A composite sound absorption superstructure based on multi-frequency resonance and a design method thereof

Abstract

The application discloses a composite sound absorption superstructure based on multi-frequency resonance and a design method thereof. The composite sound absorption superstructure based on multi-frequency resonance comprises a high-frequency sound absorption structure, a low-frequency sound absorption structure and porous sound absorption material filled in the high-frequency sound absorption structure and the low-frequency sound absorption structure. The high-frequency sound absorption structure is composed of a plurality of cells arranged in parallel and embedded in the same layer and at the same height. The low-frequency sound absorption structure comprises a plurality of cells arranged in parallel and at the same height in a straight line direction. The low-frequency sound absorption structure is arranged below the high-frequency sound absorption structure. The high-frequency sound absorption structure and the low-frequency sound absorption structure are integrally formed by 3D printing through photosensitive resin. The sound absorption structure has a plurality of different sound absorption peaks, widens a low-frequency sound absorption frequency band and significantly enhances a low-frequency broadband sound absorption capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sound absorption structure design, and particularly relates to a composite sound absorption superstructure based on multi-frequency resonance and a design method thereof. BACKGROUND

[0002] With the further development of industrial modernization, the driver and passenger have higher and higher requirements for the comfort of the truck. Since the power of the truck is large, the noise pollution problem becomes increasingly common, and the noise in the vehicle is an important factor affecting comfort. In order to suppress the noise in the vehicle when the vehicle is running, ensure that the truck has sufficient full-band sound absorption capacity in the vehicle, and prevent the noise from affecting the voice clarity in the vehicle when the car audio system is working, a sound absorption device is needed to absorb sound. In the full-band noise, the low-frequency noise is not easy to attenuate due to its long wavelength, long propagation distance and strong penetration, and its inherent weak energy dissipation makes the absorption of low-frequency noise a challenging problem that needs to be solved.

[0003] Traditional porous sound absorption materials are usually only effective for high-frequency noise, and have no obvious inhibitory effect on low-frequency noise. Moreover, due to the limitation of the acoustic mass law, the thickness of the sound absorption structure and the wavelength of the low-frequency cutoff frequency are required to be in the same order of magnitude, so that the size of the traditional porous sound absorption structure is usually large and is not easy to apply in practical engineering.

[0004] With the progress of acoustic superstructure technology, a resonant sound absorption structure with a depth subwavelength thickness is proposed, which shows excellent sound absorption performance for low-frequency noise. However, due to the characteristics of the resonant sound absorption principle, the above resonant sound absorption structure always has the shortcoming of narrow sound absorption band, and it is difficult to achieve continuous and effective noise reduction in a wide frequency band. Finally, the practical value of the current resonant sound absorption structure is very low, and it is difficult to popularize and popularize. SUMMARY

[0005] The main purpose of the present application is to provide a composite sound absorption superstructure based on multi-frequency resonance and a design method thereof, which aims to solve the problem of poor low-frequency sound absorption effect of the existing sound absorption structure.

[0006] To achieve the above purpose, the present application provides a composite sound absorption superstructure based on multi-frequency resonance, which comprises a high-frequency sound absorption structure, a low-frequency sound absorption structure and a porous sound absorption material filled in the high-frequency sound absorption structure and the low-frequency sound absorption structure, wherein,

[0007] The high-frequency sound absorption structure comprises a plurality of cells arranged in the same layer and at the same height and embedded in parallel with each other, and the low-frequency sound absorption structure comprises a plurality of cells arranged in parallel in a straight line direction and at the same height. The low-frequency sound absorption structure is located below the high-frequency sound absorption structure, and the high-frequency sound absorption structure and the low-frequency sound absorption structure are integrally formed by 3D printing using photosensitive resin.

[0008] Preferably, the cell of the high-frequency sound absorption structure comprises a hollow shell, the hollow chamber of the shell is filled with a porous sound absorption material, the inside of the shell contains a transverse partition plate to divide the chamber into multiple areas, the transverse partition plate and / or the top plate of the shell adopts a slit plate or a porous plate structure.

[0009] Preferably, the high-frequency sound absorption structure comprises a first high-frequency sound absorption cell, a second high-frequency sound absorption cell, a third high-frequency sound absorption cell and a fourth high-frequency sound absorption cell arranged in the same height, the first high-frequency sound absorption cell and the third high-frequency sound absorption cell are arranged side by side, and the second high-frequency sound absorption cell and the fourth high-frequency sound absorption cell are arranged side by side.

[0010] Preferably, the first high-frequency sound absorption cell is internally provided with a first transverse partition plate and a first vertical partition plate, the two ends of the first transverse partition plate are respectively connected with the two side wall plates of the first high-frequency sound absorption cell, the two ends of the first vertical partition plate are respectively connected with the bottom of the first transverse partition plate and the bottom plate of the first high-frequency sound absorption cell, and the first transverse partition plate and the top plate of the first high-frequency sound absorption cell adopt a slit plate.

