CN108827459A - A kind of strong reflection underwater acoustic materials and its application - Google Patents
A kind of strong reflection underwater acoustic materials and its application Download PDFInfo
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- CN108827459A CN108827459A CN201810649377.8A CN201810649377A CN108827459A CN 108827459 A CN108827459 A CN 108827459A CN 201810649377 A CN201810649377 A CN 201810649377A CN 108827459 A CN108827459 A CN 108827459A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H17/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves, not provided for in the preceding groups
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/162—Selection of materials
Abstract
The present invention relates to a kind of strong reflection underwater acoustic materials and its applications, belong to underwater acoustic materials design and underwater sound propagation control technology field.Underwater acoustic materials of the present invention need to meet following condition：Shear-wave velocity and longitudinal wave velocity ratio are greater than 10 less than the rigidity of 1/5, y major axes orientation and the stiffness ratio of x major axes orientation, main shaft and interface angle theta ≠ 0 ° and 90 °；Underwater acoustic materials of the present invention have Low ESR, high rigidity characteristic, while effective to wideband, oblique incidence sound wave, can satisfy the underwater sound strong reflection demand under deep water, hyperbaric environment；In addition, underwater acoustic materials of the present invention have a good application prospect in terms of barrier underwater noise, low frequency underwater high directivity sound source and acoustic pressure detection.
Description
Technical field
The present invention relates to a kind of underwater acoustic materials and its application with strong reflection characteristic belong to underwater acoustic materials design and the underwater sound
Transmission controe technical field.
Background technique
When sound wave is from a kind of medium incident to another medium, since impedance mismatch will appear energy reflection, this object
Reason phenomenon is known as the reflection of wave.Sound wave reflection has important application in life and scientific research：Soundproof plate by expressway is logical
It crosses and noise reflection is realized into barrier；Strong reflection using solid to air-borne sound can design two-dimensional surface sky using solid sheet
Gas acoustic waveguide.In above-mentioned sound insulation and wave guide applications, material is to influence the key factor of design, material on the reflection power of sound wave
It is thinner to reflect more strong then material requested, more meets engineering actual demand.
Impedance (Z) is the basic parameters,acoustic of acoustic medium, is defined as the product of density (ρ) and the velocity of sound (c), i.e. Z=ρ c,
The transaudient matching degree of two-phase medium can be portrayed.Reflection power of the sound wave at two-phase medium interface determine by resistance difference, two
Phase medium resistance difference is bigger, and sound wave is stronger in the reflection that interface generates, on the contrary then weaker.Metal, ceramics etc. are routinely solid
The velocity of sound of body and air is roughly the same, at most difference an order of magnitude, but high 3 magnitudes of its density ratio air, so that conventional solid
The interface reflection of big 3 orders of magnitude of body impedance ratio air, Conventional solid and air is very strong, and cm thick solid panel is i.e. ideally
Reflective air sound, therefore, Conventional solid can regard the strong reflection material for air-borne sound as.However, the density of Conventional solid, the velocity of sound
1 magnitude at most bigger than water, the i.e. impedance of conventional solid and water differ only by 1 magnitude, so Conventional solid is difficult to realize to water
The strong reflection of sound, unless using very thick and heavy solid panel, but this severely limits its applications in practical projects.Although logical
It crosses the highly-resistant materials such as solid and is difficult to realize underwater sound strong reflection, but can realize that the underwater sound is anti-by force by low resistivity materials such as air
It penetrates.For example, the impedance of air 3 magnitudes small compared with water, good underwater sound barrier is can be realized in relatively thin air layer, however, Low ESR
The extremely low critical defect of air rigidity is resulted in, hardly has any bearing capacity, is difficult to be suitable for bearing requirements
Underwater sound strong reflection demand.Since the contradiction of Low ESR and high rigidity is difficult to avoid that in isotropic material, do not study also at present
There are to the underwater sound underwater acoustic materials of strong reflection characteristic out.
Summary of the invention
Aiming at the problem that lacking underwater sound strong reflection material at present, the present invention provides a kind of strong reflection underwater acoustic materials, the water
Sound material has Low ESR, high rigidity characteristic, while effective to wideband, oblique incidence sound wave；And underwater sound material of the present invention
Material has a good application prospect in terms of barrier underwater noise, low frequency underwater high directivity sound source and acoustic pressure detection.
The purpose of the present invention is what is be achieved through the following technical solutions.
