two;

Described articulamentum comprises that four are the secondary articulamentum that 2 × 2 matrixes are arranged, and described four secondary articulamentums are equidistantly arranged, and because the size of spacing does not exert an influence to isolation frequency scope, therefore, the present invention is as long as ensure that described spacing exists;

Described secondary articulamentum comprises a structure sheaf three and lays respectively at articulamentum one and the articulamentum two of the top and bottom of described structure sheaf three;

Described structure sheaf one, the material of described structure sheaf two and described structure sheaf three is material one, the material of described articulamentum one and described articulamentum two is material two;

The density of described material one is y _mat, 1 × 10 ³kg/m ³≤ y _mat≤ 20 × 10 ³kg/m ³;

The elastic modelling quantity of described material two is x _mat, 0.1Mpa≤x _mat≤ 100Mpa.

Further, the outer surface of described periodic structure is coated with damping material.

Further, the alternately laminated setting of described periodic structure and damping material, i.e. periodic structure described in one deck, the alternately laminated setting of one deck damping material.

Further, described basic structural unit is arranged with m × m × n dot matrix form, and wherein m and n are respectively the positive integer that is more than or equal to 1;

The bottom surface of described basic structural unit is square, and described periodic structure is of a size of ma × ma × nb, the bottom surface length of side that wherein a is described basic structural unit, the height that b is described basic structural unit;

The bottom surface of described structure sheaf one is square, and the bottom surface length of side of described structure sheaf one is a;

The bottom surface of described structure sheaf two is square, and the bottom surface length of side of described structure sheaf two is a;

The bottom surface of described structure sheaf three is square, and the bottom surface length of side of described structure sheaf three is a ₁, 2a ₁=a;

The bottom surface of described articulamentum one is square, and the bottom surface length of side of described articulamentum one is a ₂;

The bottom surface of described articulamentum two is square, and the bottom surface length of side of described articulamentum two is a ₂;

The height of described structure sheaf three is b ₁, the height of the height of described structure sheaf one and described structure sheaf two is b ₁/ 2, the height of the height of described articulamentum one and described articulamentum two is b ₂, 2b ₁+ 2b ₂=b; ,

The connecting length of described articulamentum one and described structure sheaf one, the connecting length of described articulamentum one and described structure sheaf three, described articulamentum two is z with connecting length and the described articulamentum two of described structure sheaf three with the connecting length of described structure sheaf two _geo, z _geo=a ₂.

The present invention also provides a kind of method of the bionical vibration isolation material of nacre that designs above-mentioned a kind of broad band low frequency, it is characterized in that:

1) x _matand y _matconfirmation

Pass through formula $f_{\mathrm{upper}}=f_1^{\mathrm{up}}\left(x_{\mathrm{mat}}\right)$ With $f_{\mathrm{lower}}=\frac{f_1^{\mathrm{low}}\left(x_{\mathrm{mat}}\right)*f_2^{\mathrm{low}}\left(y_{\mathrm{mat}}\right)}{n_{\mathrm{mat}}}$ Calculate x _matand y _mat,

$f_1^{\mathrm{up}}\left(x_{\mathrm{mat}}\right)=0.0248x_{\mathrm{mat}}^3-4.7808x_{\mathrm{mat}}^2+362.47x_{\mathrm{mat}}+425.075,$

$f_1^{\mathrm{low}}\left(x_{\mathrm{mat}}\right)=0.0224x_{\mathrm{mat}}^3-4.3173x_{\mathrm{mat}}^2+331.8x_{\mathrm{mat}}+45.4886,$

$f_2^{\mathrm{low}}\left(y_{\mathrm{mat}}\right)=-0.121y_{\mathrm{mat}}^3+4.945y_{\mathrm{mat}}^2-68.196y_{\mathrm{mat}}+449.75,$

n _mat＝299.28，

F _upperfor the coboundary of isolation frequency scope, f _lowerfor the lower boundary of isolation frequency scope;

2) a, b, a ₁,, a ₂, b ₁and b ₂confirmation

By formula a _upper=32729.8/f _upper, a _lower=5909.1/f _lowerand b=2b ₁+ 2b ₂calculate a and b,

Work as a _upper=a _lowertime, a=a _upper=a _lower;

