Low-frequency broadband vibration damping device and method for airborne electronic equipment

Abstract

The application discloses a kind of airborne electronic equipment low-frequency broadband vibration damping device and vibration damping method, airborne electronic equipment low-frequency broadband vibration damping device includes base plate, base plate is set on cabinet plate shell, and one end of base plate is provided with acoustic black hole for guiding and gathering wide-frequency vibration energy to central region;The central region of acoustic black hole is laid with constraint damping layer;The center of acoustic black hole and the vibration mode wave crest on base plate are respectively provided with several dynamic vibration absorbers, and the target frequency of dynamic vibration absorber is less than the cut-off frequency of acoustic black hole.The application integrates acoustic black hole, constraint damping layer selectively laid in the energy gathering area of acoustic black hole and dynamic vibration absorber to realize continuous broadband vibration suppression from low frequency to high frequency, so as to realize continuous and efficient wide-frequency vibration suppression from low frequency to high frequency under the premise of strictly controlling additional mass.

Description

Technical Field

[0001] This invention belongs to the field of airborne electronic equipment technology, and particularly relates to a low-frequency broadband vibration reduction device and vibration reduction method for airborne electronic equipment. Background Technology

[0002] Vibration suppression is a key issue in the structural design of airborne electronic equipment, and it is particularly critical for highly integrated and reliable avionics devices such as board-type computer chassis. Broadband vibrations in the airborne environment, such as engine vibration, gas noise, and mechanical shock, directly affect the operational stability and lifespan of computer systems. Therefore, developing passive vibration reduction technologies with lightweight, wideband, and high-efficiency characteristics is of significant engineering importance.

[0003] Currently, the main passive vibration reduction technologies applicable to chassis structures include the following three categories: The first type is the acoustic black hole (ABH), which constructs a concave or convex structure with a thickness decreasing according to a power law in the chassis shell to gradually reduce the wave velocity of bending waves, thereby concentrating vibration energy in a specific area. A damping layer is usually attached to the tip of the ABH to dissipate energy. However, this technology has limitations in chassis applications: its effective vibration reduction frequency band is mainly in the mid-to-high frequency range, while its effect on suppressing low-frequency vibrations is insufficient. At the same time, its performance is highly dependent on the performance and coverage area of ​​the attached damping layer. To broaden the frequency band, a large amount of damping material is often required, which leads to a significant increase in structural weight. The second category is surface-mounted damping layer technology. This technology dissipates vibration energy by attaching viscoelastic damping materials to the surface of the chassis shell, using the strain within the material. It has the advantages of wide-band dissipation characteristics and simple manufacturing process. However, to achieve good vibration reduction effect, it often requires large-area or even full-coverage application of damping layers in airborne applications. This introduces significant added mass, which conflicts with the strict lightweight requirements of aviation equipment. In addition, traditional uniform damping layers have limited ability to suppress specific low-frequency resonance peaks, making it difficult to optimize the design for chassis modal characteristics.

[0004] The third type is the Dynamic Vibration Absorber (DVA). This technology uses a resonator system attached to the main structure and tuned to a certain natural frequency to suppress vibrations by utilizing the opposite dynamic action. Among them, DVA is effective in suppressing single-frequency or narrow-band vibrations, but its effective bandwidth is very narrow. That is, once the excitation frequency or structural mode changes, its performance will drop significantly. If multiple modes need to be suppressed, multiple DVAs need to be arranged, which will make the system complex, occupy more space and increase weight, thus hindering the compact and lightweight design of the chassis.

[0005] To overcome the limitations of the above three individual technologies, existing technologies attempt to combine them; for example, simultaneously applying a damping layer or adding a DVA to the chassis with ABH. However, in the specific application scenario of airborne board-type computer chassis, such combinations still have the following problems: ABH, damping layer and DVA are often arranged independently, without optimized matching in energy transfer path, spatial layout and frequency characteristics, making it difficult to form an efficient coordination mechanism, that is, lacking system coordination; In pursuit of broadband performance, it is often necessary to use damping materials over a large area or to arrange multiple DVAs, which contradicts the strict requirements of airborne equipment for weight and space. In other words, it is difficult to achieve both lightweight and broadband suppression. ABH combined with damping layer is effective in suppressing low-frequency vibration. Although DVA can target low frequencies, its operating frequency band is narrow. The arrangement of multiple DVA brings weight and layout burden, which leads to an unsatisfactory overall low-frequency suppression effect and makes it difficult to achieve continuous and efficient control from low frequency to high frequency. In other words, the low-frequency suppression capability is insufficient and the frequency band connection is not smooth.

