Nonlinear metamaterial track damper based on acoustic black hole unit

Abstract

The invention relates to a nonlinear metamaterial track shock absorber based on an acoustic black hole (ABH) unit, the shock absorber is periodically installed on a track, and the shock absorber comprises a shock absorption buckle and a nonlinear metamaterial plate. The vibration reduction buckle is installed on the track and comprises a plurality of ABH units and damping bodies fully filled in the ABH units, each ABH unit is composed of four one-dimensional ABH beams, and the thickness of each ABH beam changes according to the power law; the nonlinear metamaterial plate is installed between the two vibration reduction buckles and comprises ABH units distributed periodically, damping pieces installed in the middles of the ABH units and nonlinear vibrators placed on the two sides of the damping pieces respectively. Two times of vibration reduction are achieved by arranging the vibration reduction buckle and the nonlinear metamaterial plate, and meanwhile the excellent vibration reduction performance is shown in the broadband range of main vibration of a 500-2500 Hz track in combination with the acoustic black hole, the metamaterial, the nonlinearity and the dynamic vibration absorption effect.

Description

Technical Field

[0001] The present invention relates to the technical field of track vibration reduction, and in particular to a nonlinear metamaterial track vibration reducer based on an acoustic black hole unit. Background Art

[0002] With the rapid development of rail transit, the problem of track vibration has become increasingly prominent. Track vibration mainly occurs in the wide frequency range of 500-2500Hz, which not only generates noise and affects ride comfort, but may also cause problems such as fatigue fracture of track structure and damage to on-board instruments, threatening the safety of train operation. Traditional methods of track vibration control, such as the use of heavy rails, seamless rails, ballastless tracks, elastic fasteners and floating plate tracks, and rail grinding, have many limitations. These methods have insignificant vibration reduction effects, narrow effective frequency bands, large subsequent maintenance workloads, and high economic investment. For built tracks, changing the track structure may also bring potential risks and have low applicability. Existing track vibration absorbers are mostly based on the principle of dynamic vibration absorption. By adjusting the absorber parameters, the rail vibration is controlled in a specific frequency band, but the vibration control effect in a wide frequency range is limited, and it is difficult to meet the needs of track broadband vibration reduction.

[0003] Acoustic black hole (ABH) technology has received extensive attention in the field of vibration control in recent years. Its principle is to reduce the thickness of the structure from the uniform part to the edge in the form of a power function, so that the wave propagation speed in the structure gradually decreases, and the wave energy is concentrated at the tip of the structure, and then dissipated through the damping material so that it does not reflect, thereby achieving broadband vibration control. However, the existing acoustic black hole structures are mostly linear. Due to size limitations, the effective frequency is often limited to the high-frequency range above the cutoff frequency, and the effect is not good in the low-frequency band. If its low-frequency function is to be expanded, it is usually necessary to significantly increase the size of the structure, which limits the application of acoustic black hole dampers in track vibration reduction.

[0004] Metamaterial is a kind of artificially designed composite structure. It reverse designs subunits based on the existing structure according to the product technical requirements, and obtains extraordinary physical properties that natural structures do not have by periodically arranging subunits. Typical metamaterial characteristics are Bragg scattering band gaps caused by periodic subunits and local resonance band gaps generated by resonant units, which make it produce wave propagation band gaps in the low-frequency range, providing a new technical path for low-frequency vibration reduction. However, most existing metamaterials are also linear designs with limited band gaps. Expanding the bandwidth requires the addition of a large number of resonance units, which limits their application in actual engineering.

[0005] The invention patent with publication number CN116682401A discloses a nested acoustic black hole beam structure, including two main beams, an embedded acoustic black hole body with a through hole connected between the two main beams, an acoustic black hole vibrator body embedded in the through hole of the embedded acoustic black hole body, and a damping member, the acoustic black hole vibrator body has a fitting surface matching the inner wall of the through hole of the embedded acoustic black hole body, the inner wall surface of the through hole and the fitting surface follow an exponential function, and the damping member is installed on the embedded acoustic black hole body and the acoustic black hole vibrator body; although the patent has high-efficiency vibration reduction, the acoustic black hole structure of the patent is not installed on the track, and is not optimized according to the vibration conditions of the track in a targeted manner, and the patent only has one-time vibration reduction, and the vibration reduction effect can be further improved.

