Wallboard structure of airplane

Abstract

A panel structure of an aircraft is capable of absorbing noise of a lower frequency band than the existing frequency band. An interior trimming panel (5), a second layer of sound insulation material (4), a first layer of sound insulation material (3), a beam type resonance unit (2) and an aircraft skin (1) are sequentially arranged from the inner side of the cabin to the outer side of the cabin, the first layer of sound insulation material and the second layer of sound insulation material can absorb noise of a first frequency band, and a local resonance unit is arranged between the first layer of sound insulation material and the aircraft skin. The local resonance unit (2) is provided with: a plurality of bases (21) arranged at intervals in a first direction; and a plurality of base beams (22), the plurality of base beams are arranged on the plurality of bases at intervals in a second direction crossing the first direction, the local resonance unit can absorb vibration energy of a second frequency band, and the second frequency band is lower than the first frequency band.

Description

Technical Field

[0001] The present invention relates to a vibration and noise reduction structure of an aircraft, and particularly to a vibration and noise reduction technology for an aircraft panel. Background Art

[0002] In civil aircraft, the noise inside the aircraft cabin mainly comes from the noise of the aircraft's power system and the pulsating pressure in the boundary layer of the aircraft body structure. With the continuous strict requirements of the international aviation market for the cabin comfort standard, it is required that the aircraft panel has better sound insulation performance. Moreover, since lightweight composite materials are gradually replacing traditional materials such as aluminum alloy as aircraft panels, how to improve the sound insulation performance of passenger aircraft panels made of composite materials has become an urgent problem to be solved.

[0003] In view of the above problems, there are the following two panel structures in the prior art:

[0004] First, a porous material is filled between the aircraft skin and the interior panel. The porous material is mainly composed of two materials, glass fiber and foam. This structure mainly absorbs noise in the medium and high frequency bands, but its performance in absorbing noise in lower frequency bands than the above bands is not ideal;

[0005] Second, a damping layer is pasted on the aircraft skin or a damping layer is laid in the middle of the sound insulation cotton. This structure can convert kinetic energy into heat energy through the heat loss generated by the intermolecular friction movement in the damping, so as to reduce the vibration of the panel and the sound radiation efficiency. The damping layer increases the effective surface density of the panel, so as to improve the sound insulation performance in the mass law interval of the panel, but the low-frequency sound insulation performance is still insufficient.

[0006] Therefore, in view of the above existing panel structures, how to absorb noise in lower frequency bands has become an urgent problem to be solved. Summary of the Invention

[0007] The present invention is completed in view of the above technical problems, and its purpose is to provide a panel structure of an aircraft that can block noise in lower frequency bands than the prior art.

[0008] To achieve the above object, a first aspect of the present invention provides a panel structure of an aircraft. An interior panel, a second layer of sound insulation material, a first layer of sound insulation material, and an aircraft skin are sequentially arranged from the inner side of the panel to the outer side of the panel. The first layer of sound insulation material and the second sound insulation material can absorb noise in a first frequency band. A local resonance unit is further arranged between the first layer of sound insulation material and the aircraft skin. The local resonance unit includes: a plurality of bases, and the plurality of bases are arranged at intervals in a first direction; and a plurality of base beams, and the plurality of base beams are arranged at intervals in a second direction intersecting the first direction on the plurality of bases. The local resonance unit can absorb noise in a second frequency band, and the second frequency band is lower than the first frequency band.

[0009] According to the above structure, the local resonance unit is a beam structure with multiple base beams arranged crosswise on multiple bases. Through the refined beam resonator, it couples with the aircraft skin to vibrate, effectively suppressing the low-frequency vibration of the skin, thereby reducing the radiated noise from the aircraft skin into the aircraft cabin.

[0010] In addition, since the local resonance unit is arranged between the first layer of sound insulation material and the aircraft skin, there is no need to separately set up a space to accommodate the local resonance unit. Thus, the space utilization rate of the aircraft cabin door can be improved.