[0006] Therefore, in response to the comprehensive requirements of airborne board-type computer chassis for broadband (especially low-frequency) vibration suppression, lightweighting and structural compactness, existing technologies still lack a composite vibration reduction scheme that can achieve deep synergy among ABH, damping layer and DVA. In other words, there is an urgent need for a vibration reduction technology that can achieve continuous and efficient broadband vibration suppression from low frequency to high frequency under the premise of strict control of added mass. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, this invention provides a low-frequency broadband vibration reduction device and method for airborne electronic equipment, which can effectively suppress broadband vibrations from low to high frequencies.

[0008] The objective of this invention is achieved through the following technical solution: In a first aspect, a low-frequency broadband vibration damping device for airborne electronic equipment is provided, comprising: The base plate is mounted on the chassis shell, and one end of the base plate is equipped with an acoustic black hole for guiding and converging broadband vibration energy to the central region. A confined damping layer is laid in the central region of the acoustic black hole; Several dynamic vibration absorbers are respectively set at the center of the acoustic black hole and at the peak of the vibration mode on the base plate. The target frequency of the dynamic vibration absorbers is less than the cutoff frequency of the acoustic black hole.

[0009] Furthermore, two acoustic black holes are symmetrically arranged on both sides of the base plate, and two constraint damping layers are laid in the central area of ​​the two acoustic black holes respectively. Two dynamic vibration absorbers are installed at the center of the two acoustic black holes, and one dynamic vibration absorber is installed in the middle of the foundation slab.

[0010] Furthermore, the low-frequency broadband vibration damping device for airborne electronic equipment includes two transverse reinforcing ribs and two longitudinal reinforcing ribs installed on the base plate, with the two ends of the longitudinal reinforcing ribs extending to the two transverse reinforcing ribs respectively. Two acoustic black holes are set between two transverse reinforcing ribs, two longitudinal reinforcing ribs are located between the two acoustic black holes, and a dynamic vibration absorber is located between the two longitudinal reinforcing ribs.

[0011] Furthermore, acoustic black holes have a concave structure, and the thickness of this concave structure decreases radially from the outside towards the center in a power-law manner; or Acoustic black holes have a convex structure, and the thickness of the convex structure decreases in a power law from the center of the depression outwards along the radial direction.

[0012] Furthermore, the constraint damping layer includes a metal constraint layer and a viscoelastic damping core layer disposed on one end face of the metal constraint layer for attaching the acoustic black hole.

[0013] Furthermore, the metal constraint layer is aluminum foil or steel plate; and / or The viscoelastic damping core layer is a rubber layer or a polymer layer.

[0014] Furthermore, the dynamic vibration absorber includes a base, a damping element, a spring element, and a mass element. The lower ends of the damping element and the spring element are coaxially connected to the base, the upper end of the damping element is connected to the upper part of the spring element, the damping element is located inside the spring element, and the lower end of the mass element is coaxially connected to the upper part of the spring element.

[0015] Furthermore, the cutoff frequency of acoustic black holes The calculation formula is:

[0016] in, The thickness is uniform outside the ABH region on the base plate. Let be the radius of the acoustic black hole. The Young's modulus of the base plate material. The Poisson's ratio is the material of the base plate. The density of the base plate material.

[0017] Furthermore, the base plate is made of aluminum alloy.