[0006] Therefore, it is an urgent problem to provide a track vibration damper that can perform multiple vibration reduction and further improve the broadband vibration reduction effect. Summary of the invention

[0007] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a nonlinear metamaterial track vibration damper based on acoustic black hole unit.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] According to one aspect of the present invention, a nonlinear metamaterial track damper based on an acoustic black hole unit is provided, wherein the damper is used to reduce the vibration of the track, and the damper is periodically installed on the track, and the damper comprises a damping buckle, an ABH unit and a nonlinear metamaterial plate, wherein the damping buckle is installed on the track, and the damping buckle comprises a damping body filling the interior of the ABH unit and a plurality of ABH units, wherein the ABH unit is composed of four one-dimensional ABH beams, and the thickness of the ABH beam varies according to a power law, and the nonlinear metamaterial plate is installed between two damping buckles, and the nonlinear metamaterial plate comprises a damping member, a nonlinear oscillator and periodically distributed ABH units, wherein the damping member and the nonlinear oscillator are both installed in the ABH unit of the nonlinear metamaterial plate, and the damping member is installed in the middle of the ABH unit and the nonlinear oscillator is respectively placed on both sides of the damping member.

[0010] As a preferred technical solution, the damping body fills the interior of the ABH unit in the vibration-damping buckle, the damping component is installed in the middle part of the periodically distributed ABH unit in the nonlinear metamaterial plate, the damping component divides each ABH unit in the nonlinear metamaterial plate into two cavities, and the nonlinear oscillator is installed in the cavity.

[0011] As a preferred technical solution, the vibration-damping buckle includes a first buckle, a second buckle and a fixing portion, the first buckle and the second buckle are movably connected, and the fixing portion is symmetrically mounted on the first buckle and the second buckle.

[0012] As a preferred technical solution, the vibration-damping buckle includes an isolation plate, the isolation plate is mounted on the second buckle, the nonlinear metamaterial plate is mounted in the isolation plate, and the isolation plate is in contact with the first buckle.

[0013] As a preferred technical solution, the vibration-damping buckle comprises a bottom plate, the bottom plate is mounted on the second buckle, the isolation plate is mounted on the bottom plate, and the length of the bottom plate is smaller than the length of the isolation plate.

[0014] As a preferred technical solution, the first buckle includes an L-shaped connecting portion, and the connecting portion and the bottom plate in the second buckle are connected by threads.

[0015] As a preferred technical solution, the vibration-damping buckle is installed in the uniform thickness area at both ends of the nonlinear metamaterial plate, and the isolation plate in the vibration-damping buckle separates the nonlinear metamaterial plate from the track.

[0016] As a preferred technical solution, the four one-dimensional ABH beams are symmetrical double-leaf structures.

[0017] As a preferred technical solution, the thickness h of the one-dimensional ABH beam is ABH Changes, there are the following formulas:

[0018]

[0019] x is the position coordinate, m is the power law exponent, and β is the coefficient of the power function.

[0020] As a preferred technical solution, the damping element is made of a damping material, and the damping material is rubber.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The nonlinear metamaterial rail vibration damper based on acoustic black hole units proposed in the present invention includes two parts: a vibration damping buckle and a nonlinear metamaterial plate. The vibration damping buckle of the present invention has multiple built-in ABH units and uses its energy focusing and damping dissipation effects to reduce the vibration transmission of the rail; while the nonlinear metamaterial plate periodically arranges ABH units and installs damping bodies and nonlinear oscillators therein, combining the high-frequency damping effect of acoustic black holes, the low-frequency band gap characteristics of metamaterials, the nonlinear broadband energy transfer mechanism, and the dynamic vibration absorption effect of the overall structure at a specific natural frequency, thereby realizing broadband vibration control of the rail. The combination of the vibration damping buckle and the nonlinear metamaterial plate forms two vibration damping processes, so that the rail vibration damper can show excellent vibration damping performance in the wide frequency band range of the main vibration of the rail from 500 to 2500Hz.

[0023] 2. The present invention introduces a nonlinear oscillator into the acoustic black hole unit of the metamaterial plate, which not only combines the advantages of the acoustic black hole and the metamaterial, but also uses nonlinearity to generate high-order harmonics to achieve broadband energy transfer from low frequency to high frequency, thereby enhancing the low-frequency performance of the acoustic black hole structure, broadening the band gap range of the metamaterial, making up for the effective frequency defects of existing acoustic black holes and metamaterials, and improving the practical application value of acoustic black holes and metamaterials.