[0011] Preferably, the second high-frequency sound absorption cell is internally provided with a second transverse partition plate, a third transverse partition plate and a second vertical partition plate, the two ends of the second transverse partition plate and the third transverse partition plate are connected with the two side wall plates of the second high-frequency sound absorption cell, the two ends of the second vertical partition plate are respectively connected with the bottom of the second transverse partition plate and the bottom plate of the second high-frequency sound absorption cell, the second transverse partition plate adopts a porous plate, the top plate of the second high-frequency sound absorption cell adopts a slit plate, and the second vertical partition plate divides the shell below the third transverse partition plate into a left shell and a right shell, the inside of the left shell is provided with a partition plate, the height of the partition plate is lower than the height of the internal chamber of the left shell, and the top plate of the right shell adopts a slit plate.

[0012] Preferably, the slit width of the top plate of the right shell is smaller than the slit width of the top plate of the second high-frequency sound absorption cell, and the slit directions of the top plate of the right shell and the top plate of the second high-frequency sound absorption cell are arranged vertically.

[0013] Preferably, the third high-frequency sound absorption cell is internally provided with a fourth transverse partition plate, a fifth transverse partition plate and a third vertical partition plate, the two ends of the fourth transverse partition plate and the fifth transverse partition plate are connected with the two side wall plates of the third high-frequency sound absorption cell, the two ends of the third vertical partition plate are respectively connected with the bottom of the fifth transverse partition plate and the bottom plate of the third high-frequency sound absorption cell, the fourth transverse partition plate and the fifth transverse partition plate adopt a slit plate, the top plate of the third high-frequency sound absorption cell adopts a porous plate, the third vertical partition plate divides the shell below the fifth transverse partition plate into a left second shell and a right second shell, the inside of the left shell is provided with a partition plate, the height of the partition plate is lower than the height of the internal chamber of the left shell, and the top plate of the right second shell adopts a slit plate.

[0014] Preferably, the fourth high-frequency sound absorption cell is internally provided with a sixth transverse partition plate and a fourth vertical partition plate, two ends of the sixth transverse partition plate are connected with two side wall plates of the fourth high-frequency sound absorption cell, two ends of the fourth vertical partition plate are respectively connected with a bottom of the sixth transverse partition plate and a bottom plate of the fourth high-frequency sound absorption cell, and the sixth transverse partition plate and the top plate of the fourth high-frequency sound absorption cell are both provided with a plurality of holes.

[0015] Preferably, the top plate of the cell of the low-frequency sound absorption structure is provided with an insertion plate integrally formed thereon, the insertion plate extends downwardly to the top plate, and a plurality of slits are formed on the insertion plate to form an internal insertion slit structure.

[0016] The application further provides a design method of the above-mentioned composite sound absorption superstructure based on multi-frequency resonance, which comprises the following steps:

[0017] The structure parameters of the low-frequency sound absorption structure are preliminarily determined according to a low-frequency target sound absorption frequency band, including the slit width of the internal insertion slit, the depth of the internal insertion slit, the structure height and the thickness.

[0018] The structure parameters of the high-frequency sound absorption structure are determined according to a medium-high frequency target sound absorption frequency band, including the hole radius of the porous plate of each cell, the slit width of the slit on the slit plate, the length and distance of the partition plate, the structure height and the thickness.

[0019] According to the above-mentioned structure parameters, the low-frequency sound absorption structure and the high-frequency sound absorption structure are coupled, the porous sound absorption material is filled, the finite element simulation model is established for sound absorption simulation, and the sound absorption coefficient curve is obtained.

[0020] According to the sound absorption coefficient curve, the structure parameters of each cell are corrected to obtain the structure parameters of the final composite sound absorption superstructure based on multi-frequency resonance.

[0021] The composite sound absorption superstructure based on multi-frequency resonance has the following beneficial effects:

[0022] 1. The sound absorption structure has multiple different sound absorption peaks, widens the low-frequency sound absorption frequency band, and significantly enhances the low-frequency broadband sound absorption capacity.

[0023] 2. The sound absorption structure solves the problem that the existing acoustic superstructure can only absorb sound at a specific frequency and has a narrow sound absorption frequency band, and greatly improves the sound absorption performance of the structure.

[0024] 3. The sound absorption structure can realize continuous broadband sound absorption in the low-frequency range by adjusting the slit width and slit depth of the high-frequency sound absorption structure and the low-frequency sound absorption structure, thereby adjusting the sound absorption frequency range, moving the sound absorption frequency band to the low frequency, and effectively applying to engineering.

[0025] 4. The sound absorption structure is neat, light and thin in overall structure, and is easy to install and use. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1a Front view structural schematic diagram of a first embodiment of a composite sound absorption superstructure based on multi-frequency resonance of the present application;

[0027] Figure 1b Perspective structural schematic diagram of the first embodiment of the composite sound absorption superstructure based on multi-frequency resonance of the present application;

[0028] Figure 1c Front view structural schematic diagram of Figure 1b ;

[0029] Figure 1d Side view structural schematic diagram of Figure 1b ;

[0030] Figure 1e Top view structural schematic diagram of Figure 1b ;

[0031] Figure 2 Perspective structural schematic diagram of a high-frequency sound absorption structure in the first embodiment of the composite sound absorption superstructure based on multi-frequency resonance of the present application;

[0032] Figure 3 Perspective structural schematic diagram of a first high-frequency sound absorption unit in the first embodiment of the composite sound absorption superstructure based on multi-frequency resonance of the present application;

