Composite Materials

Abstract

To provide a composite member in which deterioration and deformation of fasteners are suppressed.SOLUTION: The panel 10 as a composite member has a main body 12 including a resin 20 as a base material and carbon fibers 22 in the resin 20, a first region 12A including a fastening portion 14 for fastening to the reinforcement 30 in the main body 12, and a second region 12B provided around the first region 12A in the main body 12. The product has the following two features. The first region 12A is composed of carbon fibers 22 with carbon nanotubes 24 added, and the second region 12B has fewer carbon fibers 22 with carbon nanotubes 24 added than the first region 12A.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a composite member containing fibers in a resin. [Background technology]

[0002] Patent Document 1 discloses a fiber-reinforced resin member that increases the fiber volume ratio of a fastening portion where another part is attached and suppresses the impregnation of the fastening portion with resin, thereby enabling easy bolt tightening without pre-drilling a bolt hole. In the fiber-reinforced resin member, by impregnating the fastening portion with resin, deterioration and deformation of the fastening portion are suppressed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-256769 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a fiber-reinforced resin member such as that in Patent Document 1, by increasing the fiber density, it is possible that the resin will not penetrate between the fibers even if it is impregnated with resin. In other words, increasing the fiber density in a fastening portion with another member may actually weaken the bonding strength between the fibers, which may cause deterioration and deformation of the fastening portion.

[0005] An object of the present invention is to provide a composite member in which deterioration and deformation of fastening portions are suppressed. [Means for solving the problem]

[0006] The composite material described in claim 1 has a main body portion containing a resin as a base material and fibers in the resin, a first region in the main body portion that is composed of the fibers to which nanomaterial has been added and includes a fastening portion for fastening to another member, and a second region in the main body portion that is provided around the first region and has less of the fibers to which nanomaterial has been added than in the first region.

[0007] The composite member described in claim 1 contains fibers in a resin and is fastened to another member at a fastening portion provided in the main body. The main body of the composite member has a first region having the fastening portion and a second region provided around the first region. Since more nanomaterial is added to the fibers included in the first region than to the fibers included in the second region, the density of the nanomaterial in the fastening portion is higher than that of the surrounding region. Therefore, with this composite member, the bonding strength between the fibers can be ensured and deterioration and deformation of the fastening portion can be suppressed.

[0008] A composite material according to a second aspect of the present invention is the composite material according to the first aspect, wherein the boundary between the first region and the second region is inclined with respect to the fastening direction.

[0009] According to the composite member of claim 2, it is possible to ensure an adhesive area between two regions having different amounts of nanomaterial added, and therefore it is possible to ensure a sufficient bonding strength at the boundary between the two regions.

[0010] A composite material according to a third aspect of the present invention is the composite material according to the first or second aspect, wherein the thickness of the first region in the fastening portion is equal to or greater than half the thickness of the main body portion.

[0011] According to the composite material described in claim 3, by setting the lower limit of the thickness of the first region to half the thickness of the main body, it is possible to suppress deterioration and deformation of the fastening portion while reducing the amount of costly nanomaterial used.

[0012] The composite material described in claim 4 is the composite material described in any one of claims 1 to 3, wherein the outer edge of the first region is in the range of 1.5D to 5D, where D is the diameter of the bolt fastened in the fastening portion.

[0013] According to the composite material described in claim 4, by setting the range of the first region to a range of 1.5 to 5 times the diameter of the bolt, it is possible to suppress deterioration and deformation of the fastening part while reducing the amount of costly nanomaterial used.

[0014] The composite material described in claim 5 is a composite material described in any one of claims 1 to 4, wherein in the second region near the boundary between the first region and the second region, the fibers to which the nanomaterial has been added and the fibers to which the nanomaterial has not been added are mixed, and in locations in the second region away from the boundary, the fibers to which the nanomaterial has not been added are used.

[0015] According to the composite material of claim 5, a sudden change in the content of the nanomaterial at the boundary between the first region and the second region is suppressed, so that peeling at the boundary can be suppressed.

[0016] A composite material according to a sixth aspect of the present invention is the composite material according to any one of the first to fifth aspects, wherein the nanomaterial is derived from a natural material.