[0024] 3. The present invention is a passive shock absorber, which consists of only buckles and shock absorbers. It does not require complex sensors, controllers, and energy supply systems, which not only reduces the complexity of the system, but also improves the reliability of the system. The shock absorber is installed between the two buckles, and the buckles are connected by threads inside, which can be directly connected to the existing track. The installation process is simple and fast, and there is no need for large-scale modification of the track, and the strength and rigidity of the track structure are not changed. There is no increase in safety risks, which ensures the normal operation of rail transit.

[0025] 4. Compared with the traditional rail vibration control method, the present invention has the advantages of high control efficiency, wide frequency range, high robustness, and sub-unit design. In addition, due to its simple structure and small number of parts, it does not require complicated maintenance equipment and technology, which greatly reduces the maintenance cost. Only simple inspection and maintenance are required, such as checking whether the buckle is loose and whether the acoustic black hole unit is damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of the nonlinear metamaterial plate of the present invention;

[0028] Figure 3 It is a schematic diagram of the structure of the vibration-damping buckle of the present invention;

[0029] Figure 4 It is a schematic diagram of the use of the shock absorber of the present invention;

[0030] Figure 5 This is a numerical simulation result diagram of the present invention;

[0031] Figure 6 This is a graph of laboratory test results of the present invention.

[0032] 1. Track; 2. Vibration-damping buckle; 3. Nonlinear metamaterial plate; 4. ABH unit; 5. Damping body; 6. Nonlinear oscillator; 7. First buckle, 8. Second buckle. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0034] In the prior art, it is common to use acoustic black hole units to reduce vibration, but most of them only have one vibration reduction process, and the connectors installed on the track are not optimized. In addition, the acoustic black hole has low-frequency limitations, and the vibration reduction effect needs to be improved.

[0035] In view of the above problems, the present invention provides a nonlinear metamaterial rail vibration damper based on acoustic black hole units; the vibration damping buckle of the present invention has multiple built-in ABH units, and uses their energy focusing and damping dissipation to reduce the vibration transmission of the rail; and the nonlinear metamaterial plate periodically arranges ABH units, and installs damping bodies and nonlinear oscillators therein, combining the high-frequency damping effect of the acoustic black hole, the low-frequency band gap characteristics of the metamaterial, the nonlinear broadband energy transfer mechanism, and the dynamic vibration absorption effect of the overall structure at a specific natural frequency, thereby realizing broadband vibration control of the rail. The combination of the vibration damping buckle and the nonlinear metamaterial plate forms two vibration damping processes, so that the rail vibration damper can show excellent vibration damping performance in the wide frequency band range of the main vibration of the rail from 500 to 2500Hz. The present invention introduces nonlinear oscillators into the acoustic black hole unit of the metamaterial plate, which not only combines the advantages of acoustic black holes and metamaterials, but also uses nonlinearity to generate high-order harmonics to achieve broadband energy transfer from low frequency to high frequency, thereby enhancing the low-frequency performance of the acoustic black hole structure, broadening the band gap range of the metamaterial, making up for the effective frequency defects of existing acoustic black holes and metamaterials, and improving the practical application value of acoustic black holes and metamaterials. The present invention is a passive vibration damper, and the structure is only composed of buckles and vibration absorbers. No complex sensors, controllers and energy supply systems are required, which not only reduces the complexity of the system, but also improves the reliability of the system. The vibration absorber is installed between two buckles, and the buckles are connected by threads inside, which can be directly connected to the existing track. The installation process is simple and fast, and there is no need for large-scale modification of the track. The strength and rigidity of the track structure are not changed, and the safety risk is not increased, which ensures the normal operation of rail transit. Compared with traditional rail vibration control methods, the present invention has the advantages of high control efficiency, wide frequency range, high robustness, and sub-unit design. In addition, due to its simple structure and small number of parts, it does not require complex maintenance equipment and technology, which greatly reduces maintenance costs. Only simple inspections and maintenance are required, such as checking whether the buckles are loose and whether the acoustic black hole unit is damaged.