[0018] Secondly, a method for low-frequency broadband vibration reduction of airborne electronic equipment is provided, utilizing a low-frequency broadband vibration reduction device for airborne electronic equipment, including the following steps: Acoustic black holes guide and concentrate broadband vibrational energy to their central region; The confined damping layer converts mechanical energy into thermal energy in the energy-converging region at the center of the acoustic black hole to dissipate mid-to-high frequency vibrations. Dynamic vibration absorbers target and suppress low-frequency vibrations.

[0019] The beneficial effects of this invention are as follows: Acoustic black holes guide and converge broadband vibration energy; specifically, the bending waves generated when the external broadband vibration excites the chassis plate will propagate to the ABH array area. Due to the power-law variable thickness characteristics of ABH, the wave velocity of the mid-to-high frequency components is significantly reduced and the wavelength is compressed, so the vibration energy can be effectively guided and strongly converged in the thin area of ​​the central region of ABH. The constrained damping layer efficiently dissipates mid-to-high frequency energy. Specifically, the high-amplitude mid-to-high frequency vibrations concentrated in the central region of ABH cause significant shear deformation in the constrained damping layer laid in this region. Under the constraint of the constrained layer, the viscoelastic damping core layer generates greater strain, thereby efficiently converting the mechanical energy concentrated here into heat energy and dissipating it. The dynamic vibration absorber targets and suppresses low-frequency energy. Specifically, for low-frequency vibration components with a weak ABH effect, their energy cannot be effectively concentrated, but these low-frequency components will still cause considerable vibration response in the central region of ABH. At this time, the DVA tuned to the corresponding low frequency can be excited. The mass element of the DVA can generate a force that is opposite to the vibration of the chassis plate and acts directly on the source region of energy concentration through the mounting point, thereby targeting and suppressing specific low-frequency vibrations. In other words, the acoustic black hole, the constrained damping layer, and the dynamic vibration absorber do not work independently, but rather achieve broadband vibration reduction through a synergistic mechanism. Specifically, the three processes of "the acoustic black hole guiding and converging broadband vibration energy," "the constrained damping layer efficiently dissipating mid-to-high frequency energy," and "the dynamic vibration absorber targeting and suppressing low-frequency energy" overlap in physical space and complement each other in the frequency domain. The synergy of these three processes enables a wide-band vibration reduction effect from targeted suppression of low-frequency modes to efficient reduction of mid-to-high frequency bands. Therefore, this invention can achieve efficient broadband vibration suppression from low to high frequencies. Meanwhile, by concentrating and selectively laying the constraint damping layer in the central area of ​​the ABH, rather than covering the entire chassis shell, the amount of damping material can be reduced to the greatest extent while ensuring efficient energy dissipation, thus resolving the contradiction between efficient vibration reduction and the strict lightweight requirements of aviation equipment; the dynamic vibration absorbers are arranged in a targeted manner to avoid the space and weight burden caused by simply stacking multiple dynamic vibration absorbers; therefore, the present invention can strictly control the added mass. Attached Figure Description

[0020] The invention will now be described in more detail with reference to embodiments and the accompanying drawings. Figure 1 An installation diagram of the present invention is shown; Figure 2 A schematic diagram of the structure of the present invention is shown; Figure 3This shows a schematic diagram of the structure at the acoustic black hole in this invention; Figure 4 A schematic diagram of the dynamic vibration absorber in this invention is shown; Figure 5 This diagram shows the dimensions of the dynamic vibration absorber in this invention. Figure 6 Frequency response curves of specific embodiments of the present invention are shown; In the accompanying drawings, the same parts use the same reference numerals. The drawings are not to scale.

[0021] Figure label: 1. Chassis shell; 2. Base plate; 201. Transverse reinforcing rib; 202. Longitudinal reinforcing rib; 3. Acoustic black hole; 4. Dynamic vibration absorber; 401. Base; 402. Spring element; 403. Damping element; 404. Mass element; 5. Constraint damping layer. Detailed Implementation

[0022] The invention will now be further described with reference to the accompanying drawings.

