An elastic wave asymmetric mode conversion device and a method of manufacturing the same

Abstract

The application discloses an elastic wave asymmetric mode conversion device and a preparation method thereof. The device comprises a substrate, a plurality of long patches and a plurality of short patches are pasted on the substrate, the long patches are parallel and equidistant to each other, the short patches are parallel and equidistant to each other, the length of the long patches is greater than that of the short patches, longitudinal wave pick-up and transverse wave pick-up are pasted on the substrate near the long patches and the short patches, and an exciter is pasted on one end of the substrate. By pasting the special patch group structure on the substrate, the material in the specific area of the substrate plane presents anisotropy, so that the material parameters of the area meet the conditions of mode selection and mode conversion, and finally the full mode conversion transmission of longitudinal waves and the suppression of the transmission of transverse waves are realized. The device has wide application prospects in the fields of mechanical equipment vibration reduction and noise reduction, environmental energy collection, pipeline nondestructive testing and medical ultrasonic imaging.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of elastic wave mode conversion, and relates to an elastic wave asymmetric mode conversion device and a preparation method thereof. BACKGROUND

[0002] Diodes are electronic components that can realize unidirectional conduction in circuit systems, and usually play the role of circuit switches to achieve the purpose of reducing power loss. Such diodes, in reasonable connection with other circuit components such as resistors, capacitors, and inductors, can be used to make circuit systems with different functions. Diodes are very common in circuit systems such as mobile phone circuit systems, household appliance circuits, and industrial equipment. With the continuous development of science and technology, people have expanded the idea of such circuit diodes to other fields, such as the commonly used light extraction technology realized by organic light-emitting diodes, and the unidirectional liquid delivery technology realized by liquid diodes made of super-wetting membranes.

[0003] Elastic waves are very common in nature, and their impact on human production and life is very significant. With the enrichment and development of metamaterials, people's ability to manipulate elastic waves has become stronger and stronger. The asymmetric transmission of transverse and longitudinal wave energy after mode conversion of elastic waves is a recent research hotspot. Elastic wave diodes have great application potential in the asymmetric transmission of energy and can realize effective elastic wave isolation, selection, and conversion. The mode conversion mechanism can realize the asymmetric transmission of elastic transverse and longitudinal wave energy. Such a mechanism generally contains two components: mode selection and mode conversion. Fluid-like metamaterials can achieve mode selection, and cross-mode interferometers or double-peak impedance matching elements studied in recent years can enable efficient conversion of wave energy of different modes. The propagation characteristics of elastic waves in thin plates have been extensively studied, so they are often used as basic elements for transmitting elastic waves. By designing different hole patterns on the thin plate, the material exhibits specific anisotropy, and the elastic constants of the material satisfy certain conditions for efficient mode conversion and suppression of transverse wave propagation. However, due to the particularity of these designs, they may damage the surface of the structure or cause the structure to lose its function while achieving high-efficiency asymmetric mode conversion. These are unacceptable in engineering practice, so the hole pattern design on the surface of such materials may weaken the strength of the structure and even cause the device to lose its function, greatly limiting the application of elastic wave diodes in engineering practice. SUMMARY

[0004] The purpose of the present application is to solve the technical problem of the prior art that high-efficiency mode conversion requires damaging the surface of the structure and may cause the structure to lose its function, and to provide an elastic wave asymmetric mode conversion device and a preparation method thereof.

[0005] To achieve the above object, the present application adopts the following technical solutions to achieve the above object:

[0006] In a first aspect, the present application provides an elastic wave asymmetric mode conversion device, comprising a base; a column of long patches and a column of short patches are pasted on the base; the long patches are parallel and equidistant to each other; the short patches are parallel and equidistant to each other; the length of the long patches is greater than that of the short patches; a longitudinal wave pick-up and a transverse wave pick-up are pasted on the side of the base close to the long patches and the short patches; and an exciter is also pasted on one end of the base.

[0007] Further, the horizontal directional angle θ1 of the long patches is -34° to -60°, and the horizontal directional angle θ2 of the short patches is 30° to 70°.

[0008] Further, the horizontal directional distance a x of the centroid of the long patches and the short patches is greater than 20mm, and the vertical directional distance a y is greater than 3mm.