[0036] Example 1

[0037] like Figure 1-Figure 4 As shown, a nonlinear metamaterial track vibration damper based on acoustic black hole unit is used to reduce the vibration of track 1. The vibration damper is periodically installed on track 1. The vibration damper includes vibration damping buckles 2, ABH units 4 and nonlinear metamaterial plates 3. The vibration damping buckles 2 are installed on track 1. The vibration damping buckles 2 include a damping body filling the inside of the ABH unit 4 and multiple ABH units 4. The ABH unit 4 is composed of four one-dimensional ABH beams, and the thickness of the ABH beam varies according to a power law. The nonlinear metamaterial plate 3 is installed between two vibration damping buckles 2. The nonlinear metamaterial plate 3 includes a damping member 5, a nonlinear oscillator 6 and periodically distributed ABH units 4. The damping member 5 and the nonlinear oscillator 6 are both installed in the ABH unit 4 of the nonlinear metamaterial plate 3. The damping member 5 is installed in the middle of the ABH unit 4 and the nonlinear oscillator 6 is respectively placed on both sides of the damping member 5.

[0038] The damping body fills the interior of the ABH unit 4 in the vibration-damping buckle 2, and the damping member 5 is installed in the middle part of the periodically distributed ABH unit 4 in the nonlinear metamaterial plate 3. The damping member 5 divides each ABH unit 4 in the nonlinear metamaterial plate 3 into two cavities, and the nonlinear oscillator 6 is installed in the cavity.

[0039] The vibration-damping buckle 2 is installed in the uniform thickness area at both ends of the nonlinear metamaterial plate 3 , and the isolation plate in the vibration-damping buckle 2 separates the nonlinear metamaterial plate 3 from the track 1 .

[0040] In this embodiment, the nonlinear metamaterial track vibration absorber based on acoustic black hole (ABH) units of the present invention is periodically installed on the track 1, the ABH units 4 can be one, two, or more, and are periodically arranged in the nonlinear metamaterial plate 3, and the ABH units 4 on the vibration-absorbing buckle 2 can also be one, two, or more. This design enables the vibration absorber to combine the advantages of the acoustic black hole structure and the metamaterial to achieve excellent vibration reduction effect in a wider frequency range.

[0041] The track vibration is transmitted to the nonlinear metamaterial plate 3 through the vibration reduction buckle 2. The vibrator 6 vibrates and collides with the ABH unit 4 continuously, which can produce nonlinear phenomena, including the most typical high-order harmonics and resonance peaks shifting to high frequencies, which can transfer low-frequency vibration energy to high frequencies, and then dissipate the energy through the high-frequency damping effect of the acoustic black hole, thereby further enhancing the low-frequency vibration reduction effect. At the same time, a thin film is set on the outside so that the nonlinear vibrator 6 can only move in the cavity of the ABH unit 4 and will not run out of the ABH unit 4.

[0042] The thickness of the one-dimensional ABH beam changes according to a power function. As the core component for achieving vibration reduction, the unique power-law thickness structure of the ABH structure plays a key role. When the bending wave in the track propagates to the ABH beam, due to the power-law variation of the thickness, the phase velocity and group velocity of the wave gradually decrease, causing the energy to accumulate in the ABH part, and then dissipate the energy through the damping material covering the ABH part, thereby suppressing the broadband vibration in the medium and high frequency bands. In the actual design process, the value of the power-law exponent will be optimized according to the frequency range of the required vibration reduction and the specific size of the ABH structure. After a lot of theoretical research and experimental verification, it was found that appropriately increasing the value of the power-law exponent can enhance the energy focusing characteristics, thereby effectively improving the vibration reduction effect.

[0043] The acoustic black hole unit 4 is composed of four one-dimensional ABH beams, and the four one-dimensional ABH beams are symmetrical double-leaf structures. The center point of the acoustic black hole unit 4 is used as the coordinate origin, and it is divided into four regions in the horizontal direction and the vertical direction. Each region has a one-dimensional ABH beam, and the one-dimensional ABH beams are connected to each other. Taking the vertical direction as an example, it is divided into two left and right regions, that is, a symmetrical double-leaf setting.

[0044] The thickness variation of the one-dimensional ABH beam is given by the following formula:

[0045] h ABH (x) = βx m

[0046] x is the position coordinate, m is the power law index, and β is the coefficient of the power function. The value range of β is generally less than 1. Simply put, the steeper the power function, the better the energy focusing effect, so it is generally achieved by setting a larger m. Generally, m is 2. When m is 3, the effect is better than 2. Taking a larger value will have a better effect. However, considering the difficulty of processing, the effect of 3 is better than 2, which is generally sufficient.