For isotropic material, there are unavoidable contradictions between Low ESR and high rigidity.However, being ground by theory
Study carefully discovery, which can then be avoided that in anisotropic solid material.Enter from the transaudient problem of anisotropic solid material interface
Hand can be adjusted impedance by the shearing wave of excitation anisotropic solid material, realize extremely low equivalent acoustic impedance, from
And achieve the purpose that strong reflection, and this adjusting will not generate significant impact to the rigidity of anisotropic solid material, it is full
The foot requirement of Low ESR and high rigidity.Specific theory analysis process is described below：
As shown in Figure 1, interface left area is water, interface right area is anisotropic solid material, and anisotropy is solid
Body material main shaft and interface angle theta ≠ 0 ° and 90 °；Plane wave from left area normal incidence to interface, incidence wave will excite it is each to
Shearing wave and longitudinal wave in anisotropic solid material, wave vector direction is consistent with interface normal direction, and a part of acoustic energy is anti-raw anti-at interface
It penetrates, another part is then transmitted into anisotropic solid material, consider that the interface condition of continuity can acquire sound pressure reflection coefficient,
In formula, R is reflection coefficient, ZsFor the equivalent acoustic impedance of anisotropic solid material, ρ0For the density of water, c0For water
The velocity of sound, ρsFor the density of anisotropic solid material, cTFor the velocity of wave of shearing wave, cLFor the velocity of wave of longitudinal wave, vLFor longitudinal wave polarization
Parameter, g are regulatory factor.
By above-mentioned relation formula it is found that equivalent acoustic impedance ZsNot only with p-wave impedance ρscLCorrelation, at the same with regulatory factor g phase
It closes, i.e., it is related to the shearing wave of excitation.For isotropic solid material, no matter whether its main shaft is parallel with interface, respectively to same
Property solid material is only inspired pure In-plane modes vL=0, regulatory factor g perseverance is 1, equivalent acoustic impedance ZsOnly determined by p-wave impedance
It is fixed.For anisotropic solid material, when main shaft is parallel with interface, anisotropic solid material equally only inspires pure longitudinal wave
Mode, equivalent acoustic impedance are only determined by p-wave impedance；And main shaft and interface it is not parallel when, the shearing wave of anisotropic solid material
Mode will also be excited, and longitudinal wave is also no longer pure p-wave model v at this timeLIt is 1 that ≠ 0, regulatory factor g are no longer permanent.Therefore, by setting
Count the adjustable reflection coefficient of shearing wave property of anisotropic solid material.
Make g minimum as a result, adjusting anisotropic solid material properties according to the above analysis, strong reflection effect can be realized
Fruit.Specific practice：It is required that cT/cLRatio it is as small as possible, while requiring longitudinal wave polarization parameter vLIt is as big as possible, that is, require
Anisotropic degree is sufficiently large, so that the longitudinal wave degree of polarization propagated is higher.Although anisotropic solid material can be made by changing g
The equivalent acoustic impedance of material is extremely low, but its rigidity is really smaller by being influenced, and at interface, normal stiffness size isWith longitudinal wave modulus in same magnitude, this is high rigidity advantage not available for air layer.
In conclusion the strong reflection underwater acoustic materials for having both Low ESR and high rigidity then need to meet following condition：
(1) shear-wave velocity is much smaller than longitudinal wave velocity, c in the underwater acoustic materialsT/cL< 1/5；
(2) the underwater acoustic materials rigidity has strong anisotropy, Ky/Kx> 10, KxIt is the underwater acoustic materials in x main shaft square
To rigidity, KyFor the underwater acoustic materials y major axes orientation rigidity；
(3) major axes orientation and interface are not parallel in the underwater acoustic materials, θ ≠ 0 ° and 90 °, preferablySo that equivalent acoustic impedance is minimum.
The strong reflection underwater acoustic materials are five mold materials of honeycomb being made of hexagon unit cell, and the unit cell is by Y shape bar
With cavity form, Y shape bar is intersected in unit cell by a vertical bar and left and right two symmetrical braces to be constituted, vertical bar and
Two disjoint other ends of brace are located at three non-conterminous vertex in hexagon；Wherein, each in five mold materials
Parameter meets following relational expression,
θ ≠ 0 ° and 90 °；
Q=ml；
In formula, l is the length of brace, and m is the length of vertical bar, and t is the thickness of vertical bar and brace, and β is the extension of vertical bar
Angle between line and brace.