[0017] According to the composite member as defined in claim 6, it is possible to suppress an increase in cost compared to the case where carbon nanotubes are used as the nanomaterial, and further, it is possible to achieve carbon neutrality. Effect of the Invention

[0018] According to the present invention, the fiber density of the fastening portion can be increased. [Brief description of the drawings]

[0019] [Figure 1] FIG. 2 is a plan view of the panel and reinforcement of the first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of a joint portion between a panel and a reinforcement in the first embodiment. [Diagram 3] FIG. 11 is a cross-sectional view of a joint portion between a panel and a reinforcement in a second embodiment. [Figure 4] FIG. 11 is a cross-sectional view of a joint portion between a panel and a reinforcement in a third embodiment. [Diagram 5] FIG. 13 is a cross-sectional view of a joint portion between a panel and a reinforcement in the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] [First embodiment] 1 and 2 show a panel 10 of this embodiment and a reinforcement 30 to which the panel 10 is fixed. The reinforcement 30 is an example of another member. The panel 10 as a composite member includes a main body 12 made of carbon fiber reinforced plastics (CFRP). The main body 12 has an insertion hole 14A through which a bolt 42 is inserted, and the bolt 42 is screwed into a nut 44 to form a portion to which a fastening force is applied as a fastening portion 14. Here, the portion to which the fastening force is applied is the periphery of the insertion hole 14A, and includes at least the range to which the head of the bolt 42 contacts.

[0021] 2, the main body 12 of the panel 10 has a first region 12A including the fastening portion 14, and a second region 12B provided around the first region. In this embodiment, a boundary portion 12C which is a boundary between the first region 12A and the second region 12B is inclined with respect to the fastening direction of the bolt 42, i.e., the axial direction. More specifically, it is inclined in a direction away from the insertion hole 14A as it goes from the bottom to the top of the main body 12.

[0022] The panel 10 includes a resin 20 as a base material and carbon fibers 22 that are fibers contained in the resin 20. In FIG. 2, the extension direction of the carbon fibers 22 is set to one direction extending from the front to the back of the drawing, but this is not limited thereto, and the extension direction of the carbon fibers 22 may be changed for each layer, or the carbon fibers 22 may be woven vertically and horizontally (the same applies to other embodiments). Here, the carbon fibers 22 in the first region 12A have carbon nanotubes 24, which are nanomaterials, added to their surfaces. The state in which the carbon nanotubes 24 are added to the carbon fibers 22 includes not only a state in which the carbon nanotubes 24 are attached to the surfaces of the carbon fibers 22, but also a state in which the carbon nanotubes 24 are dispersed on and around the surfaces of the carbon fibers 22. On the other hand, the carbon nanotubes 24 are not added to the carbon fibers 22 in the second region 12B.

[0023] Note that, carbon nanotubes 24 may be added to carbon fibers 22 in the second region 12B, so long as the weight ratio of carbon fibers 22 to which carbon nanotubes 24 have been added is smaller than that in the first region 12A.

[0024] The panel 10 of this embodiment can be manufactured by laminating prepregs in which carbon fibers 22 are impregnated with resin 20, and then molding by pressing. Here, the carbon fibers 22 in the prepregs constituting the first region 12A have carbon nanotubes 24 added to their surfaces in advance. In addition, in the vicinity of the fastening portion 14, the prepregs having carbon nanotubes 24 are laminated while being shifted in the radial direction of the insertion hole 14A, so that an inclined boundary portion 12C can be formed.

[0025] The main body 12 of the panel 10 may be manufactured by a method of impregnating a molded body of carbon fiber 22 shaped into the shape of the main body 12 with liquid resin, or by a method of press molding a sheet molding compound (SMC).

[0026] As described above, in this embodiment, the carbon fibers 22 included in the first region 12A are doped with the carbon nanotubes 24, and the carbon fibers 22 included in the second region 12B are doped with the carbon nanotubes 24. Therefore, the density of the carbon nanotubes 24 in the fastening portion 14 is higher than that in the surrounding area of ​​the fastening portion 14.