[0023] This invention provides a low-frequency broadband vibration reduction device for airborne electronic equipment, such as... Figure 1-5 As shown, it includes: Base plate 2 is mounted on chassis shell 1. One end of base plate 2 is provided with an acoustic black hole 3 for guiding and converging broadband vibration energy to the central region. Constraint damping layer 5 is laid in the central region of acoustic black hole 3; Several dynamic vibration absorbers 4 are respectively set at the center of the acoustic black hole 3 and at the peak of the vibration mode wave on the base plate 2. The target frequency of the dynamic vibration absorbers 4 is less than the cutoff frequency of the acoustic black hole 3. The constraint damping layer 5 includes a metal constraint layer and a viscoelastic damping core layer disposed on one end face of the metal constraint layer and used to attach the acoustic black hole 3. The dynamic vibration absorber 4 includes a base 401, a damping element 403, a spring element 402, and a mass element 404. The lower ends of the damping element 403 and the spring element 402 are coaxially connected to the base 401. The upper end of the damping element 403 is connected to the upper part of the spring element 402. The damping element 403 is located inside the spring element 402. The lower end of the mass element 404 is coaxially connected to the upper part of the spring element 402.

[0024] It is understandable that the acoustic black hole 3 guides and converges broadband vibration energy; specifically, the bending wave generated when the external broadband vibration excites the chassis shell 1 will propagate to the ABH array region. Due to the power-law variable thickness characteristics of ABH, the wave velocity of the mid-to-high frequency components is significantly reduced and the wavelength is compressed, so the vibration energy can be effectively guided and strongly converged in the thin area of ​​the central region of ABH. The constrained damping layer 5 efficiently dissipates mid-to-high frequency energy. Specifically, the high-amplitude mid-to-high frequency vibrations concentrated in the central region of ABH cause the constrained damping layer 5 laid in this region to undergo significant shear deformation. Under the constraint of the constrained layer, the viscoelastic damping core layer generates greater strain, thereby efficiently converting the mechanical energy concentrated here into heat energy and dissipating it. The dynamic vibration absorber 4 targets and suppresses low-frequency energy. Specifically, for low-frequency vibration components with a weak ABH effect (especially the inherent modes of the chassis), their energy cannot be effectively concentrated. However, these low-frequency components will still cause considerable vibration response in the central region of ABH. At this time, the DVA tuned to the corresponding low frequency can be excited. The mass element 404 of the DVA can generate a force that is opposite to the vibration of the chassis plate 1 and directly acts on the source region of energy concentration through the mounting point, thereby targeting and suppressing specific low-frequency vibrations. In other words, the acoustic black hole 3, the constraint damping layer 5, and the dynamic vibration absorber 4 do not work independently, but achieve broadband vibration reduction through a synergistic mechanism. Specifically, the three processes of "acoustic black hole 3 guiding and converging broadband vibration energy," "constraint damping layer 5 efficiently dissipating mid-to-high frequency energy," and "dynamic vibration absorber 4 targeting and suppressing low-frequency energy" overlap in physical space (all concentrated in the central region of ABH) and complement each other in the frequency domain (DVA is responsible for low frequencies, ABH guides mid-to-high frequencies, and constraint damping layer 5 mainly dissipates mid-to-high frequencies). Their synergy enables a wide-bandwidth, highly efficient vibration reduction effect from targeted suppression of low-frequency modes to mid-to-high frequency modes. Therefore, this invention integrates the acoustic black hole 3, constraint damping layer 5, and dynamic vibration absorber 4 into a cohesive design. By optimizing the matching relationship between their spatial layout and frequency characteristics, a synergistic working mechanism of "energy convergence - local efficient dissipation - low-frequency targeted cancellation" and a complete passive vibration reduction link are formed, achieving system-level gain beyond simple superposition, thereby enabling efficient broadband vibration suppression from low to high frequencies. Meanwhile, the constraint damping layer 5 is concentrated and selectively laid in the central area of ​​the ABH, rather than covering the entire area of ​​the chassis shell 1. This can greatly reduce the amount of damping material used while ensuring efficient energy dissipation, thus resolving the contradiction between efficient vibration reduction and the strict lightweight requirements of aviation equipment. The dynamic vibration absorbers 4 are arranged in a targeted manner to avoid the space and weight burden caused by simply stacking multiple dynamic vibration absorbers 4. Therefore, the present invention can strictly control the added mass.