A kind of low frequency high directivity sound source component, the component include energy converter and arc reflection plate, the arc reflection
Plate is using made of underwater acoustic materials of the present invention；
Energy converter is placed on the focal position of arc reflection plate, and cambered surface of the sound wave through arc reflection plate that energy converter generates is anti-
High directivity plane sound wave, the directly incident test target of high directivity plane sound wave are formed after penetrating；Wherein, high directivity plane sound
The directive property of wave determines by the wave length of sound that the radius of arc reflection plate is generated with energy converter, the radius of general arc reflection plate with
Wave length of sound ratio is not less than 5.
A kind of acoustic pressure probe assembly, the component include hydrophone and arc reflection plate, and the arc reflection plate is to use
Made of underwater acoustic materials of the present invention；
Hydrophone is placed on the focal position of arc reflection plate, and the sound wave for reaching arc reflection plate cambered surface is reflected by cambered surface
To focal position, enhance the received acoustic signals intensity of focal point hydrophone.Acoustic signals enhance degree and arc reflection plate
Radius is related, and radius is bigger, and the sound wave for reaching arc reflection plate is more, then the sound wave for reflexing to focus is also more, then sound wave is believed
Number enhancing degree it is bigger.In practical applications, according to the intensity of sound wave to be measured, the size of arc reflection plate is rationally set.
Beneficial effect
Strong reflection underwater acoustic materials of the present invention have Low ESR, high rigidity characteristic, while to wideband, oblique incidence sound wave
Effectively, it can satisfy the underwater sound strong reflection demand under deep water, hyperbaric environment；And underwater acoustic materials of the present invention are in barrier water
Lower noise, low frequency underwater high directivity sound source and acoustic pressure detection aspect have a good application prospect.
Detailed description of the invention
Fig. 1 is anisotropic solid material and the transaudient schematic diagram of water termination.
Fig. 2 is strong reflection underwater acoustic materials described in embodiment 1 and the underwater sound reflection coefficient comparison diagram for waiting thick steel plates.
Fig. 3 is that the unit cell of five mold materials of the present invention is configured schematic diagram.
Fig. 4 is five mold materials described in embodiment 2 and waits thick steel plates to the contrast schematic diagram of underwater sound barriering effect.
Fig. 5 is the application schematic diagram of low frequency underwater high directivity sound source component described in embodiment 3.
Fig. 6 is the application schematic diagram of acoustic pressure probe assembly described in embodiment 4.
Wherein, 1- arc reflection plate, 1-1- vertical bar, 1-2- brace, 1-3- cavity, 2- energy converter, 3- test target, 4- water
Listen device.
Specific embodiment
The present invention is further elaborated with reference to the accompanying drawings and detailed description.
Embodiment 1
Be respectively adopted steel plate, strong reflection underwater acoustic materials of the present invention preparation strong reflection template die quefrency range be 0~
The thickness of 700Hz, steel plate and strong reflection plate is 21mm, and water medium wavelength is at least 119 times of plate thickness.The density and volume of water
Modulus is ρ0=1000kg/m3And K0=2.25GPa, density, Young's modulus and the Poisson's ratio of steel plate are respectively ρsteel=
7800kg/m3、Esteel=220GPa and vsteel=0.28, density, rigidity and its five modular character parameters of strong reflection plate are respectively
ρs=0.5 ρ0、Kx=0.1K0、Ky=10K0, π=0.999, μ=0.001.The master of strong reflection underwater acoustic materials described in the present embodiment
Axis and interface angle theta=15 °, the shearing wave of excitation and the ripple ratio of longitudinal wave are cT/cL≈ 0.015, longitudinal wave polarization parameter are vL
P-wave impedance can be reduced by two magnitudes by the above parameter, to obtain the equivalent acoustic impedance for being far below water by=- 1.405.Its
In, π, μ are two five modular character parameters of definition, it is specifically defined and is detailed in following formula, K in formulaxIt is material in the rigid of x major axes orientation
Degree, KyRigidity for material in y major axes orientation, KxyFor the coupling stiffness of two principal direction of material, GxyFor the modulus of shearing of material；
From sound pressure reflection coefficient shown in Fig. 2 it is found that steel plate is almost fully transparent to the underwater sound, and the reflection system of strong reflection plate
Number very close 1.For example, water medium wavelength is about 1400 times of plate thickness or so, the reflection system of strong reflection plate when frequency is 50Hz
Number is up to | R |=0.993, and it is almost impossible in traditional material for extreme sub-wavelength strong reflection.