[0027] For example, as disclosed in JP 2019-59871 A, it is known that in carbon fiber reinforced resin, by providing carbon nanotubes on the surface of the carbon fiber, the peel strength against the base resin is improved and the mechanical strength is improved. Therefore, as in this embodiment, by using carbon fiber 22 with carbon nanotubes 24 added to the surface near the fastening portion 14 where the fastening force is applied, the mechanical strength of the main body portion 12 can be improved without increasing the density of the carbon fiber 22. As a result, deterioration and deformation of the fastening portion 14 can be suppressed.

[0028] Moreover, since the mechanical strength of the main body 12 can be improved without increasing the density of the carbon fibers 22, insufficient impregnation of the resin 20 is suppressed when the panel 10 is manufactured by the above-mentioned method of impregnating with the resin 20. Furthermore, compared to the case where deterioration and deformation of the fastening portion 14 are suppressed by providing a metal collar or the like in the insertion hole 14A, this embodiment is advantageous in terms of cost because additional parts such as a metal collar and additional man-hours during manufacturing are not required.

[0029] On the other hand, nanomaterials such as carbon nanotubes 24 are generally expensive, and if nanomaterials are used for the entire part, there is a problem that applications are limited from a cost perspective. In contrast, in this embodiment, carbon nanotubes 24 are added only to first region 12A including fastening portion 14, so manufacturing costs are reduced compared to when carbon nanotubes 24 are used for the entire main body portion 12.

[0030] Furthermore, when a carbon fiber reinforced resin has a plurality of regions with different mechanical strengths, it is difficult to ensure the bonding strength at the boundary between the regions. In contrast, in the panel 10 of the present embodiment, the boundary 12C between the first region 12A and the second region 12B is inclined with respect to the axial direction, which is the fastening direction of the bolt 42. Therefore, according to the present embodiment, the bonding area between the first region 12A and the second region 12B can be ensured, and the bonding strength between them can be ensured, compared to the case where the boundary 12C is formed perpendicular to the fastening direction.

[0031] [Second embodiment] The second embodiment differs from the first embodiment in the arrangement of the first region 12A and the second region 12B. The differences from the first embodiment will be described below. Note that the same components as those in the first embodiment are given the same reference numerals as those in the first embodiment, and detailed description thereof will be omitted.

[0032] As shown in Fig. 3, in this embodiment, the insertion hole 14A is disposed so as to straddle the first region 12A and the second region 12B, and the fastening portion 14 is included in both the first region 12A and the second region 12B. The range in which the first region 12A is disposed in the thickness direction of the main body portion 12 is determined by the thickness of the main body portion 12. Specifically, the thicknesses t1 and t2 of the first region 12A in the fastening portion 14 are set within a range of 80% to 90% of the thickness T of the main body portion 12. In Fig. 3, the thickness t1 of the first region 12A is the thickness on the radial inner side of the fastening portion 14, and the thickness t2 of the first region 12A is the thickness on the radial outer side of the fastening portion 14.

[0033] In fastening portion 14 having the structure of this embodiment, the thicknesses t1, t2 of first region 12A are set to be equal to or greater than half the thickness T of main body portion 12, thereby ensuring mechanical strength. Therefore, according to panel 10 of this embodiment, by reducing first region 12A in the thickness direction of main body portion 12, it is possible to suppress deterioration and deformation of fastening portion 14 while reducing the amount of costly carbon nanotubes 24 used. In addition, this embodiment has the same effects as the first embodiment.

[0034] [Third embodiment] The third embodiment differs from the first and second embodiments in the arrangement of the first region 12A and the second region 12B. The differences from the first embodiment will be described below. Note that the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof will be omitted.

[0035] 4, in this embodiment, although the insertion hole 14A is disposed in the first region 12A, the fastening portion 14 is included in both the first region 12A and the second region 12B. The range in which the first region 12A is disposed in the width direction of the main body 12 is determined by the diameter of the bolt 42. Specifically, the outer diameter d of the outer edge of the first region 12A in the fastening portion 14 is set in the range of 1.5D to 5D, where D is the diameter of the bolt 42.

[0036] In the fastening portion 14 having the structure of this embodiment, the outer diameter d of the first region 12A is set in the range of 1.5 to 5 times the diameter D of the bolt 42, thereby ensuring mechanical strength. Therefore, according to the panel 10 of this embodiment, by reducing the first region 12A in the width direction of the main body 12, it is possible to suppress deterioration and deformation of the fastening portion while reducing the amount of costly carbon nanotubes 24 used. In addition, this embodiment has the same effects as the first embodiment.