Work as a _upper≠ a _lowertime, a=(a _upper+ a _lower)/2;

Wherein, a/b ₁=x _geo, a ₂/ b ₂=y _geo, a ₂=z _geo, 1≤x _geo≤ 9,2≤y _geo≤ 8,0 < z _geo≤ 30mm;

Pass through formula $f_{\mathrm{upper}}=g_1^{\mathrm{up}}\left(y_{\mathrm{geo}}\right)$ With $f_{\mathrm{lower}}=\frac{g_1^{\mathrm{low}}\left(x_{\mathrm{geo}}\right)*g_2^{\mathrm{low}}\left(y_{\mathrm{geo}}\right)*g_3^{\mathrm{low}}\left(z_{\mathrm{geo}}\right)}{n_{\mathrm{geo}}}$ Calculate x _geo, y _geoand z _geo,

Suppose parameter x _geoand z _geoproduce similar band gap impact effect,

$g_1^{\mathrm{low}}\left(x_{\mathrm{geo}}\right)=g_3^{\mathrm{low}}\left(z_{\mathrm{geo}}\right),$ Owing to passing through $f_{\mathrm{upper}}=g_1^{\mathrm{up}}\left(y_{\mathrm{geo}}\right)$ Can determine parameter y _geo, only remaining x _geoand z _geoparameter is undetermined, but because only have an equation, can not determine two undetermined parameters, that is to say that can exist multiple situation to organize solution all meets equation more the present invention only provides and determines the wherein straightforward procedure of one group of solution, so carry out such hypothesis;

$g_1^{\mathrm{up}}\left(y_{\mathrm{geo}}\right)=-0.6625y_{\mathrm{geo}}^2+85.765y_{\mathrm{geo}}+298.68,$

$g_1^{\mathrm{low}}\left(x_{\mathrm{geo}}\right)=-1.9643x_{\mathrm{geo}}^2+46.3029x_{\mathrm{geo}}-12.8063,$

$g_2^{\mathrm{low}}\left(y_{\mathrm{geo}}\right)=-2.075y_{\mathrm{geo}}^2+54.27y_{\mathrm{geo}}-15.82,$

$g_3^{\mathrm{low}}\left(z_{\mathrm{geo}}\right)=-0.0994z_{\mathrm{geo}}^2+10.185z_{\mathrm{geo}}-7.49,$

n _geo＝7126。Further, in the time of given frequency f, pass through formula

calculate f _upperand f _lower, wherein f is the centre frequency of isolation frequency scope, supposes a=a _upper=a _lower.

Compared with prior art, basic structural unit of the present invention has quite wide low bandgap, and can adjust material parameter and geometric parameter according to the vibration environment of vibration isolation material application, thereby can adjust the target bandgap range of vibration isolation material, the present invention has the designability of band gap, vibration isolating effect highly significant in bandgap range, can design for varying environment, reach the effect to elastic wave shielding, the present invention can also combine with traditional damping material, further improves vibration isolating effect.

The present invention can extensively promote in fields such as vibration isolation materials for the foregoing reasons.

Brief description of the drawings

Below in conjunction with the drawings and specific embodiments, the present invention is further detailed explanation.

Fig. 1 is basic structural unit of the present invention space schematic diagram.

Fig. 2 is the top view of basic structural unit of the present invention.

Fig. 3 is basic structural unit side view of the present invention.

Fig. 4 is longitudinal transfer curve figure that the specific embodiment of the present invention and other materials contrast.

Fig. 5 is the lateral transport performance diagram that the specific embodiment of the present invention and other materials contrast.

When Fig. 6, the three-dimensional of the specific embodiment of the present invention can be with graph of a relation.

Fig. 7 is the bionical vibration isolation material structural representation of a kind of nacre of the broad band low frequency that is provided with mount pad.

