Honeycomb structure

Abstract

In a honeycomb structure having multiple cells composed of partitions, the energy absorption efficiency is improved. [Solution] The honeycomb structure 10 comprises a plurality of sheet materials 11 in which peaks and valleys are alternately arranged in a first direction, and the plurality of sheet materials 11 are joined to each other in a second direction perpendicular to the first direction so as to form a plurality of cells 14 arranged in a honeycomb shape, and each cell 14 includes a pair of wall portions 17, 17 which are joined to other adjacent cells 14 on one or the other side in the second direction as part of its partition wall 16, and each of the pair of wall portions 17, 17 includes a first joint portion 17a which extends in the first direction in a cross section perpendicular to the extending direction of each cell 14, and a second joint portion 17b which extends in a direction different from the first direction in the cross section.

Description

Technical Field

[0001] The present invention relates to a honeycomb structure.

Background Art

[0002] Patent Document 1 discloses a honeycomb structure having a plurality of columnar cells extending in the vertical direction. The partition walls constituting each cell include a pair of double-wall structures arranged opposite to each other and extending in the same direction. A space (small cell) is formed in a part of each double-wall structure.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The honeycomb structure of Patent Document 1 is formed by bonding corrugated sheets in which ridges and valleys are alternately formed. When pressure is applied to this honeycomb structure from the vertical direction of the cells, peeling is likely to occur from the portion where the corrugated sheets are joined. If peeling at this joined portion occurs excessively easily, buckling of other portions of the corrugated sheet becomes less likely to occur, and the buckling pitch (buckling period) of that portion becomes longer. That is, when the honeycomb structure is used as an energy absorption member, there is concern about a decrease in energy absorption efficiency due to insufficient bonding strength of the above-mentioned joined portion.

[0005] The object of the present invention is to improve the energy absorption efficiency in a honeycomb structure having a plurality of cells formed by partition walls.

Means for Solving the Problems

[0006] A honeycomb structure according to one aspect of the present invention comprises a plurality of sheet materials having alternating peaks and valleys in a first direction. The plurality of sheet materials are joined to each other in a second direction perpendicular to the first direction so as to form a plurality of cells arranged in a honeycomb pattern. Each of the cells includes a pair of wall portions joined to other adjacent cells on one or the other side in the second direction as part of its partition wall. Each of the pair of wall portions includes a first joint and a second joint. In a cross section perpendicular to the stretching direction of each of the cells, the first joint extends in the first direction. In the cross section, the second joint extends in a direction different from the first direction. [Effects of the Invention]

[0007] According to the present invention, energy absorption efficiency can be improved in a honeycomb structure having multiple cells composed of partition walls. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a perspective view of a honeycomb structure according to an embodiment. [Figure 2A] Figure 2A is a view of the sheet material according to the embodiment, seen from the Z direction. [Figure 2B] Figure 2B is a cross-sectional view of a first example of a honeycomb structure according to the embodiment. [Figure 3A] Figure 3A is a cross-sectional view of a first example of a wall portion according to the embodiment. [Figure 3B] Figure 3B is a diagram illustrating the peeling force applied to the second joint shown in Figure 3A. [Figure 4A] Figure 4A is a cross-sectional view of a second example of a wall according to the embodiment. [Figure 4B] Figure 4B is a cross-sectional view of a third example of a wall portion according to the embodiment. [Figure 5A] Figure 5A is a cross-sectional view of a second example of a honeycomb structure according to the embodiment. [Figure 5B] Figure 5B is a cross-sectional view of a third example of a honeycomb structure according to the embodiment. [Modes for carrying out the invention]

[0009] The honeycomb structure 10 according to the embodiment will be described below with reference to the drawings. Elements having the same function will be denoted by the same reference numeral, and redundant explanations will be omitted. Also, for the sake of convenience of explanation, mutually orthogonal X direction (first direction), Y direction (second direction), and Z direction will be defined.

