Acoustic structure material and structure

Abstract

To provide an acoustic material having a function as a structure material and can be lightened compared to combination of a metallic face material and an acoustic material.SOLUTION: An acoustic structure material includes: a fiber-reinforced plastic first plate; an acoustic material layer of at least three layers which are laminated on the first plate and have mutually different inherent acoustic impedances; and a fiber-reinforced plastic second plate which is arranged between the layers of the acoustic material layer and in which the acoustic material layer of at least two layers is inserted between the first plate and the second plate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an acoustic material that functions as a structural material and a structure including the same. [Background technology]

[0002] 2. Description of the Related Art Conventionally, acoustic materials such as sound absorbing materials that absorb sound waves and sound insulating materials that block sound waves have been known. For example, Patent Document 1 discloses a sound insulating plate that is a plate-shaped sound insulating material.

[0003] The sound insulation board of Patent Document 1 includes a sound insulation body made of a rubber elastic body with a recess formed on one side, and a cover member that covers the one side of the sound insulation body. The cover member has rubber layers arranged on both sides and a fiber-reinforced resin layer arranged between the rubber layers, and the shape of the cover member is maintained over time by the fiber-reinforced resin layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-166779 A Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, plate-shaped acoustic materials do not have the strength and bending rigidity required for structural materials. Therefore, acoustic materials are joined to metal surface materials such as steel plates, and are used in a combined state with the metal surface materials. When acoustic materials are combined with metal structural surface materials, the weight is inevitably increased and the sound absorption performance is reduced.

[0006] The present disclosure has been made in consideration of the above circumstances, and its purpose is to provide an acoustical material that also functions as a structural material and can achieve weight reduction compared to a combination of a metal panel material and an acoustical material. [Means for solving the problem]

[0007] In order to solve the above problems, an acoustic structure material according to one embodiment of the present disclosure comprises: A first plate made of fiber-reinforced plastic; At least three acoustic material layers are laminated on the first plate and have different specific acoustic impedances; The acoustic material is provided with a second plate made of fiber-reinforced plastic, which is arranged between the layers of acoustic material and has at least two layers of the acoustic material sandwiched between the first plate and the second plate.

[0008] Moreover, a structure according to one aspect of the present disclosure is characterized by comprising a frame member and the acoustic structural material coupled to the frame member. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide an acoustic material that also functions as a structural material and can be made lighter than a combination of a metal panel material and an acoustic material. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view of an acoustic structural material according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic cross-sectional view of an acoustic structure material according to the first modification. [Diagram 3] FIG. 3 is a schematic diagram of a structure including an acoustic structural material. [Figure 4] FIG. 4 is a schematic cross-sectional view of an acoustic structure material according to the second modification. [Diagram 5] FIG. 5 is a schematic cross-sectional view of an acoustic structure material according to the third modification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Next, an embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic cross-sectional view of an acoustic structural material 1 according to one embodiment of the present disclosure. The acoustic structural material 1 shown in Fig. 1 is an acoustic material that also functions as a structural material, in other words, a structural material that also functions as an acoustic material. The structural material has strength and bending rigidity that can be a component (i.e., a structural material) of a structure such as a building, a ship, a car, or an aircraft.

[0012] The acoustic structure material 1 comprises a first FRP plate 41, a plurality of acoustic material layers 3 laminated on the first FRP plate 41, and a second FRP plate 42 arranged between the acoustic material layers 3. Of the two faces of the acoustic structure material 1 facing the lamination direction X of the acoustic material layers 3, one is designated as the front face and the other is designated as the back face. Sound waves enter the acoustic structure material 1 from the front face.

[0013] The first FRP plate 41 and the second FRP plate 42 are plate-shaped members made of fiber reinforced plastics (FRP). Fiber reinforced plastics are reinforced plastics whose strength is improved by compounding fibers such as glass fiber, resin fiber, and carbon fiber with epoxy resin or phenolic resin. Fiber reinforced plastics have a higher specific strength than metal materials and can be made lighter than metal materials with equivalent strength. The thickness of each of the first FRP plate 41 and the second FRP plate 42 is preferably about 1 / 16 to 1 / 4 of the wavelength of the highest frequency in the frequency band to be attenuated.

[0014] The first FRP plate 41 forms the back surface of the acoustic structure material 1. On the first FRP plate 41, a plurality of acoustic material layers 3 are laminated in the lamination direction X.

