Composite film metamaterial structure and rail vehicle

Abstract

The application relates to the technical field of vibration sound insulation, and provides a composite film metamaterial structure and a railway vehicle. The film metamaterial structure comprises a first flexible cladding layer, a metamaterial unit plate layer, a hard support layer and a second flexible cladding layer arranged in sequence. The metamaterial unit plate layer comprises a support frame, an elastic film and a mass piece. The support frame is provided with a plurality of mounting through holes, the elastic film covers the support frame and seals one side opening of the mounting through holes, and the mass piece is located on the elastic film corresponding to the mounting through holes. The hard support layer is arranged on the side, away from the elastic film, of the metamaterial unit plate layer and is opposite to the opening of the mounting through holes. The above film metamaterial structure can replace the 5mm sound insulation felt layer included in the position with a sectional combination sound insulation value of the high-speed motor train unit greater than or equal to 52 dB, realizes light weight under the condition that other parts of the large-section combination structure of the vehicle body remain unchanged, and ensures that the sound insulation performance is not reduced.

Description

Technical Field

[0001] This application relates to the field of vibration and sound insulation technology, specifically to a composite thin-film metamaterial structure and a rail vehicle. Background Technology

[0002] Currently, the interior design of high-speed trains faces the dual core demands of lightweighting and high sound insulation. Large interior components, as key parts of the overall sound insulation system, directly determine the acoustic comfort inside the train. Currently, the industry commonly uses 5mm thick sound insulation felt as the main material for interior sound insulation. While this felt can achieve a measured sound insulation of 34dB-36dB, it has a significant drawback: its surface weight is as high as 8.5-10.5kg / ㎡, resulting in excessive weight and significantly increasing the vehicle's load burden, which contradicts the industry trend of lightweighting and energy conservation in high-speed trains.

[0003] While existing acoustic thin-film metamaterials possess the inherent advantage of lightweight design, their sound insulation performance has significant shortcomings when used alone: ​​the surface weight of a conventional 10mm thick acoustic thin-film metamaterial composite structure is only 5-7kg / ㎡, and its sound insulation performance is only 19-25dB, which is far lower than that of 5mm thick sound insulation felt. Therefore, it cannot directly replace sound insulation felt to meet the sound insulation standards of high-speed train interiors, which has made it difficult for acoustic thin-film metamaterials to be applied in the field of high-speed train interiors.

[0004] There is a significant research gap in the existing technology for sound insulation systems of interior components in high-speed trains: the industry generally focuses on the performance optimization of individual sound insulation materials, and has not conducted quantitative research on the contribution of sound insulation increment under the actual working condition of overall sound insulation of interior components ≥52dB; after extensive field testing, it has been verified that under this high sound insulation condition, 5mm thick sound insulation felt contributes only 4-0.5dB to the sound insulation increment of interior components. The high self-weight of the sound insulation felt and the extremely low incremental contribution constitute a serious technical mismatch. Simply using the sound insulation felt would result in a huge waste of lightweight resources, and existing patents and published literature have not disclosed sound insulation material optimization schemes under this special working condition.

[0005] The information disclosed in the background section is only intended to enhance the understanding of the background of this application, and therefore may contain information that is not part of the prior art known to those skilled in the art. Summary of the Invention

[0006] This application provides a composite thin-film metamaterial structure and a rail vehicle to solve the problem that existing thin-film metamaterial structures do not incorporate sound insulation design for train interiors and cannot simultaneously achieve lightweighting and sound insulation performance.

[0007] To achieve the above objectives, this application provides the following technical solution: A composite thin-film metamaterial structure includes a first flexible covering layer, a metamaterial unit plate layer, a rigid support layer, and a second flexible covering layer arranged sequentially. The metamaterial unit plate includes a support frame, an elastic film, and a mass sheet; the support frame has several mounting through holes, the elastic film covers the support frame and closes one side opening of the mounting through holes; the mass sheet is located on the elastic film corresponding to the mounting through holes; The rigid support layer is disposed on the side of the metamaterial unit plate layer away from the elastic film and is opposite to the opening of the mounting through hole; The first flexible covering layer is connected to the side of the metamaterial unit plate layer opposite to the rigid support layer, and the second flexible covering layer is connected to the side of the rigid support layer opposite to the metamaterial unit plate layer.

