CN1118794C - Composite material with negative elastic constant and its making process - Google Patents
Composite material with negative elastic constant and its making process Download PDFInfo
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- CN1118794C CN1118794C CN 00106033 CN00106033A CN1118794C CN 1118794 C CN1118794 C CN 1118794C CN 00106033 CN00106033 CN 00106033 CN 00106033 A CN00106033 A CN 00106033A CN 1118794 C CN1118794 C CN 1118794C
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- 239000002131 composite material Substances 0.000 title abstract 6
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- TWDJIKFUVRYBJF-UHFFFAOYSA-N Cyanthoate Chemical compound CCOP(=O)(OCC)SCC(=O)NC(C)(C)C#N TWDJIKFUVRYBJF-UHFFFAOYSA-N 0.000 claims 1
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Abstract
The present invention relates to a low-frequency sound-isolating composite material and a preparing method thereof. The composite material has base material, a quantity of soft elastic material areas and hard material areas, wherein the base material is used as ordinary structural material; the soft elastic material areas are arranged in the base material; the hard material areas with high density and rigidity are inlaid in the soft elastic material areas. The composite material can have one or more than one resonance frequency; at the resonance frequency, the transmission of sound waves is largely blocked. The base material can form composite material which has favorable structural performance, and fairly thin composite material can be used to provide shields for voice with fairly low frequencies.
Description
The combined material that the present invention relates to shows negative elastic constant, particularly relates to the material and the method for making thereof that are applicable to the low frequency sound insulation.
There are various materials of trying hard to intercept transfer voice.Existing combined material with sound insulation function comprises the abatvoix of being narrated as United States Patent (USP) 5564241, is provided with sound absorbing layer in this abatvoix, perhaps posts sound absorbing layer on structural sheet.And other material of narration is some very complicated combined materials in United States Patent (USP) 5512715.It is found that in all cases, the shielding that low-frequency sound wave is provided all is difficult.Maximum difficulty is that for scattering or reflective sound wave, the size of scatterer must have the identical order of magnitude with wave length of sound.Because the wavelength of low-frequency sound is long, so shielding material must be very thick or very soft.Obviously, in the many application that comprise building industry, in the occasion that admissible thickness is restricted, very thick material is unfavorable.Because soft material can shorten wavelength, so can make thin layer during with very soft material, still, its use is subjected to the low restriction of material structure intensity again.
Usually, the static elasticity constant of material is positive, and this is a constitutionally stable necessary condition, otherwise spontaneous deformation meeting makes system reach a lower elastic energy level.If elastic constant be not on the occasion of, then just mean instability, still, if negative elastic constant is possible, under some characteristic frequency, these sound waves can not transmit in this material so at least.Therefore, under low frequency, there is the material of negative elastic constant can make quite thin material that the sound wave of characteristic frequency is played sound filter or sound panel.
The purpose of this invention is to provide a kind of combined material that in particular frequency range, has negative elastic constant at least, to shield or to isolate the sound wave of these frequencies
Therefore, first aspect can be regarded as, and the invention reside in provides a kind of combined material, this material has the stock of general structured material, and some soft elastic material districts in this matrix material and some are embedded in the quite high and high stiff materials district of rigidity of density in the soft elastic material.
Therefore, second aspect, a kind of method that provides is provided, being manufactured on the combined material that has negative elastic constant on some finite frequency, this combined material is included in that to inlay density in the soft elastic material zone quite high and the high hard particles of rigidity is inlayed the soft elastic material zone and in being used as the matrix material of structured material.
The invention has the advantages that the combined material that is provided can have one or more resonant frequency, on these frequencies, the transmission of sound wave is obstructed greatly.Matrix material can form the good combined material of structural behaviour, also can provide shielding to the sound of suitable low frequency with quite thin combined material.
Can adjust to eliminate some characteristic frequency combined material by the size and dimension of selecting particle, (frequency) scope of broad perhaps can be provided by the particle that mixes different size and shape.
Narrate the present invention below with reference to the accompanying drawings, accompanying drawing comprises:
Fig. 1 represents a representational xsect of a possibility embodiment of the present invention;
Fig. 2 represents the curve of one embodiment of the invention and other material comparative result.