[0025] It should be noted that the target frequency of the dynamic vibration absorber 4 is lower than the cutoff frequency of the acoustic black hole 3. That is, the target frequency of the dynamic vibration absorber 4 is set below the cutoff frequency of the acoustic black hole 3, so as to specifically suppress the low-frequency modes with weak acoustic black hole 3 effect. Thus, the mid-to-high frequency suppression capabilities complement each other, thereby achieving wide-band vibration control from low to high.

[0026] It should also be noted that the base plate 2 is the main load-bearing structure, and the base plate 2 can be an aluminum alloy plate.

[0027] In one embodiment, two acoustic black holes 3 are symmetrically arranged on both sides of the base plate 2, and two constraint damping layers 5 are respectively laid in the central region of the two acoustic black holes 3. Two dynamic vibration absorbers 4 are respectively installed at the center of the two acoustic black holes 3, and one dynamic vibration absorber 4 is installed in the middle of the foundation plate 2.

[0028] It is understandable that the center of the acoustic black hole 3 is the convergence point of high-frequency energy, and there is a position with large low-frequency modal strain in the middle of the base plate 2. Therefore, the dynamic vibration absorber 4 is installed in the center of the acoustic black hole 3 and the middle of the base plate 2 respectively.

[0029] In one embodiment, the low-frequency broadband vibration reduction device for airborne electronic equipment includes two transverse reinforcing ribs 201 and two longitudinal reinforcing ribs 202 disposed on the base plate 2, with the two ends of the longitudinal reinforcing ribs 202 extending to the two transverse reinforcing ribs 201 respectively. Two acoustic black holes 3 are set between two transverse reinforcing ribs 201, two longitudinal reinforcing ribs 202 are located between the two acoustic black holes 3, and a dynamic vibration absorber 4 is located between the two longitudinal reinforcing ribs 202.

[0030] It should be noted that, in order to ensure the ABH effect, the two acoustic black holes 3 are arranged between the two transverse reinforcing ribs 201. The reinforcing ribs originally arranged in the chassis shell 1 can be removed. At the same time, the thickness of the base plate 2 is increased to ensure the rigidity of the base plate 2.

[0031] In one embodiment, the acoustic black hole 3 is a concave structure, and the construction thickness of the concave structure decreases in a power law from the outer side to the center of the concave structure in the radial direction; the acoustic black hole 3 can also be a convex structure, and the construction thickness of the convex structure decreases in a power law from the center of the concave structure to the outer side in the radial direction.

[0032] It should be noted that, in this invention, the acoustic black hole 3 is preferably a concave structure, specifically a milled pit structure; wherein, the construction thickness of the concave structure is... ,in, The distance from the geometric center of the concave structure. To achieve the minimum achievable remaining thickness; to ensure that the cutoff frequency of the ABH is as low as possible, the ABH radius, a characteristic dimension of the ABH, should be as large as possible, and the bending wave velocity should be able to gradually decrease to near zero as it approaches the center of the ABH, thereby achieving energy convergence.

[0033] It should be noted that the feature size, ABH radius, and remaining thickness of a single ABH unit are determined based on the chassis thickness, material, and target frequency band.

[0034] In one embodiment, the metal constraint layer is a thin aluminum foil or steel plate, and the viscoelastic damping core layer is a rubber layer or polymer layer with a high loss factor; the constraint damping layer 5 is laid on the surface of the ABH structure array, and its outline is basically in contact with the ABH recessed area.

[0035] It should be noted that the constraint damping layer 5 does not cover the entire area of ​​the chassis 1, but is selectively and concentratedly laid in the area where the ABH array is located, especially the recessed area of ​​the ABH. This is because the ABH effect has concentrated the broadband vibration energy in this area, and laying the constraint damping layer 5 here can achieve the highest energy dissipation efficiency and mass ratio. In addition, the thickness and area of ​​the constraint damping layer 5 are matched with the size of the ABH unit.

