A band gap real-time adjustable pneumatic driving type broadband vibration isolation metamaterial and a preparation method and application thereof

Abstract

A kind of band gap real-time adjustable pneumatic drive type broadband vibration isolation metamaterial and its preparation method and application.The present application belongs to the field of mechanical metamaterials.The present application is to solve the technical problem of low efficiency and low reliability caused by the cumbersome band gap adjustment method of existing vibration isolation materials.The metamaterial of the present application includes several series of basic units, the basic unit is a one-piece structure, the top and bottom are both cylindrical, the middle part is a truncated cone, the diameters of the top and bottom cylindrical correspond to the diameters of the top and bottom surfaces of the truncated cone, the basic unit has a cavity inside, the shape is the same as the overall shape of the middle part and the bottom, and the bottom cylindrical and the top cylindrical have first and second through holes respectively, which are in communication with the cavity.The present application realizes the broadband real-time adjustment of the band gap through structural design and pneumatic drive, and has the advantages of simple structure, easy processing and strong environmental adaptability, and can be used normally in conventional and various extreme environments.

Description

Technical Field

[0001] This invention belongs to the field of mechanical metamaterials, specifically relating to a pneumatically driven broadband vibration isolation metamaterial with real-time adjustable bandgap, its preparation method, and its application. Background Technology

[0002] In recent years, as fields such as aerospace, transportation, and ultra-precision manufacturing and measurement have developed towards operating under extreme conditions or reaching performance limits, the demand for vibration isolation structures has become increasingly urgent, posing new challenges to the structure and performance of vibration isolators. Traditional vibration isolation methods are mostly based on mechanical structures, using magnetic springs, air springs, etc., to achieve vibration isolation. Meanwhile, to achieve low-frequency vibration isolation, a quasi-zero stiffness nonlinear method has been proposed, utilizing the idea of ​​stiffness cancellation to suppress low-frequency or ultra-low-frequency vibrations based on the parallel combination of positive and negative stiffness mechanisms. However, these structures are large in size and heavy in weight, and the mechanical structure inevitably introduces mechanical friction, resulting in shortcomings in terms of lightweighting and stability.

[0003] Mechanical metamaterials are periodic materials / structures designed based on artificial microstructures. They possess numerous mechanical properties and laws that differ significantly from natural materials or structures, such as negative stiffness, negative Poisson's ratio, and negative thermal expansion, providing a new approach for realizing intelligent adjustable vibration isolation structures. The performance and dynamic response of traditional vibration isolation structures are difficult to alter after manufacturing, limiting their operation to a fixed frequency range, which greatly restricts the development and potential applications of vibration isolation technology. Current control methods based on magnetic and electric fields suffer from strong environmental dependence and complex operation, hindering their use in extreme environments (such as the seabed). Furthermore, in traditional vibration isolation structures, mass blocks are the core element, adjusting the bandgap by adding different mass blocks; however, such structures suffer from cumbersome operation, low efficiency, and low reliability. Therefore, there is an urgent need to develop a novel vibration isolation structure to solve these problems. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problems of low efficiency and low reliability caused by the cumbersome bandgap adjustment methods of existing vibration isolation materials, and to provide a pneumatically driven broadband vibration isolation metamaterial with real-time adjustable bandgap, its preparation method and application.

[0005] One objective of this invention is to provide a pneumatically driven broadband vibration isolation metamaterial with real-time adjustable bandgap, comprising several basic units connected in series. Each basic unit is an integral structure, with a cylinder at the top and bottom and a truncated cone in the middle. When connected in series, the bottom of one basic unit is connected to the bottom of another basic unit, and the top of one basic unit is connected to the top of another basic unit. The diameter of the top cylinder is equal to the diameter of the top surface of the truncated cone, and the diameter of the bottom cylinder is equal to the diameter of the bottom surface of the truncated cone. Each basic unit has a cavity inside, located in the middle and bottom of the basic unit, and the cavity has the same shape as the overall shape formed by the middle and bottom of the basic unit. The bottom cylinder and the top cylinder have a first through hole and a second through hole communicating with the cavity, respectively, at their axial centers.

[0006] Further specified, the radius R of the bottom surface of the truncated cone is 2-3 times the radius r of the top surface, and the angle α between the generatrix of the truncated cone and the bottom surface is arctan[h / 2(r1-r)]°, where h is the cavity height and r1 is the radius of the bottom surface of the cavity.