Detailed description of the invention

As depicted in figs. 1 and 2, the bionical vibration isolation material of a kind of nacre of broad band low frequency, has a periodic structure, and described periodic structure is made up of multiple basic structural units;

Described basic structural unit comprises the structure sheaf 1 connecting successively along described periodic structure short transverse, articulamentum and structure sheaf 22;

Described articulamentum comprises that four are the secondary articulamentum that 2 × 2 matrixes are arranged, and described four secondary articulamentums are equidistantly arranged, and spacing is 5mm;

Described secondary articulamentum comprises a structure sheaf 33 and lays respectively at articulamentum 1 and the articulamentum 25 of the top and bottom of described structure sheaf 33, and described spacing is that 5mm refers to four spacing between described structure sheaf 33;

Described structure sheaf 1, the material of described structure sheaf 22 and described structure sheaf 33 is material one, the material of described articulamentum 1 and described articulamentum 25 is material two;

The density of described material one is y _mat, 1 × 10 ³kg/m ³≤ y _mat≤ 20 × 10 ³kg/m ³;

The elastic modelling quantity of described material two is x _mat, 0.1Mpa≤x _mat≤ 100Mpa.

Described basic structural unit is arranged with m × m × n dot matrix form, wherein m=n=3;

The bottom surface of described basic structural unit is square, and described periodic structure is of a size of 3a × 3a × 3b, the bottom surface length of side that wherein a is described basic structural unit, the height that b is described basic structural unit;

The bottom surface of described structure sheaf 1 is square, and the bottom surface length of side of described structure sheaf 1 is a;

The bottom surface of described structure sheaf 22 is square, and the bottom surface length of side of described structure sheaf 22 is a;

The bottom surface of described structure sheaf 33 is square, and the bottom surface length of side of described structure sheaf 33 is a ₁, 2a ₁=a;

The bottom surface of described articulamentum 1 is square, and the bottom surface length of side of described articulamentum 1 is a ₂;

The bottom surface of described articulamentum 25 is square, and the bottom surface length of side of described articulamentum 25 is a ₂;

The height of described structure sheaf 33 is b ₁, the height of the height of described structure sheaf 1 and described structure sheaf 22 is b ₁/ 2, the height of the height of described articulamentum 1 and described articulamentum 25 is b ₂, 2b ₁+ 2b ₂=b;

The connecting length of described articulamentum 1 and described structure sheaf 1, the connecting length of described articulamentum 1 and described structure sheaf 33, described articulamentum 25 is z with connecting length and the described articulamentum 25 of described structure sheaf 33 with the connecting length of described structure sheaf 22 _geo, z _geo=a ₂.

Given frequency f is 276Hz, passes through computing formula: a _upper=32729.8/f _upper, a _lower=5909.1/f _lowerand a=a _upper=a _lower,

Can obtain $a=\frac{32729.8+5909.1}{2\&times;276}=70\mathrm{mm},$

And then obtain f _upper=467.5685Hz, f _lower=84.4155Hz,

X _matand y _matconfirmation:

Pass through formula $f_{\mathrm{upper}}=f_1^{\mathrm{up}}\left(x_{\mathrm{mat}}\right)$ With $f_{\mathrm{lower}}=\frac{f_1^{\mathrm{low}}\left(x_{\mathrm{mat}}\right)*f_2^{\mathrm{low}}\left(y_{\mathrm{mat}}\right)}{n_{\mathrm{mat}}}$ Calculate x _matand y _mat,

$f_1^{\mathrm{up}}\left(x_{\mathrm{mat}}\right)=0.0248x_{\mathrm{mat}}^3-4.7808x_{\mathrm{mat}}^2+362.47x_{\mathrm{mat}}+425.075,$

$f_1^{\mathrm{low}}\left(x_{\mathrm{mat}}\right)=0.0224x_{\mathrm{mat}}^3-4.3173x_{\mathrm{mat}}^2+331.8x_{\mathrm{mat}}+45.4886,$

$f_2^{\mathrm{low}}\left(y_{\mathrm{mat}}\right)=-0.121y_{\mathrm{mat}}^3+4.945y_{\mathrm{mat}}^2-68.196y_{\mathrm{mat}}+449.75,$

n _mat＝299.28，

due to equation at 0.1Mpa≤x _matin≤100Mpa, be dull, can be in the hope of x _mat=0.1174MPa, similar to the elastic modelling quantity of silicon rubber, described articulamentum 1 and described articulamentum 25 are chosen silicon rubber as using material.

