Porous photonic crystal sandwich plate for suppressing flutter and design method thereof

Abstract

The invention discloses a porous photonic crystal sandwich plate for suppressing flutter and a design method thereof, and belongs to the technical field of vibration suppression of spacecraft structures. The porous photonic crystal sandwich plate is composed of a matrix sandwich plate and periodically embedded local resonance units, the matrix sandwich plate is composed of an upper aluminum skin, a lower aluminum skin and an aluminum honeycomb core layer, each local resonance unit is composed of an upper coating layer, a lower coating layer and a scatterer, and the local resonance units and the matrix sandwich plate form photonic crystals in a honeycomb core filling mode. Light flexible materials are adopted, the mass of the phononic crystal sandwich plate is reduced, the local resonance units are embedded into the honeycomb core layer, extra in-cabin space does not need to be occupied, and the vibration suppression device is suitable for vibration suppression of a communication satellite. By designing hole structures with specific shapes on the coating layer and the scatterer, the equivalent stiffness and mass distribution are regulated and controlled, the band gap range is optimized, and the inhibition performance of the sandwich plate on satellite flutter is remarkably improved by utilizing the band gap characteristic of the local resonance type photonic crystal.

Description

Technical Field

[0001] The present invention relates to the technical field of spacecraft structure vibration suppression, and particularly relates to a porous phononic crystal sandwich panel for suppressing flutter and a design method thereof. Background Art

[0002] The vibration control of spacecraft structures has always been a key concern in the field of space applications. During the in-orbit operation of communication satellites, broadband flutter generated by disturbing components such as momentum wheels seriously affects the accuracy of on-board equipment and communication stability. Traditional flutter suppression technologies often have problems such as large weight, large volume, and poor frequency band tunability. In addition, multiple vibration isolators need to be deployed in the satellite cabin to cope with multi-source disturbances, further exacerbating the mass and space problems, which is contrary to the development trend of spacecraft miniaturization and lightweight.

[0003] Due to its elastic wave bandgap characteristics, phononic crystals show unique potential in the field of vibration reduction. A phononic crystal is a periodic structure, and each periodic unit is called a phononic crystal unit cell. The unit cell consists of scatterers, claddings, and matrices. By designing the structural parameters of the unit cell, a phononic crystal can generate a bandgap, and within the bandgap range, it will absorb the energy of elastic waves, thereby suppressing the propagation of vibration and noise. Existing phononic crystals have made some application progress in the fields of subways and ships, but there are problems such as dependence on rigid materials for scatterers, high mass density, and large structural volume, making it difficult to meet the lightweight requirements of satellites.

[0004] Now, a three-dimensional power-law frustum phononic crystal structure is disclosed. The unit of this phononic crystal includes a frustum matrix, an elastic cladding, and a scatterer, etc. The lower end face of the frustum matrix extends downward to form a connecting part, the elastic cladding is embedded in a cylindrical installation cavity, and a rod-shaped scatterer is inserted into the installation groove formed by the elastic cladding; by periodically attaching this unit to flat plate structures with different thicknesses, the propagation of elastic waves within the bandgap range can be blocked. However, this structure requires attaching a power-law frustum structure to a thin plate-like structure, which occupies a large volume, and in the actual use process, the attached frustum and rod-shaped scatterer may fall off, making it difficult to meet the application scenarios with harsh conditions.

[0005] In summary, the current phononic crystal structures have a large volume cost, are heavy and prone to falling off, and are difficult to meet the application requirements of spacecraft lightweight. Summary of the Invention

[0006] In order to meet the application requirements of spacecraft structure lightweight, the present invention provides a porous phononic crystal sandwich panel for suppressing flutter and a design method thereof. By calculating the band structure curve of the porous phononic crystal sandwich panel, the bandgap frequency range is determined to suppress the flutter propagating to the phononic crystal sandwich panel.

[0007] The present invention adopts the following technical solutions:

[0008] On one hand, the present invention provides a porous phononic crystal sandwich panel for suppressing flutter, which includes a matrix sandwich panel and locally resonant units arranged periodically and embedded in the middle of the matrix sandwich panel; the matrix sandwich panel is composed of an upper aluminum skin thin plate, a lower aluminum skin thin plate, an aluminum honeycomb core layer between the upper and lower aluminum skin thin plates, and a bolt pressing seat for fixing the whole upper and lower structure; the locally resonant unit is composed of a cladding layer and a scatterer wrapped by the cladding layer; the locally resonant unit is pasted in the aluminum honeycomb core layer in the form of filling the honeycomb core, and forms a phononic crystal with the matrix sandwich panel; holes are respectively drilled on the cladding layer and the scatterer to adjust the band gap range of the phononic crystal.