[0047] The nonlinear metamaterial rail damper based on ABH units is periodically distributed along the rail direction and installed at the bottom of the rail through connecting components. The connecting components are made of high-strength and high-toughness materials, such as high-strength alloy steel. These materials have excellent mechanical properties, which can ensure that the connection between the damper and the rail is firm and will not loosen or break during the long-term vibration of the rail. At the same time, the structural design of the connecting components has also been carefully optimized, such as the special buckle structure, which contains multiple ABH units, which can reduce the transmission of rail vibration by energy focusing and damping dissipation. At the same time, it has the advantages of easy installation and disassembly, and adapts to the shape of the rail, which can ensure that the damper is always stably installed in a long-term vibration environment, avoiding the vibration reduction effect caused by looseness, and ensuring the safe and stable operation of the rail system.

[0048] The working principle of the present invention is:

[0049] When the track vibrates, the wave propagates along the track and is transmitted to the vibration absorber through the buckle. The track vibration absorber first reduces the vibration transmission through the vibration-reducing buckle, and then attenuates the transmitted vibration through the metamaterial vibration absorber, thereby effectively suppressing the track vibration.

[0050] 1. The metamaterial vibration absorber based on the nonlinear acoustic black hole unit contains four synergistic vibration reduction mechanisms, as follows:

[0051] a. Low-frequency bandgap characteristics of metamaterials: Due to the periodic distribution of acoustic black hole units inside the metamaterial absorber and the periodic installation of the absorber along the track, a wave propagation bandgap is generated in the low-frequency range, hindering the propagation of waves. Here, we design according to the main resonance frequency band of the track (Pinned-Pinned resonance frequency band), so that the wave is blocked when propagating in this frequency band, thereby effectively suppressing the vibration of this frequency band and ensuring the safe and stable operation of the track system.

[0052] b. Acoustic black hole high-frequency damping effect: Due to the unique power-law thickness variation of the acoustic black hole structure, the incident wave entering the acoustic black hole from the uniform part is compressed, the wave propagation speed gradually decreases, and the energy is focused on the acoustic black hole part, and then dissipated through the damping material, so that high-frequency broadband vibration control can be achieved. Here we design according to the main vibration frequency range of the orbit (500-2500Hz) so that the wave energy in this frequency band can be effectively dissipated through the acoustic black hole effect.

[0053] c. Nonlinear oscillator cross-band energy transfer mechanism: Due to the introduction of nonlinear oscillators in the acoustic black hole unit, the free vibration of the oscillator collides with the acoustic black hole through-hole, which will generate high-order harmonics. The high-order harmonics can transfer the energy at the low-frequency fundamental wave to the high frequency, realizing cross-band wide-band energy transfer from low frequency to high frequency, resulting in a reduction in low-frequency vibration. This can not only enhance the low-frequency performance of the acoustic black hole, but also broaden the band gap range of the metamaterial, make up for the effective frequency defects of the existing acoustic black hole and metamaterial, and further improve the broadband performance of the vibration absorber.

[0054] d. Dynamic vibration absorption of vibration absorber: Since the vibration absorber itself has a natural frequency, when the vibration frequency of the track is close to the natural frequency of the vibration absorber, the vibration absorber and the track will be coupled and resonated, and the vibration of the vibration absorber will be used to suppress the vibration of the track, so that the vibration of the track is significantly attenuated. By adjusting the structural parameters of the vibration absorber, the natural frequency of the vibration absorber can be changed, so that the dynamic vibration absorption effect can be exerted in a wider frequency range, further improving the overall performance of the vibration absorber.

[0055] The synergistic effect of these four vibration reduction mechanisms enables the metamaterial vibration absorber to exhibit excellent vibration reduction performance within the main vibration frequency range of the track.

[0056] 2. The working principle of the vibration reduction buckle based on the linear acoustic black hole unit is as follows:

[0057] The vibration-damping buckle is used to install the metamaterial vibration absorber at the bottom of the track to ensure the stability of the overall structure. During the vibration of the track, the connecting parts can withstand the relative movement and force between the vibration absorber and the track to prevent the structure from loosening or deforming. It enables the vibration energy to be transferred in an orderly manner between the track and the vibration absorber. When the track is excited by vibration, the buckle transfers the vibration energy to the metamaterial vibration absorber at the bottom. The acoustic black hole unit built into the buckle itself can use its energy focusing and damping dissipation to reduce the transmission of vibration energy, so that the entire system works together to enhance the vibration reduction effect. The design of the buckle structure must not only consider the vibration reduction performance, but also ensure a close connection with the track, and the convenience of installation and disassembly, so that it can be efficiently carried out when the vibration absorber is maintained or replaced in the later stage, reducing maintenance time and cost, and reducing the impact on the normal operation of rail transit.