[0007] Further defined, the distance t from the bottom surface of the cavity to the bottom surface of the basic unit. b ≥ Height t of the top cylinder s The distance t from the bottom surface of the cavity to the bottom surface of the basic unit b ≥ Cavity height h ≥ Height t of the top cylinder s The distance t from the cavity sidewall to the truncated cone sidewall is not less than 1 / 3 of the cavity height h, and the difference l between the radius R of the truncated cone bottom surface and the radius r1 of the cavity bottom surface is greater than or equal to the distance t from the cavity sidewall to the truncated cone sidewall.

[0008] Further specifying, the radius r of the 1 / 3 truncated cone top surface is greater than or equal to the radii r of the first through hole and the second through hole. c ≥ Cavity height h.

[0009] Further, the number of basic units N ≥ 2.

[0010] Further specifying, the metamaterial is made of elastomeric rubber.

[0011] Furthermore, the elastomeric rubber includes polyurethane rubber, natural rubber, and butadiene rubber.

[0012] The second objective of this invention is to provide a method for preparing a pneumatically driven broadband vibration isolation metamaterial with a real-time adjustable bandgap, wherein the method includes:

[0013] First, a mold is prepared by 3D printing. Then, the mold is preheated, followed by vacuum casting and constant temperature curing to obtain the metamaterial.

[0014] Further restrictions apply: the mold should be preheated to 60-70℃.

[0015] Further, the constant temperature curing temperature is 60-70℃, and the time is 2-3 hours.

[0016] The third objective of this invention is to provide a method for adjusting the bandgap of the aforementioned broadband vibration isolation metamaterial, wherein the method achieves real-time adjustment of the metamaterial bandgap by regulating the internal pressure of the cavity through air filling.

[0017] The fourth objective of this invention is to provide an aerodynamically driven broadband vibration isolation metamaterial with real-time adjustable bandgap for application in aerospace, transportation, and deep-sea environments.

[0018] The significant advantages of this invention compared to existing technologies are:

[0019] (1) Through ingenious structural design, this invention proposes a broadband vibration isolation metamaterial with a real-time adjustable bandgap based on pneumatic drive. It has advantages such as small size, simple structure, light weight, easy molding, and real-time adjustable bandgap, and can be well matched with different working conditions. At the same time, the pneumatic drive is simple to operate and has strong environmental adaptability. It can be used normally in both conventional and various extreme environments, further expanding the application of vibration isolation structures and providing a feasible solution for the development of intelligent adaptive metamaterials.

[0020] (2) The cavity is the main deformation region of the structure. When the metamaterial is subjected to external loads, the cavity will undergo elastic deformation, exhibiting a nonlinear response. The two sides of the cavity are supporting walls (the distance from the cavity sidewall to the bottom cylindrical sidewall). Their functions are twofold: first, to provide load constraints, limiting displacement during cavity compression and ensuring axial deformation of the structure; and second, to maintain structural airtightness, providing a structural basis for later bandgap adjustment based on pneumatic drive. The cavity has cylindrical mass blocks at the top and bottom, with flow channels also provided on them to facilitate gas flow. In this invention, another function of the mass blocks is to facilitate later bonding and assembly between units to form a multi-unit series structure.

[0021] (3) When gas is injected into the metamaterial, the structural stiffness changes significantly due to the change in internal pressure, thereby altering its natural frequency and consequently changing the metamaterial's bandgap. The bandgap shifts towards the high-frequency region as the cavity pressure increases. When the cavity pressure is 20 kPa, the starting frequency of the structural bandgap increases by 393%, approximately 4.9 times that of the unpressurized structure, and the bandgap width can also be adjusted approximately 5-6 times. Real-time adjustment of the metamaterial's bandgap can be achieved through real-time control of the gas pressure for different operating conditions.

[0022] (4) This invention achieves real-time adjustment of the bandgap through structural design and aerodynamic drive, breaking the problem that the performance of traditional vibration isolation structures is difficult to change after manufacturing, improving the application potential of metamaterials in the field of vibration isolation, and providing a possible way for the realization of intelligent adaptive structures.

[0023] (5) The metamaterial of the present invention can achieve broadband bandgap adjustment, has a simple structure, is easy to process, and can be mass-produced through additive manufacturing technology. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the basic unit structure of the broadband vibration isolation metamaterial of the present invention;

[0025] Figure 2 This is a front view of the broadband vibration isolation metamaterial of the present invention;

[0026] Figure 3 The figures show the quasi-static compression response curves of the basic unit structure in the broadband vibration isolation metamaterial of this invention under different cavity pressures.

[0027] Figure 4 The curves show the stiffness variation of the basic unit structure in the broadband vibration isolation metamaterial of this invention under different cavity pressures.