[0033] Figure 4 Perspective structural schematic diagram of a second high-frequency sound absorption unit in the first embodiment of the composite sound absorption superstructure based on multi-frequency resonance of the present application;

[0034] Figure 5 Perspective structural schematic diagram of a third high-frequency sound absorption unit in the first embodiment of the composite sound absorption superstructure based on multi-frequency resonance of the present application;

[0035] Figure 6 Perspective structural schematic diagram of a fourth high-frequency sound absorption unit in the first embodiment of the composite sound absorption superstructure based on multi-frequency resonance of the present application;

[0036] Figure 7 Perspective structural schematic diagram of a low-frequency sound absorption structure in the first embodiment of the composite sound absorption superstructure based on multi-frequency resonance of the present application;

[0037] Figure 8 Sound absorption coefficient curve of the first embodiment of the composite sound absorption superstructure based on multi-frequency resonance of the present application;

[0038] Figure 9 Design method flowchart of the first embodiment of the composite sound absorption superstructure based on multi-frequency resonance of the present application.

[0039] In the figure, 1-first high frequency sound absorbing cell; 2-second high frequency sound absorbing cell; 3-third high frequency sound absorbing cell; 4-fourth high frequency sound absorbing cell; 5-low frequency sound absorbing structure; 6-top plate of the first high frequency sound absorbing cell; 7-right side of the first transverse partition; 8-left side of the first transverse partition; 9-first vertical partition; 10-top plate of the second high frequency sound absorbing cell; 11-second transverse partition; 12-third transverse partition; 13-second vertical partition; 14-first partition plate; 15-top plate of the third high frequency sound absorbing cell 3; 16-fourth transverse partition; 17-fifth transverse partition; 18-third vertical partition; 19-second partition plate; 20-top plate of the fourth high frequency sound absorbing cell; 21-right side of the sixth transverse partition; 22-left side of the sixth transverse partition; 23-fourth vertical partition; 24-first low frequency sound absorbing structure; 25-second low frequency sound absorbing structure; 26-third low frequency sound absorbing structure; 27-fourth low frequency sound absorbing structure; 28-fifth low frequency sound absorbing structure; 29-sixth low frequency sound absorbing structure; 30-porous sound absorbing material.

[0040] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0041] It should be understood that the specific embodiments described herein merely exemplify the application and do not limit the application.

[0042] It should be noted that in the description of the present application, the terms "transverse", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0043] The present application proposes a composite sound absorbing superstructure based on multi-frequency resonance.

[0044] The present application proposes a first embodiment of a composite sound absorbing superstructure based on multi-frequency resonance. Referring to Figures 1a to 1c In this embodiment, a composite sound absorbing superstructure based on multi-frequency resonance includes a high frequency sound absorbing structure, a low frequency sound absorbing structure 5 and a porous sound absorbing material 30 filled in the high frequency sound absorbing structure and the low frequency sound absorbing structure 5, wherein,

[0045] The high-frequency sound absorption structure is composed of a plurality of cells arranged in parallel at the same height and embedded together. The low-frequency sound absorption structure 5 is composed of a plurality of cells arranged in parallel at the same height and in a straight line. The low-frequency sound absorption structure 5 is arranged below the high-frequency sound absorption structure and in series. The high-frequency sound absorption structure and the low-frequency sound absorption structure 5 are integrally formed by 3D printing using photosensitive resin.

[0046] The resonant sound absorption structure has inherent frequency. When the incident sound wave passes through the resonant sound absorption structure, the incident sound wave will resonate with the resonant sound absorption structure as the frequency changes, and a large amount of sound energy will be absorbed. The resonant sound absorption structure has excellent sound absorption performance near the resonant frequency and weak sound absorption performance outside the resonant frequency. The porous material includes fiber material, foam material and metal material, which can effectively absorb high-frequency sound waves. A large amount of sound waves is trapped in the porous material due to the short wavelength of high-frequency sound waves, and the sound waves propagate between the pores. Due to the viscous effect of air, the sound waves will rub against the pore wall and be consumed. When the sound wave propagates in the porous material, the volume is compressed, the temperature is increased, and the surrounding solid structure exchanges heat. The present application combines the advantages of resonant sound absorption structure and porous material.

[0047] Specifically, the cell of the high-frequency sound absorption structure includes a hollow shell, the hollow chamber of the shell is filled with porous sound absorption material 30, the shell contains a transverse partition plate to divide the chamber into multiple areas, and the transverse partition plate and / or the top plate of the shell adopt a gap plate or a porous plate structure.

[0048] In this embodiment, the high-frequency sound absorption structure and the low-frequency sound absorption structure 5 are both cuboid structures. The overall size of the high-frequency sound absorption structure is 72x32x67mm. The plurality of holes of the porous plate are uniformly arranged. The gaps on the gap plate are arranged at equal intervals. The thickness of the transverse partition plate and the gap plate is 1mm.

[0049] Specifically, referring to Figure 2 , referring to Figure 2 , the high-frequency sound absorption structure includes a first high-frequency sound absorption cell 1, a second high-frequency sound absorption cell 2, a third high-frequency sound absorption cell 3 and a fourth high-frequency sound absorption cell 4 arranged at the same height. The first high-frequency sound absorption cell 1 and the third high-frequency sound absorption cell 3 are arranged side by side, and the second high-frequency sound absorption cell 2 and the fourth high-frequency sound absorption cell 4 are arranged side by side.