[0011] The panel structure of the aircraft in the second aspect of the present invention is based on the panel structure of the aircraft in the first aspect of the present invention. Both the base and the base beam are strip-shaped, and the base beam is made of a damping layer or other viscoelastic material.

[0012] According to the above structure, since both the base and the base beam are strip-shaped, simply adjusting the length and thickness of the base beam can set the natural frequency of the beam structure. Thus, resonance with the vibration from the aircraft skin can be achieved through a simple structure.

[0013] The panel structure of the aircraft in the third aspect of the present invention is based on the panel structure of the aircraft in the first or second aspect of the present invention. Multiple bases are arranged at equal intervals.

[0014] According to the above structure, since multiple bases are arranged at equal intervals, the energy of vibration at one frequency can be absorbed. In other words, the frequency of vibration can be stabilized.

[0015] The panel structure of the aircraft in the fourth aspect of the present invention is based on the panel structure of the aircraft in the first or second aspect of the present invention. Multiple bases are arranged at unequal intervals.

[0016] According to the above structure, since multiple bases are arranged at unequal intervals, the energy of vibration at multiple frequencies can be absorbed. In other words, noise at multiple frequencies (i.e., broadband) can be absorbed.

[0017] The panel structure of the aircraft in the fifth aspect of the present invention is based on the panel structure of the aircraft in the first or second aspect of the present invention. In the local resonance unit, the base beam is fixed to the base by double-sided tape, strong glue or Velcro.

[0018] According to the above structure, since in the local resonance unit, the base beam is fixed to the base by double-sided tape, strong glue or Velcro, the base beam can be reliably fixed to the base and will not easily come loose even when the local resonance unit resonates with the vibration of the aircraft skin.

[0019] The panel structure of the aircraft according to the sixth aspect of the present invention is based on the panel structure of the aircraft according to the fifth aspect of the present invention. The first layer of sound insulation material is formed with a plurality of partition walls arranged in the second direction. A first groove corresponding to a plurality of the base beams is formed between the plurality of partition walls. A plurality of second grooves are formed at positions corresponding to the base in the first direction of the plurality of partition walls. The cross-sectional area of the second groove is larger than the cross-sectional area of the base beam.

[0020] According to the above structure, since both the first groove and the second groove are recessed in the first layer of sound insulation material, and the base and the base beam are respectively embedded in the second groove and the first groove for combination, there is no need to separately provide a space to accommodate the base beam, and the space between the first layer of sound insulation material and the base beam can be fully utilized, improving the space utilization rate.

[0021] The panel structure of the aircraft according to the seventh aspect of the present invention is based on the panel structure of the aircraft according to the sixth aspect of the present invention. A cavity is formed between the first layer of sound insulation material and the base beam.

[0022] According to the above structure, since a cavity is formed between the first layer of sound insulation material and the base beam, the first layer of sound insulation material can be prevented from directly squeezing the base beam and causing it to undergo elastic deformation. In this way, the low-frequency sound insulation performance of the resonator can be prevented from being damaged.

[0023] The panel structure of the aircraft according to the eighth aspect of the present invention is based on the panel structure of the aircraft according to the first aspect or the second aspect of the present invention. The base beam is made of foam rubber, polyimide foam or thermally compressed melamine foam.

[0024] According to the above structure, since the base beam is made of foam rubber, polyimide foam or thermally compressed melamine foam, the kinetic energy of the vibration from the aircraft skin can be converted into heat energy, thereby reducing the sound radiation energy in the cabin.

[0025] The panel structure of the aircraft according to the ninth aspect of the present invention is based on the panel structure of the aircraft according to the first aspect or the second aspect of the present invention. The first layer of sound insulation material is made of a viscoelastic foam material.

[0026] According to the above structure, since the first layer of sound insulation material is made of a viscoelastic foam material, high-frequency noise can be absorbed.

[0027] The panel structure of the aircraft according to the tenth aspect of the present invention is based on the panel structure of the aircraft according to the first aspect or the second aspect of the present invention. The second layer of sound insulation material is made of a glass fiber material.

