阅读说明：本技术 一种声学超材料及其制备方法 (Acoustic metamaterial and preparation method thereof ) 是由 张金虎 张天烨 张闯 张宇 于 2021-07-26 设计创作，主要内容包括：本发明提供了一种声学超材料及其制备方法,包括基体及微纳米颗粒；所述微纳米颗粒均匀分散在所述基体中。其制备方法包括以下步骤：S1,将硅橡胶与稀释剂混合均匀形成胶体；S2,向胶体中微纳米颗粒,搅拌均匀,超声分散得到复合溶液；S3,复合溶液经真空除泡后,转移至模具中,在55-65℃下恒温加热40-50min后取出冷却至室温,即得到所述声学超材料。该声学超材料的声学性能和力学性能连续可调。(The invention provides an acoustic metamaterial and a preparation method thereof, wherein the acoustic metamaterial comprises a substrate and micro-nano particles; the micro-nano particles are uniformly dispersed in the matrix. The preparation method comprises the following steps: s1, uniformly mixing the silicon rubber and the diluent to form a colloid; s2, uniformly stirring micro-nano particles in the colloid, and performing ultrasonic dispersion to obtain a composite solution; and S3, removing bubbles of the composite solution in vacuum, transferring the composite solution into a mold, heating at the constant temperature of 55-65 ℃ for 40-50min, taking out, and cooling to room temperature to obtain the acoustic metamaterial. The acoustic metamaterial has continuously adjustable acoustic performance and mechanical performance.)

1. An acoustic metamaterial is characterized by comprising a substrate and micro-nano particles; the micro-nano particles are uniformly dispersed in the matrix.

2. The acoustic metamaterial according to claim 1, wherein the substrate comprises silicone rubber and a diluent.

3. The acoustic metamaterial according to claim 1, wherein the micro-nano particles are tungsten powder or titanium powder.

4. The acoustic metamaterial according to claim 1, wherein the mass ratio of the silicone rubber to the diluent is 2: 0-3.

5. The acoustic metamaterial according to claim 1, wherein the mass ratio of the matrix to the micro-nano particles is 1: 0.1-4.

6. The acoustic metamaterial according to claim 1, wherein the micro-nano particles have a particle size of 50nm to 5 μm.

7. A method for preparing an acoustic metamaterial according to any one of claims 1 to 6, comprising the steps of:

s1, uniformly mixing the silicon rubber and the diluent to form a colloid;

s2, uniformly stirring micro-nano particles in the colloid, and performing ultrasonic dispersion to obtain a composite solution;

and S3, removing bubbles of the composite solution in vacuum, transferring the composite solution into a mold, heating at the constant temperature of 55-65 ℃ for 40-50min, taking out, and cooling to room temperature to obtain the acoustic metamaterial.

8. The method for preparing the acoustic metamaterial according to claim 6, wherein the mass ratio of the silicone rubber to the diluent is 2: 0-3.

9. The method for preparing the acoustic metamaterial according to claim 6, wherein the mass ratio of the matrix to the micro-nano particles is 1: 0.1-4.

10. The method for preparing the acoustic metamaterial according to claim 6, wherein the micro-nano particles have a particle size of 50nm to 5 μm.

Technical Field

The invention relates to an acoustic metamaterial and a preparation method thereof, belonging to the technical field of preparation of metamaterials.

Background

Acoustics is an important branch of physics, and mainly studies wave generation, transmission, reception and its effect. Acoustics plays an indispensable, even irreplaceable role in national major demands, and the application of acoustics is ubiquitous from the defense field to the civil field, such as underwater acoustics, marine exploration, ultrasonic medical diagnosis and treatment, noise control and the like. However, the conventional acoustic materials are difficult to implement precise and efficient sound wave manipulation, and limit the application of acoustics. In recent years, the emergence of acoustic metamaterials (metamaterials) endows the acoustic disciplines with a completely new life, and greatly promotes the development and progress of acoustic materials. Compared with the traditional acoustic material, the acoustic metamaterial has extraordinary physical properties which are not possessed by the traditional material, so that various novel acoustic phenomena and functions such as acoustic negative refraction, acoustic stealth, acoustic sub-wavelength imaging, acoustic holography, acoustic perfect absorption and the like are realized, great development potential is presented, and the acoustic metamaterial becomes a very leading topic in the modern acoustic field.