[0015] Each acoustic material layer 3 is composed of a sheet-like or plate-like acoustic material. The laminated acoustic material layers 3 include a reflective layer 31 and at least two sound-absorbing layers 32. The sound-absorbing layer 32 has a function of absorbing and attenuating sound waves. The reflective layer 31 is the back structure of the sound-absorbing layer 32, and has a function of absorbing sound waves and attenuating sound waves by reflecting them in the opposite phase. The reflective layer 31 is disposed on the rearmost side of the multiple acoustic material layers 3, and the surface of the first FRP board 41 and the rear surface of the reflective layer 31 are joined.

[0016] 1 has three acoustic material layers 3, the first acoustic material layer 3 counting from the back surface of the acoustic structure material 1 being a reflective layer 31, and the second and third acoustic material layers 3 being sound absorbing layers 32. However, the number of acoustic material layers 3 is not limited to this embodiment, and the acoustic structure material 1 only needs to have at least three acoustic material layers 3.

[0017] The constituent material and structure of the acoustic material layer 3 are selected according to the usage mode of the acoustic structure material 1. Assuming that the acoustic structure material 1 according to this embodiment is used underwater, the sound absorbing layer 32 is made of a bubble-dispersed viscoelastic material and has the function of absorbing sound waves and attenuating reflected waves underwater. The bubble-dispersed viscoelastic material is a viscoelastic material such as rubber or rubber-like resin in which a large number of fine bubbles are dispersed approximately uniformly. The bubble-dispersed viscoelastic material may be a foam. Alternatively, the sound absorbing layer 32 may be made of a pore-structured viscoelastic material. The thickness of the sound absorbing layer 32 is preferably about 1 / 16 to 1 / 4 of the wavelength of the highest frequency in the frequency band to be attenuated.

[0018] The index value K1 (K1=specific acoustic impedance of sound absorbing layer 32 / specific acoustic impedance of water), which represents the specific acoustic impedance of the sound absorbing layer 32 based on the specific acoustic impedance of water, is preferably 0.5 to 0.9. In other words, the specific acoustic impedance of the sound absorbing layer 32 is smaller than the specific acoustic impedance of water.

[0019] The multiple sound absorbing layers 32 included in the acoustic structure material 1 have different specific acoustic impedances. In detail, the specific acoustic impedance of the multiple sound absorbing layers 32 is the largest for the sound absorbing layer 32 arranged on the most front side, and the smallest for the sound absorbing layer 32 arranged on the most rear side. The difference in specific acoustic impedance between the sound absorbing layer 32 arranged on the most front side among the multiple sound absorbing layers 32 and water is small enough to suppress the reflection of sound waves. When the acoustic structure material 1 includes three or more sound absorbing layers 32, the specific acoustic impedance of the multiple sound absorbing layers 32 decreases from the sound absorbing layer 32 arranged on the front side toward the rear side.

[0020] The reflecting layer 31 according to the present embodiment is made of a bubble-dispersed viscoelastic material or a pore-structured viscoelastic material. The reflecting layer 31 may be made of a material different from that of the sound-absorbing layer 32. The reflecting layer 31 has a sufficient amount of bubbles inside, compared to the sound-absorbing layer 32, in order to absorb low-frequency sounds and reflect sound waves in the opposite phase due to the difference in acoustic impedance. Such a reflecting layer 31 has a lower specific gravity and a lower hardness, compared to the sound-absorbing layer 32. The thickness of the reflecting layer 31 is preferably about 1 / 32 to 1 / 16 of the wavelength of the highest frequency in the frequency band to be attenuated. The index value K2 (K2=specific acoustic impedance of the reflecting layer 31 / specific acoustic impedance of water), which represents the specific acoustic impedance of the reflecting layer 31 based on the specific acoustic impedance of water, is preferably 0.2 or more and 0.4 or less. In other words, the specific acoustic impedance of the reflecting layer 31 is smaller than the specific acoustic impedance of the sound-absorbing layer 32.

[0021] The second FRP plate 42 is disposed between the sound absorbing layers 32 stacked in the stacking direction X. That is, from the rear side, the first FRP plate 41, the reflective layer 31, the first sound absorbing layer 32, the second FRP plate 42, and the second sound absorbing layer 32 are stacked. The FRP plate and the acoustic material layer 3, and the acoustic material layers 3 are joined together by adhesive, and the stacked FRP plates and the acoustic material layers 3 are integrated.