[0028] According to the above structure, since the second layer of sound insulation material is made of fiberglass material, sound waves are reflected at the interface of the two layers of materials, which can further absorb high-frequency noise and improve the heat insulation performance of the wall panel. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 It is a schematic diagram showing the layout form of the local resonance unit in the wall panel structure of the aircraft in this embodiment.

[0031] Figure 2 It is a schematic diagram showing the structure of the wall panel structure of the aircraft in this embodiment except for the interior panel 5.

[0032] Figure 3 It is a schematic diagram showing the structure of the local resonance unit in the wall panel structure of the aircraft in this embodiment.

[0033] Figure 4 It is a schematic diagram showing the structure of the first layer of sound insulation material in the wall panel structure of the aircraft in this embodiment.

[0034] Figure 5 It is a schematic diagram showing the wall panel structure of the aircraft in this embodiment along Figure 2 the cross-sectional view obtained by cutting along the solid line A-A in

[0035] Figure 6 It is a schematic diagram showing the wall panel structure of the aircraft in this embodiment along Figure 2 the cross-sectional view obtained by cutting along the dashed line B-B in

[0036] Figure 7 It is a schematic diagram showing the wall panel structure of the aircraft in this embodiment along Figure 2 the cross-sectional view obtained by cutting along the dashed line C-C in

[0037] Figure 8 It is a curve graph showing the sound insulation performance of the wall panel structure of the aircraft in this embodiment and the existing wall panel structure.

[0038] Figure 9 It is a schematic diagram showing the structure of the local resonance unit in the wall panel structure of the aircraft in the variant embodiment of this embodiment.

[0039] (Symbol Description)

[0040] 100 Wall panel structure of the aircraft;

[0041] 1 Aircraft skin;

[0042] 2 local resonance unit;

[0043] 21 base;

[0044] 22 foundation beam;

[0045] 23 cavity;

[0046] 3. The first layer of sound insulation material;

[0047] 31 next door;

[0048] 311 first groove;

[0049] 312 second groove;

[0050] 4. Second layer of sound insulation material;

[0051] 5 interior panels;

[0052] 6 horizontal frames;

[0053] 7 Long Stringer. DETAILED DESCRIPTION

[0054] Below, refer to Figures 1 to 9 Embodiments of the aircraft panel structure according to the present invention and modifications thereof will be described. Figure 1 Schematic diagram showing the arrangement of the aircraft panel structure in the aircraft skin according to the present embodiment. Figure 2 It is a schematic diagram showing the overall structure of the aircraft panel structure according to the present embodiment. Figure 3 Schematic diagram showing the structure of a local resonance unit in the panel structure of an aircraft according to the present embodiment. Figure 4 It is a schematic diagram showing the structure of the first layer of the sound insulating material in the aircraft panel structure according to the present embodiment. Figure 5 The wall panel structure of the aircraft according to the present embodiment is shown along Figure 2 The sectional view obtained by cutting along the solid line AA in FIG. Figure 6 The wall panel structure of the aircraft according to the present embodiment is shown along Figure 2 The cross-sectional view obtained by cutting along the dotted line BB in FIG. Figure 7 The wall panel structure of the aircraft according to the present embodiment is shown along Figure 2 The cross-sectional view obtained by cutting along the CC dotted line in FIG. Figure 8 It is a graph showing the sound insulation performance of the aircraft panel structure according to the present embodiment and the conventional panel structure. Figure 9 It is a schematic diagram showing the structure of a local resonance unit in a wall panel structure of an aircraft according to a modified example of the present embodiment.