[0037] [Fourth embodiment] The fourth embodiment is different from the first embodiment in the structure near the boundary 12C between the first region 12A and the second region 12B. The differences from the first embodiment will be described below. Note that the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof will be omitted.

[0038] 5, in this embodiment, in the second region 12B near the boundary 12C, carbon fibers 22 to which carbon nanotubes 24 have been added are mixed with carbon fibers 22 to which carbon nanotubes 24 have not been added. Moreover, in the second region 12B, in a location away from the boundary 12C, carbon fibers 22 to which carbon nanotubes 24 have been added are not present.

[0039] According to this embodiment, by suppressing a sudden change in the content of the carbon nanotubes 24 at the boundary 12C, which is the boundary between the first region 12A and the second region 12B, it is possible to suppress peeling at the boundary 12C.

[0040] [Fifth embodiment] In the above fourth embodiment, carbon nanotubes are used as the nanomaterial, but in the fifth embodiment, cellulose nanofibers derived from natural materials are used as the nanomaterial. Note that the structure other than the nanomaterial is the same as in the fourth embodiment, so detailed description will be omitted.

[0041] In this embodiment, too, the same effects as those of the fourth embodiment can be obtained. Note that, like carbon nanotubes, cellulose nanofibers are also expensive materials, but like carbon nanotubes, only a small amount of cellulose nanofiber needs to be added. Therefore, according to this embodiment, the increase in cost of the panel 10 can be suppressed. Also, cellulose nanofibers are natural materials derived from plants. That is, because carbon dioxide is absorbed by photosynthesis during the growth process of plants, so-called carbon neutrality can be achieved by using cellulose nanofibers as a nanomaterial.

[0042] In the first to third embodiments, cellulose nanofibers may be used instead of carbon nanotubes. In this case, in addition to the effects of each embodiment, it is possible to suppress cost increases and achieve carbon neutrality. EXAMPLES

[0043] Examples of the present invention will be described below with reference to Tables 1 and 2. In each table, "CNT" stands for carbon nanotube, and "CNF" stands for cellulose nanofiber.

[0044] [Table 1]

[0045] Table 1 is a table summarizing the structures and effects of Examples 1 to 5. Example 1 has a structure similar to that of the first embodiment shown in FIG. 2. Example 2 has a structure similar to that of the second embodiment shown in FIG. 3, in which the thickness of the first region 12A in the fastening portion 14 is set to 50% of the main body portion 12. Example 3 has a structure similar to that of the third embodiment shown in FIG. 4, in which the area of ​​the first region 12A in the fastening portion 14 is set to be 1.2 times that of the bolt 42. Example 4 has a structure similar to that of the fourth embodiment shown in FIG. 5, in which carbon nanotubes 24 are mixed in the vicinity of the boundary portion 12C. Example 5 has a structure similar to that of Example 4, in which cellulose nanofibers are used instead of the carbon nanotubes 24.

[0046] According to each of the examples, by including carbon nanotubes 24 or cellulose nanofibers in the fastening portion, it is possible to ensure the joining strength even 100 days after fastening the bolt 42, and to reduce costs. Note that in Example 2, since the fastening portion 14 includes the second region 12B that does not include carbon nanotubes 24 in the thickness direction, the joining strength is lower than in the other examples, but the amount of carbon nanotubes 24 used is reduced, which is advantageous in terms of cost.

[0047] [Table 2]

[0048] Table 2 is a table summarizing the structures and effects of Comparative Examples 1 to 6. Comparative Example 1 is an example in which the resin 20 does not contain carbon fiber 22, and a metal collar is provided in the insertion hole 14A. Comparative Example 2 is an example in which the main body 12 is formed from carbon fiber 22 to which no carbon nanotubes 24 have been added. Comparative Example 3 is an example in which the entire main body 12 is formed from resin 20 containing carbon nanotubes 24, but not carbon fiber 22. Comparative Examples 4 to 6 are examples in which the entire main body 12 is made of carbon fiber 22 to which carbon nanotubes 24 have been added.