$\frac{f_1^{\mathrm{low}}\left(x_{\mathrm{mat}}\right)*f_2^{\mathrm{low}}\left(y_{\mathrm{mat}}\right)}{n_{\mathrm{mat}}}=84.4155\mathrm{Hz},$ Due to equation $\frac{f_1^{\mathrm{low}}\left(x_{\mathrm{mat}}\right)*f_2^{\mathrm{low}}\left(y_{\mathrm{mat}}\right)}{n_{\mathrm{mat}}}$ 1 × 10 ³kg/m ³≤ y _mat≤ 20 × 10 ³kg/m ³inside dull, can be in the hope of y _mat=2.6975 × 10 ³kg/m ³, similar to the density of aluminium, described structure sheaf 1, described structure sheaf 22 and described structure sheaf 33 are chosen aluminium as using material.

A, b, a ₁,, a ₂, b ₁and b ₂confirmation:

By formula a _upper=32729.8/f _upper, a _lower=5909.1/f _lowerand b=2b ₁+ 2b ₂calculate a and b, a=a _upper=a _lower=70mm;

Wherein, a/b ₁=x _geo, a ₂/ b ₂=y _geo, a ₂=z _geo, 1≤x _geo≤ 9,2≤y _geo≤ 8,0 < z _geo≤ 30mm;

Pass through formula $f_{\mathrm{upper}}=g_1^{\mathrm{up}}\left(y_{\mathrm{geo}}\right)$ With $f_{\mathrm{lower}}=\frac{g_1^{\mathrm{low}}\left(x_{\mathrm{geo}}\right)*g_2^{\mathrm{low}}\left(y_{\mathrm{geo}}\right)*g_3^{\mathrm{low}}\left(z_{\mathrm{geo}}\right)}{n_{\mathrm{geo}}}$ Calculate x _geo, y _geoand z _geo,

$g_1^{\mathrm{up}}\left(y_{\mathrm{geo}}\right)=-0.6625y_{\mathrm{geo}}^2+85.765y_{\mathrm{geo}}+298.68,$

$g_1^{\mathrm{low}}\left(x_{\mathrm{geo}}\right)=-1.9643x_{\mathrm{geo}}^2+46.3029x_{\mathrm{geo}}-12.8063,$

$g_2^{\mathrm{low}}\left(y_{\mathrm{geo}}\right)=-2.075y_{\mathrm{geo}}^2+54.27y_{\mathrm{geo}}-15.82,$

$g_3^{\mathrm{low}}\left(z_{\mathrm{geo}}\right)=-0.0994z_{\mathrm{geo}}^2+10.185z_{\mathrm{geo}}-7.49,$

n _geo＝7126；

due to equation at 2≤y _geoin≤8, be dull, can be in the hope of y _geo=2, z _geo=a ₂, 2b ₂=a ₂;

$\frac{g_1^{\mathrm{low}}\left(x_{\mathrm{geo}}\right)*g_2^{\mathrm{low}}\left(y_{\mathrm{geo}}\right)*g_3^{\mathrm{low}}\left(z_{\mathrm{geo}}\right)}{n_{\mathrm{geo}}}84.4155\mathrm{Hz},$

Abbreviation obtains suppose parameter x _geoand z _geoproduce similar band gap impact effect,

$g_1^{\mathrm{low}}\left(x_{\mathrm{geo}}\right)=84.4134\mathrm{Hz},g_3^{\mathrm{low}}\left(z_{\mathrm{geo}}\right)=84.4134\mathrm{Hz},$

Due to equation at 1≤x _geoin≤9, be dull, can be in the hope of x _geo=2.3299, due to equation at 0 < z _geoin≤30mm, be dull, can be in the hope of z _geo=9.9994mm.Thereby can obtain b ₁=30.0442mm, a ₂=9.9994mm, b ₂=4.9997mm, b=2b ₁+ 2b ₂=70.0878mm.

The bionical vibration isolation material of nacre (being illustrated as three-dimensional nacre material) of described a kind of broad band low frequency and aluminium block (being illustrated as aluminium), simple stratified material (being illustrated as the simple stratified material of the aluminium-silicon rubber) performance of silicon rubber piece (being illustrated as silicon rubber) and aluminium sheet and the alternately laminated setting of silicane rubber plate contrasts, examine or check the transmission characteristic of its vertical and horizontal, the test of the line number of going forward side by side value.Transmission coefficient is that output displacement response responds divided by input displacement, conventionally response curve is described with logarithmic form, comparing result as shown in Figure 4 and Figure 5, from figure, curve can be found out, the bionical vibration isolation material of nacre of described a kind of broad band low frequency is in the frequency range of low-frequency ultra-wideband gap, be laterally or longitudinally all to have significant effectiveness in vibration suppression, its attenuating can reach 200dB, is far longer than other three kinds of materials.