[0055] For the convenience of detailed description of the embodiments of the panel structure of the aircraft of the present invention, Figure 3 the arrangement direction of the multiple bases 21 in Figure 3 is set as the first direction (i.e., the X direction), and the arrangement direction of the multiple base beams 22 is set as the second direction (i.e., the Y direction). In this embodiment, the X direction and the Y direction are orthogonal as

[0056] (Panel structure of the aircraft in the first embodiment)

[0057] As Figure 1 shown, in this embodiment, multiple cross frames 6 and multiple stringers 7 are arranged in a cross pattern to form an aircraft cabin frame, and an aircraft skin 1 is wrapped around the outside of the frame. The local resonance unit 2 of this embodiment is installed in the area surrounded by the cross frame 6, the stringer 7, and the aircraft skin 1, and the first layer of sound insulation material 3, the second layer of sound insulation material 4, and the interior trim panel 5 are stacked in sequence on the inner side of the local resonance unit. Although in the actual application scenario, the local resonance unit 2 is installed in each area surrounded by the cross frame 6, the stringer 7, and the aircraft skin 1, for the convenience of illustration, in this embodiment, as Figure 1 shown, the local resonance unit 2 is installed in only one of the areas.

[0058] The local resonance unit 2 of this embodiment includes: six bases 21 (as Figure 3 shown), all six bases are strip-shaped and are arranged at equal intervals along the X direction on the inner surface of the aircraft skin 1 (to adapt to the curved shape of the aircraft skin 1); twelve base beams 22 (as Figure 3 shown), all twelve base beams are strip-shaped and are arranged along the Y direction and fixed to the six bases 21 by double-sided tape, strong glue, Velcro, etc.

[0059] As Figures 5 - 7 shown, on the inner side of the cabin door of the local resonance unit 2 (i.e., Figure 5 the upper side in

[0060] ), the first layer of sound insulation material 3 is stacked, the second layer of sound insulation material 4 is stacked on the inner side of the first layer of sound insulation material 3, and the interior trim panel 5 is stacked on the inner side of the second layer of sound insulation material 4. Among them, the first layer of sound insulation material 3 is made of a viscoelastic foam material that can absorb the first frequency band, and the second layer of sound insulation material 4 is made of a glass fiber material that can absorb the first frequency band. Figure 4As shown, the first layer of sound insulation material 3 is provided with a plurality of partition walls 31 extending upward from the bottom, and the plurality of partition walls 31 are arranged along the Y direction. A first groove 311 is formed between two adjacent partition walls 31, and the first groove 311 covers each base beam 22 when the first layer of sound insulation material 3 covers the base 21 as shown in Figure 6 shown. Moreover, a second groove 312 is formed on each partition wall 31. The positions of these second grooves 312 in the X direction correspond to the base 21, and their dimensions in the X direction (i.e., Figure 6 the width l in) are larger than the dimensions of the base 21 in the X direction, and their dimensions in the up and down direction (i.e., Figure 6 the thickness h in) are also larger than the dimensions of the base 21 in the up and down direction. Thus, when the first layer of sound insulation material 3 covers the base beam 22, the second grooves 312 cover the base 21 respectively, and a cavity 23 is formed between the first layer of sound insulation material 3 and the base beam 22. Thereby, it can be avoided that the base beam 22 is squeezed and deformed under the pressure from the first layer of sound insulation material 3, and the performance of the base beam 22 in absorbing low-frequency noise can be avoided from being damaged.

[0061] In addition, regarding the dimension settings of the base 21, the base beam 22, the first layer of sound insulation material 3, and the second layer of sound insulation material 4 in the local resonance unit 2, specifically, the thickness of each base 21 is set to about 1-2 mm, and it has a certain compressive strength to support the upper base beam 22, the first layer of sound insulation material 3, and the second layer of sound insulation material 4. As shown in Figure 6 shown, the elastic modulus E, the thickness h, and the width l of each base beam 22 satisfy the following formula:

[0062]

[0063] Among them, E is the elastic modulus of the material of the base beam 22, which is a constant representing the characteristics of this material, ρ is the density of the base beam 22, h represents the thickness of the base beam 22, and l represents the width of the base beam 22. The elastic modulus E among them satisfies the following formula:

[0064]