[0058] The vibration-damping buckle 2 comprises a first buckle 7, a second buckle 8 and a fixing portion, wherein the first buckle 7 and the second buckle 8 are movably connected, and the fixing portion is symmetrically mounted on the first buckle 7 and the second buckle 8.

[0059] The vibration-damping buckle 2 comprises an isolation plate, the isolation plate is mounted on the second buckle 8 , the nonlinear metamaterial plate 3 is mounted in the isolation plate, and the isolation plate is in contact with the first buckle 7 .

[0060] The vibration-damping buckle 2 comprises a bottom plate, which is mounted on the second buckle 8 , and the isolation plate is mounted on the bottom plate, wherein the length of the bottom plate is smaller than the length of the isolation plate.

[0061] The first buckle 7 includes an L-shaped connecting portion, and the connecting portion and the bottom plate of the second buckle 8 are connected by threads.

[0062] In this embodiment, the first clip 7 and the second clip 8 are connected by bolts or screws, and threaded holes are respectively set at the bottom of the first clip 7 and the second clip 8. The bolts are passed through the threaded holes and screwed in to complete the installation and positioning of the first clip 7 and the second clip 8.

[0063] The damping element is made of a damping material, and the damping material is rubber.

[0064] In this embodiment, rubber damping is laid in each ABH unit to dissipate the energy focused on the ABH tip. Because the thickness of the acoustic black hole in an ideal state can be reduced to zero, the incident wave propagating from the uniform end to the ABH end can be completely focused on the ABH tip without reflection. However, due to the limitation of processing accuracy, when the thickness is reduced to a certain extent, truncation will occur. The occurrence of truncation will cause the reflection coefficient of the bending wave to increase by 60-70%, affecting the ABH vibration reduction effect. Laying a small amount of damping can dissipate most of the energy and enhance the vibration reduction effect. The nonlinear oscillator 6 is made of 45 steel, and the damping element is made of rubber material. It is installed in the nonlinear metamaterial plate 3 made of 45 steel to realize the composite material production.

[0065] from Figure 5 and Figure 6 It can be seen that after using the track vibration damper proposed in the present invention, the track vibration reduction effect is greatly improved, and its multiple vibration reduction mechanisms work synergistically as follows:

[0066] a. Bandgap effect: Due to the periodic arrangement of acoustic black hole units in the metamaterial damper and the periodic arrangement along the orbital direction, a bandgap is generated near the Pinned-Pinned resonance frequency band, at which time the propagation of bending waves is hindered (e.g. Figure 5 The gray bar area shown in the figure effectively suppresses the vibration of the track within this frequency band and ensures the safe and stable operation of the track system.

[0067] b. Damping effect: Due to the wavelength compression and amplitude increase caused by the acoustic black hole, the bending waves in the medium and high frequency bands are focused on the tip area of ​​the acoustic black hole, and the focused energy is dissipated through the damping material (i.e. the typical energy focusing and high-frequency damping characteristics of the acoustic black hole structure), thereby achieving broadband vibration suppression in the medium and high frequency bands, thereby reducing the vibration amplitude of the track. Figure 5 As shown by the grey dotted line, within the medium and high frequency band of 500-2500 Hz, installing vibration absorbers can significantly reduce the track vibration displacement transmission rate, effectively reducing the medium and high frequency vibration of the track.

[0068] c. Dynamic vibration absorption effect: When the vibration frequency of the track is close to the natural frequency of the vibration absorber, the vibration absorber and the track form a coupled resonance system, and the original resonance peak of the track is split into two small resonance peaks, so that the vibration of the track is significantly attenuated (such as Figure 5 By adjusting the structural parameters of the shock absorber, the dynamic vibration absorption can be exerted in a wider frequency range, further improving the overall performance of the shock absorber.

[0069] d. Nonlinear energy transfer effect: Due to the high-order harmonics generated by the nonlinear oscillator, the energy at the low-frequency fundamental wave is transferred to the high frequency, resulting in the reduction of low-frequency vibration. Figure 6As shown by the medium grey dotted line, in the low frequency range of 0-1000 Hz, the vibration amplitude is greatly reduced, which makes up for the effective frequency defects of existing acoustic black holes and metamaterials and further improves the broadband performance of the vibration absorber.