[0049] According to Comparative Example 1, the number of steps increases due to bonding the metal collar to the insertion hole 14A, and therefore, it is disadvantageous in terms of cost compared to the other Examples. According to Comparative Example 2, although the density of the carbon fibers 22 is increased, the carbon nanotubes 24 are not included, and the joint strength decreases 100 days after the bolt 42 is fastened, causing the bolt 42 to loosen. This is due to the occurrence of creep in the fastening portion 14. According to Comparative Example 3, even if the carbon fibers 22 are not included, it is possible to ensure a certain degree of joint strength. However, since the content of the carbon nanotubes 24 is high, it is the most disadvantageous in terms of cost. Comparative Examples 4 to 6 contain the carbon nanotubes 24 throughout the main body portion 12, and therefore, although it is possible to ensure a certain degree of joint strength, it is disadvantageous in terms of cost compared to the other Examples.

[0050] As described above, according to each of the examples, it is possible to ensure the joining strength without increasing the cost compared to each of the comparative examples. In other words, deterioration and deformation of the fastening portion 14 are suppressed.

[0051] [remarks] In each of the above embodiments, the panel 10 as a composite member is made of carbon fiber reinforced plastics (CFRP), but this is not limiting. For example, the panel 10 may be made of glass fiber reinforced plastics (GFRP).

[0052] In the above first to fourth embodiments (FIGS. 2 to 5), the carbon nanotubes 24 are attached to the surfaces of the carbon fibers 22, but the present invention is not limited to this, and the carbon nanotubes 24 may be present dispersed on the surfaces of the carbon fibers 22 and in their surroundings. In this case, the carbon nanotubes 24 are also present between the carbon fibers 22 in the first region 12A. Similarly, in the case of using cellulose nanofibers as the nanomaterial instead of carbon nanotubes as in the fifth embodiment, the cellulose nanofibers may be dispersed in the same manner.

[0053] In the first to fourth embodiments, carbon nanotubes 24 are used as the nanomaterial. In the fifth embodiment, cellulose nanofibers are used as the nanomaterial. However, the present invention is not limited to this, and other nanomaterials such as fullerene may be used.

[0054] The second to fourth embodiments may be combined with each other. For example, in the vicinity of the boundary portion 12C of the second or third embodiment, the carbon fibers 22 to which the carbon nanotubes 24 are added may be mixed with the carbon fibers 22 to which the carbon nanotubes 24 are not added. In addition, when cellulose nanofibers are used as the nanomaterial instead of carbon nanotubes, the aspects of each embodiment may be combined.

[0055] The present invention is suitable for joining structural parts of a vehicle. For example, it can be applied to joining a bulkhead and a reinforcement. When the present invention is applied to a structural part of a vehicle, the strength of the fastening part 14 is ensured and deterioration and deformation of the fastening part 14 are suppressed, so that the torsional rigidity of the vehicle body is increased. [Explanation of symbols]

[0056] 10 Panel (composite material) 12 Main body 12A First area 12B Second area 12C Boundary 14 Fastening Part 20 Resin 22 Carbon fiber (fiber) 24 Carbon nanotubes (nanomaterials) 30 Reinforcement (other parts) 42 Volts

Claims

1. A main body portion including a resin as a base material and fibers in the resin; A first region in the main body portion is made of the fiber to which a nanomaterial is added and includes a fastening portion for fastening the main body portion to another member; a second region provided around the first region in the main body and having fewer fibers to which the nanomaterial is added than in the first region; having In the second region near the boundary between the first region and the second region, the fibers to which the nanomaterial has been added and the fibers to which the nanomaterial has not been added are mixed, A composite member, wherein in the second region, in areas away from the boundary portion, the fibers are composed of fibers to which the nanomaterial is not added.

2. The composite member according to claim 1 , wherein a boundary between the first region and the second region is inclined with respect to the fastening direction.

3. The composite member according to claim 1 or 2, wherein a thickness of the first region in the fastening portion is equal to or greater than half a thickness of the main body portion.

4. The composite material according to any one of claims 1 to 3, wherein an outer edge of the first region is in a range of 1.5D to 5D, where D is the diameter of a bolt fastened in the fastening portion.

5. The composite material according to any one of claims 1 to 4, wherein the nanomaterial is derived from a natural material.

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