[0050] Referring to Figure 3, the first high-frequency sound absorption cell 1 is internally provided with a first horizontal partition plate and a first vertical partition plate 9, both ends of the first horizontal partition plate are connected with two side wall plates of the first high-frequency sound absorption cell 1 respectively, both ends of the first vertical partition plate 9 are connected with the bottom of the first horizontal partition plate and the bottom plate of the first high-frequency sound absorption cell 1 respectively, and the first horizontal partition plate and the top plate 6 of the first high-frequency sound absorption cell 1 adopt a gap plate. The gap widths of the first horizontal partition plate located on the left and right sides of the first vertical partition plate 9 are different.

[0051] In the embodiment, the size of the first high-frequency sound absorption cell 1 is 48*20*67mm. The gap width of the top plate of the first high-frequency sound absorption cell 1 is 0.8mm, and the top plate contains 31 gaps. The interval height between the first horizontal partition plate and the top plate of the first high-frequency sound absorption cell 1 is H1=15mm. The left side gap of the first horizontal partition plate has a width of 0.6mm and a length of L1=29mm, and contains 19 gaps. The right side gap of the first horizontal partition plate has a width of 0.5mm and a length of L2=16mm, and contains 10 gaps. The height of the first vertical partition plate 9 is H2=49mm.

[0052] The sound wave enters the lower rectangular cavity through the top plate 6 of the first high-frequency sound absorption cell 1, and then enters the lower rectangular cavity separated by the first vertical partition plate 9 through the first horizontal partition plate. Due to the difference in sound pressure on both sides of the plate, the high-frequency sound wave will vibrate back and forth in the gap, and in the process, it will continuously rub against the inner wall of the gap, so that the high-frequency sound wave energy will be dissipated in the form of sound energy under the thermal viscous effect of the gap. The resonance of the Helmholtz resonance cavity and the porous sound absorption material 30 make part of the high-frequency sound wave energy dissipate in the form of sound energy. Through the above sound energy dissipation process, the structure has multiple different sound absorption peaks, widens the high-frequency sound absorption frequency band, and significantly enhances the high-frequency broadband sound absorption capacity.

[0053] Referring to Figure 4 , the second high-frequency sound absorption cell 2 is internally provided with a second horizontal partition plate 11, a third horizontal partition plate 12 and a second vertical partition plate 13, both ends of the second horizontal partition plate 11 and the third horizontal partition plate 12 are connected with two side wall plates of the second high-frequency sound absorption cell 2, both ends of the second vertical partition plate 13 are connected with the bottom of the second horizontal partition plate 11 and the bottom plate of the second high-frequency sound absorption cell 2 respectively, the second horizontal partition plate 11 adopts a porous plate, the top plate 10 of the second high-frequency sound absorption cell 2 adopts a gap plate, the second vertical partition plate 13 divides the shell below the third horizontal partition plate 12 into a left shell and a right shell, the left shell is internally provided with a partition plate (which is a first partition plate 14), the height of the second vertical partition plate 13 and the partition plate is lower than the height of the internal cavity of the left shell, and the top plate of the right shell adopts a gap plate.

[0054] The gap width of the top plate of the right shell is less than the gap width of the top plate 10 of the second high-frequency sound absorption cell 2, and the gap directions of the top plate of the right shell and the top plate 10 of the second high-frequency sound absorption cell 2 are vertically arranged. The first partition plate 14 divides the shell below the third transverse partition plate 12 into a folded space sound absorption structure.

[0055] The size of the second high-frequency sound absorption cell 2 is 24x12x67mm. The gap width of the top plate 10 of the second high-frequency sound absorption cell 2 is 0.8mm, and contains 15 gaps. The interval H3 between the second transverse partition plate 11 and the top plate 10 of the second high-frequency sound absorption cell 2 is 10mm. The diameter of the hole on the second transverse partition plate 11 is 0.6mm, and contains 36 perforations. The third transverse partition plate 12 is located at H4=20mm below the second transverse partition plate 11. The gap width of the third transverse partition plate 12 is 0.5mm, and contains 6 long L5=10.5mm gaps. The height of the second vertical partition plate 13 and the partition plate is 30mm, and the second vertical partition plate 13 and the partition plate are arranged alternately up and down with a spacing L4=6.5mm, which divides the cavity into a zigzag structure, i.e. a folded space sound absorption structure.

[0056] The sound wave enters the rectangular cavity below through the top plate 10 of the second high-frequency sound absorption cell 2, then enters the rectangular cavity below through the second transverse partition plate 11, and finally enters the zigzag cavity below through the third transverse partition plate 12. Similarly, the high-frequency sound wave vibrates back and forth in the gap and the micro-perforation to generate thermal viscous effect to realize sound energy dissipation, and the resonance based on the Helmholtz resonance cavity and the porous sound absorption material 30 make part of the high-frequency sound wave energy produce sound energy dissipation. Through the above sound energy dissipation process, the structure has multiple different sound absorption peaks, widens the high-frequency sound absorption frequency band, and significantly enhances the high-frequency broadband sound absorption capacity.