[0070] The innovative features of the present invention are mainly reflected in the following parts:

[0071] Structural innovation: A nonlinear metamaterial structure consisting of acoustic black hole (ABH) units based on power-law thickness distribution is designed, and the ABH unit adopts a built-in double-leaf structure, which avoids the fatigue strength and safety issues of the ABH tip, and breaks through the structural mode of the traditional rail vibration absorber. Compared with traditional vibration absorbers, this innovative structure utilizes the unique performance and periodic arrangement of the ABH unit to achieve the synergistic effect of multiple vibration reduction mechanisms and broaden the vibration reduction frequency band. Traditional vibration absorber structures can often only reduce vibration through a single physical mechanism and cannot meet the needs of broadband vibration reduction. The metamaterial structure of the present invention, through clever design, gives full play to the energy focusing and damping effects of the acoustic black hole unit, the band gap characteristics of the metamaterial, the nonlinear energy transfer mechanism, and the dynamic vibration absorption effect of the entire structure, providing a new structural idea for rail vibration reduction. In addition, the connection parts are innovatively designed. The vibration reduction buckle of the built-in ABH unit can reduce the transmission of rail vibration, and cooperate with the metamaterial vibration absorber to further control rail vibration.

[0072] Innovation in vibration reduction mechanism: The coordinated work of the four vibration reduction mechanisms of energy focusing and damping effect, band gap characteristics, nonlinear energy transfer and dynamic vibration absorption is realized, and the vibration reduction frequency band is widened. Traditional rail vibration reduction methods usually rely on only one or two vibration reduction mechanisms, and it is difficult to achieve effective vibration reduction in a wide frequency range. The present invention organically combines the four vibration reduction mechanisms, gives full play to their respective advantages in different frequency ranges, and achieves comprehensive suppression of rail vibration. For example, near the Pinned-Pinned resonance frequency band of the rail, vibration is mainly suppressed by the band gap effect; in the medium and high frequency bands, the energy focusing characteristics of the acoustic black hole structure are used to achieve wide-band vibration suppression; in the ultra-low frequency range, energy is transferred to high frequencies through nonlinear effects, and then energy is dissipated through acoustic black holes; in addition, it can also be combined through dynamic vibration absorption near specific natural frequencies. This innovative combination of vibration reduction mechanisms greatly improves the performance of the shock absorber. Experimental data show that the vibration reduction effect of the rail can be greatly improved by using the vibration reduction mechanism of the present invention.

[0073] The beneficial effects of the present invention are mainly reflected in the following parts:

[0074] Excellent vibration reduction performance: It exhibits good vibration reduction performance in the wide frequency band of 500-2500Hz, and can more effectively reduce broadband track vibration than traditional shock absorbers. Through numerical simulation and experimental verification, at certain specific frequencies, the track vibration acceleration can be reduced by more than 50%. For example, during the operation of the train, when the track is excited by different frequencies, the shock absorber of the present invention can significantly reduce the vibration response of the track, reduce the wear and fatigue damage of the track, increase the service life of the track, and reduce the operating cost.

[0075] Simple structure: Compared with the complex active vibration reduction system, the present invention is a passive vibration reduction device, which is composed only of an acoustic black hole unit and connecting parts, and does not require complex sensors, controllers and energy supply systems. This not only reduces the complexity of the system, but also improves the reliability of the system. Active vibration reduction systems usually require a large number of sensors to monitor vibration signals, and perform complex calculations and controls through controllers, which are prone to failure and have high maintenance costs. The vibration reduction device of the present invention has a simple structure, reduces failure points, reduces maintenance difficulty and costs, and greatly improves the stability and economy of the track vibration reduction system.

[0076] Easy installation: The installation structure is reasonably designed and can be directly connected to the existing track, and the installation process is simple and fast. By adopting standardized connection methods, such as snap-on connection, the installation time and labor costs can be effectively reduced. In actual engineering applications, the installers can quickly install the shock absorber of the present invention without large-scale modification of the track, which improves the construction efficiency, reduces the impact on the normal operation of rail transit, and ensures the normal operation of rail transit.

[0077] Low maintenance cost: Due to the simple structure, small number of parts, and no need for complex maintenance equipment and technology, the maintenance cost is greatly reduced. Compared with traditional track vibration reduction equipment, the vibration reducer of the present invention only needs simple inspection and maintenance during maintenance, such as checking whether the connecting parts are loose and whether the acoustic black hole unit is damaged. At the same time, due to its high reliability, it reduces the need for frequent replacement of parts, further reduces maintenance costs, prolongs the service life of the track, and has significant economic benefits.