[0010] As shown in Figures 1 and 2A, the X direction is the ribbon direction of the sheet material 11 and the direction in which the peaks 12 and valleys 13 constituting the sheet material 11 are arranged alternately. The Y direction is the tension direction of the sheet material 11, the stacking direction of the sheet material 11, and the direction in which the multiple cells 14 are arranged in a line. The Z direction is the height direction of the honeycomb structure 10 and the stretching direction of each cell 14.

[0011] The honeycomb structure 10 is composed of, for example, multiple sheet materials 11. The sheet materials 11 are so-called corrugated sheets formed in a wave shape. As shown in Figure 2A, the sheet material 11 has peaks 12 and valleys 13. The peaks 12 and valleys 13 are arranged alternately in the X direction and extend parallel to each other in the Z direction. The peaks 12 protrude to one side in the Y direction with respect to the XZ plane. Conversely, the valleys 13 are recessed to the other side in the Y direction with respect to the XZ plane.

[0012] Two adjacent sheet materials 11 are joined to each other in the Y direction. Specifically, as shown in Figure 2A, the valley portion 13 of one of the two sheet materials 11 and the peak portion 12 of the other are joined to each other. This joining forms a plurality of cells 14 arranged in a honeycomb pattern and their partition walls 16. That is, the honeycomb structure 10 comprises a plurality of cells 14 arranged in a honeycomb pattern. Joining refers to the connection between structural materials by welding, bonding, brazing, etc. These methods are appropriately selected depending on the material of the sheet material 11.

[0013] The sheet material 11 is, for example, a sheet material such as a metal foil made of aluminum or the like, a fiber reinforced plastic (FRP) sheet, or a paper material. The thickness of the sheet material is not particularly limited, but is, for example, on the order of 0.01 mm to 5 mm. FRP is, for example, aramid fiber reinforced plastic (AFRP), carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), or the like. The matrix resin of FRP is, for example, a thermosetting resin such as an epoxy resin, a polyester resin, a vinyl ester resin, or a phenol resin, or a thermoplastic resin such as a polypropylene resin, a polyamide resin, a polycarbonate resin, or a polyetherimide resin.

[0014] As shown in FIG. 2B, each cell 14 forms a space 15 having a substantially hexagonal cross section as viewed from the Z direction and extends in the Z direction. Two cells 14 adjacent in the Y direction are arranged in the Y direction via their respective partition walls 16.

[0015] Each cell 14 has a partition wall 16 that forms a space 15 inside it. Each cell 14 includes a pair of wall portions 17, 17 as a part of its partition wall 16. Further, each cell 14 has a pair of wall portions 18, 18 and a pair of wall portions 19, 19 as other parts of the partition wall 16. Each pair of wall portions is arranged to face each other across the space 15 of the cell 14 and surrounds the space 15 of the cell 14 as a whole.

[0016] The pair of wall portions 17, 17 are arranged in the Y direction. The pair of wall portions 18, 18 are arranged in a direction inclined to one side with respect to the Y direction. The pair of wall portions 19, 19 are arranged in a direction inclined to the other side with respect to the Y direction. In one cell 14, one wall portion 17 - 19 of each pair is included in a part (for example, the peak portion 12) of one sheet material 11. Also, the other wall portion 17 - 19 of each pair is included in a part (for example, the valley portion 13) of the other sheet material 11.

[0017] As shown in FIG. 3A, the wall portion 17 is formed by joining its cell 14 and another cell 14 adjacent to one side or the other side of the cell 14 in the Y direction. That is, the wall portion 17 has a double-wall structure formed by joining the joint surfaces 20, 20 (see FIG. 2A) of two sheet materials 11, 11. The wall portion 17 does not have an intentional space (small cell) shown in Patent Document 1. That is, the joint surfaces 20, 20 of the two sheet materials 11, 11 forming the wall portion 17 are in close contact with each other throughout the entire area of the wall portion 17. When the joint surfaces 20, 20 are joined by welding, in order to enhance the adhesion between the two, projections (not shown) that can flow during welding may be integrally provided on the joint surface 20.