[0009] Preferably, the cladding layer includes an upper cladding layer and a lower cladding layer; the upper surface of the upper cladding layer is fixedly pasted with the upper aluminum skin thin plate, and the lower surface is fixedly pasted with the upper surface of the scatterer; the upper surface of the lower cladding layer is fixedly pasted with the lower surface of the scatterer, and the side surface is fixedly pasted with the side wall of the aluminum honeycomb core layer.

[0010] Preferably, the phononic crystal adopts a light flexible material, wherein the cladding layer adopts ethylene-vinyl acetate copolymer (EVA) material, and the scatterer adopts silicone rubber material.

[0011] On the other hand, the present invention provides a design method for a porous phononic crystal sandwich panel for suppressing flutter. By designing hole structures with specific shapes on the upper cladding layer, the lower cladding layer and the scatterer, the equivalent stiffness and mass distribution are regulated, the band gap range of the phononic crystal is optimized, and the flutter suppression performance of the sandwich panel for satellites is significantly improved by using the band gap characteristics of the locally resonant phononic crystal.

[0012] Preferably, the unit design of the porous phononic crystal needs to satisfy that the band gap frequency range is in the frequency band with high flutter amplitude value to improve the flutter suppression ability of the porous phononic crystal sandwich panel. By calculating the starting frequency and the cut-off frequency of the phononic crystal unit after drilling holes on the upper cladding layer, the lower cladding layer and the scatterer and adjusting the structural dimensions, the regulation of the band gap range is realized; the starting frequency and the cut-off frequency of the band gap are designed according to the following formula:

[0013]

[0014]

[0015] In the formula, f e1 is the starting frequency of the band gap, k e1 is the equivalent stiffness of the locally resonant unit, m e1 is the equivalent mass of the locally resonant unit, f e2 is the cut-off frequency of the band gap, m e2The equivalent mass of the substrate. The equivalent stiffness of the local resonance unit is provided by the coating layer and the scatterer. By perforating the coating layer and the scatterer, the starting frequency and the cut-off frequency of the bandgap can be changed, so as to realize the regulation of the flutter suppression frequency band.

[0016] Preferably, the width of the upper coating layer is 20 - 39.5 mm, the thickness is 1 - 2 mm, and the relative filling rate is 32% - 100%; the width of the scatterer is 20 - 39.5 mm, the thickness is 4 - 13 mm, and the relative filling rate is 50% - 100%; the width of the lower coating layer is 15 - 39.5 mm, the thickness is 1 - 2 mm, and the relative filling rate is 50% - 100%; by adjusting the structural parameters within the dimensional range, the bandgap range is adjusted to suppress the low-frequency flutter frequency band of 0 - 400 Hz.

[0017] As can be seen from the above technical solutions, compared with the prior art, the present invention provides a porous phononic crystal sandwich panel for suppressing flutter, having the following beneficial effects:

[0018] (1) The present invention generates a bandgap through the local resonance effect of the porous phononic crystal, absorbs elastic waves within the bandgap range, thereby improving the effect of the sandwich panel in suppressing flutter.

[0019] (2) The present invention reduces the mass of the phononic crystal by perforating the coating layer and the scatterer, and at the same time regulates the flutter suppression frequency band.

[0020] (3) The present invention embeds local resonance units in the honeycomb core of a common sandwich panel to form a phononic crystal, reducing the volume space required to form the phononic crystal. The porous phononic crystal sandwich panel combines the broadband vibration damping performance of the honeycomb sandwich panel and the bandgap characteristics of the phononic crystal, further improving the flutter suppression performance.

[0021] (4) The scatterer and the coating layer of the present invention are both prepared from flexible materials with low stiffness and small mass density. The overall mass density is small, and the upper coating layer and the lower coating layer are respectively connected to the scatterer by different pasting methods to ensure that the scatterer will not fall off, better meeting the lightweight application requirements of spacecraft. Brief Description of the Drawings

[0022] Figure 1 It is a structural diagram of a porous phononic crystal sandwich panel for suppressing flutter provided by the present invention;

[0023] Figure 2 For the present invention Figure 1 The structural diagram of a single cell of the porous phononic crystal in the present invention;

[0024] Figure 3 For the present invention Figure 2 The decomposition schematic diagram of the local resonance unit in the single cell structure of the porous phononic crystal;

[0025] Figure 4 The energy band diagram of a porous phononic crystal sandwich panel for suppressing flutter provided by the present invention;

[0026] Figure 5 The vibration transmission diagram of a porous phononic crystal sandwich panel for suppressing flutter provided by the present invention.