[0036] In one embodiment, the dynamic vibration absorber 4 includes a base 401, a damping element 403, a spring element 402, and a mass element 404. The mass element 404 may be a miniature mass block. The lower ends of the damping element 403 and the spring element 402 are coaxially connected to the base 401, the upper end of the damping element 403 is connected to the upper part of the spring element 402, the damping element 403 is located inside the spring element 402, and the lower end of the mass element 404M is coaxially connected to the upper part of the spring element 402.

[0037] It should be noted that the natural frequency of the dynamic vibration absorber 4 A rough design is being developed; among which, Depend on Figure 5 The geometric parameters of the spring element 402 and the damping element 403 are jointly determined and can be repeatedly iterated by finite element calculation, so that the resonant frequency of the dynamic vibration absorber 4 gradually approaches the design frequency; in addition, since the shape of the dynamic vibration absorber 4 is complex, the dynamic vibration absorber 4 can be fabricated by 3D printing technology; the damping element 403 is a prism structure, and the width of the prism determines the magnitude of its damping force.

[0038] In one embodiment, the cutoff frequency of acoustic black hole 3 The calculation formula is:

[0039] in, The thickness of the ABH region on base plate 2 is uniform and can be 3mm. The radius of acoustic black hole 3 can be 0.08m; since base plate 2 is made of aluminum alloy, The material of base plate 2 has a Young's modulus of 70 GPa. The material of base plate 2 has a Poisson's ratio of 0.33. The material density of base plate 2 is 2700 kg / m³. 3 ; Therefore, the cutoff frequency of acoustic black hole 3 can be calculated. It is 658Hz.

[0040] Since ABH cannot focus vibration energy below 658Hz, the composite structure of ABH and constraint damping layer 5 cannot achieve low-frequency vibration suppression. Dynamic vibration absorber 4 needs to suppress the modes of base plate 2 below 658Hz, expand the vibration suppression range, and thus achieve low-frequency broadband vibration reduction. The modes and frequency response of ABH and base plate 2 are calculated by finite element method. Based on the modal nodes and the center position of ABH, the position of DVA and the tuning frequency of DVA suppression are determined.

[0041] According to the frequency response curve obtained from finite element analysis, foundation slab 2 is prone to resonance at 227Hz and 573Hz; according to its mode shape contour plot, the 227Hz mode peak is close to... Figure 2 Between the two longitudinal reinforcing ribs 202, a dynamic vibration absorber 4 can be arranged between the two longitudinal reinforcing ribs 202; and the 573Hz modal vibration peak is close to the center of the two ABHs. Since the structure is symmetrical, two dynamic vibration absorbers 4 with a mass only half that of the dynamic vibration absorber 4 between the longitudinal reinforcing ribs 202 will be designed and placed at the center of the two ABHs respectively to jointly suppress the 573Hz mode.

[0042] This invention also provides a method for low-frequency broadband vibration reduction of airborne electronic equipment, utilizing a low-frequency broadband vibration reduction device for airborne electronic equipment, comprising the following steps: Acoustic black hole 3 guides and gathers broadband vibrational energy to its central region; The confined damping layer 5 converts mechanical energy into thermal energy in the energy-gathering region at the center of the acoustic black hole 3 to dissipate mid-to-high frequency vibrations. The dynamic vibration absorber 4 targets and suppresses low-frequency vibrations.

[0043] A specific implementation example is given below.

[0044] Using a 3mm thick aluminum alloy chassis base plate as the base plate 2, a diameter is precisely milled to achieve this. ,depth Power index , An ABH pit array; a constraint damping layer 5 with a total thickness of 0.66 mm is attached to the surface of each ABH pit, wherein the viscoelastic damping core layer has a thickness of 0.64 mm and is made of butyl rubber. A DVA with a natural frequency tuned to 227Hz is installed at the center of each ABH pit, and is designated as DVA1 and DVA2 respectively. The mass element 404 of DVA1 and DVA2 has a mass of approximately 25g. A DVA with a natural frequency of 573Hz is arranged between the two longitudinal reinforcing ribs 202 on the base plate 2 and is designated as DVA3. The mass element 404 of DVA3 has a mass of 50g. In spring elements 402 of DVA1 and DVA2, the length of the upper cantilever beam Lower cantilever beam length In the spring element 402 of DVA3, the length of the upper cantilever beam is... Lower cantilever beam length All other geometric parameters of DVA1, DVA2, and DVA3 are identical, and the cantilever beam width is the same. Cantilever beam thickness The first height of spring element 402 The first height of spring element 402 The spring element 402 is made of PLA plastic; the damping element 403 has the following dimensions: length, width, and height. Its material is butyl rubber.

