A sandwich panel for vibration isolation, waveguiding and vibration concentration

Abstract

The application discloses a kind of interlayer plates for vibration isolation, waveguide and vibration aggregation.The interlayer plate includes upper partition, lower partition, and multiple band gap regulation units arranged between the upper partition and the lower partition.The band gap regulation unit includes upper elastomer, core vibrator, coil and lower elastomer.The opposite sides of the upper elastomer and the lower elastomer are fixed with the two ends of the core vibrator respectively.The opposite sides of the upper elastomer and the lower elastomer are fixed with the opposite sides of the upper partition and the lower partition respectively.Both the upper elastomer and the lower elastomer are made of magnetorheological fluid;The coil is wrapped outside the core vibrator.In the interlayer plate structure of the application, the magnetorheological elastomer and the core vibrator coil serve as the core layer, combining the magnetic source and the vibrator into one, and the electromagnetic coil can provide an internal magnetic field, without the need for additional external magnets or electromagnetic devices, greatly saving space usage.The interlayer plate provided by the application can be switched between vibration isolation plate, waveguide plate and vibration wave concentration plate under the condition of changing the current supply mode.

Description

TECHNICAL FIELD

[0001] The present application relates to the fields of intelligent metamaterials, mechanical structures, electromagnetic technology, and the like, and particularly relates to a vibration isolation and noise reduction sandwich plate commonly used in mechanical systems or engineering practices. BACKGROUND

[0002] Plate structures are commonly used components in mechanical systems, civil engineering, and the like. Among them, sandwich plates are widely used in engineering practices due to their light weight, high bending stiffness, and good sound and vibration isolation performance. It is of great significance to reduce vibration and noise, especially in the low frequency band. However, the band gap frequency range of the traditional sandwich plate is fixed and cannot be intelligently adjusted, making it difficult to adapt to different application scenarios.

[0003] Magnetorheological elastomers are a kind of intelligent materials prepared by mixing ferromagnetic particles such as carbonyl iron powder into high polymer polymers such as silicone rubber base, whose mechanical properties such as stiffness can change rapidly in real time with an applied magnetic field. In recent years, semi-active vibration and noise controllers based on magnetorheological elastomers (such as vibration isolators, vibration absorbers, and sound absorbers) have received a lot of research and attention. Traditional magnetorheological elastomer sandwich plates generally use magnetorheological elastomers as the core layer, often requiring external magnetic fields or electromagnetic coil devices, resulting in a relatively large space occupation and a high band gap frequency.

[0004] The local resonance type intelligent metamaterial structure has the characteristics of generating a low-frequency band gap with small size, providing a new idea for low-frequency vibration and noise reduction. Therefore, it is of great significance to design a low-frequency adjustable band gap vibration and noise reduction sandwich plate with compact structure based on magnetorheological elastomers and local resonance principles. SUMMARY

[0005] The purpose of the present application is to provide a compact magnetorheological elastomer vibration isolation sandwich plate based on the local resonance principle. By embedding the electromagnetic coil in the core layer, it serves as both an internal magnetic field generating unit and a local resonance oscillator, thereby generating a low-frequency real-time adjustable band gap under the premise of reducing space occupation, achieving low-frequency vibration isolation and noise reduction.

[0006] A sandwich plate for vibration isolation, waveguide, and vibration aggregation includes an upper separation plate, a lower separation plate, and a plurality of band gap control units arranged between the upper separation plate and the lower separation plate. The band gap control unit includes an upper elastomer, a core oscillator, a coil, and a lower elastomer. The opposite sides of the upper and lower elastomers are fixed to the two ends of the core oscillator, respectively. The opposite sides of the upper and lower elastomers are fixed to the opposite sides of the upper and lower separation plates, respectively. Both the upper and lower elastomers are made of magnetorheological elastomers; the coil is arranged on the outside of the core oscillator.

[0007] The sandwich plate is used as a vibration isolation plate, a waveguide plate or a vibration wave concentrating plate. In the case of using the sandwich plate as a vibration isolation plate, all the coils are energized, and the directions of the magnetic fields on the axes of any two adjacent band gap regulation units are opposite; the magnetic fields change the stiffness of the upper and lower elastic bodies, so that the externally input vibration waves fall within the band gap range of each band gap regulation unit.