[0027] Reference numerals: 1, upper aluminum skin thin plate; 2, lower aluminum skin thin plate; 3, aluminum honeycomb core layer; 4, local resonance unit; 5, bolt pressing seat; 6, matrix; 7, coating layer; 71, upper coating layer; 72, lower coating layer; 8, scatterer. Specific embodiments

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in detail below with reference to the accompanying drawings in the embodiments of the present invention. The embodiments described in the present invention are only partial embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0029] The present invention provides a porous phononic crystal sandwich panel for suppressing flutter, including a matrix sandwich panel and local resonance units arranged periodically and embedded in the matrix sandwich panel; the matrix sandwich panel is composed of an upper aluminum skin thin plate, a lower aluminum skin thin plate, an aluminum honeycomb core layer between the upper and lower aluminum skin thin plates, and a bolt pressing seat for fixing the entire upper and lower structures; the local resonance unit is composed of a coating layer and a wrapped scatterer; the local resonance units are pasted in the aluminum honeycomb core layer in the form of filling the honeycomb, forming a phononic crystal with the matrix sandwich panel; holes are respectively drilled in the coating layer and the scatterer to adjust the bandgap range of the phononic crystal.

[0030] As Figure 1 shown, the present invention proposes a structure of a porous phononic crystal sandwich panel for suppressing flutter, which is composed of several local resonance units embedded between matrix sandwich panels. The matrix sandwich panel is composed of an upper aluminum skin thin plate 1, a lower aluminum skin thin plate 2, an aluminum honeycomb core layer 3, and a bolt pressing seat 5. The bolt pressing seat 5 is used to fixedly connect the matrix sandwich panel to the satellite cabin body through bolts. The local resonance unit 4 is composed of a coating layer 7 and a scatterer 8, and is embedded in each hole of the aluminum honeycomb core layer 3. Each hole is a honeycomb-shaped matrix, forming a porous phononic crystal sandwich panel. As Figure 2As shown in the figure, the porous phononic crystal unit cell consists of a honeycomb-shaped matrix 6, a cladding layer 7, and a scatterer 8. The honeycomb-shaped matrix 6 is made of aluminum alloy material, the cladding layer 7 is made of ethylene-vinyl acetate copolymer EVA material, and the scatterer 8 is made of silicone rubber material. The thickness of the upper and lower aluminum skin plates of the honeycomb-shaped matrix is 0.5 mm, the thickness of the side wall of the honeycomb-shaped matrix 6 in the aluminum honeycomb core layer is 0.25 mm, and the distance between adjacent honeycomb-shaped matrices is 40 mm. The width of the upper cladding layer is 20 - 39.5 mm, the thickness is 1 - 2 mm, and the relative filling rate is 32% - 100%; the width of the scatterer is 20 - 39.5 mm, the thickness is 4 - 13 mm, and the relative filling rate is 50% - 100%; the width of the lower cladding layer is 15 - 39.5 mm, the thickness is 1 - 2 mm, and the relative filling rate is 50% - 100%; by adjusting the structural parameters within the size range, the bandgap range can be adjusted to suppress the low-frequency flutter frequency band of 0 - 400 Hz.

[0031] After splitting the local resonance unit embedded in the honeycomb-shaped matrix, as Figure 3 shown, the lower surface of the upper cladding layer 71 is fixedly adhered to the upper surface of the scatterer 8, the upper surface of the lower cladding layer 72 is fixedly adhered to the lower surface of the scatterer 8, and the side surface is fixedly adhered to the side wall of the aluminum honeycomb core layer 3.

[0032] By designing the structural parameters of the porous phononic crystal unit cell, the bandgap range can be adjusted. In order to suppress the low-frequency flutter within 0 - 400 Hz of the satellite cabin panel, the start frequency and cut-off frequency of the bandgap are designed according to the following formulas:

[0033]

[0034] In the formula, f e1 is the start frequency of the bandgap, k e1 is the equivalent stiffness of the local resonance unit, m e1 is the equivalent mass of the local resonance unit, f e2 is the cut-off frequency of the bandgap, m e2 is the equivalent mass of the matrix. The designed start frequency of the bandgap of the porous phononic crystal is 221 Hz, and the cut-off frequency is 277 Hz, meeting the requirements of the low-frequency flutter frequency band of 0 - 400 Hz.