[0008] Optionally, the metamaterial unit plate layer consists of several layers, with each layer of the metamaterial unit plate layer arranged along the thickness direction; a flexible vibration isolation layer is provided between adjacent metamaterial unit plate layers.

[0009] Optionally, the flexible vibration isolation layer sandwiched between two adjacent metamaterial unit plates is distributed in a mirror-symmetric manner.

[0010] Optionally, the thickness of the flexible vibration isolation layer is 1.5-2.5 mm.

[0011] Optionally, the flexible vibration isolation layer is a rubber layer or a sealing cotton layer.

[0012] Optionally, the support frame is a plastic frame, an aluminum alloy frame, or a stainless steel frame, with a thickness of 1.5-5mm.

[0013] Optionally, the rigid support layer is a PC material layer.

[0014] This application also provides a rail vehicle, including a car body, the car body having at least one of a pantograph top plate cross-sectional structure, a pantograph floor cross-sectional structure, and a lead car sightseeing area floor cross-sectional structure; The cross-sectional structure includes the composite thin film metamaterial structure described in any of the above embodiments, wherein the thickness of the composite thin film metamaterial structure is less than or equal to 10 mm.

[0015] Optionally, the cross-sectional structure of the pantograph top plate includes, from top to bottom, a sound insulation board layer, a vehicle body profile layer, a damping coating layer, a sound insulation felt layer, a sound-absorbing cotton layer, the composite film metamaterial layer, and an interior panel layer.

[0016] Optionally, both the pantograph floor cross-sectional structure and the sightseeing area floor cross-sectional structure of the lead vehicle include: The structure includes a sound-absorbing base layer, a damping slurry layer, a vehicle body profile layer, a damping slurry layer, a floor support layer, a drainage layer, a sound-absorbing material layer, the composite film metamaterial layer, the wood plywood layer, and the floor fabric layer.

[0017] This application provides a composite thin-film metamaterial structure, comprising a first flexible covering layer, a metamaterial unit plate layer, a rigid support layer, and a second flexible covering layer arranged sequentially. The metamaterial unit plate layer includes a support frame, an elastic film, and a mass sheet. The support frame has several mounting through holes, and the elastic film covers the support frame and closes one side opening of the mounting through holes. The mass sheet is located on the elastic film corresponding to the mounting through holes. The rigid support layer is disposed on the side of the metamaterial unit plate layer away from the elastic film and is opposite to the opening of the mounting through holes. The first flexible covering layer is connected to the side of the metamaterial unit plate layer away from the rigid support layer, and the second flexible covering layer is connected to the side of the rigid support layer away from the metamaterial unit plate layer.

[0018] The composite thin-film metamaterial structure and rail vehicle provided in this application embodiment have the following technical advantages compared to the prior art: In this application, the composite thin-film metamaterial structure includes a first flexible covering layer, a metamaterial unit plate layer, a rigid support layer, and a second flexible covering layer arranged sequentially. The rigid support layer provides support to prevent the sound-absorbing cotton layer below from being tightly bonded to the flexible covering layer, thus preventing the thin-film resonant unit from losing its sound insulation effect and protecting the space while providing sound insulation. The aforementioned thin-film metamaterial structure can replace the 5mm sound insulation felt layer in the section of the high-speed train with a cross-sectional sound insulation of ≥52dB, achieving weight reduction without changing the other aspects of the large cross-sectional composite structure of the train body, while ensuring that the sound insulation performance is not reduced. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the composition of a composite thin film metamaterial structure according to an embodiment of this application; Figure 2 This is a schematic diagram of the metamaterial unit plate layer in an embodiment of this application; Figure 3 This is a schematic diagram of the composition of a composite thin film metamaterial structure according to another embodiment of this application; Figure 4 A schematic diagram showing the test results of a single structure of 10mm thin-film metamaterial and 5mm sound insulation felt in a sound insulation laboratory. Figure 5 This is a schematic diagram showing the test results of a combination structure of a 10mm thin-film metamaterial and a 5mm sound insulation felt in a sound insulation laboratory.