[0057] Referring to Figure 5 , the third high-frequency sound absorption cell 3 is internally provided with a fourth transverse partition plate 16, a fifth transverse partition plate 17 and a third vertical partition plate 18, the two ends of the fourth transverse partition plate 16 and the fifth transverse partition plate 17 are connected with the two side walls of the third high-frequency sound absorption cell 3, the two ends of the third vertical partition plate 18 are respectively connected with the bottom of the fifth transverse partition plate 17 and the bottom plate of the third high-frequency sound absorption cell 3, the fourth transverse partition plate 16 and the fifth transverse partition plate 17 are gap plates, the top plate 15 of the third high-frequency sound absorption cell 3 is a perforated plate, and the third vertical partition plate 18 divides the shell below the fifth transverse partition plate 17 into a left two-shell and a right two-shell, the left one-shell is internally provided with a partition plate (a second partition plate 19), the height of the partition plate is lower than the height of the internal cavity of the left one-shell, and the top plate of the right two-shell is a gap plate. The second partition plate 19 forms a folded space sound absorption structure in the internal shell.

[0058] The gap width of the top plate of the right two-shell is less than the gap width of the fourth transverse partition plate 16, and the gap directions of the top plate of the right two-shell and the fourth transverse partition plate 16 are vertically arranged.

[0059] The size of the third high-frequency sound absorption cell 3 is 24x20x67mm. The top plate 15 of the third high-frequency sound absorption cell 3 has a radius of 0.8mm and contains 63 perforations, and a fourth transverse partition plate 16 with a slit width of 0.7mm at a lower position H6=10mm contains 15 slits. A fifth transverse partition plate 17 with a slit width of 0.6mm is distributed on the right side at a lower position H7=17mm and contains 11 slits with a length L8=10.5mm. A third vertical partition plate 18 with a length H10=31mm and a fifth transverse partition plate 17 below the partition plate with a length H9=32mm are staggered above and below with a spacing L7=7mm, which divides the cavity into a zigzag structure, thereby forming a folded space sound absorption structure.

[0060] The sound wave enters the lower rectangular cavity through the top plate 15 of the third high-frequency sound absorption cell 3, then enters the lower rectangular cavity through the fourth transverse partition plate 16, and finally enters the lower zigzag cavity through the right side of the fifth transverse partition plate 17. Similarly, the high-frequency sound wave vibrates back and forth in the slits and micro-perforations to generate thermal viscous effect for sound energy dissipation, and the resonance based on the Helmholtz resonance cavity and the porous sound absorption material 30 cause part of the high-frequency sound wave energy to generate sound energy dissipation. Through the above sound energy dissipation process, the structure has multiple different sound absorption peaks, widens the high-frequency sound absorption frequency band, and significantly enhances the high-frequency broadband sound absorption capability.

[0061] Reference Figure 6 The sixth transverse partition plate and the fourth vertical partition plate 23 inside the fourth high-frequency sound absorption cell 4 are connected at both ends of the sixth transverse partition plate to the two side walls of the fourth high-frequency sound absorption cell 4, and the two ends of the fourth vertical partition plate 23 are connected to the bottom of the sixth transverse partition plate and the bottom plate of the fourth high-frequency sound absorption cell 4, respectively. The sixth transverse partition plate and the top plate 20 of the fourth high-frequency sound absorption cell 4 are both porous plates.

[0062] The size of the fourth high-frequency sound absorption cell 4 is 48x12x67mm. The top plate 20 of the fourth high-frequency sound absorption cell 4 is a porous plate with a radius of 0.7mm and contains 72 perforations. The sixth transverse partition plate is distributed left and right at a lower position H11=20mm, where the right part has a radius of 0.6mm, a length of L10=30mm, and contains 48 perforations, and the left part has a radius of 0.5mm, a length of L9=15mm, and contains 24 perforations; the lower end of the boundary between the left and right parts is a fourth vertical partition plate 23 with a length H12=44mm.

[0063] The sound waves pass through the top plate 20 of the fourth high-frequency sound absorption cell 4 into the lower rectangular cavity, and then pass through the left and right sides of the sixth transverse partition into the lower rectangular cavities separated by the fourth vertical partition 23. Similarly, the high-frequency sound waves vibrate back and forth in the micro-perforation to generate thermal viscous effect to achieve sound energy dissipation, and the resonance based on the Helmholtz resonator and the porous sound absorption material 30 make part of the high-frequency sound wave energy produce sound energy dissipation. Through the above sound energy dissipation process, the structure has multiple different sound absorption peaks, widens the high-frequency sound absorption frequency band, and significantly enhances the high-frequency broadband sound absorption capacity.

[0064] Referring to Figure 7 The top plate of the cell of the low-frequency sound absorption structure 5 is provided with an insert plate integrally formed thereon, the insert plate extends downward of the top plate, and a plurality of slits are formed on the insert plate to form an internal insertion slit structure. The frequency range of the low-frequency sound absorption structure 5 is 225-10000Hz.