[0035] Example

[0036] The structural parameters of the designed porous phononic crystal are as follows: the width of the upper cladding layer 71 is 20 mm, the thickness is 1 mm, the width of the central regular hexagonal hole is 8 mm, and the widths of the 6 diagonal holes are all 3.1 mm. The width of the scatterer 8 is 20 mm, the thickness is 11 mm, the width of the central regular hexagonal hole is 8 mm, the widths of the 6 diagonal holes are 2.5 mm, and the hole depth is 1.2 mm. The width of the lower cladding layer 72 is 39.5 mm, the thickness is 1 mm, and the height of the 12 right trapezoidal holes on the opposite sides is 7.9 mm. The pore shapes of the cladding layer 7 and the scatterer 8 change the equivalent stiffness and mass by changing the relative filling rate, thereby adjusting the bandgap characteristics of the porous phononic crystal.

[0037] The band curves are usually used to reflect the bandgap characteristics of phononic crystals. To analyze the bandgap characteristics of porous phononic crystals, the finite element software is used to calculate the band curves of the porous phononic crystal. The structural parameters and material parameters of the porous phononic crystal are set in the finite element software, and the characteristic frequency analysis is carried out. The 8th-order characteristic frequency is calculated, and the band curve of the porous phononic crystal is obtained as Figure 4 shown. The shaded area represents the bandgap range of the porous phononic crystal. The frequency range of 221 - 277 Hz has no connection of band curves, forming two continuous complete bandgaps, and the total bandgap width is 56 Hz.

[0038] As Figure 5 shown is the vibration transmission curve of a porous phononic crystal sandwich panel designed by the present invention for suppressing flutter. The porous phononic crystal sandwich panel shows excellent flutter suppression performance in the low-frequency flutter frequency band of 0 - 400 Hz. The honeycomb sandwich panel and the flexible material with low stiffness enable the entire porous phononic crystal sandwich panel to maintain a flutter suppression effect of -10 dB in the range of 0 - 400 Hz; in addition, Figure 5 the dashed box in is the bandgap range of 221 - 277 Hz of the porous phononic crystal sandwich panel. In the bandgap range, the porous phononic crystal absorbs elastic waves, improving the flutter suppression effect. The maximum suppression effect can reach -44 dB, and the average flutter suppression effect in the entire bandgap range can reach -25 dB. The porous phononic crystal sandwich panel simultaneously has the broadband vibration damping ability of the honeycomb sandwich panel in the range of 0 - 400 Hz and the bandgap range of 221 - 277 Hz of the phononic crystal, resulting in an improved flutter suppression effect.

[0039] The cladding layer is divided into an upper cladding layer and a lower cladding layer, which are respectively pasted on the upper surface and the lower surface of the scatterer to jointly wrap the scatterer. Holes are drilled in the upper cladding layer and the lower cladding layer respectively to adjust the bandgap range of the phononic crystal and at the same time reduce the mass of the phononic crystal. Holes are drilled on the upper surface of the scatterer to help adjust the bandgap range.

[0040] The present invention uses lightweight flexible materials to reduce the mass of the phononic crystal sandwich panel. The cladding layer is made of ethylene-vinyl acetate copolymer material, and the scatterer is made of silicone rubber. The overall structure is flexible, lightweight, and not easily detached during operation. Both the cladding layer and the scatterer are designed in a regular hexagonal structure, which is convenient for embedding into the honeycomb core layer. The local resonance units are embedded in the honeycomb core layer without occupying additional cabin space, making it suitable for suppressing the flutter of communication satellites. By designing hole structures with specific shapes on the cladding layer and the scatterer, the equivalent stiffness and mass distribution are regulated, the bandgap range is optimized, and the flutter suppression performance of the sandwich panel is significantly improved by utilizing the bandgap characteristics of the locally resonant phononic crystal.

[0041] The matrix of the porous phononic crystal sandwich panel consists of a regular hexagonal aluminum honeycomb core and two thin plates on the upper and lower sides. Local resonance units are filled in each hexagonal honeycomb core to form a porous phononic crystal, reducing the volume space required to form the phononic crystal.