[0020] Figure label: Composite thin film metamaterial structure 100; First flexible covering layer 10, metamaterial unit plate layer 20, rigid support layer 30, second flexible covering layer 40, flexible vibration isolation layer 50; Support frame 21, elastic membrane 22, mass sheet 23, mounting through hole 211. Detailed Implementation

[0021] This invention discloses a composite thin-film metamaterial structure and a rail vehicle to solve the problem that existing thin-film metamaterial structures do not incorporate sound insulation design for the interior of high-speed trains and cannot simultaneously achieve lightweighting and sound insulation performance.

[0022] To make the technical solutions and advantages of the embodiments of this application clearer, the exemplary embodiments of this application will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not an exhaustive list of all embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0023] While existing acoustic thin-film metamaterials possess a natural advantage in terms of lightweight design, their sound insulation performance is significantly lacking when used alone. A conventional 10mm thick acoustic thin-film metamaterial composite structure weighs only 5-7 kg / m², with a sound insulation capacity of only 19-25 dB, far lower than that of 5mm thick sound insulation felt. Therefore, it cannot directly replace sound insulation felt to meet the sound insulation requirements of high-speed train interiors. However, when the sound insulation of a high-speed train section reaches a certain level, the proportion of sound insulation provided by sound insulation felt decreases. In this case, using a composite thin-film metamaterial structure as a replacement achieves lightweight design without compromising sound insulation performance.

[0024] Based on this, this application provides a composite thin-film metamaterial structure for replacing the 5mm sound insulation felt layer included in a composition with a cross-sectional sound insulation of ≥52dB.

[0025] Please see Figure 1-5 In one specific embodiment, the composite thin film metamaterial structure 100 provided in this application includes a first flexible covering layer 10, a metamaterial unit plate layer 20, a rigid support layer 30, and a second flexible covering layer 40 arranged sequentially. A rigid support layer 30 is disposed on the side of the metamaterial unit plate 20 away from the elastic film 22 and opposite to the opening of the mounting through hole 211; a first flexible covering layer 10 is connected to the side of the metamaterial unit plate 20 away from the rigid support layer 30, and a second flexible covering layer 40 is connected to the side of the rigid support layer 30 away from the metamaterial unit plate 20.

[0026] The metamaterial unit plate 20 includes a support frame 21, an elastic film 22, and a mass sheet 23. In this embodiment, the support frame 21 can be made of rigid plastic or lightweight metal by injection molding or die casting. The size of the support frame 21 should be as small as possible, preferably no larger than 30cm*30cm, to ensure sufficient frame rigidity and a near-rigid body configuration to allow the film and mass sheet to function effectively. Several mounting through holes 211 are arrayed on it. The elastic film 22 can be adhesively bonded to the support frame 21, sealing one side opening of the mounting through holes 211, thereby forming a closed acoustic resonant cavity with one side opening. The mass plate 23 is fixedly mounted on the elastic membrane 22. When external sound waves act on this structure, the local resonance system formed by the elastic membrane 22 and the mass plate 23 is excited. Through the vibration of the membrane and the dissipation of sound energy, noise of a specific frequency is blocked. Specifically, the modal frequencies and mode shapes of the metamaterial unit plate 20 can be calculated using COMSOL commercial software to identify the specific frequencies to be blocked. When the elastic membrane moves vertically upward slightly, the corresponding mass plate moves vertically downward slightly, and the phases are opposite, the corresponding frequencies fully exert their blocking effect. Preferably, the elastic membrane 22 and the support frame 21 are fixed with threaded fasteners. Several threaded fasteners are evenly arranged around the circumference of the support frame 21 to achieve the fixation of the two.