[0009] Further, the long patches and the short patches are both in the shape of a strip, and the two ends are semicircular arc structures.

[0010] Further, the base, the long patches and the short patches are pasted by using strong foundry glue.

[0011] Further, the strong foundry glue is mixed by A glue and B glue in a weight ratio of 1:1.

[0012] Further, the longitudinal wave pick-up and the transverse wave pick-up are pure nickel sheets, and the exciter is a pure nickel strip.

[0013] Further, the longitudinal wave pick-up and the transverse wave pick-up are flush with the side close to the long patches or the short patches.

[0014] Further, the long patches and the short patches are metal materials.

[0015] In a second aspect, the present application provides a preparation method of the elastic wave asymmetric mode conversion device, comprising the following steps:

[0016] After the A glue and the B glue in the strong foundry glue are mixed uniformly in a mass ratio of 1:1, they are applied to one side of the long patches and the short patches, then the long patches and the short patches are arranged into two columns equidistantly and pasted on the base;

[0017] Two pure nickel sheets with different sizes are pasted on one side of the long patches, two pure nickel sheets same as the side of the long patches are pasted on one side of the short patches, and then a pure nickel strip is pasted on one side of the long patches or the short patches;

[0018] The elastic wave asymmetric mode conversion device is obtained by pressing a weight of no less than 15 Kg on the long patch and the short patch for 12 hours.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] The present application discloses an elastic wave asymmetric mode conversion device and a preparation method thereof. When a longitudinal wave electrical signal is applied to an exciter on the long patch side, the exciter drives the base to generate a mechanical longitudinal wave signal and propagate along the surface. When the mechanical longitudinal wave signal passes through the patch structure group, wave reflection and transmission occur. The reflected signal is transmitted to the longitudinal wave pickup and the transverse wave pickup on the long patch side. The transmitted signal is transmitted to the longitudinal wave pickup and the transverse wave pickup on the short patch side. The longitudinal wave pickup and the transverse wave pickup convert the mechanical longitudinal wave signal and the mechanical transverse wave signal into corresponding electrical signals and transmit them to a filter instrument. After filtering, the signals are transmitted to an oscilloscope, and the mode conversion efficiency on both sides can be calculated. The present application realizes the full mode conversion transmission of longitudinal waves and the suppression of transverse wave transmission by pasting a special patch group structure on the base, making the material in the specific area of the base plane anisotropic, so that the material parameters in this area meet the conditions of mode selection and mode conversion. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0022] Figure 1 The present application is a patch position and size schematic diagram;

[0023] Figure 2 The present application is a patch pasting schematic diagram;

[0024] Figure 3 The present application is a left-right high-efficiency mode conversion test schematic diagram of the embodiment;

[0025] Figure 4 The present application is a right-left high-efficiency reflected longitudinal wave test schematic diagram of the embodiment;

[0026] Figure 5 The present application is a left-right high-efficiency mode conversion schematic diagram of the embodiment;

[0027] Figure 6 The present application is a right-left high-efficiency longitudinal wave reflection schematic diagram of the embodiment;

[0028] Figure 7 The modal conversion transmission efficiency curve of the embodiment of the present application.

[0029] Wherein: 1-base; 2-long patch; 3-short patch; 4-A glue; 5-B glue; 6-strong foundry glue; 9-vibration exciter; 10-longitudinal wave pick-up; 11-transverse wave pick-up; 12-sine longitudinal wave signal; 13-transverse wave signal. DETAILED DESCRIPTION

[0030] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative work fall within the scope of protection of the present application.

[0032] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0033] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the present application is used, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0034] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly inclined. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0035] In the description of the embodiments of the present application, it also needs to be explained that, unless explicitly specified and limited, if the terms "arrange", "install", "connect", "connect" appear, they should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0036] The present application will be further described in detail below with reference to the accompanying drawings:

[0037] Referring to Figure 3 With Figure 4 , the present application provides an elastic wave asymmetric mode conversion device, comprising a base body 1; a plurality of long patches 2 and a plurality of short patches 3 are pasted on the base body 1; the plurality of long patches 2 are arranged parallel to each other and equidistantly; the plurality of short patches 3 are arranged parallel to each other and equidistantly; the length of the long patch 2 is greater than the length of the short patch 3; the longitudinal wave pick-up 10 and the transverse wave pick-up 11 are pasted on one side of the base body 1 close to the long patch 2 and one side close to the short patch 3; the base body 1 is also pasted with an exciter 9 at one end. By pasting a special patch group structure on the base body 1, the material in a specific area of the base body 1 plane presents anisotropy, so that the material parameters of the area meet the conditions of mode selection and mode conversion, and finally realize the full mode conversion transmission of longitudinal wave and at the same time suppress the transmission of transverse wave. It has broad application prospect in the fields of mechanical equipment vibration and noise reduction, environmental energy collection, pipeline nondestructive testing, medical ultrasonic imaging and the like.

[0038] Referring to Figure 1 With Figure 2 , in a feasible embodiment of the present application, the parameters involved in the long patch 2 and the short patch 3 include a total of 11, which are a0, l1, d1, l2, d2, θ1, θ2, a x , a y , h1, h2. Wherein a0 is the effective width of the superstructure. l1 is the total length of the long patch structure, that is, the diameter of the circle and the long side of the center rectangle. d1 is the width of the long patch structure, that is, the width of the center rectangle is also the diameter of the circle. l2 is the total length of the short patch structure, that is, the diameter of the circle and the long side of the center rectangle. d2 is the structure width of the short patch, that is, the width of the center rectangle is also the diameter of the circle. θ1 is the deflection angle of the long patch structure, and θ2 is the deflection angle of the short patch structure. a x is the horizontal distance between the centers of the long patch structure and the short patch structure. a yThe vertical distance between the centers of the long patch structure and the short patch structure is h1 and h2, wherein h1 is the thickness of the long patch structure, and h2 is the thickness of the short patch structure; the angle of the long patch 2 in the horizontal direction is θ1, and the angle of the short patch 3 in the horizontal direction is θ2, wherein θ1 is -34° to -60°, and θ2 is 30° to 70°.

[0039] The distance between the centers of the long patch 2 and the short patch 3 in the horizontal direction is a x The vertical distance between the centers of the long patch 2 and the short patch 3 is greater than 20 mm. y The vertical distance between the centers of the long patch 2 and the short patch 3 is greater than 3 mm.

[0040] The long patch 2 and the short patch 3 are both in the shape of a strip, and the two ends are in the shape of a semicircle.

[0041] The long patch 2 and the short patch 3 are adhered to the base 1 by using strong foundry glue 6, which is mixed by A glue 4 and B glue 5 in a weight ratio of 1:1.

[0042] The longitudinal wave pickup 10 and the transverse wave pickup 11 are pure nickel sheets, and the vibration exciter 9 is a pure nickel strip.

[0043] The longitudinal wave pickup 10 and the transverse wave pickup 11 are flush with one side of the long patch 2 or the short patch 3, and the long patch 2 and the short patch 3 are made of metal materials.

[0044] The embodiment of the application further discloses a preparation method of the elastic wave asymmetric mode conversion device, which comprises the following steps:

[0045] S1, the A glue 4 and the B glue 5 in the strong foundry glue are mixed uniformly in a mass ratio of 1:1, and then are applied to one side of the long patch 2 and the short patch 3, then the long patch 2 and the short patch 3 are arranged into two rows at equal intervals and are adhered to the base 1;

[0046] S2, two pure nickel sheets with different sizes are adhered to one side of the base 1 of the long patch 2, two pure nickel sheets same as those on the side of the long patch 2 are adhered to one side of the base 1 of the short patch 3, and then a pure nickel strip is adhered to one side of the base 1 of the long patch 2 or the short patch 3;

[0047] S3, a weight of no less than 15 Kg is pressed on the long patch 2 and the short patch 3, and the elastic wave mode conversion device is obtained after curing for 12 h.