[0018] The wall portion 17 includes a first joint portion 17a and a second joint portion 17b. The first joint portion 17a extends linearly in a cross section orthogonal to the extending direction (i.e., the Z direction) of each cell 14. For example, in the cross section, the first joint portion 17a extends in the X direction. The first joint portion 17a is provided, for example, on each side of the second joint portion 17b in the X direction.

[0019] On the other hand, the second joint portion 17b extends in a direction different from the X direction in the above-mentioned cross section. For example, as shown in FIG. 3A, the second joint portion 17b extends in the X direction while meandering between one side and the other side in the Y direction. In other words, the second joint portion 17b has a meandering waveform cross section in the Y direction. In this case, the second joint portion 17b includes a first convex portion 21a protruding to one side in the Y direction and a second convex portion 21b protruding to the other side in the Y direction with respect to the first joint portion 17a.

[0020] When the honeycomb structure 10 receives a relatively large load (pressure) such as an impact from the Z direction, a force that opens the joint surfaces 20, 20 to one side and the other side in the Y direction is generated in the partition wall 16. In other words, a force that separates two adjacent cells 14, 14 in the Y direction is generated in the partition wall 16. This force is referred to as a peeling force F for convenience. FIG. 3A shows the direction of the peeling force F generated at each position of the partition wall 16.

[0021] Since the peeling force F is the force that separates the two sheet materials 11 from each other, its direction is generally parallel to the Y direction, which is the lamination direction of the sheet materials 11. Therefore, when the first joint 17a is extended in the X direction, a peeling force F perpendicular to the first joint 17a is generated at the first joint 17a.

[0022] A peeling force F, roughly parallel to the Y direction, is also applied to the second joint 17b. As described above, in a cross-section perpendicular to the Z direction, the second joint 17b extends in a direction different from the X direction. In other words, in this cross-section, the direction of extension of the second joint 17b is not perpendicular to the direction of the peeling force F. Therefore, the peeling force F at the second joint 17b is divided into a first component force F1 parallel to the extension direction of the second joint 17b and a second component force F2 perpendicular to the extension direction of the second joint 17b.

[0023] The first component force F1 is a force generated in the shear direction of the second joint 17b. The second joint 17b is stretched in this shear direction. Therefore, the strength of the second joint 17b against the first component force F1 is relatively large. The second component force F2 is a force that causes delamination in the second joint 17b in a direction perpendicular to the stretching direction of the second joint 17b. However, since this force is a component of the delamination force F, it is smaller than the delamination force F. As a result, the bonding force between the sheet materials 11, 11 at the second joint 17b is greater than that at the first joint 17a. In other words, the formation of the second joint 17b can increase the bonding force between the two cells 14, thereby improving the energy absorption efficiency of the entire honeycomb structure 10.

[0024] As shown in Figure 3A, both the first protrusion 21a and the second protrusion 21b may be formed by curved surfaces. In this case, the first protrusion 21a is curved toward one side in the Y direction, and the second protrusion 21b is curved toward the other side in the Y direction.

[0025] As shown in Figures 4A and 4B, the first protrusion 21a and the second protrusion 21b may both be formed by a plurality of planes. In this case, the first protrusion 21a includes two planes 22a and 22b that become closer together as they are moved toward one side in the Y direction. Similarly, the second protrusion 21b includes two planes 23a and 23b that become closer together as they are moved toward the other side in the Y direction.

[0026] Planes 22a and 22b may be connected to each other via an intermediate surface 22c at the tip side of the first protrusion 21a, as shown in Figure 4A. Alternatively, planes 22a and 22b may be directly connected to each other, as shown in Figure 4B. Similarly, planes 23a and 23b may be connected to each other via an intermediate surface 23c at the tip side of the second protrusion 21b, as shown in Figure 4A. Alternatively, planes 23a and 23b may be directly connected to each other, as shown in Figure 4B.