[0045] To demonstrate the beneficial effects of the embodiments of the present invention, a frequency response experiment can be conducted on the embodiments. Specifically, the chassis equipped with the low-frequency broadband vibration reduction device of the on-board electronic equipment is fixed on the vibration test bench. The vibration test bench is subjected to sweep frequency acceleration excitation with an excitation frequency of 5~2000Hz and an excitation amplitude of 0.5g. A point between the two ABH of the base plate 2 is taken as the test point, and its acceleration response is tested. Frequency response curve as Figure 6 As shown: At the DVA operating frequencies, namely 227Hz and 573Hz, the peak attenuation is significant, with vibration attenuation reaching 25dB at both points. In addition, an additional peak appears in each of their corresponding frequency ranges, which is related to the introduction of one degree of freedom of DVA, proving the effect of DVA. In the mid-to-high frequency range, the peak values ​​all show varying degrees of attenuation, which is related to the energy convergence and dissipation of ABH and the energy dissipation of damping. An average vibration attenuation of 1.4dB is achieved throughout the entire frequency band. As can be seen, the embodiments of the present invention, through the integrated and synergistic design of the ABH structure, the constraint damping layer 5, and the DVA, produce a significant synergistic gain effect and achieve efficient vibration reduction in low-frequency wideband.

[0046] In another embodiment, the ABH structure can be arranged on the side wall or top of the chassis to achieve multi-directional, multi-modal vibration suppression.

[0047] In another embodiment, the constraint damping layer 5 may employ a patterned design that matches but does not completely cover the shape of the ABH array, for example, it may be laid only in the deepest central circular region of the ABH, in order to further reduce the amount of material used.

[0048] In summary, this invention integrates the acoustic black hole 3 structure array, the constraint damping layer 5 selectively laid in the energy convergence region of ABH, and the dynamic vibration absorber 4 with a tuning frequency lower than the cutoff frequency of ABH and installed at the center of ABH or the modal peak, in order to achieve continuous broadband vibration suppression from low frequency to high frequency. The present invention concentrates and selectively lays the constraint damping layer 5 in the recessed area of ​​the ABH structure, rather than covering the entire area of ​​the chassis shell 1; while ensuring efficient energy dissipation, it greatly reduces the amount of damping material used, so as to resolve the contradiction between efficient vibration reduction and the strict lightweight requirements of aviation equipment. This invention precisely sets the tuning frequency of the DVA below the cutoff frequency of the ABH structure, specifically for suppressing low-frequency fixed modes with weak ABH effects (especially frequencies below the critical point determined by the ABH cutoff frequency calculation formula). This invention effectively fills the "shortcoming" of vibration reduction in the low-frequency range of ABH technology, and achieves seamless continuous broadband vibration suppression from low to high frequencies. The installation of the DVA in this invention is based on the mode shape (peak position) of the chassis base plate 2 and the ABH central region (energy convergence point) determined by finite element analysis. The number of DVAs and the size of the mass blocks are also designed differently according to the specific modal characteristics, which is conducive to the "targeted" suppression of specific low-frequency modes by the DVA, improves the low-frequency vibration reduction efficiency, and avoids the space and weight burden caused by simply stacking multiple DVAs.