[0048] Embodiment:

[0049] Reference Figure 3 An aluminum plane material with a size of 1000 mm*2000 mm*0.5 mm is used as the base 1, and the density of the aluminum material is 2700 Kg / m 3A glue 4 and B glue 5 are mixed in a mass ratio of 1:1 to obtain strong casting glue 6; the strong casting glue 6 is applied to one side of the long patch 2 and the short patch 3, then the long patch 2 and the short patch 3 are laid flat on an aluminum plane, pressed hard and then a weight of no less than 15 Kg is pressed at positions 7 and 8, and the patch structure group is effective after curing for 12 hours. Repeat the above process, and a plurality of patch structure groups are pasted in sequence to form a column, and the spacing between each patch structure group is a0, then a group of pure nickel patches with different sizes are pasted on both sides of the patch group, one of which is 54mm x 41mm x 0.15mm in size, used as a longitudinal wave pickup 10 for receiving longitudinal wave signals; the other is 31mm x 41mm x 0.15mm in size, used as a transverse wave pickup 11 for receiving transverse wave signals. A pure nickel strip is pasted on one end of the substrate 1 near the long patch 2, with a size of 27mm x 400mm x 0.15mm, used as an exciter 9 for exciting longitudinal wave signals. The parameters of the patch structure group are a0=30mm, l1=31mm, d1=10.4mm, l2=23.1mm, d2=13.8mm, θ1=-44°, θ2=49°, a x =40.2mm, a y =6.6mm, h1=0.6mm, h2=0.37mm.

[0050] A group of longitudinal wave signal excitations are applied to the exciter 9, which drives the substrate 1 to generate mechanical longitudinal wave signals and propagate along the surface. When the mechanical longitudinal wave signals pass through the patch structure group, wave reflection and transmission occur. The reflected signals are transmitted to the left longitudinal wave pickup 10 and the transverse wave pickup 11, and the transmitted signals are transmitted to the right longitudinal wave pickup 10 and the transverse wave pickup 11. The longitudinal wave pickup 10 and the transverse wave pickup 11 convert the mechanical longitudinal wave signals and the mechanical transverse wave signals into corresponding electrical signals and transmit them to the filtering instrument. After filtering, the signals are transmitted to the oscilloscope, and the left-right modal conversion efficiency can be calculated.

[0051] As shown in Figure 4 , the exciter 9 is located on the right side of the aluminum plane, i.e. the longitudinal wave signal is excited from the right side. Similar to the process of Figure 3 , the longitudinal wave pickup 10 and the transverse wave pickup 11 record the corresponding transverse and longitudinal wave signals, and the right-left reflected longitudinal wave efficiency can be calculated.

[0052] Figure 5 and Figure 6 are the transverse displacement and longitudinal displacement signal graphs near the center line of the aluminum plane at 96kHz. 12 is the excited sinusoidal longitudinal wave signal, and 13 is the converted transverse wave signal. As shown in Figure 5As shown, when the longitudinal wave passes through the positions of long patch 2 and short patch 3, the energy of the longitudinal wave is greatly attenuated. When the longitudinal wave is excited, there is almost no transverse wave signal on the left, while a sinusoidal transverse wave signal with a significant amplitude appears on the right. This indicates that the structure of long patch 2 and short patch 3 causes a mode conversion in the longitudinal wave signal on the left. Figure 6 As shown, when the longitudinal wave signal 12 is excited from the right side, there is neither a transverse wave signal 13 nor a longitudinal wave signal 12 on the left side; the longitudinal wave signal is reflected back to the right side. This indicates that the structure group of long patch 2 and short patch 3 causes the longitudinal wave signal on the right side to be reflected.

[0053] Figure 7 The graphs show the waveform conversion efficiency curves for left-to-right transverse and longitudinal waves, and the longitudinal wave reflection efficiency curves for right-to-left longitudinal waves. Within the 81kHz-98kHz range, the highest left-to-right longitudinal-transverse wave conversion efficiency and the highest right-to-left longitudinal wave reflection efficiency are clearly observed near 96kHz. The maximum values ​​are all close to 100%. Figure 7 Proof attached Figure 3 The long patch 2 and short patch 3 structure group can achieve high-efficiency waveform conversion and suppress transverse wave transmission within a certain frequency range, thereby achieving the effect of elastic wave diode and greatly increasing the possibility of practical engineering applications of elastic wave diode.