[0028] Figure 5 The transmissivity curves of vibration isolation metamaterials with different numbers of basic units (N = 2, 4, 6, 10, 20, 30) in the embodiments of the present invention are shown in the form of transmissivity curves without cavity pressure.

[0029] Figure 6 The transmissivity curves of vibration isolation metamaterials with different numbers of basic units (N = 2, 4, 6, 10, 20, 30) in the embodiments of the present invention at a cavity pressure of 20 kPa are shown.

[0030] Figure 7 The time-domain response curve of the broadband vibration isolation metamaterial (N=4) of the present invention at a frequency of 200Hz is shown. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0032] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0033] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used in the following embodiments, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such a composition, step, method, article, or apparatus.

[0034] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range. In this specification and claims, range definitions may be combined and / or interchanged, unless otherwise stated, these ranges include all subranges contained therein.

[0035] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0036] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] Example 1: Combination Figure 1-2 This embodiment of a pneumatically driven broadband vibration isolation metamaterial with real-time adjustable bandgap includes several basic units connected in series. The basic unit is an integral structure, with the top 1-1 and bottom 1-3 being cylinders and the middle 1-2 being a truncated cone. When connected in series, the bottom of one basic unit is connected to the bottom of another basic unit, and the top of one basic unit is connected to the top of another basic unit. The diameter of the top cylinder 1-1 is equal to the diameter of the top surface of the truncated cone 1-2, and the diameter of the bottom cylinder 1-3 is equal to the diameter of the bottom surface of the truncated cone 1-2. The basic unit has a cavity 1-4 inside, which is located in the middle 1-2 and bottom 1-3 of the basic unit. The cavity 1-4 has the same shape as the overall shape formed by the middle 1-2 and bottom 1-3 of the basic unit. The bottom cylinder 1-3 and the top cylinder 1-1 have a first through hole 1-5 and a second through hole 1-6 communicating with the cavity 1-4, respectively.

[0040] The radius of the base of truncated cone 1-2 is R = 37 mm, the radius of the top surface of truncated cone 1-2 is r = 15 mm, and the angle α between the generatrix of truncated cone 1-2 and the base is arctan[h / 2(r1-r)]°;

[0041] The distance t from the bottom surface of cavity 1-4 to the bottom surface of the basic unit b =5mm, the height t of the top cylinder 1-1 s =3mm, cavity height h=2.7mm, distance t=1mm from sidewall 1-4 of cavity to sidewall 1-2 of truncated cone;

[0042] The radius of the first through hole 1-5 is equal to the radius of the second through hole 1-6 (r). c =5mm;

[0043] The difference between the base radius R of the truncated cone 1-2 and the base radius r1 (=35mm) of the cavity 1-4 is l=2mm.

[0044] The cavity is the main deformation region of the structure. When the metamaterial is subjected to external loads, the cavity undergoes elastic deformation, exhibiting a nonlinear response. Supporting walls (the distance from the cavity sidewall to the bottom cylindrical sidewall) on both sides of the cavity serve two purposes: first, to provide load constraints, limiting displacement during cavity compression and ensuring axial deformation; second, to maintain structural airtightness, providing a structural basis for subsequent bandgap adjustment based on pneumatic drive. Cylindrical mass blocks are located above and below the cavity, with flow channels also provided on them to facilitate gas flow. In this invention, another function of the mass blocks is to facilitate subsequent bonding and assembly between units to form a multi-unit series structure.

[0045] Preparation method: First, a mold is prepared by 3D printing. Then, the mold is preheated to 65°C. Next, the working chamber is evacuated to a vacuum environment and polyurethane elastic rubber (elastic modulus of 15 MPa, purchased from Dongguan Jiarui Model Technology Co., Ltd.) is injected. After 90 seconds, atmospheric pressure is restored, and then the material is cured at 65°C for 2.5 hours to obtain the metamaterial. During the preparation process, it is crucial to prevent moisture intrusion, otherwise, a large number of bubbles will form in the cured material, affecting the preparation accuracy. Furthermore, the mold preheating stage is critical; excessively low mold temperature will result in incomplete curing of the structure and affect the dimensional accuracy of the sample. The metamaterial of this invention can achieve wide bandgap adjustment, has a simple structure, is easy to process, and can be mass-produced using additive manufacturing technology.

[0046] The quasi-static compressive mechanics curves and stiffness variation curves of the basic unit described in the above embodiments under different cavity pressures are as follows: Figure 3 , 4 As shown in the figure, the results indicate that as the compressive load increases, the volume of the shell gradually decreases, the internal air pressure increases, and the stiffness of the structure increases accordingly.