As shown in Figure 6, the letter of abscissa is the characteristic point of wave vector in the first brief Brillouin zone, characterizes complete three-dimensional direction of wave travel; Curve in Fig. 6 is dispersion curve or band structure, characterizes the relation of wave vector and frequency, therefrom can find out different frequency velocity of wave propagation and direction; Under three-dimensional situation, the bionical vibration isolation material of nacre of described a kind of broad band low frequency there will be quite wide low bandgap (84.4155Hz-467.5685Hz), three-dimensional material can have abundanter dispersion relation at low frequency region, and at many straight bands of the same appearance of high-frequency region, thereby there are multiple more continuous band gap.This can cause the frequency decay area of non-constant width to occur, is applicable to the needs of engineering vibration and noise reducing.

As shown in Figure 7, the upper and lower surface of the bionical vibration isolation material of nacre of described a kind of broad band low frequency is respectively equipped with mount pad.

The above; it is only preferably detailed description of the invention of the present invention; but protection scope of the present invention is not limited to this; any be familiar with those skilled in the art the present invention disclose technical scope in; be equal to replacement or changed according to technical scheme of the present invention and inventive concept thereof, within all should being encompassed in protection scope of the present invention.

Claims (6)

1. the bionical vibration isolation material of the nacre of broad band low frequency, is characterized in that, has a periodic structure, and described periodic structure is made up of multiple basic structural units;

Described basic structural unit comprises the structure sheaf one connecting successively along described periodic structure short transverse, articulamentum and structure sheaf two;

Described articulamentum comprises that four are the secondary articulamentum that 2 × 2 matrixes are arranged, and described four secondary articulamentums are equidistantly arranged;

Described secondary articulamentum comprises a structure sheaf three and lays respectively at articulamentum one and the articulamentum two of the top and bottom of described structure sheaf three;

Described structure sheaf one, the material of described structure sheaf two and described structure sheaf three is material one, the material of described articulamentum one and described articulamentum two is material two;

The density of described material one is y _mat, 1 × 10 ³kg/m ³≤ y _mat≤ 20 × 10 ³kg/m ³;

The elastic modelling quantity of described material two is x _mat, 0.1Mpa≤x _mat≤ 100Mpa.

2. the bionical vibration isolation material of the nacre of a kind of broad band low frequency according to claim 1, is characterized in that: the outer surface of described periodic structure is coated with damping material.

3. the bionical vibration isolation material of the nacre of a kind of broad band low frequency according to claim 1, is characterized in that: the alternately laminated setting of described periodic structure and damping material.

4. according to the bionical vibration isolation material of nacre of a kind of broad band low frequency described in the arbitrary claim of claims 1 to 3, it is characterized in that: described basic structural unit is arranged with m × m × n dot matrix form, and wherein m and n are respectively the positive integer that is more than or equal to 1;

The bottom surface of described basic structural unit is square, and described periodic structure is of a size of ma × ma × nb, the bottom surface length of side that wherein a is described basic structural unit, the height that b is described basic structural unit;

The bottom surface of described structure sheaf one is square, and the bottom surface length of side of described structure sheaf one is a;

The bottom surface of described structure sheaf two is square, and the bottom surface length of side of described structure sheaf two is a;

The bottom surface of described structure sheaf three is square, and the bottom surface length of side of described structure sheaf three is a ₁, 2a ₁=a;

The bottom surface of described articulamentum one is square, and the bottom surface length of side of described articulamentum one is a ₂;

The bottom surface of described articulamentum two is square, and the bottom surface length of side of described articulamentum two is a ₂;

The height of described structure sheaf three is b ₁, the height of the height of described structure sheaf one and described structure sheaf two is b ₁/ 2, the height of the height of described articulamentum one and described articulamentum two is b ₂, 2b ₁+ 2b ₂=b;

The connecting length of described articulamentum one and described structure sheaf one, the connecting length of described articulamentum one and described structure sheaf three, described articulamentum two is z with connecting length and the described articulamentum two of described structure sheaf three with the connecting length of described structure sheaf two _geo, z _geo=a ₂.

