Collision energy absorption structure

Abstract

To provide a collision energy absorbing structure that is able to prevent excessive increase in weight while improving collision energy absorbing performance.SOLUTION: A collision energy absorbing structure 1 comprises: a shell portion 10 including an outer surface 12 including a load assumed-surface 11 and an inner surface 14 defining a closed cross-sectional cavity 13, and extending in one direction; and a reinforcing portion 20 extending in an extending direction of the shell portion 10 and attached to a position opposite to the load assumed-surface 11 of the inner surface 14 of the shell portion 10. The shell portion 10 includes a resin portion 22 provided on a side opposite the load assumed-surface 11 with the cavity 13 therebetween. The bending rigidity of the reinforcing portion 20 is set to be equal to or lower than the bending rigidity of the shell portion 10. The breaking moment of the reinforcing portion 20 or the sum of the breaking moment of the reinforcing portion 20 and the total plastic moment of the reinforcing portion 20 is set to be equal to or less than the sum of the total plastic moment of the shell portion 10 and the breaking moment of the shell portion 10.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a collision energy absorption structure.

Background Art

[0002] For structural members constituting the body of an automobile, a railway vehicle, or the like, weight reduction from the viewpoint of reducing environmental impact and improvement of collision energy absorption performance from the viewpoint of collision safety are required. As related art, Patent Document 1 discloses a shock absorption member assumed to be applied to a pillar or the like of a vehicle body. The shock absorption member of Patent Document 1 includes a metal structure, a metal cover, and an FRP (fiber reinforced resin) material sandwiched therebetween, and utilizes the fact that the FRP material is widely broken by bending stress due to a collision or the like to increase the amount of absorbed collision energy.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For structural members of a vehicle body such as a center pillar (B pillar), high collision energy absorption performance is required from the viewpoint of collision safety, while weight reduction is also required from the viewpoint of reducing environmental impact. However, these requirements are in a trade-off relationship. That is, in order to improve the collision energy absorption performance, it is necessary to increase the reaction force when a load is applied. However, if an attempt is made to increase the reaction force, the weight of the structural member will increase.

[0005] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a collision energy absorption structure capable of suppressing excessive weight increase while improving the collision energy absorption performance.

Means for Solving the Problem

[0006] A collision energy absorption structure according to an aspect of the present disclosure has an outer surface including a load assumption surface and an inner surface defining a cavity with a closed cross-section, a shell portion extending in one direction, and a reinforcing portion extending in the extending direction of the shell portion and attached to a position on the inner surface of the shell portion facing the load assumption surface. The shell portion includes a first portion including the load assumption surface and formed of a metal plate, and a second portion provided separately from the first portion at a position facing the load assumption surface through the cavity and joined to the first portion. The second portion is formed of a metal plate or an FRP plate, and includes a first plate member to which the reinforcing portion is attached and joined to the first portion, and a second plate member provided on the opposite side of the load assumption surface across the cavity and formed by FRP, at a position farther from the cavity than the first plate member. and, in a state separated from the first plate member, adhere to the first portion at a location different from the first plate member The bending rigidity of the reinforcing portion is set to be equal to or less than the bending rigidity of the shell portion, and the breaking moment of the reinforcing portion, or the sum of the breaking moment of the reinforcing portion and the full plastic moment of the reinforcing portion, is set to be equal to or less than the sum of the full plastic moment of the shell portion and the breaking moment of the shell portion.

[0008] The reinforcing portion may be separated from the load assumption surface of the first portion. The reinforcing portion may be in contact with the load assumption surface of the first portion. . The The shell portion may further include a third portion located between the load assumption surface and the reinforcing portion and formed of a metal plate. The length of the reinforcing portion may be set to 1 / 10 to 1 / 2 of the length of the shell portion. The reinforcing portion may be formed of foamed plastic or steel wool.

Advantages of the Invention

[0009] According to the present disclosure, it is possible to provide a collision energy absorption structure capable of improving the absorption performance of collision energy while suppressing an excessive increase in weight.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present disclosure will be described with reference to FIGS. 1 to 5. The collision energy absorption structure according to this embodiment is a long structure extending in one direction and is used as a structural member constituting a vehicle body such as an automobile or a railway vehicle. For example, it is applicable to the center pillar (B pillar) of an automobile. Hereinafter, for convenience of explanation, the X direction, Y direction, and Z direction that are orthogonal to each other are defined. The X direction, Y direction, and Z direction are the width direction, height direction, and extension direction (longitudinal direction) of the collision energy absorption structure, respectively. When the collision energy absorption structure is used as the above-mentioned center pillar, the X direction corresponds to the front-rear direction of the vehicle body, the Y direction corresponds to the outer side in the vehicle width direction, and the Z direction corresponds to the up-down direction of the vehicle body. It is assumed that the load of the collision object is applied to the load assumption surface 11 (see FIG. 1).