[0049] In the description of this invention, it should be understood that the terms "upper", "lower", "bottom", "top", "front", "rear", "inner", "outer", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0050] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A low-frequency broadband vibration reduction device for airborne electronic equipment, characterized in that, include: A base plate (2) is mounted on a chassis shell (1). One end of the base plate (2) is provided with an acoustic black hole (3) for guiding and converging broadband vibration energy to the central region. A constraint damping layer (5) is laid in the central region of the acoustic black hole (3); A plurality of dynamic vibration absorbers (4) are respectively disposed at the center of the acoustic black hole (3) and at the vibration mode peak on the base plate (2). The target frequency of the dynamic vibration absorber (4) is less than the cutoff frequency of the acoustic black hole (3).

2. The low-frequency broadband vibration reduction device for airborne electronic equipment according to claim 1, characterized in that, Two acoustic black holes (3) are symmetrically arranged on both sides of the base plate (2), and two constraint damping layers (5) are respectively laid in the central area of ​​the two acoustic black holes (3). Two dynamic vibration absorbers (4) are respectively set at the center of the two acoustic black holes (3), and one dynamic vibration absorber (4) is set at the middle of the base plate (2).

3. The low-frequency broadband vibration reduction device for airborne electronic equipment according to claim 2, characterized in that, It includes two transverse reinforcing ribs (201) and two longitudinal reinforcing ribs (202) disposed on the base plate (2), with the two ends of the longitudinal reinforcing ribs (202) extending to the two transverse reinforcing ribs (201) respectively. Two acoustic black holes (3) are disposed between the two transverse reinforcing ribs (201), two longitudinal reinforcing ribs (202) are located between the two acoustic black holes (3), and a dynamic vibration absorber (4) is located between the two longitudinal reinforcing ribs (202).

4. The low-frequency broadband vibration reduction device for airborne electronic equipment according to claim 1 or 2, characterized in that, The acoustic black hole (3) has a concave structure, and the thickness of the concave structure decreases radially from the outside to the center of the concave structure in a power law manner; or The acoustic black hole (3) is a convex structure, and the thickness of the convex structure decreases in a power law from the center of the depression outwards in the radial direction.

5. The low-frequency broadband vibration reduction device for airborne electronic equipment according to claim 1 or 2, characterized in that, The constraint damping layer (5) includes a metal constraint layer and a viscoelastic damping core layer disposed on one end face of the metal constraint layer for attaching the acoustic black hole (3).

6. The low-frequency broadband vibration reduction device for airborne electronic equipment according to claim 5, characterized in that, The metal constraint layer is aluminum foil or steel plate; and / or The viscoelastic damping core layer is a rubber layer or a polymer layer.

7. The low-frequency broadband vibration reduction device for airborne electronic equipment according to claim 1 or 2, characterized in that, The dynamic vibration absorber (4) includes a base (401), a damping element (403), a spring element (402), and a mass element (404). The lower ends of the damping element (403) and the spring element (402) are coaxially connected to the base (401). The upper end of the damping element (403) is connected to the upper part of the spring element (402). The damping element (403) is located inside the spring element (402). The lower end of the mass element (404) is coaxially connected to the upper part of the spring element (402).

8. The low-frequency broadband vibration reduction device for airborne electronic equipment according to claim 1, characterized in that, The cutoff frequency of the acoustic black hole (3) The calculation formula is: in, The uniform thickness of the outer ABH region on the base plate (2) is as follows: The radius of the acoustic black hole (3) is... The Young's modulus of the material of the base plate (2) is... Based on the material Poisson's ratio of the base plate (2), The material density of the base plate (2).

9. The low-frequency broadband vibration reduction device for airborne electronic equipment according to claim 1 or 8, characterized in that, The base plate (2) is an aluminum alloy plate.

10. A method for low-frequency broadband vibration reduction of airborne electronic equipment, characterized in that, The low-frequency broadband vibration reduction device for airborne electronic equipment according to any one of claims 1-9 includes the following steps: Acoustic black holes (3) guide and converge broadband vibrational energy to their central region; The confined damping layer (5) converts mechanical energy into thermal energy in the energy-gathering region at the center of the acoustic black hole (3) to dissipate mid-to-high frequency vibrations; The dynamic vibration absorber (4) targets and suppresses low-frequency vibration.

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