5. a method for the bionical vibration isolation material of nacre of design a kind of broad band low frequency claimed in claim 4, is characterized in that:

1) x _matand y _matconfirmation

Pass through formula $f_{\mathrm{upper}}=f_1^{\mathrm{up}}\left(x_{\mathrm{mat}}\right)$ With $f_{\mathrm{lower}}=\frac{f_1^{\mathrm{low}}\left(x_{\mathrm{mat}}\right)*f_2^{\mathrm{low}}\left(y_{\mathrm{mat}}\right)}{n_{\mathrm{mat}}}$ Calculate x _matand y _mat,

$f_1^{\mathrm{up}}\left(x_{\mathrm{mat}}\right)=0.0248x_{\mathrm{mat}}^3-4.7808x_{\mathrm{mat}}^2+362.47x_{\mathrm{mat}}+425.075,$

$f_1^{\mathrm{low}}\left(x_{\mathrm{mat}}\right)=0.0224x_{\mathrm{mat}}^3-4.3173x_{\mathrm{mat}}^2+331.8x_{\mathrm{mat}}+45.4886,$

$f_2^{\mathrm{low}}\left(y_{\mathrm{mat}}\right)=-0.121y_{\mathrm{mat}}^3+4.945y_{\mathrm{mat}}^2-68.196y_{\mathrm{mat}}+449.75,$

n _mat＝299.28，

F _upperfor the coboundary of isolation frequency scope, f _lowerfor the lower boundary of isolation frequency scope;

2) a, b, a ₁,, a ₂, b ₁and b ₂confirmation

By formula a _upper=32729.8/f _upper, a _lower=5909.1/f _lowerand b=2b ₁+ 2b ₂calculate a and b,

Work as a _upper=a _lowertime, a=a _upper=a _lower;

Work as a _upper≠ a _lowertime, a=(a _upper+ a _lower)/2;

Wherein, a/b ₁=x _geo, a ₂/ b ₂=y _geo, a ₂=z _geo, 1≤x _geo≤ 9,2≤y _geo≤ 8,0 < z _geo≤ 30mm;

Pass through formula $f_{\mathrm{upper}}=g_1^{\mathrm{up}}\left(y_{\mathrm{geo}}\right)$ With $f_{\mathrm{lower}}=\frac{g_1^{\mathrm{low}}\left(x_{\mathrm{geo}}\right)*g_2^{\mathrm{low}}\left(y_{\mathrm{geo}}\right)*g_3^{\mathrm{low}}\left(z_{\mathrm{geo}}\right)}{n_{\mathrm{geo}}}$ Calculate x _geo, y _geoand z _geo,

Suppose parameter x _geoand z _geoproduce similar band gap impact effect,

$g_1^{\mathrm{low}}\left(x_{\mathrm{geo}}\right)=g_3^{\mathrm{low}}\left(z_{\mathrm{geo}}\right),$

$g_1^{\mathrm{up}}\left(y_{\mathrm{geo}}\right)=-0.6625y_{\mathrm{geo}}^2+85.765y_{\mathrm{geo}}+298.68,$

$g_1^{\mathrm{low}}\left(x_{\mathrm{geo}}\right)=-1.9643x_{\mathrm{geo}}^2+46.3029x_{\mathrm{geo}}-12.8063,$

$g_2^{\mathrm{low}}\left(y_{\mathrm{geo}}\right)=-2.075y_{\mathrm{geo}}^2+54.27y_{\mathrm{geo}}-15.82,$

$g_3^{\mathrm{low}}\left(z_{\mathrm{geo}}\right)=-0.0994z_{\mathrm{geo}}^2+10.185z_{\mathrm{geo}}-7.49,$

n _geo＝7126。

6. method according to claim 5, is characterized in that: in the time of given frequency f, pass through formula calculate f _upperand f _lower, wherein f is the centre frequency of isolation frequency scope, supposes a=a _upper=a _lower.