[0027] A rigid support layer 30 is disposed on the side of the metamaterial unit plate 20 facing away from the elastic film 22, and its surface is opposite to the opening of the mounting through hole 211. The rigid support layer 30 acts as an acoustic reflector backplate, forming a closed air cavity with the elastic film 22; such as a steel plate or a rigid resin plate. The depth of this cavity determines the resonant frequency of the metamaterial unit. The rigid support layer 30 and the support frame 21 can be fixed with threaded fasteners to improve stability. Preferably, by adjusting the thickness of the rigid support layer 30 or setting internal protrusions, the sound insulation frequency band can be further broadened or multi-peak sound insulation can be achieved. Simultaneously, when this composite film metamaterial structure 100 is applied to the cross-sectional structure of a rail vehicle, the next layer is generally a sound-absorbing cotton layer. To prevent the metamaterial unit plate 20 from losing its sound insulation effect after the sound-absorbing cotton layer and the elastic film 22 are tightly bonded, the aforementioned rigid support layer 30 is provided, serving to protect the space and provide sound insulation.

[0028] To further enhance the overall sealing, weather resistance, and damping performance of the metamaterial structure, this embodiment provides flexible covering layers on both sides of the metamaterial unit plate 20. In one embodiment, the first flexible covering layer 10 is connected to the side of the metamaterial unit plate 20 away from the rigid support layer 30, i.e., directly attached to the outer surface of the elastic film 22 or the outer end face of the support frame 21, to protect the elastic film 22 from external moisture and dust erosion and to provide additional surface damping. The second flexible covering layer 40 is connected to the side of the rigid support layer 30 away from the metamaterial unit plate 20, serving to seal the back cavity, prevent sound leakage, and buffer installation stress. In one embodiment, the flexible covering layer may specifically be a flexible fabric, such as soft cloth; or a rubber layer, etc.

[0029] In one embodiment, to further broaden the sound insulation bandwidth of the composite thin-film metamaterial structure 100 and improve its attenuation capability for broadband noise, the metamaterial unit plate layer 20 of this embodiment consists of several layers, with each layer of metamaterial unit plate layer 20 arranged sequentially along the thickness direction of the main structure. Simultaneously, a flexible vibration isolation layer 50 is provided between adjacent layers of metamaterial unit plate layer 20.

[0030] Single-layer thin-film metamaterials typically have a narrow effective sound insulation bandwidth. This embodiment constructs a multi-level acoustic resonance system by stacking several metamaterial unit plates 20 along their thickness direction. Each metamaterial unit plate 20 can have different resonance parameters. For example, by changing the areal density of each elastic film 22, the mass of the mass sheet 23, or adjusting the back cavity depth formed by each rigid support layer 30, each layer can resonate and absorb sound for different target noise frequency bands. The synergistic effect of the multi-layer structure allows the composite thin-film metamaterial structure 100 to achieve the superposition of multiple sound insulation peaks within an extremely thin thickness, thereby obtaining excellent broadband low-frequency sound insulation performance.

[0031] A flexible vibration isolation layer 50 is set between multiple rigid or semi-rigid metamaterial unit plates 20 to ensure that the elastic membrane 22 has sufficient space for vertical displacement under the action of the oscillator; at the same time, it indirectly improves the overall sound insulation performance. The flexible vibration isolation layer 50 can be made of butyl rubber, polyurethane elastomer, or high-damping silicone material, and plays a role in mechanical decoupling between adjacent metamaterial unit plate layers 20. When sound waves penetrate the first layer of metamaterial unit plate layer 20, they must pass through the flexible vibration isolation layer 50 before reaching the second layer, which can effectively reflect and block the transmission path of solid sound waves.