However, most of the existing acoustic metamaterials realize different equivalent medium parameters by a 3D printing or pillar inserting method, and the material is often rigid and cannot be continuously adjustable in structure, so that the acoustic artificial device is single in function; the lattice constant of the material is generally over millimeter magnitude, and the acoustic metamaterial generally requires that the wavelength of sound waves is far greater than the lattice constant, namely long wave is approximate, so the magnitude of the lattice constant limits the control performance of high-frequency sound waves, and the broadband effect in a high-frequency range cannot be achieved.

Disclosure of Invention

The invention provides an acoustic metamaterial and a preparation method thereof, which can effectively solve the problems.

The invention is realized by the following steps:

an acoustic metamaterial comprises a substrate and micro-nano particles; the micro-nano particles are uniformly dispersed in the matrix.

As a further improvement, the matrix comprises silicon rubber and a diluent.

As a further improvement, the micro-nano particles are tungsten powder or titanium powder.

As a further improvement, the mass ratio of the silicon rubber to the diluent is 2: 0-3.

As a further improvement, the mass ratio of the matrix to the micro-nano particles is 1: 0.1-4.

As a further improvement, the particle size of the micro-nano particles is 50nm-5 μm.

The preparation method of the acoustic metamaterial comprises the following steps:

s1, uniformly mixing the silicon rubber and the diluent to form a colloid;

s2, uniformly stirring micro-nano particles in the colloid, and performing ultrasonic dispersion to obtain a composite solution;

and S3, removing bubbles of the composite solution in vacuum, transferring the composite solution into a mold, heating at the constant temperature of 55-65 ℃ for 40-50min, taking out, and cooling to room temperature to obtain the acoustic metamaterial.

As a further improvement, the mass ratio of the silicon rubber to the diluent is 2: 0-3.

As a further improvement, the mass ratio of the matrix to the micro-nano particles is 1: 0.1-4.

As a further improvement, the particle size of the micro-nano particles is 50nm-5 μm.

The invention has the beneficial effects that:

according to the acoustic metamaterial, the base material is added with the micro-nano particles and uniformly dispersed, the refractive index of sound waves can be regulated and controlled in a large range and continuously, and the mechanical property can be regulated and controlled in a large range and continuously.

The acoustic metamaterial takes micro-nano particles as scatterers, has a lattice constant in the micron and nano level, has an excellent control effect on high-frequency sound waves, and has a very large frequency band range.

The acoustic metamaterial has high deformation capacity, can realize continuous and adjustable space of the artificial metamaterial through external force action such as stretching, rotating and the like, and enriches the acoustic function of the same artificial device.

The preparation process of the acoustic metamaterial is simple, convenient to operate and low in cost; meanwhile, different molds can be used according to requirements to prepare the composite materials with different initial forms, and the application scenarios are rich.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is an SEM image of the acoustic metamaterial provided in example 1 of the present invention (the mass fraction of the tungsten powder is 60%).

Fig. 2 is a graph of density theory and measurement results of the acoustic metamaterial provided in embodiment 1 of the present invention.

Fig. 3 is a graph of the sound velocity theory and the measurement result of the acoustic metamaterial provided in embodiment 1 of the present invention.

Fig. 4 is a graph of an acoustic impedance theory and a measurement result of the acoustic metamaterial provided in embodiment 1 of the present invention.

Fig. 5 is a stress-strain curve of the acoustic metamaterial provided in embodiment 2 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

The embodiment of the invention provides an acoustic metamaterial, which comprises a substrate and micro-nano particles; the micro-nano particles are uniformly dispersed in the matrix.

The substrate comprises silicon rubber and a diluent. The silicone rubber may be a commercially available silicone rubber, such as silicone rubber Ecoflex 00-30. The diluent is a Silicon Thinner diluent.

The micro-nano particles are selected from tungsten powder, titanium powder and the like, but are not limited to the tungsten powder and the titanium powder.

The mass ratio of the silicone rubber to the diluent is 2: 0-3. The mass ratio of the matrix to the micro-nano particles is 1: 0.1-4. The type and the mass fraction of the micro-nano particles are main parameters influencing the mechanical property (Young modulus and the like) and the acoustic property (refractive index, acoustic impedance and the like) of the material, the content of the diluent Silicon Thinner can change the mechanical property of the composite material and influence the gelling capacity, and the higher the content of the diluent Silicon Thinner is, the lower the limit of the adding quantity of the micro-nano particles is.

The particle size of the micro-nano particles is 50nm-5 mu m.

The embodiment also provides a preparation method of the acoustic metamaterial, which comprises the following steps:

and S1, uniformly mixing the silicon rubber and the diluent to form a colloid.