[0022] The first FRP plate 41 and the second FRP plate 42 are substantially parallel to each other. The reflective layer 31 and the sound absorbing layer 32 are sandwiched between the first FRP plate 41 and the second FRP plate 42, which are arranged in parallel. However, the arrangement of the second FRP plate 42 is not limited to this embodiment. It is sufficient that the acoustic material layer 3 is arranged on the surface of the acoustic structure material 1, and at least two layers of the acoustic material layer 3 are arranged between the first FRP plate 41 and the second FRP plate 42. For example, when the acoustic structure material 1 has three layers of sound absorbing layers 32, as shown in FIG. 2, the reflective layer 31 and two layers of sound absorbing layers 32 may be arranged between the first FRP plate 41 and the second FRP plate 42. However, in order to increase the rigidity of the acoustic structure material 1, it is preferable that the first FRP plate 41 and the second FRP plate 42 are arranged apart from each other in the stacking direction X. From this viewpoint, it is preferable that the second FRP plate 42 is disposed between a pair of acoustic material layers 3 from the front surface side of the acoustic structure material 1 .

[0023] Here, the acoustic function of the acoustic structure material 1 configured as above will be described. Sound waves are incident on the surface of the acoustic structure material 1 from the outside. The acoustic material layer 3 (more specifically, the surface sound absorbing layer 32) is exposed on the surface of the acoustic structure material 1, and the difference in specific acoustic impedance between the water and the surface acoustic material layer 3 is sufficiently small, so that reflection of the sound waves is suppressed. A part of the sound waves incident on the surface sound absorbing layer 32 is absorbed, and the remaining part is transmitted. A part of the sound waves transmitted through the surface sound absorbing layer 32 is reflected by the second FRP plate 42 and absorbed by the surface sound absorbing layer 32, and the remaining part passes through the second FRP plate 42 and enters the sound absorbing layer 32 between the FRP plates 41, 42. A part of the sound waves that enter this sound absorbing layer 32 is absorbed, and the remaining part is transmitted and enters the reflecting layer 31. A part of the sound wave incident on the reflective layer 31 is absorbed, the remaining part is reflected in the opposite phase and causes attenuative interference with the incident sound wave, and the remaining part passes through the reflective layer 31 and is reflected by the first FRP plate 41. A part of the sound wave reflected by the first FRP plate 41 is absorbed by the reflective layer 31, and the remaining part passes through the reflective layer 31 and is reflected at the interface between the reflective layer 31 and the sound absorbing layer 32. In this way, the sound wave is absorbed and attenuated as it is repeatedly reflected in the reflective layer 31. The combination of the reflective layer 31 and the first FRP plate 41 absorbs the incoming sound wave and suppresses the transmission of the sound wave to the back surface of the acoustic structure material 1.

[0024] Next, an application example of the acoustic structural material 1 will be described. Fig. 3 is a schematic diagram of a structure 10 equipped with the acoustic structural material 1. In the application example of the acoustic structural material 1 shown in Fig. 3, the acoustic structural material 1 is used in a structure 10 that constitutes a structure. The structure 10 comprises a frame member 5 that serves as a framework, and an acoustic structural material 1 attached to this frame member 5. The frame member 5 is, for example, a shaped steel. The acoustic structural material 1 is placed on the frame member 5 so that the frame member 5 comes into contact with a first FRP plate 41 that is the back surface of the acoustic structural material 1, and the frame member 5 and the acoustic structural material 1 are joined with fasteners such as bolts.

[0025] <<Variation>> Next, a modified example of the above embodiment will be described. In the description of this modified example, the same or similar members as those in the above embodiment will be denoted by the same reference numerals in the drawings, and the description thereof will be omitted.

[0026] In the above embodiment, the acoustic structure material 1 includes two FRP plates, the first FRP plate 41 and the second FRP plate 42, but the acoustic structure material 1 may include three or more FRP plates. In this case, as shown in Fig. 4, the sound absorbing layer 32 may be three or more layers, and a third FRP plate 43 may be disposed between the sound absorbing layers 32. Alternatively, as shown in Fig. 5, the third FRP plate 43 may be disposed between the reflective layer 31 and the sound absorbing layer 32. By including the third FRP plate 43 in the acoustic structure material 1 in this way, the mass of the acoustic structure material 1 increases by the amount of the third FRP plate 43, but the strength of the acoustic structure material 1 can be improved by the third FRP plate 43.

[0027] [Summary] The acoustic structural material 1 according to the first aspect of the present disclosure comprises: A first plate made of fiber reinforced plastic (corresponding to the first FRP plate 41 in the above embodiment), At least three acoustic material layers 3 are laminated on the first plate 41 and have different specific acoustic impedances from each other; It comprises a second plate (corresponding to the second FRP plate 42 in the above embodiment) made of fiber reinforced plastic, which is arranged between the acoustic material layers 3 and has at least two acoustic material layers 3 sandwiched between it and the first plate 41.