[0027] As shown in Figure 5A, in a cross-section perpendicular to the Z direction, the length Ly of cell 14 along the Y direction may be longer than the respective lengths Lx of the pair of wall sections 17, 17 along the X direction. The length Ly of cell 14 along the Y direction is the length along the Y direction of wall section 18 and wall section 19 that connect one end of the pair of wall sections 17, 17 to the other end. Note that wall section 18 and wall section 19 may be located on the same plane (see Figure 5A) or they may be inclined relative to each other. In the former case, for example as shown in Figure 5A, cell 14 may have a rectangular cross-sectional shape with wall section 17 as the short side and wall sections 18 and 19 as the long sides.

[0028] As shown in Figure 5B, each cell 14 may have a pair of curved walls 24, 24 connecting one of a pair of wall portions 17, 17 to the other. Each curved wall 24 is composed of wall portions 18 and 19 located on one or the other side of the space 15 in the X direction. Note that the wall portions 18 and 19 may have a curvature that forms a single curved surface as a whole, or they may have curvatures that constitute individual curved surfaces.

[0029] (1) The honeycomb structure 10 according to this embodiment comprises a plurality of sheet materials 11 in which peaks 12 and valleys 13 are alternately arranged in the X direction (first direction). The plurality of sheet materials 11 are joined to each other in the Y direction (second direction) perpendicular to the X direction so as to form a plurality of cells 14 arranged in a honeycomb shape. Each cell 14 also includes a pair of wall portions 17, 17 that are joined to other cells 14 adjacent to it on one or the other side in the Y direction as part of its partition wall. Each wall portion 17 includes a first joint portion 17a and a second joint portion 17b. The first joint portion 17a extends in the X direction in a cross section perpendicular to the extension direction (Z direction) of the cell 14. On the other hand, the second joint portion 17b extends in a direction different from the X direction in the cross section described above.

[0030] When the honeycomb structure 10 is subjected to a relatively large load (pressure) such as an impact from the Z direction, the peeling force F described above is applied to the first joint 17a and the second joint 17b of each wall section 17. At the first joint 17a, almost all of this peeling force F contributes to the peeling of the first joint 17a. On the other hand, at the second joint 17b, a portion of the peeling force F is converted into a shear force, so the component of the peeling force F that contributes to the peeling of the second joint 17b is reduced. Therefore, the strength against the peeling force F for the wall section 17 as a whole is improved. In other words, the bonding force between the two cells 14 can be increased, the increase in buckling pitch can be suppressed, and the energy absorption efficiency of the entire honeycomb structure 10 can be improved.

[0031] (2) The second joint 17b may include a first protrusion 21a that protrudes to one side in the Y direction relative to the first joint 17a. In this case, a recess is formed in one of the two sheet materials 11, 11 that constitute the wall 17, and a protrusion is formed on the other side that is inserted into the recess. The recess and the protrusion are joined to each other in the Y direction and constitute the first protrusion 21a. The protruding direction of the first protrusion 21a is parallel to the Y direction. Therefore, even when the honeycomb structure 10 is subjected to a load from the X direction, the first protrusion 21a makes it difficult for the two sheet materials 11, 11 to be misaligned along the X direction.

[0032] (3) In addition to the first protrusion 21a described above, the second joint 17b may include a second protrusion 21b that protrudes to the other side in the Y direction relative to the first joint 17a. That is, the second joint 17b may have a cross-section that meanders in the Y direction (see Figure 3A). In this case, the occurrence of relative displacement of the two sheet materials 11, 11 along the X direction can be further suppressed.

[0033] (4) The first protrusion 21a and the second protrusion 21b may be formed by curved surfaces. In this case, the formation of sheet material 11 (wall portion 17) including extremely bent surfaces in the wall portion 17 can be suppressed, and the occurrence of localized stress concentration can be suppressed.