[0008] In the case of using the sandwich plate as a waveguide plate, the parameters of the band gap regulation units are adjusted according to the frequency of the vibration waves to be transmitted, so that the frequency of the vibration waves to be transmitted is within the band gap range of the band gap regulation units when the coils are not energized. In the working process, a vibration wave transmission path is planned on the sandwich plate; the vibration wave transmission path passes through a plurality of band gap regulation units in turn. The coils in the band gap regulation units on the vibration wave transmission path are energized, and the remaining coils are not energized, and the directions of the magnetic fields on the axes of any two adjacent band gap regulation units along the vibration wave transmission path are opposite. The frequency of the vibration waves to be transmitted is outside the band gap of each band gap regulation unit on the vibration wave transmission path, and the externally input vibration waves propagate along the vibration wave transmission path. By using the waveguide characteristics, the vibration waves can be guided and manipulated to propagate to a specific vibration absorber or energy collector, thereby effectively controlling low-frequency vibrations.

[0009] In the case of using the sandwich plate as a vibration wave concentrating plate, the parameters of the band gap regulation units are adjusted according to the frequency of the vibration waves to be concentrated, so that the frequency of the vibration waves to be concentrated is within the band gap range of the band gap regulation units when the coils are not energized. In the working process, a vibration wave output position is set on the sandwich plate; the vibration wave output position coincides with the axial position of one of the band gap regulation units. The coil in the vibration wave output position is energized, and the remaining coils are not energized, so that the frequency of the vibration waves is outside the band gap of the band gap regulation unit at the vibration wave output position. The energy of the externally input vibration waves is concentrated to the vibration wave output position for output.

[0010] Preferably, each band gap regulation unit is arranged in a matrix.

[0011] Preferably, the cross sections of the upper elastic body, the core oscillator and the lower elastic body are circular and have the same shape.

[0012] Preferably, the upper partition and the upper elastic body, the lower partition and the lower elastic body, and the core oscillator and the upper and lower elastic bodies are adhered by coating uncured magnetorheological fluid to solidify the magnetorheological fluid.

[0013] Preferably, the upper and lower partitions are plates with a thickness of 2 mm; the upper and lower elastic bodies are cylindrical bodies with a thickness of 2 mm and a diameter of 20 mm; and the core oscillator is a cylindrical body with a height of 8 mm and a diameter of 20 mm.

[0014] Preferably, the upper and lower elastic bodies are prepared from carbonyl iron powder, silicone rubber and silicone oil in a mass ratio of 7:1.5:1.5.

[0015] Compared with the prior art, the present application has the following advantages:

[0016] 1. In the sandwich plate structure of the present application, the magneto-rheological elastomer and the iron-core vibrator coil serve as the core layer, combining the magnetic source and the vibrator into one, and the electromagnetic coil can provide an internal magnetic field, without the need for adding external magnets or electromagnetic devices, thus greatly saving space.

[0017] 2. The sandwich plate structure of the present application uses the local resonance unit of the magneto-rheological elastomer and the iron-core vibrator coil, which can realize low-frequency adjustable band gap, thus increasing the applicability of the structure to low-frequency vibration isolation and noise reduction occasions.

[0018] 3. The sandwich plate structure of the present application can control the strength of the coil current to construct a line defect state path, thus realizing active control of the waveguide of the elastic wave. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 FIG. 1 is a side view of a sandwich plate and its magnetic field circuit according to an embodiment of the present application.

[0020] Figure 2 FIG. 2 is a top view of a sandwich plate and its magnetic field circuit according to an embodiment of the present application.

[0021] Figure 3 FIG. 3 is a band diagram and a transmission rate diagram of a sandwich plate according to an embodiment of the present application.

[0022] Figure 4 FIG. 4 is a transmission rate diagram of a sandwich plate according to an embodiment of the present application under different coil currents.

[0023] Figure 5 FIG. 5 is a top view of a sandwich plate and its magnetic field circuit according to another embodiment of the present application. DETAILED DESCRIPTION

[0024] The present application will be further described below with reference to the accompanying drawings.