[0065] Wherein, F refers to the applied external force, S refers to the cross-sectional area of the base beam 22, dL refers to the amount of deformation of the base beam under the action of the external force F, and L refers to the original length of the base beam 22. When the type of material of the base beam is determined, its elastic modulus E is also determined accordingly. As the material of the base beam 22, damping rubber or viscoelastic porous material is usually used. In this embodiment, as the damping rubber, foam rubber is preferably used, and as the viscoelastic porous material, melamine foam is preferably used. When the type of material of the base beam 22 is determined, its elastic modulus E is also determined. On this basis, according to the above formula (1), by setting the height h and thickness l of the base beam 22, the resonance frequency f of the local resonance unit 2 can be obtained.

[0066] Thus, when the vibration frequencies (here referring to the frequencies in the second frequency band below 500 Hz) at different positions of the aircraft skin 1 are different, by appropriately setting the height h and thickness l of the base beam 22 in the local resonance unit 2 at that position, the resonance frequency f of the local resonance unit 2 can be made to match the vibration frequency of the aircraft skin 1, so that the local resonance unit 2 and the aircraft skin 1 can undergo coupled resonance. In this way, the vibration energy of the vibration from the aircraft skin 1 is greatly reduced when passing through the local resonance unit 2, thereby absorbing the noise in the second frequency band from the aircraft skin 1.

[0067] In this embodiment, the frequency band above 400 Hz is defined as the second frequency band, and the frequency band less than 5000 Hz is defined as the first frequency band.

[0068] To more intuitively illustrate the performance of the panel structure of the aircraft of the present invention in absorbing the noise in the second frequency band, the performance of the panel structure of the aircraft of the present invention and the panel structure of the existing aircraft in absorbing the noise in the second frequency band are respectively plotted with solid lines and dashed lines in Figure 8 .

[0069] As Figure 8 shown, the horizontal axis represents different vibration frequencies, and the vertical axis represents the sound transmission loss (Sound Transmission Loss TL) at different vibration frequencies. The solid line represents the panel structure of the existing aircraft composed of the aircraft skin and a homogeneous damping material layer, and the dashed line represents the panel structure of the aircraft of the present invention composed of the aircraft skin and local resonance units.

[0070] As Figure 8 shown, within the second frequency band less than 400 Hz, the solid line is below the dashed line, which means that the sound transmission loss of the panel structure of the aircraft skin + local resonance unit of the present invention is smaller than that of the panel structure of the existing aircraft skin + damping layer, especially at the frequency close to 400 Hz, the sound transmission loss of the panel structure of the aircraft skin + local resonance unit of the present invention is much smaller than that of the panel structure composed of the existing aircraft skin + damping material layer.

[0071] It can be seen therefrom that within the second frequency band, the panel structure of the aircraft of the present invention is overall superior in sound insulation performance to the panel structure of existing aircraft. In other words, according to the panel structure of the aircraft of the present invention, the noise in the second frequency band can be effectively absorbed.

[0072] Regarding the dimensions of the first sound insulation material 3 and the second sound insulation material 4, in the present embodiment, the thickness of the first sound insulation material 3 (i.e., Figures 5 - 7 the dimension in the up and down direction in Figure 5 ) is set to about 5 mm, and a foam pore material with a certain structural strength is used. The thickness of the second sound insulation material 4 (i.e.,

[0073] (Technical effects of the panel structure of the aircraft of the first embodiment)

[0074] According to the panel structure of the aircraft of the present embodiment, since the local resonance unit is a beam structure and the width and thickness of the base beam therein are designed to be dimensions that can absorb the noise in the second frequency band, therefore, compared with the prior art, the noise in the second frequency band can be absorbed.

[0075] Since the base beam is buried in the first sound insulation material, the overall height dimension of the device can be reduced. Therefore, the space between the first sound insulation material and the aircraft skin can be used to arrange the local resonance unit, thereby improving the space utilization rate of the aircraft door.