[0032] Furthermore, the two adjacent metamaterial unit plates 20 are mirror-symmetrically distributed between them via a flexible vibration isolation layer 50 sandwiched between them. This symmetrical structure causes the mass plates 23 to be concentrated on both sides of the flexible vibration isolation layer 50, forming a high-density resonant core region. When sound waves penetrate the first flexible covering layer and reach this core region, they encounter severe acoustic impedance mismatch. Combined with the energy dissipation of the shear deformation of the flexible vibration isolation layer 50, the blocking efficiency for mid-to-low frequency noise can be greatly improved. In one embodiment, the flexible vibration isolation layer 50 is a rubber layer or a sealing cotton layer; its thickness is 1.5-2.5 mm.

[0033] In another embodiment, the support frame 21 is a plastic frame, an aluminum alloy frame, or a stainless steel frame with a thickness of 1.5-5mm; the rigid support layer 30 is a PC material layer.

[0034] In one specific embodiment, the elastic film 22 of the metamaterial unit layer 20 provided in this application is a PVC film with a density of 1.3-1.4 g / m³. 2 The material has a Young's modulus of 550-600 MPa, a tensile strength at break of 12.8-13.8 MPa, an elongation at break of 94-99%, a surface tension of approximately 60 mN / m, and an adhesion strength to metal of 80 N / m. The support frame 21 is a 3mm thick aluminum frame, and the mass plates 23 are semi-circular stainless steel sheets with a mass of 0.12-0.18g. First, a 3mm thick aluminum frame is fabricated. After applying tension, a PVC film is pasted onto the lower surface of the aluminum frame. Three mass plates 23 are evenly arranged in the 75*15mm mounting through-holes 211 on the side where the film is pasted to the aluminum frame, thus forming the first layer of metamaterial unit plate 20. Then, a 2mm thick soft rubber pad with a hardness ≤45 Shore A or sealing cotton (flexible vibration isolation layer 50) is pasted under the 3mm support frame 21 to ensure sufficient space for vertical displacement of the PVC film under the action of the oscillator. The second layer of metamaterial unit panel 20 is then placed and mirrored from the first layer. The final layer is a 1mm PC board (rigid support layer 30) bonded to the support frame 21. This is to address the issue that if the underlying layer, consisting of sound-absorbing cotton from the train set, is tightly bonded to the membrane, the membrane resonant panel will lose its sound insulation effect. This design aims to protect the space and provide sound insulation, ultimately forming the membrane core layer. Bolt connections are added to the frame to improve stability. Additionally, the first and second flexible covering layers 40 are both 0.8mm thick soft cloth.

[0035] Sound insulation test environment description: Sound-emitting chamber 111m 3 Reverberation time (100-5kHz) 3.01-1.44s, receiving chamber 123m² 3Reverberation time (100-5kHz) 2.51-1.31s, noise floor 16dB(A), maximum testable sound insulation 65dB. Test specimen dimensions 1225mm*1073mm, using B&K equipment. Figure 4 A schematic diagram comparing the test results of a single structure of a 10mm thin-film metamaterial and a 5mm sound insulation felt in a sound insulation laboratory. Figure 5 This is a schematic diagram comparing the test results of a combination structure of 10mm thin-film metamaterial and 5mm sound insulation felt in a sound insulation laboratory.

[0036] Based on the test results, the sound insulation of a single 10mm metamaterial structure is 11dB lower than that of a single 5mm sound insulation felt. However, when the combined structure achieves a sound insulation ≥52dB (the exact value varies between laboratories; this value is based on the test parameters from the aforementioned laboratories), the 5mm sound insulation felt material can replace the 10mm thin-film metamaterial composite panel, achieving both no loss and improvement in sound insulation, while reducing the weight by 2-3kg / m². 2 By only changing the internal non-load-bearing structure, this combined structure has engineering applications.