[0025] Embodiment 1

[0026] As Figure 1 and 2As shown in the figure, a kind of sandwich plate for vibration isolation, waveguide and vibration aggregation is used as sound insulation board, which includes upper partition plate 1, lower partition plate 6, and a plurality of band gap regulation units arranged in matrix between upper partition plate 1 and lower partition plate 6.The band gap regulation unit includes upper elastomer 2, core vibrator 3, coil 4 and lower elastomer 5.The opposite sides of upper elastomer 2 and lower elastomer 5 are fixed with the two ends of core vibrator 3 respectively.The opposite sides of upper elastomer 2 and lower elastomer 5 are fixed with the opposite sides of upper partition plate 1 and lower partition plate 6 respectively.Both upper elastomer 2 and lower elastomer 5 use magnetic fluid;coil 4 is wound outside core vibrator 3.The cross section of upper elastomer 2, core vibrator 3 and lower elastomer 5 is circular with the same shape.The adhesion between upper partition plate 1 and upper elastomer 2, between lower partition plate 6 and lower elastomer 5, and between core vibrator 3 and upper elastomer 2 and lower elastomer 5 is realized by coating uncured magnetic fluid to make the magnetic fluid solidify.Both upper partition plate 1 and lower partition plate 6 use soft magnetic material, which can guide magnetism and be part of magnetic path.In this embodiment, both upper partition plate 1 and lower partition plate 6 use iron plate.

[0027] When different currents are input into coil 4, the magnetic field at the position of upper elastomer 2 and lower elastomer 5 changes, and then the natural frequency of the whole band gap regulation unit changes.When the natural frequency of the whole band gap regulation unit falls within the band gap range of the externally input vibration wave, the vibration wave cannot continue to propagate backward through the band gap regulation unit, so as to achieve the effect of inhibiting vibration.

[0028] As shown in the figure, Figure 1 and 2 When the sandwich plate is used for vibration isolation, all coils are electrified, and the coils in any two adjacent band gap regulation units apply opposite currents, so that the magnetic field generated by any coil is just opposite to the magnetic field generated by its adjacent (4-neighbor) coils in the upper and lower directions, and then any coil forms a magnetic field loop 7 through its core vibrator, the upper elastomer connected thereto, the upper partition plate, the upper elastomer connected to the adjacent band gap regulation unit, the core vibrator of the adjacent band gap regulation unit, the lower elastomer connected to the adjacent band gap regulation unit, the lower partition plate and the lower magnetic fluid elastomer connected to the band gap regulation unit, so as to increase the magnetic field intensity at the position of upper elastomer and lower elastomer under the same current size, and reduce the current size required for adjusting upper elastomer and lower elastomer. Figure 2 In the figure, the symbol "×" represents that the magnetic field direction is perpendicular to the paper surface inward, and the symbol "·" represents that the magnetic field direction is perpendicular to the paper surface outward.

[0029] The band gap of the sandwich plate structure and the waveguide can be actively regulated by controlling the current of the coil. When the current of the coil is increased, the magnetic field generated by the coil is also increased, the stiffness of the magneto-rheological elastomer in the magnetic field is increased, the resonance frequency is also increased, the band gap moves to high frequency and is widened. Conversely, as the current decreases, the band gap moves to low frequency and narrows, thereby achieving the vibration isolation effect for different frequency vibration waves.

[0030] As an optional technical solution, the upper partition plate 1 and the lower partition plate 6 are both partition plates with a thickness of 2 mm; the upper elastomer 2 and the lower elastomer 5 are both cylinders with a thickness of 2 mm and a diameter of 20 mm; and the core vibrator 3 is a cylinder with a height of 8 mm and a diameter of 20 mm.

[0031] As an optional technical solution, the band gap regulation unit has a total of 48 units arranged in a 6x8 array. The center distance (i.e. the lattice constant) of any two adjacent band gap regulation units is 40 mm.

[0032] As an optional technical solution, the upper elastomer 2 and the lower elastomer 5 are prepared from carbonyl iron powder, silicone rubber and silicone oil in a mass ratio of 7:1.5:1.5.

[0033] The band diagram of the sandwich plate for vibration isolation, waveguide and vibration aggregation and the corresponding transmissibility diagram are shown in Figure 3 The diagram transmissibility is obtained by simulation using COMSOL Multiphysics 6.0 software. The specific method of simulation is as follows:

[0034] 1. The magneto-rheological elastomer vibration isolation sandwich plate is equivalent to a thin plate-spring-mass model. The thin partition plate is regarded as a thin shell structure, and the magneto-rheological elastomer, the core vibrator and the coil 4 are regarded as a spring-mass system. The structural mechanics module is used, and the shell interface is selected for characteristic frequency and frequency domain research.