[0078] Significant social benefits: effectively reduce the noise generated by track vibration, improve the quality of life of residents along the line, and reduce environmental noise pollution. With the continuous development of rail transportation, the noise generated by track vibration has an increasingly serious impact on the lives of residents along the line. The shock absorber of the present invention can significantly reduce track vibration, thereby reducing the generation of noise, creating a quieter and more comfortable living environment for residents along the line, and has important social benefits.

[0079] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A nonlinear metamaterial rail vibration absorber based on an acoustic black hole unit, the vibration absorber is used to absorb vibrations of a rail (1), characterized in that: The vibration absorber is periodically mounted on a track (1), and comprises a vibration-absorbing buckle (2), an ABH unit (4) and a nonlinear metamaterial plate (3). The vibration-absorbing buckle (2) is mounted on the track (1), and comprises a damping body filling the interior of the ABH unit (4) and a plurality of ABH units (4). The ABH unit (4) is composed of four one-dimensional ABH beams, and the thickness of the ABH beam varies according to a power law. The nonlinear metamaterial plate (3) is mounted between two vibration-absorbing buckles (2). The nonlinear metamaterial plate (3) comprises a damping element (5), a nonlinear oscillator (6) and periodically distributed ABH units (4). The damping element (5) and the nonlinear oscillator (6) are both mounted on the ABH unit (4) of the nonlinear metamaterial plate (3), and the damping element (5) is mounted in the middle of the ABH unit (4) and the nonlinear oscillator (6) is respectively placed on both sides of the damping element (5).

2. A nonlinear metamaterial rail vibration damper based on an acoustic black hole unit according to claim 1, characterized in that: The damping body fills the interior of the ABH unit (4) in the vibration-damping buckle (2); the damping member (5) is installed in the middle part of the periodically distributed ABH unit (4) in the nonlinear metamaterial plate (3); the damping member (5) divides each ABH unit (4) in the nonlinear metamaterial plate (3) into two cavities; and the nonlinear oscillator (6) is installed in the cavity.

3. The nonlinear metamaterial rail vibration damper based on acoustic black hole unit according to claim 1, characterized in that: The vibration-damping buckle (2) comprises a first buckle (7), a second buckle (8) and a fixing portion, wherein the first buckle (7) and the second buckle (8) are movably connected, and the fixing portion is symmetrically mounted on the first buckle (7) and the second buckle (8).

4. The nonlinear metamaterial rail vibration damper based on acoustic black hole unit according to claim 1, characterized in that: The vibration-damping buckle (2) comprises an isolation plate, the isolation plate is mounted on the second buckle (8), the nonlinear metamaterial plate (3) is mounted in the isolation plate, and the isolation plate is in contact with the first buckle (7).

5. The nonlinear metamaterial rail vibration damper based on acoustic black hole unit according to claim 4, characterized in that: The vibration-damping buckle (2) comprises a bottom plate, the bottom plate is mounted on the second buckle (8), the isolation plate is mounted on the bottom plate, and the length of the bottom plate is smaller than the length of the isolation plate.

6. The nonlinear metamaterial rail vibration damper based on acoustic black hole unit according to claim 5, characterized in that: The first buckle (7) comprises an L-shaped connecting portion, and the connecting portion and the bottom plate of the second buckle (8) are connected via threads.

7. The nonlinear metamaterial rail vibration damper based on acoustic black hole unit according to claim 4, characterized in that: The vibration-damping buckle (2) is installed in the uniform thickness area at both ends of the nonlinear metamaterial plate (3), and the isolation plate in the vibration-damping buckle (2) separates the nonlinear metamaterial plate (3) from the track (1).

8. The nonlinear metamaterial rail vibration damper based on acoustic black hole unit according to claim 1, characterized in that: The four one-dimensional ABH beams are symmetrical double-leaf structures.

9. The nonlinear metamaterial rail vibration damper based on acoustic black hole unit according to claim 1, characterized in that: The thickness h of the one-dimensional ABH beam ABH Changes, there are the following formulas: h ABH (x)=βx m x is the position coordinate, m is the power law exponent, and β is the coefficient of the power function.

10. The nonlinear metamaterial rail vibration damper based on acoustic black hole unit according to claim 1, characterized in that: The damping element is made of a damping material, and the damping material is rubber.

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