Fig. 3 is the synoptic diagram of a possibility of the present invention embodiment;
Fig. 4 represents the theoretical model result's of one embodiment of the invention curve representation;
The curve representation of theoretical value of Fig. 5 one embodiment of the invention and actual experiment value.
Curve representation explanation among Fig. 3:
The gum ball
The rubber sphere of gum ball and tape tree fat
Resin adds the Metal Ball of coat with rubber
DESCRIPTION OF THE PREFERRED
The present invention relates to the combined material that some have negative elastic constant.This material mainly is used in the transmission that weakens sound in the particular frequency range.Therefore, this combined material is as sound, and particularly the isolated body of low-frequency sound or barricade are useful especially.This combined material can be used for various application, comprises sound insulation and makes elasticity waveguide and elastic wave reflex device.
In order to guarantee stability of structure, a condition precedent is that static spring constant is positive.Not that negative elastic constant can cause spontaneous deformation, causes material may reach a lower elastic energy level.But at some, the effective elastic constant that in comprising the combined material of two or more constituent element, may occur bearing, and don't destroy stability of structure.In other words, the microcosmic elastic constant is timing in whole combined material, in some frequency range, and concerning the transmission ripple, the phasic difference mutually-180 of the phase place of effective stress and effective strain °.If the microstructure size of combined material is much smaller than wavelength, this notion of bearing the effect elastic constant is effective so.Have been found that this composition has beyond thought novel character.
In a preferred embodiment, this combined material can have the low frequency region of one or more negative elastic constant.These frequency fields can obtain by the design parameter that changes composition adjusting.In these frequency fields, this negative elastic constant can stop the transmission of elastic wave, and in fact these ripples can fade away.
With reference now to accompanying drawing and at least one preferred embodiment, the manufacturing ultimate principle of this composition is narrated.
According to definition, remove elastic constant and be the proportionality constant between the stress and strain, it is the function of elastic response.Negative elastic constant means that directly stress response and strain differ 180 ° on phase place.
Should be noted that, when signal frequency changes by resonant frequency, response function reindexing.For example, when resonant frequency be ω
0The time, be higher than ω so
0Frequency the time because the inertia of system, the response of system adds 180 ° in source with hysteresis.Therefore.Can reach a conclusion, in order to produce negative elastic constant, we can adopt the combined material with low-frequency elastic resonance.
With reference to figure 1, as shown in the figure, the microstructure unit of three group of components compounds can have certain resonance.In Fig. 1, the hard particle of " A " expression, material that this particle is quite high by density and rigidity is high such as steel or tin are made." B " expression is enclosed in the high and rigidity higher material soft elastic material on every side of this density, as rubber.At last, " C " represents matrix material, and matrix material can be any structure material or plastics, polymkeric substance one concrete, organic glass etc.
Can suppose to be Elastic Contact at the interface between " A " and " B " and between " B " and " C ".Owing between two kinds high rigidity materials " A " and " C ", have soft elastic material " B ", so may there be the low-frequency resonance that causes by the relative motion between particle " A " and the matrix.This specific resonant frequency is determined by the elastic constant of soft material " B " and the density of material " B " and two kinds of materials of hard particles " A ".
Might there be many resonance modes.The low-limit frequency resonance mode is because the center of mass motion of the relative matrix of particle causes, the upper frequency pattern is that the resonance mode by soft elastic material causes.
Because the size of particle " A " is very big less than the impedance mismatching between low frequency wavelength and matrix material and the soft material " B ", so can only there be energy seldom to transfer to scatterer from the transmission ripple.But this situation can have rapid variation near resonant frequency.On resonant frequency, the virtual impedance of " A " and " B " assembled unit increases, thereby the energy of ripple may be transferred to the resonance scattering body.Particularly, on the frequency a little less than resonant frequency, effective elastic constant may be born.Thereby in these frequencies, ripple can not transmit, and is absorbed consumingly.
Embodiment 1
Lift the manufacture process example and the experimental data of a particular now.
In order to make rough surface, at first with the H that dilutes
2O: HCL: H
2O
2(5: 1: 1) carry out surface treatment to quite monodispersed Metal Ball, and in stove, heating is two hours under 80 ℃ temperature then.The ball of having handled with the silicone seal material coated of mineral turpentine dilution afterwards.The rubber school layer that is coated on the ball was placed 10 hours.At last, the metallic particles of coat with rubber is mixed with fast-curing resin, be configured as the sheet material that thickness is 12mm then.