[0035] 2. A geometric model of the thin partition plate is established, and geometric points corresponding to the axes of the magneto-rheological elastomer and the core vibrator coil are established on the partition plate as equivalent nodes.

[0036] 3. The spring and mass equivalent to the magneto-rheological elastomer and the core vibrator coil are established by selecting a lumped mechanical system. First, a spring-mass subsystem with node a is established; then, a plurality of spring-mass subsystem instances are established, and in this embodiment, 48 subsystem instances are established, and the node names 1-48 of each subsystem instance are instantiated. Then, the corresponding external source is established for each subsystem instance, and the node name corresponding to the label is set to the node name 1-48 of the subsystem instance.

[0037] 4. In the multi-physical field, a lumped-structure connection corresponding to each external source is established, and a specific external source and an equivalent node in the corresponding geometric model are selected, thereby associating the equivalent spring-mass system established by the lumped mechanical system with the geometric model established by the shell structure.

[0038] 5. A point in the shell is selected as an excitation point and a unit displacement is specified, and at the same time, a point probe is defined to pick up the response point displacement.

[0039] 6. A finite element mesh model is established, and the transmissibility curve of the structure is calculated and plotted by sweeping the frequency.

[0040] As shown in Figure 4 , the transmissibility of the sandwich plate under different coil currents is simulated by using the above method. When the coil current increases from 0.0 A to 0.5 A and then to 1.0 A, the corresponding bandgap range increases from 143.8-227.7 Hz to 148.9-242.9 Hz and then to 174.5-278.6 Hz.

[0041] Example 2

[0042] As shown in Figure 5 , a compact magneto-rheological elastomer sandwich plate based on local resonance is used as a waveguide plate; the structure of the sandwich plate is the same as that of Example 1. At this time, the parameters of the bandgap regulating unit are adjusted according to the frequency of the transmitted vibration wave, so that the frequency of the transmitted vibration wave is within the bandgap range of the bandgap regulating unit when the coil is not powered.

[0043] During operation, a vibration wave transmission path is planned on the sandwich plate; the vibration wave transmission path passes through a plurality of bandgap regulating units in turn. The coils in the bandgap regulating units on the vibration wave transmission path are powered, and the remaining coils are not powered, and the current directions of any two adjacent bandgap regulating units along the vibration wave transmission path are opposite, so that the magnetic field directions of the adjacent two bandgap regulating units on the axis are opposite, forming separate magnetic field paths along the vibration wave transmission path.

[0044] The stiffness of the upper elastomer 2 and the lower elastomer 5 in each bandgap regulating unit on the vibration wave transmission path changes under the action of the magnetic field, thereby changing the bandgap; so that the frequency of the transmitted vibration wave is outside the bandgap on the vibration wave transmission path, and the transmitted vibration wave is constrained on the vibration wave transmission path, thereby obtaining a vibration waveguide plate capable of forming an adjustable propagation path.

[0045] The principle of forming the waveguide plate is that line defect states are introduced in the sandwich plate structure, a preset path line defect is formed by purposefully designing the arrangement path of the energized coil, and thus the active control of the elastic wave waveguide is realized. The U-shaped line defect path formed by the energization of each band gap regulation unit on the vibration wave transmission path is as shown in FIG. 8. Figure 5 Figure 5 In the figure, the symbol "×" represents that the magnetic field direction is inwardly perpendicular to the paper, and the symbol "·" represents that the magnetic field direction is outwardly perpendicular to the paper. Due to the energization of the coil located on the line defect path, the stiffness of the magneto-rheological elastomer on the path is obviously increased than that outside the path, and thus the U-shaped line defect state is formed. When the elastic wave is incident from the left side of the sandwich plate, the elastic wave will propagate along the U-shaped line defect path to the right side of the sandwich plate.

[0046] Embodiment 3

[0047] A compact magneto-rheological elastomer sandwich plate based on local resonance is used as a vibration wave amplifier; the structure of the sandwich plate is the same as that of Embodiment 1. At this time, the parameters of the band gap regulation unit are adjusted according to the frequency of the transmitted vibration wave, so that the frequency of the amplified vibration wave is within the band gap range of the band gap regulation unit when the coil is not energized.