[0054] The design concept of this invention is as follows:

[0055] The design concept of this invention is as follows: First, anisotropy is achieved by attaching a patch structure to a homogeneous surface, thereby enabling mode conversion. The four conditions for full-mode conversion transmission theory are: (1) phase matching condition; (2) impedance matching condition; (3) polarization condition; and (4) weak-mode coupling condition. Based on these four conditions, an initial patch structure is designed to achieve high-efficiency mode conversion transmission. Second, longitudinal waves are incident on the left side, while transverse waves are on the right. The longitudinal wave incident on the right is reflected back after passing through the metamaterial region, while the transverse wave on the left remains unconverted. Considering that the longitudinal wave is a tensile wave in the x-direction and the transverse wave is a shear wave in the y-direction, the propagation of the longitudinal wave incident on the opposite side can be suppressed by the natural frequencies of the longitudinal and transverse waves propagating in the matrix. Therefore, a second patch is designed in the initial patch structure to suppress the propagation of the transverse wave when the longitudinal wave is incident in the opposite direction, thereby achieving unidirectional high-efficiency mode conversion.

[0056] By attaching special patch structures to the base plane, the material in a specific area of ​​the base plane becomes anisotropic, thereby enabling the material parameters in that area to meet the conditions for mode selection and mode conversion, ultimately achieving full mode conversion transmission of longitudinal waves while simultaneously suppressing the transmission of transverse waves.

[0057] The above merely describes the preferred embodiments of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An elastic wave asymmetric mode conversion device, characterized in that, The substrate includes a substrate (1); a row of long patches (2) and a row of short patches (3) are attached to the substrate (1); the long patches (2) are parallel to each other and equidistant from each other; the short patches (3) are parallel to each other and equidistant from each other; the length of the long patches (2) is greater than the length of the short patches (3); longitudinal wave pickups (10) and transverse wave pickups (11) are attached to both the side of the substrate (1) near the long patches (2) and the side near the short patches (3); an exciter (9) is also attached to one end of the substrate (1).

2. The elastic wave asymmetric mode conversion device according to claim 1, characterized in that, The horizontal deflection angle θ1 of the long patch (2) is -34° to -60°, and the horizontal deflection angle θ2 of the short patch (3) is 30° to 70°.

3. The elastic wave asymmetric mode conversion device according to claim 2, characterized in that, The horizontal distance a between the centroids of the long patch (2) and the short patch (3) x The vertical spacing a is greater than 20mm. y It is greater than 3mm.

4. The elastic wave asymmetric mode conversion device according to claim 3, characterized in that, Both the long patch (2) and the short patch (3) are strip-shaped with semi-circular ends.

5. The elastic wave asymmetric mode conversion device according to claim 1, characterized in that, The substrate (1) is bonded to the long patch (2) and the short patch (3) using strong casting adhesive (6).

6. The elastic wave asymmetric mode conversion device according to claim 5, characterized in that, The high-strength casting adhesive (6) is made by mixing adhesive A (4) and adhesive B (5) in a weight ratio of 1:

1.

7. The elastic wave asymmetric mode conversion device according to claim 6, characterized in that, The longitudinal wave pickup (10) and the transverse wave pickup (11) are made of pure nickel sheets; the exciter (9) is made of pure nickel strips.

8. The elastic wave asymmetric mode conversion device according to claim 7, characterized in that, The longitudinal wave pickup (10) and the transverse wave pickup (11) are flush with the side of the long patch (2) or the short patch (3).

9. The elastic wave asymmetric mode conversion device according to claim 8, characterized in that, The long patch (2) and the short patch (3) are made of metal.

10. A method for preparing an elastic wave asymmetric mode conversion device according to any one of claims 1-9, characterized in that, Includes the following steps: Mix the A glue (4) and B glue (5) in the strong casting adhesive at a mass ratio of 1:1 and apply them evenly to one side of the long patch (2) and the short patch (3). Then arrange the long patch (2) and the short patch (3) in two rows at equal intervals and stick them on the substrate (1). Two pure nickel sheets of different sizes are pasted on one side of the substrate (1) of the long patch (2); two pure nickel sheets of the same size as those on the side of the long patch (2) are pasted on one side of the substrate (1) of the short patch (3); and then a pure nickel strip is pasted on one side of the substrate (1) of either the long patch (2) or the short patch (3). A weight of no less than 15 kg is applied to the long patch (2) and the short patch (3), and after curing for 12 hours, an elastic wave asymmetric mode conversion device is obtained.

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