[0012] FIG. 1 is a perspective view showing an example of a collision energy absorption structure 1 according to the present embodiment. FIG. 2 is a cross-sectional view of the collision energy absorption structure 1, FIG. 2(a) is a cross-sectional view on the YZ plane, (b) is a cross-sectional view taken along line IIB-IIB in FIG. 2(a), and FIG. 2(c) is a cross-sectional view taken along line IIC-IIC in FIG. 2(a).

[0013] As shown in FIG. 1, the collision energy absorption structure 1 includes a shell portion 10. The shell portion 10 has an outer surface 12 including a load assumption surface 11 and an inner surface 14 forming a closed-section cavity 13, and extends in the Z direction. The shell portion 10 includes, for example, a first portion 15 and a second portion 16 that are formed as separate bodies from each other.

[0014] The first portion 15 is formed of a metal plate and is bent or curved toward the second portion 16 so as to form the cavity 13. The metal plate constituting the first portion 15 is, for example, a high-tensile steel plate or an ultra-high-tensile steel plate, and its plate thickness is, for example, 1 mm or less.

[0015] In the shell portion 10 formed by the first portion 15, a load assumption surface 11 is set in a portion facing the second portion 16 through the cavity 13. The load assumption surface 11 is an area where a collision of an object such as a vehicle is assumed. For example, when performing a three-point bending test for evaluating the bending rigidity, which is one of the characteristics of the collision energy absorption structure 1, the bending load is applied to a predetermined position within the load assumption surface 11. Note that the load assumption surface 11 only defines an area where a collision object is likely to collide, and there is no physical property difference from the surrounding surfaces.

[0016] The second portion 16 is located at a position facing the load assumption surface 11 through the cavity 13. The second portion 16 is joined to the first portion 15 so as to close the cavity 13 formed by the bending or curving of the first portion 15. Therefore, the surface of the first portion 15 facing the cavity 13 and the surface of the second portion 16 also serve as the inner surface 14 of the shell portion 10 that defines the closed-section cavity 13.

[0017] As shown in FIGS. 1 and 2, the second part 16 includes a first plate member 17 and a second plate member 18. The first plate member 17 is composed of a metal plate or an FRP (fiber reinforced resin) plate, and is parallel to the XZ plane, for example.

[0018] The second plate member 18 is located at a position farther from the cavity 13 than the first plate member 17 along the Y direction. The second plate member 18 is composed of an FRP plate and is parallel to the XZ plane, for example. Note that the FRP may be CFRP (carbon fiber reinforced plastic), for example.

[0019] In this way, only the second plate member 18, or both the first plate member 17 and the second plate member 18 are composed of FRP plates. That is, the shell part 10 includes a resin part 22 provided on the side opposite to the load assumption surface 11 with the cavity 13 interposed therebetween. By adopting an FRP plate for at least the second plate member 18, weight reduction can be achieved compared with the case of using a metal plate with equivalent bending rigidity.

[0020] The distance between the first plate member 17 and the second plate member 18 along the Y direction is arbitrary. That is, as shown in FIGS. 3(a) a) and 3(b), the second plate member 18 may be adhered to the first plate member 17 with an adhesive or the like. As shown in FIGS. 3(b) and 3(d), it may be adhered to the first part 15 with an adhesive or the like while leaving a predetermined interval in the Y direction. In the latter case, since the first plate member 17 and the second plate member 18 are separated from each other in the direction in which the bending of the collision energy absorption structure 1 progresses, weight reduction of the entire collision energy absorption structure 1 is possible, and crushing of the second plate member 18 can be suppressed.

[0021] The shapes of the first part 15 and the second part 16 at the joint are not limited to those shown in FIG. 2. For example, as shown in FIG. 3(a), the width of the second part 16 is set larger than the width of the first part 15, and the first plate member 17 of the second part 16 may be joined to the end 15a of the metal plate constituting the first part 15 by welding or the like. In this case, the second plate member 18 is adhered to the first plate member 17 with an adhesive or the like.

[0022] Also, as shown in FIG. 3(b), the width of the first plate member 17 may be set to be equal to or less than the width of the first portion 15, and the width of the second plate member 18 may be set to be greater than the width of the first portion 15. In this case, the first plate member 17 is joined to the inner surface 14 of the shell portion 10 (the first portion 15) by welding or the like, and the second plate member 18 is adhered to the end portion 15a of the metal plate constituting the first portion 15 by an adhesive or the like.