S2, uniformly stirring micro-nano particles in the colloid, and performing ultrasonic dispersion to obtain a composite solution; the stirring may be mechanical stirring, so that the components are initially dispersed; the ultrasonic dispersion enables further uniform dispersion of the components while achieving preliminary defoaming.

And S3, removing bubbles of the composite solution in vacuum, transferring the composite solution into a mold, heating at the constant temperature of 55-65 ℃ for 40-50min, taking out, and cooling to room temperature to obtain the acoustic metamaterial. The vacuum defoaming fully defoams the composite solution, and provides the performance of the acoustic metamaterial.

As a further improvement, the mass ratio of the silicon rubber to the diluent is 2: 0-3.

As a further improvement, the mass ratio of the matrix to the micro-nano particles is 1: 0.1-4.

As a further improvement, the particle size of the micro-nano particles is 50nm-5 μm.

Example 1

1) Mixing Part A, Part B and Silicon thinker of Ecoflex 00-30 together according to the weight ratio of 1: 1;

2) weighing 1-5 μm tungsten powder, and mixing according to the mass fractions of 0%, 10%, 25%, 40% and 60% in the colloid in the step 1;

3) the components are initially uniformly dispersed in a mechanical stirring manner;

4) placing the sample in an ultrasonic cleaner, and ultrasonically oscillating for a plurality of minutes to further uniformly disperse the components (the dispersion is more uniform as can be seen from SEM images), and simultaneously preliminarily removing bubbles;

5) then the sample is placed in a vacuum box for fully defoaming;

6) pouring the mixture into a mold, putting the mold into a thermostat with the temperature of 60 ℃, adding the mixture for 45 minutes, and taking the mixture out to obtain the acoustic metamaterial.

Example 2

Part A, Part B and Silicon thinker of Ecoflex 00-30 are in a weight ratio of 1: 0, tungsten powder is added in a mass fraction of 0%, 40%, 50% and 60%, and other operations are the same as in example 1.

And testing the mechanical and acoustic properties of the obtained acoustic metamaterial, wherein the testing methods are respectively as follows:

and (3) testing the acoustic performance:

1) the sound velocity of the acoustic metamaterial is measured by adopting an insertion substitution method, and the specific method is that two identical receiving and transmitting combined immersion transducers are oppositely placed in a water tank at a distance of about 2-3cm, a signal generator channel 1 is directly connected with an oscilloscope channel 1, the channel 2 is connected with a transmitting transducer, a receiving transducer is connected with the oscilloscope channel 2, two channels of the signal generator both transmit burst signals, the waveform is set to be sine, the period number is 5, the amplitude is 10V, and an oscilloscope trigger source is set to be the channel 1. And recording the waveform of the oscilloscope in an empty field environment, placing the sample between the two transducers, and recording the waveform of the oscilloscope.

2) The sound velocity calculation method performs processing according to equation (1):

where d is the thickness of the sample (obtained by a vernier caliper or thickness gauge), cw is the speed of sound of water (set here at 1483m/s), and Δ t is the difference in the two waveform offset times.

3) The test results are shown in FIG. 3.

And (3) testing mechanical properties:

1) the sample is tested in a uniaxial stretching mode by adopting an Instron (microtester5948) micro-force stretcher, the section of the stretching test sample is dumbbell-shaped, the thickness of the stretching test sample is 2mm, the distance between clamps is measured by a vernier caliper, and the stretching speed is set to be 10 mm/min.

2) Data processing: the stress and strain are calculated according to the following formula:

wherein σ is stress, F is tensile force, S is sample sectional area, ε is strain, Δ L is sample length variation, and L is distance between clamps (original length).

3) The test results are shown in FIG. 5.

The method based on Multiple Scattering Theory (MST) is used for analyzing sound velocity measurement results, and the basic idea is to calculate the effective longitudinal wave number k of the random distribution of scatterers (micro-nano particles) dispersed in a matrix (silicon rubber)_LThe expression is as follows:

where ρ is_eff＝Φρ₁+(1-Φ)ρ₀

Where Φ is the volume fraction, ρ₁Is the density of micro-nano particles, rho₀Density of the base (Silicone rubber), K₁Is the volume modulus, K, of micro-nano particles₀Bulk modulus of the base (Silicone rubber), G₁Shear modulus of micro-nano particles, G₀The shear modulus of the matrix (silicone rubber). The theoretical curves are shown in the attached figures 2, 3 and 4.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.