Carry out the measurement of transfer voice with following method.Being installed in below the above-mentioned plate and top electro coupled oscillator and detector is connected respectively to function generator (HPPM5139) and bitubular loudspeaker (Dual Microphone Supply) (B﹠amp; K Model5935) on.Micropkonic output is connected on the digital oscilloscope (HP PM 3365).Under fixing input voltage, when changing frequency, just can read the intensity of sound of transmission.
Experimental result is illustrated among Fig. 2, as can be seen, rapid transmission do not occur with the rubber sphere of gum ball and tape tree fat and sink on the contrary, add in the situation of Metal Ball of coat with rubber at resin, material shows the effect that weakens transmission significantly in 100 hertz frequency windows.In the minimum point of transmission, the energy that spreads out of only is 3% of low-frequency pole limit value, and the thickness of sample that this effect takes place only is 1/330 of resin medium wavelength, about 4 meters of the wavelength under this frequency.See obviously also that under upper frequency second sink.Because this sample is to make with quite monodispersed ball, so, can predict, it is sagging to adopt polydisperse club to widen.And if change average-size, it is big more that minimum transmission frequency also can move a ball, and resonant frequency is just low more, as the same on the contrary.
The phenomenon that observes in order to understand, and confirm basic thought of the present invention, we have carried out numerical evaluation.The unit that our consideration has geometric configuration shown in Figure 3.Because substrate medium is quite hard, it is very big comparing with this unit at the wavelength of the low frequency wave of this transmission of materials.Therefore, in zero-order approximation, we can be the motion process of unit and basal body interface simple evenly displacement.Hard particle " A " is treated to perfect rigidity.Resulting elastic movement simultaneous equations and state (stress one strain stress relation) equation solves with analytical method.In addition, because the unit is much smaller than wavelength, so concerning the transmission ripple, effectively vertical elastic constant C connects rendeing a service f and displacement components u by relational expression f=-k2cu, wherein K is a wave vector, and here we have considered compressional wave.
(the Rameau constant of resin is got and is done λ=2.4 * 10 to adopt the actual experiment parameter
9N/m
2, μ=2.4 * 10
9N/m
2, density is got and is made 1.3g/cm
3For soft rubber, these parameters are got and are done λ=2.4 * 10
2N/m
2, μ=4.4 * 10
4N/m
2, density=1.05g/cm
3Metal Ball is considered to rigidity, and its density is 7.8g/cm
3) institute's result calculated is illustrated in Fig. 4.As can be seen, as the experiment seen, 500 and 1800Hz between two resonance are arranged.Bear being lower than on some frequencies of resonance effective elastic constant.This is appreciated that as follows physically, in any simple harmonic motion, acceleration, thus power always with 180 ° of the phasic differences mutually of displacement.This is because acceleration is the secondary note of the ancient Chinese merchant of displacement to the time.In being lower than the zone of resonance, the motion of hard particles and matrix displacement same-phase.Hard particles is applied to making a concerted effort and the displacement same-phase on the matrix, therefore with matrix in 180 ° of the phasic differences mutually of power.The counteracting of this power means, concerning ripple, has " softening " of a kind of material, and is final, just becomes negative elastic constant when power that hard particles applies surpasses power in the matrix.When frequency surpassed resonant frequency, the phase place of the motion of particle and matrix displacement was inconsistent.Therefore, power becomes synchronous, concerning ripple, has the sclerosis of an effective elastic constant.
Bear and imitate elastic constant and for the wave transfer characteristic of combined material direct influence is arranged, for this point is described, as the function of frequency, we have calculated transmission coefficient.Its result is illustrated in Fig. 5 as a comparison with experimental data, can see, with regard to the frequency location of transmission minimum, two results are consistent.