[0034] (5) The first protrusion 21a may include two planes 22a and 22b whose distance from each other along the X direction decreases as it moves toward one side in the Y direction. The second protrusion 21b may also include two planes 23a and 23b whose distance from each other along the X direction decreases as it moves toward the other side in the Y direction. In this case, in a cross section perpendicular to the Z direction, both the first protrusion 21a and the second protrusion 21b will have a wedge-shaped cross section. Therefore, when the honeycomb structure 10 is subjected to a load from the X direction, this wedge suppresses the relative displacement of the two sheet materials 11, 11 in the X direction, and prevents damage to the wall portion 17.

[0035] (6) In a cross section perpendicular to the Z direction, the length Ly of each cell 14 along the Y direction may be longer than the respective lengths Lx of a pair of wall sections 17, 17 along the X direction. In this case, the aspect ratio of the cell 14 in the cross section exceeds 1. When the honeycomb structure is assumed to have cells with a rectangular cross section having an aspect ratio of more than 1, generally, the load during buckling is more likely to be applied to the wall forming the short side of the cell, and the buckling pitch is smaller than the buckling pitch of the wall forming the long side of the cell. Therefore, the progression of failure of the honeycomb structure due to buckling of the wall forming the long side can be suppressed, and the energy absorption efficiency (amount of energy absorbed) can be improved. In this embodiment, a second joint 17b is formed on the wall section 17 corresponding to the short side, which is prone to the load during buckling. This improves the strength of the wall section 17 against load (buckling), suppresses delamination, and maintains improved energy absorption efficiency.

[0036] (7) Each cell 14 may have a curved wall 24 as another part of its partition wall, connecting one of a pair of wall sections 17, 17 to the other. That is, wall sections 18 and 19 may be formed as a curved wall 24. By curving the walls that form the long sides of the cell, the strength against buckling is increased compared to when the walls are flat, and the energy absorption efficiency can be improved.

[0037] The embodiments and modifications described above are merely illustrative examples provided to facilitate understanding of the invention. The technical scope of the invention is not limited to the specific technical matters disclosed in the embodiments and modifications above, but also includes various modifications, changes, and alternative technologies that can be easily derived therefrom. [Explanation of Symbols]

[0038] 10 Honeycomb structure 11 Sheet material 12 Yamabe 13 Tanibe 14 cells 1616 17 Wall 17a 1st joint 17b 2nd joint 18 Wall 19 Wall 21a First protrusion 21b Second protrusion

Claims

1. It comprises multiple sheet materials in which peaks and valleys are arranged alternately in the first direction, The plurality of sheet materials are joined to each other in a second direction perpendicular to the first direction so as to form a plurality of cells arranged in a honeycomb pattern. Each of the cells includes a pair of wall portions that, as part of its partition wall, are joined to other cells adjacent to it on one or the other side in the second direction. Each of the pair of wall portions is, A first joint extending in the first direction in a cross-section perpendicular to the extension direction of each cell, A second joint portion extending in a direction different from the first direction in the cross-section, including, Honeycomb structure.

2. The second joint portion includes a first protrusion that projects from the first joint portion to one side in the second direction, The honeycomb structure according to claim 1.

3. The second joint portion includes a second protrusion that projects from the first joint portion toward the other side in the second direction, The honeycomb structure according to claim 2.

4. The first and second protrusions are formed by curved surfaces. The honeycomb structure according to claim 3.

5. The first protrusion includes two planes whose distance from each other decreases as it moves toward one side in the second direction, The second protrusion includes two planes whose distance from each other decreases as it moves toward the other side in the second direction. The honeycomb structure according to claim 3.

6. In the cross-section, the length of each cell along the second direction is longer than the length of each of the pair of wall portions along the first direction. A honeycomb structure according to any one of claims 1 to 5.

7. Each of the cells has, as an additional part of its partition wall, a pair of curved walls connecting one of the pair of wall sections to the other. The honeycomb structure according to claim 6.

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