[0065] The low-frequency sound absorption structure 5 is sequentially arranged from left to right as the first to sixth low-frequency sound absorption structures. The internal insertion slit width D13 of the first low-frequency sound absorption structure 24 is 0.8mm, and the depth H13 is 26mm; the internal insertion slit width D14 of the second low-frequency sound absorption structure 25 is 0.7mm, and the depth H14 is 36.1mm; the internal insertion slit width D15 of the third low-frequency sound absorption structure 26 is 1mm, and the depth H15 is 4mm; the internal insertion slit width D16 of the fourth low-frequency sound absorption structure 27 is 1.4mm, and the depth H16 is 3mm; the internal insertion slit width D17 of the fifth low-frequency sound absorption structure 28 is 1.7mm, and the depth H17 is 16mm; and the internal insertion slit width D18 of the sixth low-frequency sound absorption structure 29 is 0.5mm, and the depth H18 is 61mm.

[0066] It should be noted that the bottom plate of the shell of each cell of the high-frequency sound absorption structure is provided with a slit for communication with the cell of the low-frequency sound absorption structure 5 below, and the bottom plate of the high-frequency sound absorption structure is provided with six slits for communication with the first to sixth low-frequency sound absorption structures 5. Specifically, the through slit of the bottom plate of the high-frequency sound absorption structure is matched with the internal insertion slit on the upper surface of the low-frequency sound absorption structure, thereby being in communication with each other to form a high-low frequency connecting slit.

[0067] The sound waves of the high-frequency sound absorption structure pass into the internal insertion slit structure through the high-low frequency connecting slit (the connecting slit between the high-frequency sound absorption structure and the low-frequency sound absorption structure 5 can be seen from FIG. 1), and due to the sound pressure difference on both sides, the sound waves vibrate back and forth in the internal insertion slit and continuously rub the inner wall in the process, so that the low-frequency sound wave energy produces sound energy dissipation under the thermal viscous effect of the internal insertion slit, and finally the low-frequency sound wave energy produces sound energy dissipation again based on the resonance of the Helmholtz resonator and the porous sound absorption material 30. The process of achieving sound energy dissipation by connecting multiple cells makes the structure have multiple different sound absorption peaks, widens the low-frequency sound absorption frequency band, and significantly enhances the low-frequency broadband sound absorption capacity.

[0068] The sound absorption resonator body structure is prepared by 3D printing, the printing method is SLA, and the printing material is photosensitive resin, wherein the elastic modulus is 2.5*109Pa, the density is 1160kg / m 3 , and the Poisson's ratio is 0.41. The porous sound absorption material 30 is filled in the cavity inside each cell by glass fiber cotton, the porosity of the porous sound absorption material 30 is 0.973±0.1, the static flow resistance is 3253±100Pa·s / m, the tortuosity is 1.113, the thermal characteristic length is 399.1μm, and the viscous characteristic length is 138.6μm.

[0069] Specifically, in the calculation of the impedance of the sound absorption structure, the following method is adopted.

[0070] The surface impedance Z of the porous plate sound absorption structure is: K

[0071]

[0072] In the formula, m is the relative sound mass; r is the relative sound resistance; ω is the angular frequency:

[0073]

[0074] In the formula, t is the thickness of the porous plate; k r is the sound resistance rate constant; k m is the sound mass constant; μ is the kinematic viscosity coefficient of air, μ=η / ρ0=1.48*10-5m 2 / s; σ is the perforation rate; d is the hole diameter; k is the perforation constant,

[0075] The surface impedance Z of the gap plate sound absorption structure is: X

[0076] Z X =r+jωm

[0077] In the formula, m is the relative sound mass; r is the relative sound resistance; ω is the angular frequency:

[0078]

[0079] In the formula, t is the thickness of the gap plate; k r is the sound resistance rate constant; k m is the sound mass constant; μ is the kinematic viscosity coefficient of air, μ=η / ρ0; σ is the slotted rate; d is the slot width; k is the perforation constant,

[0080] The surface impedance Z of the folded space sound absorption structure is: D

[0081] Z​​​D = Z p + φ · Z L1 ,

[0082] where Z p and Z L1 are the surface impedance at the entrance of the first channel of the folded space and the panel with micro-slits, respectively; φ = S0 / S i is the correction factor, S0= m x w and S i = m0x w i are the cross-sectional areas of the slit panel and the folded channel, respectively.

[0083] The surface impedance ZL1 at the entrance of the first channel of the folded space and the panel impedance Zp with micro-slits are:

[0084]

[0085] where the effective propagation impedance of the sound wave in the folded space is The equivalent length in the ith sub-channel is denoted as l i ; t0, d f , σ are the panel thickness, slit width and slit ratio of the slit panel, respectively; Δt = -d / πln(sinπσ / 2) is the end correction factor; ω is the angular frequency; ρ0= 1.29 kg / m 3 is the air density; μ0= 1.48 x 10 -5 m 2 / s is the kinematic viscosity coefficient of air.

[0086] The surface impedance Z N of the resonant cavity sound absorption structure with an inserted slit is:

[0087]

[0088] where:

[0089]

[0090] where k ef is the equivalent wave number; Z ef is the equivalent impedance; l re is the effective height of the inserted slit; l sc is the height of the cavity part beside the inserted slit; l bc is the height of the back cavity; S r is the cross-sectional area of the inserted slit in the vertical sound wave propagation direction; S sc is the cross-sectional area of the side cavity; S bc is the cross-sectional area of the back cavity; k0= ω / c0 is the wave number in the cavity; Z0= ρ0x c0 is the air characteristic impedance; R a is the surface acoustic resistance of the structure, and X a is the surface acoustic reactance of the structure.