Embodiment 2
Strong reflection underwater acoustic materials described in the present embodiment are five mold materials of honeycomb being made of hexagon unit cell, the list
Born of the same parents are made of Y shape bar and cavity 1-3, as shown in Figure 3；Fill air or vacuum in cavity 1-3, Y shape bar by a vertical bar 1-1 and
Left and right two symmetrical brace 1-2 intersect composition in unit cell, and vertical bar 1-1 and two brace 1-2 are disjoint another
End is located at three non-conterminous vertex in hexagon；Wherein, l is the length of brace 1-2, and m is the length of vertical bar 1-1, and t is
The thickness of vertical bar 1-1 and brace 1-2, β are the angle between the extended line and brace 1-2 of vertical bar 1-1；
The design parameter of strong reflection underwater acoustic materials described in the present embodiment is：T=0.4mm, β=74.2 °, m=2mm, l=
8mm；Using steel as basis material, equivalent density, rigidity and five modular character parameters are total：ρs=0.86 ρ0, Kx=
0.216K0, Ky=8.879K0, π=0.982, μ=0.057.By hexagon single cell structure along lattice vector a1、a2Translation can be with structure
At five mold materials, when the direction main shaft x of five mold materials is consistent with interface, longitudinal wave, acoustic impedance can only be inspired in five mold materials
With the roughly the same Z of waters=0.431 ρ0c0；The main shafts of five mold materials and interface are there are when angle theta=28.5 °, longitudinal wave polarization parameter
For vL=-1.017, the ratio between shear wave velocity and longitudinal wave velocity are cT/cLStrong reflection effect may be implemented in ≈ 0.063.
Five mold materials and wait that five mold materials, main shaft and the interface angle parallel with interface to main shaft are 28.5 ° respectively
Thick steel plate simulates underwater sound barriering effect, and three kinds of lamella thickness are 21mm, is as a result detailed in Fig. 4；Wherein, Fig. 4 (a) is main
The analog result for five mold materials that axis and interface angle are 28.5 °, Fig. 4 (b) are the analog results for waiting thick steel plates, and Fig. 4 (c) is main
The analog result of axis five mold materials parallel with interface.
Incident sound pressure is Gaussian pulse wave beam exp (- (π (t-tc)/3000)2)×cos(2πfc(t-tc)), it can verify
The wideband and broad-angle-incident validity for five mold materials that main shaft and interface angle are 28.5 °；Wherein, Gaussian pulse centre frequency
For fc=1kHz, amplitude half-band width are 0.6kHz, and numerical simulation is completed in COMSOL software.
From analog result it is known that in wavelength 71 times of low frequency underwater incidence bigger than plate thickness, main shaft and interface angle
For 28.5 ° of five mold materials energy good barrier incident acoustic waves (Fig. 4 (a)), and incidence wave such as almost penetrates at the thick steel plates (Fig. 4
(b)) and main shaft five mold materials (Fig. 4 (c)) parallel with interface, to confirm the importance of five mold materials main shafts deflection.
Result above demonstrate proposition the underwater sound barrier mechanism, show simultaneously strong reflection underwater acoustic materials of the present invention have wideband,
Wide angle adaptability.
Embodiment 3
Low frequency high directivity sound source is that large scale acoustic model verifies necessary equipment, is directed toward the directly incident survey of sound wave by height
Target 3 is tried, the water surface can be avoided passing through, the bottom is transferred to experiment and brings interference.Existing low frequency high directivity sound source mainly uses
Transducer array is realized, generates almost plane wave by multiple energy converters 2 while sounding, more, cost that there are 2 quantity of energy converter
Huge, the disadvantages of directive property is inadequate.
Based on strong reflection underwater acoustic materials of the present invention, the present embodiment proposes a kind of low frequency high direction sound source component,
The component includes energy converter 2 and arc reflection plate 1, and the arc reflection plate 1 is made of using underwater acoustic materials of the present invention
's；
Energy converter 2 is placed on the focal position of arc reflection plate 1, arc of the sound wave through arc reflection plate 1 that energy converter 2 generates
Formation high directivity plane sound wave after the reflection of face, the directly incident test target 3 of high directivity plane sound wave, as shown in Figure 5；Its
In, the directive property of high directivity plane sound wave is determined by the wave length of sound that the radius of arc reflection plate 1 is generated with energy converter 2, one
As arc reflection plate 1 radius and wave length of sound ratio be not less than 5, in practical applications, according to the high directivity for sound wave
It is required that the size of arc reflection plate 1 can rationally be arranged.Arc reflection plate 1 described in the present embodiment has stronger rigidity, is applicable in
In deepwater environment testing requirement, and have many advantages, such as energy converter 2 less, it is at low cost.