[0042] The upper cladding layer of the porous phononic crystal is in a regular hexagonal structure. By drilling holes in the upper cladding layer, the equivalent stiffness is changed, and the ability to regulate the bandgap is improved. The lower surface of the upper cladding layer is in contact with the scatterer by pasting, and the upper surface is in contact with the upper skin of the matrix by pasting. The upper surface of the lower cladding layer is in contact with the scatterer by pasting, and the side is in contact with the side wall of the honeycomb core. By drilling holes in the lower cladding layer, the equivalent stiffness is changed, and the ability to regulate the bandgap is improved. The different contact methods between the upper and lower cladding layers and the scatterer ensure that the equivalent stiffness is low enough to shift the bandgap range to the low frequency.

[0043] The scatterer of the locally resonant phononic crystal is in a regular hexagonal structure and is wrapped by two upper and lower cladding layers. Holes are drilled on the upper surface of the scatterer to further reduce the stiffness and improve the ability to regulate the bandgap. No holes are drilled on the lower surface to ensure a large mass ratio with the cladding layer, promoting the generation of the bandgap.

[0044] In summary, a porous phononic crystal sandwich panel for suppressing flutter according to the present invention has achieved certain effects in suppressing the flutter of spacecraft structures.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting the protection scope of the present invention; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence of the technical solutions of the present invention.

Claims

1. A porous phononic crystal sandwich panel for suppressing flutter, characterized in that, It includes a matrix sandwich panel and locally resonant units that are periodically arranged and embedded in the middle of the matrix sandwich panel; the matrix sandwich panel is composed of an upper aluminum skin thin plate, a lower aluminum skin thin plate, an aluminum honeycomb core layer between the upper and lower aluminum skin thin plates, and a bolt pressing seat for fixing the entire upper and lower structure; the locally resonant unit is composed of a cladding layer and a scatterer wrapped therein; the locally resonant unit is pasted in the aluminum honeycomb core layer in the form of filling the honeycomb core, and forms a phononic crystal with the matrix sandwich panel; holes are respectively drilled in the cladding layer and the scatterer to adjust the bandgap range of the phononic crystal.

2. The porous phononic crystal sandwich panel for suppressing flutter according to claim 1, wherein the cladding layer includes an upper cladding layer and a lower cladding layer; the upper surface of the upper cladding layer is fixedly pasted with the upper aluminum skin thin plate, and the lower surface is fixedly pasted with the upper surface of the scatterer; the upper surface of the lower cladding layer is fixedly pasted with the lower surface of the scatterer, and the side surface is fixedly pasted with the side wall of the aluminum honeycomb core layer.

3. The porous phononic crystal sandwich panel for suppressing flutter according to claim 1, wherein The phononic crystal adopts a lightweight flexible material. Among them, the cladding layer adopts ethylene-vinyl acetate copolymer (EVA) material, and the scatterer adopts silicone rubber material.

4. A design method for the porous phononic crystal sandwich panel as described in claim 1, characterized in that, By designing hole structures with specific shapes on the upper cladding layer, the lower cladding layer and the scatterer, the equivalent stiffness and mass distribution are regulated, the bandgap range of the phononic crystal is optimized, and the bandgap characteristics of the locally resonant phononic crystal are utilized to enhance the suppression of satellite flutter by the sandwich panel.

5. The design method of the porous phononic crystal sandwich panel according to claim 4, characterized in that The unit design of the phononic crystal needs to satisfy that the bandgap range is in the frequency band with a high flutter amplitude value to enhance the flutter suppression ability of the porous phononic crystal sandwich panel; by calculating the start frequency and cut-off frequency of the phononic crystal unit after drilling holes in the upper cladding layer, the lower cladding layer and the scatterer and adjusting the structural dimensions, the bandgap range regulation is realized; the start frequency and cut-off frequency of the bandgap are designed according to the following formula: where f e1 is the starting frequency of the band gap, k e1 is the equivalent stiffness of the local resonance unit, m e1 is the equivalent mass of the local resonance unit, f e2 is the cut-off frequency of the band gap, m e2 is the equivalent mass of the matrix; the equivalent stiffness of the local resonance unit is provided by the coating layer and the scatterer.

6. The design method of the porous phononic crystal sandwich panel according to claim 4 or 5, characterized in that, The width of the upper cladding layer is 20 - 39.5 mm, the thickness is 1 - 2 mm, and the relative filling rate is 32% - 100%; the width of the scatterer is 20 - 39.5 mm, the thickness is 4 - 13 mm, and the relative filling rate is 50% - 100%; the width of the lower cladding layer is 15 - 39.5 mm, the thickness is 1 - 2 mm, and the relative filling rate is 50% - 100%; by adjusting the structural parameters within the dimension range, the bandgap range is adjusted to suppress the low-frequency flutter frequency band of 0 - 400 Hz.

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