[0091] The impedance of each structure can be obtained by the above formula calculation, and the surface acoustic impedance of each cell is equivalent to an electric resistance.

[0092] The structure of the present application is coupled in series and parallel by four sound absorption structures of different porous plates, slit plates, folded space sound absorption structures and interpolated slit resonant cavities. According to the acoustic-electric analogy method, the total surface acoustic impedance Z of the whole structure after series and parallel connection can be obtained by the knowledge of series and parallel connection of electric resistance.

[0093] Z={Z X1 &(Z X2 ||Z X3 )}||{Z X4 &Z K5 &Z D6}||{Z K7 &Z X8 &Z D9}||{Z K10 &(Z K11 ||Z K12 )}

[0094] &{Z N13 ||Z N14 ||Z N15 ||Z N16 ||Z N17 ||Z N18}

[0095] The sound absorption coefficient a of the final whole structure can be obtained under the condition of considering the normal sound wave incidence as follows:

[0096]

[0097] In the formula, Z0=ρ0c0 is the characteristic impedance of air. 3 ; The sound speed c0 in air is 343 m / s.

[0098] The sound absorption coefficient curve obtained by the sound absorption structure of the embodiment is shown in Figure 8 It can be seen that the average sound absorption coefficient in the frequency range of 225-10000 Hz is greater than 0.7, which shows that it has excellent low-frequency broadband sound absorption effect.

[0099] The composite sound absorption superstructure based on multi-frequency resonance proposed in the embodiment has the following beneficial effects:

[0100] 1. The sound absorption structure has multiple different sound absorption peaks, which widens the low-frequency sound absorption band and significantly enhances the low-frequency broadband sound absorption capacity.

[0101] 2、The sound absorption structure solves the problem that the existing acoustic superstructure can only absorb sound of specific frequency and has narrow sound absorption frequency band, and can greatly improve the sound absorption performance of the structure;

[0102] 3、The sound absorption structure can realize continuous broadband sound absorption in a low frequency range by adjusting the slit width and slit depth of the high-frequency sound absorption structure and the low-frequency sound absorption structure 5, thereby adjusting the sound absorption frequency range, moving the sound absorption frequency band to low frequency, and effectively applying to engineering;

[0103] 4、The sound absorption structure has a neat, thin and light overall structure, and is easy to install and use.

[0104] The application further provides a design method of a composite sound absorption superstructure based on multi-frequency resonance.

[0105] Referring to Figure 9 In this embodiment, a design method of a composite sound absorption superstructure based on multi-frequency resonance is provided, including the following steps:

[0106] Step S10, the structure parameters of the low-frequency sound absorption structure 5 are preliminarily determined according to a low-frequency target sound absorption frequency band, including the slit width of the internal slit in each cell, the depth of the internal slit sinking, the structure height and thickness;

[0107] Step S20, the structure parameters of the high-frequency sound absorption structure are determined according to a medium-high frequency target sound absorption frequency band, including the hole radius of the porous plate of each cell, the slit width of the slit on the slit plate, the length and distance of the partition plate, the structure height and thickness;

[0108] Step S30, the low-frequency sound absorption structure 5 and the high-frequency sound absorption structure are coupled according to the above structure parameters, the porous sound absorption material 30 is filled, a finite element simulation model is established for sound absorption simulation, and a sound absorption coefficient curve is obtained;

[0109] Step S40, the structure parameters of each cell are corrected according to the sound absorption coefficient curve, and the final structure parameters of the composite sound absorption superstructure based on multi-frequency resonance are obtained.

[0110] The finite element simulation model adopts the finite element simulation software COMSOL Multiphysics, and the sound absorption coefficient curve is obtained by calculation in the thermal viscous acoustic module and the pressure acoustic module.

[0111] The design method of the composite sound absorption superstructure based on multi-frequency resonance can greatly improve the sound absorption performance of the structure by designing the structure and installing it on the top plate of the truck cab to absorb the noise propagating from the outside to the truck cab. By designing the geometric parameters of the structure and using the acoustic-electric analogy method, the problems of the existing acoustic superstructure, such as only absorbing sound of specific frequency, narrow sound absorption frequency band, poor low-frequency sound absorption effect, etc. are solved.

[0112] The above merely provides the preferred embodiments of the present application, and is not intended to limit the patent scope of the present application. Any equivalent structure variations made according to the present application description and drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A composite sound-absorbing superstructure based on multi-frequency resonance, characterized in that: It includes a high-frequency sound absorbing structure, a low-frequency sound absorbing structure, and a porous sound absorbing material filled in the high-frequency sound absorbing structure and the low-frequency sound absorbing structure, wherein: The high-frequency sound absorbing structure includes a plurality of cells located on the same layer and arranged at the same height and connected in parallel with each other. The low-frequency sound absorbing structure includes a plurality of cells arranged at the same height and in parallel in a straight line. The low-frequency sound absorbing structure is located below the high-frequency sound absorbing structure. The high-frequency sound absorbing structure and the low-frequency sound absorbing structure are integrally formed by 3D printing using photosensitive resin. The high-frequency sound absorbing structure includes a first high-frequency sound absorbing cell, a second high-frequency sound absorbing cell, a third high-frequency sound absorbing cell, and a fourth high-frequency sound absorbing cell arranged at the same height. The first high-frequency sound absorbing cell and the third high-frequency sound absorbing cell are arranged side by side, and the second high-frequency sound absorbing cell and the fourth high-frequency sound absorbing cell are arranged side by side.