There is multiple embodiments needing to be suitable for suppressing, the sound wave of some characteristic frequency of shielding or absorption.As aforementioned, utilize the ball " A " of consistent size to give birth to specific response at the characteristic frequency special product.But the size that changes these balls can produce response on different frequency, thereby adopts the potpourri of the sphere of different size to provide sound insulation on needed various frequencies.And it is spherical that the shape of high density granular " A " needs not to be.If pursue characteristic frequency is had strong response, require the consistance of particle to get well so, and spherical object is realized this point easily, but, other embodiments can adopt Cylinder to reach identical purpose.
In addition, also can adopt other shape or irregular shape to widen the frequency range that material shields.
These constituent elements can adopt the combination of a lot of real materials.The material of particle " A " is compared with the soft formation of inlaying it quite high density and high rigidity, and the specific relative density between two kinds of materials can influence resonant frequency, and any stable material all might be used for this purpose.
As for material " B ", it should be much softer than material " A ".Because the elastic constant of soft material " B " also influences frequency resonance, thus in general can use as rubber or material with similarity, but also need to select.
Matrix material " C " should have than the high rigidity of soft elastic material " B ", in addition, the character of matrix material " C " must be by the operating position decision of combined material, as aforementioned, matrix material can be any structure material, as plastics, polymkeric substance-cement, organic glass or other this class material.
Therefore, can see that combined material provided by the present invention can have one or more resonant frequency, on these frequencies, the transmission of sound wave is obstructed greatly.Also can provide shielding to the sound of suitable low frequency with quite thin combined material.
Can adjust to intercept the sound wave of characteristic frequency combined material by the size and dimension of selecting particle, (frequency) scope of broad perhaps is provided by the particle that mixes different size and shape.
Though with reference to some embodiments the present invention is narrated, the professional and technical personnel can understand can carry out various variations, improvement and application to the present invention, and does not depart from the scope of appended claims defined.
Claims (8)
1. the combined material of the negative elasticity coefficient of the demonstration that is applicable to the low frequency sound insulation, this combined material has the matrix material of the general structured material of a kind of conduct, some soft elastic material districts in matrix material and the high and high stiff materials district of rigidity of density that is embedded in the soft elastic material is characterized in that: described density the mosaic area high and stiff materials that rigidity is high includes the particle of regular shape.
2. according to the described combined material of claim 1, the particle that it is characterized in that described those regular shapes is some spheric grain.
3. according to the described combined material of claim 1, it is characterized in that the particle of the described regular shape in the described material also comprises garden post rod.
4. according to the described combined material of claim 1, it is characterized in that described matrix material comprises plastics, metal, glass or polymeric material.
5. according to the described combined material of claim 4, it is characterized in that described polymeric material comprises cement material.
6. according to the described combined material of claim 1, it is characterized in that described soft elastic material comprises a kind of rubber or tartan.
7. according to the described combined material of claim 1, it is characterized in that described density height and the high stiff materials of rigidity comprise metallic particles.
8. method of making the described combined material of claim 1 is characterized in that: comprising with density that the high and high hard particles of rigidity is embedded in the soft elastic material zone and with described soft elastic material district is embedded in the matrix material.
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| CN 00106033 CN1118794C (en) | 2000-04-14 | 2000-04-14 | Composite material with negative elastic constant and its making process |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00106033 CN1118794C (en) | 2000-04-14 | 2000-04-14 | Composite material with negative elastic constant and its making process |
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| CN1118794C true CN1118794C (en) | 2003-08-20 |
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Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102314869A (en) * | 2010-07-08 | 2012-01-11 | 西北工业大学 | Negative elastic modulus acoustic super material based on hollow open ball |
| CN102568466A (en) * | 2010-12-14 | 2012-07-11 | 西北工业大学 | Tunable negative elastic modulus acoustic metamaterial |
| US9520121B2 (en) * | 2013-06-25 | 2016-12-13 | The Hong Kong University Of Science And Technology | Acoustic and vibrational energy absorption metamaterials |
| WO2015145337A1 (en) * | 2014-03-24 | 2015-10-01 | Chiappini Massimo | Composite foundations for seismic protection of building constructions |
| US11885120B2 (en) * | 2016-10-14 | 2024-01-30 | Oceanit Laboratories, Inc. | Construction materials with engineered sound attenuating properties and methods therefor |
| CN108374864B (en) * | 2018-02-09 | 2020-02-07 | 江苏科技大学 | Liquid pulsation attenuation device and method for thrust bearing |
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