[0037] This application provides a composite film metamaterial structure 100 that can replace 5mm sound insulation felt material in specific structures of EMU trains (pantograph flat top section, pantograph floor section, and sightseeing area section of the lead car), achieving lightweight cross-sectional structure without loss or improvement in sound insulation performance.

[0038] Based on the above embodiments, this application also provides a rail vehicle, including a car body, the car body having at least one of a pantograph top plate cross-sectional structure, a pantograph floor cross-sectional structure, and a sightseeing area floor cross-sectional structure of the lead car; the cross-sectional structure includes a composite thin film metamaterial structure 100 of any of the above embodiments, the thickness of the composite thin film metamaterial structure 100 being less than or equal to 10 mm.

[0039] This embodiment provides a rail vehicle, which includes, but is not limited to, high-speed trains, subway vehicles, or light rail vehicles. To address the issue of external noise entering the vehicle interior while simultaneously meeting the requirements of vehicle lightweighting and maximizing interior space, this embodiment employs a specific cross-sectional structure in noise-sensitive or high-noise-radiation areas of the vehicle body.

[0040] The cross-sectional structure comprises at least one of the following components: The pantograph top plate cross-sectional structure is located on the roof, directly opposite the pantograph mounting area. This component directly bears the aerodynamic noise and pantograph-catenary contact vibration during pantograph operation. The pantograph floor cross-sectional structure is located below the roof, on the floor above the passenger compartment (i.e., the heat and sound insulation layer inside the roof skin), used to block noise transmitted from the roof into the passenger compartment. The sightseeing area floor cross-sectional structure is located behind the driver's cab of the lead vehicle or on the floor of the sightseeing area.

[0041] In this embodiment, the composite thin-film metamaterial structure 100 is integrated into the "sandwich" layer of the vehicle body panel. Specifically, the vehicle body panel typically includes an outer skin, an inner panel, and a sound and heat insulation layer filled in between. This embodiment utilizes the composite thin-film metamaterial structure 100 to replace or partially replace the traditional glass wool / rock wool layer. This metamaterial structure, with a thickness ≤10mm, can be tightly adhered to the inner surface of the pantograph top panel or the observation area floor by means of adhesive backing, snap-fit ​​fixing, or molding, occupying almost no additional interior headroom.

[0042] In one embodiment, the pantograph top plate cross-sectional structure includes, from top to bottom, a sound insulation plate layer, a vehicle body profile layer, a damping coating layer, a sound insulation felt layer, a sound-absorbing cotton layer, a composite film metamaterial layer, and an interior panel layer.

[0043] Specifically, the pantograph top plate cross-section structure sequentially includes a sound insulation cover, a flat-top aluminum profile for the vehicle body, a 2mm damping coating layer, interior trim (3mm sound insulation felt + 20mm sound-absorbing cotton + 10mm thin-film metamaterial composite), and a 1.5mm perforated interior aluminum panel. Simply changing the aforementioned interior structure results in a weight reduction of 2-3 kg / m². 2 The sound insulation is improved by 0-1 dB.

[0044] In another embodiment, the pantograph floor cross-section structure and the sightseeing area floor cross-section structure of the lead vehicle both include: a base frame sound-absorbing layer, a damping slurry layer, a vehicle body profile layer, a damping slurry layer, a floor support layer, a drainage layer, a sound-absorbing material layer, a composite film metamaterial layer, a wood plywood layer, and a floor cloth layer.

[0045] Specifically, the cross-sectional structure of the pantograph floor and the sightseeing area floor of the lead vehicle both include a base frame sound-absorbing composite structure, a 5mm damping slurry layer, an 80mm aluminum profile layer, a 3mm damping slurry layer, a 50mm floor support layer (intermittently connecting profiles and plywood), a 10mm drainage board layer, a 40mm sound-absorbing material layer, a 10mm thin-film metamaterial composite layer, a 19.5mm plywood layer, and a 3mm floor fabric layer. The base frame sound-absorbing composite structure includes a 1.8mm metal fiber sound-absorbing panel and a 15mm sound-absorbing material layer. Simply changing the above internal structure results in a weight reduction of 2-3 kg / m². 2 The sound insulation is improved by 0-1 dB.