[0047] like Figure 2 The figure shown is a front view of the vibration isolation metamaterial model proposed in this invention, where the number of basic units in the metamaterial is defined as N. This embodiment will illustrate the influence of the value of N and the cavity pressure on the vibration isolation performance of the structure, using 20*log 10 (X n / X1) is used as the evaluation standard, X n X1 represents the output displacement response, and X2 represents the input displacement response. The curves showing the metamaterial transmissivity versus frequency under different numbers of basic elements (N = 2, 4, 6, 10, 20, 30) with no internal pressure and an internal pressure of 20 kPa are shown below. Figure 5 and Figure 6As shown, the results indicate that the initial isolation frequency of the bandgap in the unpressurized structure is 29.6 Hz. When the cavity pressure is 20 kPa, the initial frequency of the metamaterial bandgap changes from 29.6 Hz to 145.83 Hz, an increase of 393%, approximately 4.9 times that of the unpressurized metamaterial bandgap, demonstrating excellent bandgap adjustment characteristics. Furthermore, the bandgap width of the unpressurized structure is 50.8 Hz, while the bandgap width of the metamaterial at a cavity pressure of 20 kPa is 287.55 Hz, achieving a 5.6-fold adjustment and exhibiting excellent broadband adjustability.

[0048] The vibration isolation effect of metamaterial (N=4) at a specific frequency (200Hz) was analyzed, and the time-domain response is as follows: Figure 7 As shown, the output acceleration of the structure is always much smaller than the input acceleration, meaning that when the object is subjected to external vibration loads, the metamaterial structure proposed in this invention will greatly reduce the input response, exhibiting excellent vibration isolation capabilities. The metamaterial with a real-time adjustable bandgap proposed in this invention has broad application potential in aerospace, transportation, and other fields.

[0049] The above description is merely a preferred embodiment of the present invention. These specific embodiments are different implementations based on the overall concept of the present invention, and the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A pneumatically driven broadband vibration isolation metamaterial with real-time adjustable bandgap, characterized in that, It includes several basic units connected in series. The basic unit is an integral structure. The top (1-1) and bottom (1-3) are both cylinders, and the middle (1-2) is a truncated cone. When connected in series, the bottom of one basic unit is connected to the bottom of another basic unit, and the top of one basic unit is connected to the top of another basic unit. The diameter of the top cylinder is equal to the diameter of the top surface of the truncated cone, and the diameter of the bottom cylinder is equal to the diameter of the bottom surface of the truncated cone. The basic unit has a cavity (1-4) inside. The cavity (1-4) is located in the middle (1-2) and bottom (1-3) of the basic unit and has the same shape as the overall shape formed by the middle (1-2) and bottom (1-3) of the basic unit. The bottom cylinder and the top cylinder have a first through hole (1-5) and a second through hole (1-6) respectively communicating with the cavity (1-4). The bandgap adjustment method of the broadband vibration isolation metamaterial is as follows: the bandgap of the metamaterial is adjusted in real time by filling the cavity (1-4) with air to regulate the internal pressure of the cavity.

2. The metamaterial according to claim 1, characterized in that, radius of the base of the truncated cone R Radius of the top surface r 2-3 times, the angle α between the generatrix of the truncated cone and the base is arctan[ h / 2( r 1- r )]°, where h The height of the cavity (1-4) is... r 1 is the radius of the bottom surface of the cavity (1-4).

3. The metamaterial according to claim 1, characterized in that, Distance from the bottom surface of cavity (1-4) to the bottom surface of the basic unit t b ≥ Height of the top cylinder t s The distance from the sidewall of cavity (1-4) to the sidewall of the truncated cone t Not less than 1 / 3 h , R and r difference of 1 l≥ t .

4. The metamaterial according to claim 1, characterized in that, 1 / 3 r ≥ Radius of the first through hole (1-5) and the second through hole (1-6) r c ≥ h .

5. The metamaterial according to claim 1, characterized in that, Number of basic units N ≥2.

6. The metamaterial according to claim 1, characterized in that, Metamaterials are made of elastomer rubber, which includes polyurethane rubber, natural rubber, and butadiene rubber.

7. The method for preparing the metamaterial according to any one of claims 1-6, characterized in that, The method described: First, a mold is prepared by 3D printing. Then, the mold is preheated, followed by vacuum casting and constant temperature curing to obtain the metamaterial.

8. The method according to claim 7, characterized in that, Preheat the mold to 60-70℃, and maintain the curing temperature at 60-70℃ for 2-3 hours.

9. The application of the metamaterials according to any one of claims 1-6 in aerospace, transportation and deep-sea environments.

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