Embodiment 4
Sound wave can long-distance communications in water, be the important means of underwater communication and navigation, but propagate great distances
Acoustic pressure may be decreased to detectivity hereinafter, cannot achieve the detection to sound wave afterwards.
Based on strong reflection underwater acoustic materials of the present invention, the present embodiment proposes a kind of acoustic pressure probe assembly, and described group
Part includes hydrophone 4 and arc reflection plate 1, and the arc reflection plate 1 is using made of underwater acoustic materials of the present invention；
Hydrophone 4 is placed on the focal position of arc reflection plate 1, and the sound wave for reaching 1 cambered surface of arc reflection plate passes through cambered surface
Focal position is reflexed to, enhances the received acoustic signals intensity of focal point hydrophone 4, as shown in Figure 6.Acoustic signals enhance degree
Related with the radius of arc reflection plate 1, radius is bigger, and the sound wave for reaching arc reflection plate 1 is more, then reflexes to the sound wave of focus
Also more, then acoustic signals enhancing degree is bigger, is more advantageously implemented the detection to remote weak sound wave, improves hydrophone 4
Sensitivity level is detected, underwater sound telecommunication and detectivity are enhanced.In practical applications, it according to the intensity of sound wave to be measured, closes
The size of reason setting arc reflection plate 1.
In conclusion the above is merely preferred embodiments of the present invention, being not intended to limit the scope of the present invention.
All within the spirits and principles of the present invention, any modification, equivalent replacement, improvement and so on should be included in of the invention
Within protection scope.
Claims (6)
1. a kind of strong reflection underwater acoustic materials, it is characterised in that：The underwater acoustic materials are a kind of anisotropic materials, need to be met as follows
Condition：
(1) main shaft of the underwater acoustic materials and interface angle theta ≠ 0 ° and 90 °；
(2) in the underwater acoustic materials ratio of shear-wave velocity and longitudinal wave velocity less than 1/5；
(3) rigidity of the underwater acoustic materials in y major axes orientation is greater than 10 with the stiffness ratio in x major axes orientation.
2. a kind of strong reflection underwater acoustic materials according to claim 1, it is characterised in that：The underwater acoustic materials are by hexagon
Five mold materials of honeycomb that unit cell is constituted, the unit cell are made of Y shape bar and cavity (1-3), and Y shape bar is by a vertical bar (1-1)
Intersect composition in unit cell with left and right two symmetrical braces (1-2), vertical bar (1-1) and two braces (1-2) not phase
The other end of friendship is located at three non-conterminous vertex in hexagon；Wherein, each parameter satisfaction is as follows in five mold materials
Relational expression,
And
θ ≠ 0 ° and 90 °；
Q=m/l；
In formula, l is the length of brace (1-2), and m is the length of vertical bar (1-1), and t is the thickness of vertical bar (1-1) and brace (1-2)
Degree, β are the angle between the extended line and brace (1-2) of vertical bar (1-1).
3. a kind of strong reflection underwater acoustic materials according to claim 1 or 2, it is characterised in that：It is described
In formula, cTFor the velocity of wave of shearing wave, cLFor the velocity of wave of longitudinal wave, vLFor longitudinal wave polarization parameter.
4. a kind of low frequency high directivity sound source component, it is characterised in that：The component includes energy converter (2) and arc reflection plate
(1)；Wherein, arc reflection plate (1) is using made of underwater acoustic materials described in claims 1 or 2；
Energy converter (2) is placed on the focal position of arc reflection plate (1), and the sound wave that energy converter (2) generates is through arc reflection plate (1)
Cambered surface reflection after form high directivity plane sound wave, the directly incident test target (3) of high directivity plane sound wave.
5. a kind of low frequency high directivity sound source component according to claim 4, it is characterised in that：Arc reflection plate (1)
The wave length of sound ratio that radius and energy converter (2) generate is not less than 5.
6. a kind of acoustic pressure probe assembly, it is characterised in that：The component includes hydrophone (4) and arc reflection plate (1)；Wherein,
Arc reflection plate (1) is using made of underwater acoustic materials described in claims 1 or 2；
Hydrophone (4) is placed on the focal position of arc reflection plate (1), and the sound wave for reaching arc reflection plate (1) cambered surface passes through arc
Face reflexes to focal position, enhances focal point hydrophone (4) received acoustic signals intensity.
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