2. The composite sound-absorbing superstructure based on multi-frequency resonance according to claim 1, characterized in that: The cell of the high-frequency sound-absorbing structure includes a hollow shell, the interior of the hollow chamber of the shell is filled with porous sound-absorbing material, and the interior of the shell contains transverse partitions to divide its chamber into multiple areas. The transverse partitions and / or top plate of the shell adopt a slit plate or porous plate structure.

3. The composite sound-absorbing superstructure based on multi-frequency resonance according to claim 1, characterized in that: A first transverse baffle and a first vertical baffle are provided inside the first high-frequency sound absorbing cell. The two ends of the first transverse baffle are respectively connected to the two side wall panels of the first high-frequency sound absorbing cell, and the two ends of the first vertical baffle are respectively connected to the bottom of the first transverse baffle and the bottom plate of the first high-frequency sound absorbing cell. The top plates of the first transverse baffle and the first high-frequency sound absorbing cell are slotted plates.

4. The composite sound-absorbing superstructure based on multi-frequency resonance according to claim 1, characterized in that: A second transverse baffle, a third transverse baffle and a second vertical baffle are provided inside the second high-frequency sound absorbing cell. The two ends of the second transverse baffle and the third transverse baffle are connected to the two side wall panels of the second high-frequency sound absorbing cell, and the two ends of the second vertical baffle are respectively connected to the bottom of the second transverse baffle and the bottom plate of the second high-frequency sound absorbing cell. The second transverse baffle adopts a porous plate, and the top plate of the second high-frequency sound absorbing cell adopts a slit plate. The second vertical baffle divides the shell below the third transverse baffle into a left shell and a right shell. A partition plate is provided inside the left shell, and the height of the partition plate is lower than the height of the internal chamber of the left shell. The top plate of the right shell adopts a slit plate.

5. The composite sound-absorbing superstructure based on multi-frequency resonance according to claim 4, characterized in that: The gap width of the top plate of the right shell is smaller than the gap width of the top plate of the second high-frequency sound absorbing cell, and the gap directions of the top plate of the right shell and the top plate of the second high-frequency sound absorbing cell are perpendicularly arranged.

6. The composite sound-absorbing superstructure based on multi-frequency resonance according to claim 1, characterized in that: A fourth transverse baffle, a fifth transverse baffle, and a third vertical baffle are provided inside the third high-frequency sound absorbing cell. The ends of the fourth transverse baffle and the fifth transverse baffle are connected to the two side wall panels of the third high-frequency sound absorbing cell. The ends of the third vertical baffle are respectively connected to the bottom of the fifth transverse baffle and the bottom plate of the third high-frequency sound absorbing cell. The fourth transverse baffle and the fifth transverse baffle are slit plates, and the top plate of the third high-frequency sound absorbing cell is a porous plate. The third vertical baffle divides the shell below the fifth transverse baffle into two left shells and two right shells. A partition plate is provided inside the left shell, and the height of the partition plate is lower than the height of the internal cavity of the left shell. The top plate of the right shell is a slit plate.

7. The composite sound-absorbing superstructure based on multi-frequency resonance according to claim 1, characterized in that: The fourth high-frequency sound absorbing cell is provided with a sixth transverse baffle and a fourth vertical baffle. Both ends of the sixth transverse baffle are connected to the side wall panels of the fourth high-frequency sound absorbing cell. Both ends of the fourth vertical baffle are connected to the bottom of the sixth transverse baffle and the bottom plate of the fourth high-frequency sound absorbing cell, respectively. The top plates of the sixth transverse baffle and the fourth high-frequency sound absorbing cell are both porous plates.

8. The composite sound-absorbing superstructure based on multi-frequency resonance according to any one of claims 1 to 7, characterized in that: The top plate of the cell of the low-frequency sound absorbing structure is provided with an inserting plate integrally formed therewith, the inserting plate extends downward from the top plate, and a plurality of slots are formed on the inserting plate to form an inner slot structure.

9. A design method for a composite sound-absorbing superstructure based on multi-frequency resonance according to any one of claims 1 to 8, characterized in that: The following steps are involved: The structural parameters of the low-frequency sound absorption structure are preliminarily determined based on the low-frequency target sound absorption frequency band, including the width of the slots inserted in each cell, the depth of the slots sunk, the height of the structure, and the thickness; Determine the structural parameters of the high-frequency sound absorption structure based on the target mid- and high-frequency sound absorption bands, including the hole radius of each cell porous plate, the slit width on the slit plate, the length and spacing of the partition plates, the structure height, and the thickness; According to the above structural parameters, the low-frequency sound absorption structure and the high-frequency sound absorption structure are coupled, and porous sound absorption materials are filled. A finite element simulation model is established to simulate the sound absorption and obtain the sound absorption coefficient curve; The structural parameters of each cell are modified according to the sound absorption coefficient curve to obtain the final structural parameters of the composite sound-absorbing superstructure based on multi-frequency resonance.

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