[0046] The replaced composite film metamaterial structure 100 is a non-load-bearing component in the intermediate structural layer, and will not affect the load-bearing structure of the aluminum profile or the load-bearing structure of the wood plywood. Furthermore, the total thickness is 5mm thicker. Since the 40mm sound-absorbing material layer is a soft, compressible material, compression will occur during construction and installation, ensuring the overall thickness of the floor structure remains unchanged. Lightweighting is achieved through adjustments to a single structure without reducing sound insulation, thus meeting engineering requirements.

[0047] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0048] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A composite thin-film metamaterial structure, characterized in that, It includes a first flexible covering layer, a metamaterial unit plate layer, a rigid support layer, and a second flexible covering layer arranged sequentially. The metamaterial unit plate includes a support frame, an elastic film, and a mass sheet; the support frame has several mounting through holes, the elastic film covers the support frame and closes one side opening of the mounting through holes; the mass sheet is located on the elastic film corresponding to the mounting through holes; The rigid support layer is disposed on the side of the metamaterial unit plate layer away from the elastic film and is opposite to the opening of the mounting through hole; The first flexible covering layer is connected to the side of the metamaterial unit plate layer opposite to the rigid support layer, and the second flexible covering layer is connected to the side of the rigid support layer opposite to the metamaterial unit plate layer.

2. The composite thin film metamaterial structure according to claim 1, characterized in that, The metamaterial unit plate layer consists of several layers, and each layer of the metamaterial unit plate layer is arranged along the thickness direction; a flexible vibration isolation layer is provided between adjacent metamaterial unit plate layers.

3. The composite thin film metamaterial structure according to claim 2, characterized in that, The flexible vibration isolation layer sandwiched between two adjacent metamaterial unit plates is distributed in a mirror-symmetric manner.

4. The composite thin film metamaterial structure according to claim 2, characterized in that, The thickness of the flexible vibration isolation layer is 1.5-2.5 mm.

5. The composite thin-film metamaterial structure according to claim 2, characterized in that, The flexible vibration isolation layer is a rubber layer or a sealing cotton layer.

6. The composite thin film metamaterial structure according to claim 1, characterized in that, The support frame is a plastic frame, an aluminum alloy frame, or a stainless steel frame, with a thickness of 1.5-5mm.

7. The composite thin film metamaterial structure according to claim 1, characterized in that, The rigid support layer is a PC material layer.

8. A rail vehicle, characterized in that, The vehicle body includes at least one of the following: pantograph top plate cross-sectional structure, pantograph floor cross-sectional structure, and sightseeing area floor cross-sectional structure of the lead vehicle. The cross-sectional structure includes the composite thin film metamaterial structure according to any one of claims 1-7, wherein the thickness of the composite thin film metamaterial structure is less than or equal to 10 mm.

9. The composite thin film metamaterial structure according to claim 8, characterized in that, The cross-sectional structure of the pantograph top plate includes, from top to bottom, a sound insulation board layer, a vehicle body profile layer, a damping coating layer, a sound insulation felt layer, a sound-absorbing cotton layer, the composite film metamaterial layer, and an interior panel layer.

10. The composite thin film metamaterial structure according to claim 8, characterized in that, Both the pantograph floor cross-sectional structure and the sightseeing area floor cross-sectional structure of the lead vehicle include: The structure includes a sound-absorbing base layer, a damping slurry layer, a vehicle body profile layer, a damping slurry layer, a floor support layer, a drainage layer, a sound-absorbing material layer, the composite film metamaterial layer, the wood plywood layer, and the floor fabric layer.

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