[0076] (Modification example of the panel structure of the aircraft of the first embodiment)

[0077] In the first embodiment, the panel structure of the aircraft in which the bases are installed on the aircraft skin 1 at equal intervals along the X direction has been described, but the present invention is not limited thereto. It can also be as Figure 9 shown that the bases 21 are installed on the aircraft skin 1 at unequal intervals along the X direction.

[0078] Thus, according to the panel structure of the aircraft of this modification example, since the intervals between the bases are different, the frequencies at which the local resonance units formed by the bases can resonate are also different. Therefore, the noise in different frequencies of the second frequency band can be absorbed.

[0079] In addition, according to the panel structure of the aircraft of this modification example, the same technical effects as those of the first embodiment can be obtained, that is, since the panel includes a beam-type local resonance unit and the frequencies at which it resonates are different, therefore, compared with the prior art, the noise in the second frequency band can be absorbed.

[0080] Above, for the purpose of making the objectives, technical solutions, and advantages of the various embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention have been clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of the present invention to be protected.

[0081] In the above embodiment, taking 400 Hz as the boundary, the first frequency band is set to be above 400 Hz, and the second frequency band is set to be less than 400 Hz. However, the present invention is not limited thereto. Since the thickness and geometric dimensions of the aircraft skin are different at each position, the vibration frequency is also different. Thus, the first frequency band may change due to the change in position.

[0082] In the above embodiment, six bases are formed, and twelve base beams are formed. However, the present invention is not limited thereto, and the number of bases and base beams may also be other numbers.

[0083] In the above embodiment, the base beam is fixed to the base by double-sided tape, strong glue, or Velcro. However, the present invention is not limited thereto, and the base beam may also be fixed to the base in other ways.

Claims

1. An aircraft panel structure, comprising an interior panel, a second layer of sound insulation material, a first layer of sound insulation material and an aircraft skin arranged in sequence from the inside of the cabin to the outside of the cabin, wherein the first layer of sound insulation material and the second layer of sound insulation material can absorb noise in a first frequency band, It is characterized in that A local resonance unit is also arranged between the first layer of sound insulation material and the aircraft skin. The local resonance unit comprises: A plurality of bases, wherein the plurality of bases are arranged in a spaced relationship in a first direction; and a plurality of base beams, the plurality of base beams being arranged on the plurality of bases at intervals in a second direction intersecting the first direction, The local resonance unit can absorb noise in the second frequency band, The second frequency band is lower than the first frequency band.

2. The aircraft panel structure according to claim 1, characterized in that: The base and the base beam are both in the shape of long strips, and the base beam is made of viscoelastic material.

3. The aircraft panel structure according to claim 1 or 2, characterized in that: The plurality of bases are arranged in an equidistant manner.

4. The aircraft panel structure according to claim 1 or 2, characterized in that: The plurality of bases are arranged in a non-equidistant manner.

5. The aircraft panel structure according to claim 1 or 2, characterized in that: In the local resonance unit, the base beam is fixed to the base by double-sided adhesive, strong glue or Velcro.

6. The aircraft panel structure according to claim 5, characterized in that: The first layer of sound insulation material is formed with a plurality of partition walls arranged in the second direction, and first grooves corresponding to the plurality of base beams are formed between the plurality of partition walls. A plurality of second grooves are formed at positions of the plurality of partition walls corresponding to the base in the first direction. The cross-sectional area of ​​the second groove is greater than the cross-sectional area of ​​the base beam.

7. The aircraft panel structure according to claim 6, characterized in that: A cavity is formed between the first layer of sound insulation material and the base beam.

8. The aircraft panel structure according to claim 1 or 2, characterized in that: The base beam is made of foam rubber or heat-compressed melamine foam.

9. The aircraft panel structure according to claim 1 or 2, characterized in that: The first layer of sound insulation material is made of viscoelastic foam material.

10. The aircraft panel structure according to claim 1 or 2, characterized in that: The second layer of sound insulation material is made of glass fiber wool material.

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