[0028] In the acoustic structural material 1, strength and bending rigidity are provided by the first FRP plate 41 and the second FRP plate 42, which sandwich at least two layers of acoustic material 3. Therefore, the acoustic structural material 1 can be used alone as a structural material without combining it with a metal surface material such as a steel plate. Moreover, since the surface of the acoustic structural material 1 on which the sound waves are incident is composed of the acoustic material layer 3, the reflection of the sound waves on the surface is suppressed. In this way, the acoustic structural material 1 having the above configuration provides an acoustic material that also functions as a structural material, in other words, a structural material that also functions as an acoustic material. Moreover, the acoustic structural material 1 employs FRP plates as a strength element, and since FRP plates have a higher specific strength than metal surface materials, it is possible to achieve weight reduction with the same strength as the combination of metal surface materials and acoustic materials.

[0029] The acoustic structure material 1 relating to the second item of the present disclosure is the acoustic structure material 1 relating to the first item, in which the acoustic material layer 3 sandwiched between the first plate 41 and the second plate 42 includes a reflective layer 31 and a sound absorbing layer 32.

[0030] In the acoustic structure material 1 configured as above, the distance between the first plate 41 and the second plate 42 can be made larger than when only the reflective layer 31 is sandwiched between the first plate 41 and the second plate 42, and the bending rigidity of the acoustic structure material 1 can be effectively improved. In addition, by sandwiching both the reflective layer 31 and the sound absorbing layer 32 between the first plate 41 and the second plate 42, sound waves transmitted through the sound absorbing layer 32 can be reflected by the reflective layer 31 and absorbed and attenuated, and the sound insulation of the acoustic structure material 1 can be ensured.

[0031] The acoustic structural material 1 relating to the third item of the present disclosure is the acoustic structural material 1 relating to the first or second item, in which the second plate 42 is arranged between the pair of acoustic material layers 3 that is furthest from the first plate 41.

[0032] In the acoustic structure material 1 having the above configuration, the first plate 41 and the second plate 42 can be separated from each other by a large distance in the stacking direction X, so that the bending rigidity of the acoustic structure material 1 can be effectively improved.

[0033] The acoustic structure material 1 relating to the fourth item of the present disclosure is an acoustic structure material 1 relating to any of the first to third items, in which the specific acoustic impedance of the acoustic material layer 3 that is arranged furthest from the first plate 41 among the acoustic material layers 3 is smaller than the specific acoustic impedance of water.

[0034] The acoustic structural member 1 having the above-mentioned configuration is suitable for use underwater.

[0035] A structure 10 according to a fifth aspect of the present disclosure includes a frame 5 member and an acoustic structural material 1 according to any one of the first to fourth aspects coupled to the frame 5 member.

[0036] The acoustic structural material 1 provided in the structure 10 configured as above has the functions of an acoustic material and a structural material, and is lighter than an acoustic material joined to a metal surface material. Therefore, the weight of the structure 10 can be reduced.

[0037] The above discussion of the present disclosure has been presented for purposes of illustration and description, and is not intended to limit the present disclosure to the form disclosed herein. For example, in the above detailed description, various features of the present disclosure are grouped together in one embodiment for the purpose of streamlining the present disclosure, but some of the features may be combined. In addition, the features included in the present disclosure may be combined into alternative embodiments, configurations, or aspects other than those discussed above. [Explanation of symbols]

[0038] 1: Acoustic structural material 3: Acoustic material layer 5: Frame member 10 :Structure 31: Reflective layer 32: Sound absorbing layer 41: 1st FRP board (1st board) 42: 2nd FRP board (2nd board)

Claims

1. A first plate made of fiber reinforced plastic; At least three acoustic material layers are laminated on the first plate and have different specific acoustic impedances; A second plate made of fiber reinforced plastic is disposed between the layers of acoustic material and sandwiches at least two layers of the acoustic material between the first plate and the second plate. Acoustic structural materials.

2. The acoustic material layer sandwiched between the first plate and the second plate includes a reflective layer and a sound absorbing layer.

2. The acoustic structural material of claim 1.

3. The second plate is disposed between the pair of acoustic material layers furthest from the first plate.

2. The acoustic structural material of claim 1.

4. The specific acoustic impedance of the acoustic material layer disposed farthest from the first plate among the acoustic material layers is smaller than the specific acoustic impedance of water.

2. The acoustic structural material of claim 1.

5. A frame member; and an acoustic structure according to any one of claims 1 to 4 coupled to the frame member. structure.

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