[0048] In the working process, the vibration wave amplification output position is set on the sandwich plate; the vibration wave amplification output position coincides with the axis position of any one band gap regulation unit. The coil in the vibration wave amplification output position is energized, and the remaining coils are not energized, so that the frequency of the amplified vibration wave is outside the band gap of the band gap regulation unit in the vibration wave amplification output position. When the external vibration wave is input into the sandwich plate, all the vibration wave energy is concentrated to the vibration wave amplification output position, and thus the function of amplifying the vibration wave signal is achieved.​

Claims

1. A method for vibration isolation, waveguide, and vibration concentration in a sandwich panel, characterized in that: The sandwich panel includes an upper partition (1), a lower partition (6), and multiple bandgap control units disposed between the upper partition (1) and the lower partition (6); the bandgap control unit includes an upper elastic body (2), an iron core oscillator (3), a coil (4), and a lower elastic body (5); the opposite sides of the upper elastic body (2) and the lower elastic body (5) are respectively fixed to the two ends of the iron core oscillator (3); the opposite sides of the upper elastic body (2) and the lower elastic body (5) are respectively fixed to the opposite sides of the upper partition (1) and the lower partition (6); both the upper elastic body (2) and the lower elastic body (5) are magnetorheological bodies; the coil (4) is wound around the outside of the iron core oscillator (3); both the upper partition (1) and the lower partition (6) are made of soft magnetic materials that can conduct magnetism; During the vibration isolation process, all the coils of the sandwich plate are energized, and the magnetic field directions on the axes of any two adjacent bandgap control units are opposite; the magnetic field changes the stiffness of the upper elastic body (2) and the lower elastic body (5), so that the externally input vibration wave falls within the bandgap range of each bandgap control unit. In the waveguide process, a vibration wave propagation path is planned on the sandwich plate; the vibration wave propagation path passes through several bandgap control units in sequence; the coils in the bandgap control units on the vibration wave propagation path are energized, while the other coils are not energized, and the magnetic field directions on the axes of any two adjacent bandgap control units along the vibration wave propagation path are opposite; the frequency of the transmitted vibration wave is outside the bandgap of each bandgap control unit on the vibration wave propagation path, and the externally input vibration wave propagates along the vibration wave propagation path. During the vibration concentration process, a vibration wave output position is set on the sandwich panel; the vibration wave output position coincides with the axis position of one of the bandgap control units; the coil in the vibration wave output position is energized, while the other coils are not energized, so that the frequency of the vibration wave is outside the bandgap of the bandgap control unit at the vibration wave output position; the energy of the externally input vibration wave is concentrated at the vibration wave output position.

2. The method for vibration isolation, waveguide, and vibration concentration of a sandwich panel according to claim 1, characterized in that: The bandgap control units are arranged in a matrix.

3. The method for vibration isolation, waveguide, and vibration concentration of a sandwich panel according to claim 1, characterized in that: The upper elastic body (2), the iron core oscillator (3), and the lower elastic body (5) have the same circular cross-section.

4. The method for vibration isolation, waveguide, and vibration concentration of a sandwich panel according to claim 1, characterized in that: The upper partition (1) and the upper elastic body (2), the lower partition (6) and the lower elastic body (5), and the iron core oscillator (3) and the upper elastic body (2) and the lower elastic body (5) are all bonded by coating uncured magnetorheological material to cure the magnetorheological material.

5. A method for vibration isolation, waveguide, and vibration concentration of a sandwich panel according to claim 1, characterized in that: The upper partition (1) and lower partition (6) are both made of 2mm thick plate; the upper elastic body (2) and lower elastic body (5) are both cylinders with a thickness of 2mm and a diameter of 20mm; the iron core vibrator (3) is a cylinder with a height of 8mm and a diameter of 20mm.

6. The method for vibration isolation, waveguide, and vibration concentration of a sandwich panel according to claim 1, characterized in that: The upper elastomer (2) and the lower elastomer (5) are prepared by carbonyl iron powder, silicone rubber and silicone oil in a mass fraction of 7:1.5:1.5.

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