[0023] Also, as shown in FIGS. 3(c) and 3(d), the widths of the first plate member 17 and the second plate member 18 that constitute the second portion 16 may be set to be equal to or less than the width of the first portion 15. In this case, the first plate member 17 is joined to the inner surface 14 of the shell portion 10 (the first portion 15) by welding or the like. The second plate member 18 may be in close contact with the first plate member 17 by an adhesive or the like as shown in FIG. 3(c), or may be adhered to the inner surface 14 of the shell portion 10 (the first portion 15) by an adhesive or the like as shown in FIG. 3(d).

[0024] The collision energy absorption structure 1 includes a reinforcing portion 20. The reinforcing portion 20 is attached to the first plate member 17 in the cavity 13 and extends in the Z direction. In other words, the reinforcing portion 20 is attached to a position on the inner surface 14 of the shell portion 10 that faces the load assumption surface 11. Note that the cross-sectional shape of the reinforcing portion 20 is arbitrary and is not limited to the rectangle shown in FIG. 2(c).

[0025] The reinforcing portion 20 is formed of a foamed plastic such as synthetic resin, rigid urethane foam or expanded polystyrene, or steel wool, and has a length of 1 / 10 to 1 / 2 of the length of the shell portion 10 along the Z direction. Thereby, the weight of the collision energy absorption structure 1 can be reduced. Further, the width of the reinforcing portion 20 is arbitrary, for example, substantially equal to the width of the shell portion 10. Furthermore, the height of the reinforcing portion 20 is also arbitrary. That is, the reinforcing portion 20 may have a height spaced from the load assumption surface 11, or may have a height in contact with the load assumption surface 11. In the former case, the reinforcing portion 20 is spaced from the load assumption surface 11 of the first portion 15. Therefore, this portion is likely to be preferentially crushed during a collision, and an unexpected variation in the region where bending (destruction) progresses can be suppressed. On the other hand, in the latter case, the reinforcing portion 20 is in contact with the load assumption surface 11 of the first portion 15. Therefore, it is possible to suppress local crushing due to bending limited to the vicinity of the load point (collision point) of the shell portion 10.

[0026] As shown in FIG. 4, the shell portion 10 may further include a third portion 19 located between the load assumption surface 11 and the reinforcing portion 20 and formed of a metal plate. The third portion 19 is, for example, a metal plate or an FRP plate parallel to the XZ plane. The third portion 19 is connected to the inner surface 14 of the shell portion 10 (first portion 15) by a method according to its material. That is, if the third portion 19 is made of metal, the third portion 19 is joined to the shell portion 10 by welding or the like. Also, if the third portion 19 is made of FRP, the third portion 19 is adhered to the shell portion 10 by an adhesive. In either case, the reinforcing portion 20 can be fixed to the first portion 15 and the reinforcing portion 20 can be reinforced.

[0027] Also, as shown in FIG. 5, the reinforcing portion 20 may include an auxiliary plate 21. The auxiliary plate 21 is adhered to the surface 20a of the reinforcing portion 20 facing the load assumption surface 11. The material of the auxiliary plate 21 is arbitrary, for example, metal, synthetic resin or FRP. The width of the auxiliary plate 21 is set smaller than the width of the first portion 15, and a gap is formed between the auxiliary plate 21 and the first portion 15. Also, the length of the auxiliary plate 21 along the Z direction is set to be equal to or less than the length of the reinforcing portion 20.

[0028] The collision energy absorption structure 1 according to this embodiment satisfies the following conditions. (1) The bending rigidity of the reinforcing portion 20 is set to be equal to or less than the bending rigidity of the shell portion 10. (2) The breaking moment of the reinforcing portion 20, or the sum of the breaking moment of the reinforcing portion 20 and the full plastic moment of the reinforcing portion 20, is set to be equal to or less than the sum of the full plastic moment of the shell portion 10 and the breaking moment of the shell portion 10. Here, the bending rigidity is the product of the second moment of area (I) and the Young's modulus (E), and the full plastic moment is the product of the plastic section modulus (Zp) and the yield stress (σy). However, when the cross-section is composed of a plurality of materials, the bending rigidity is the sum of the products of the second moment of area and the Young's modulus of each material with respect to the neutral axis.

[0029] Each bending rigidity in condition (1) can be evaluated by a well-known three-point bending test method. For example, a three-point bending test can apply a test in accordance with the bending test method for metallic materials (JIS Z 2248) of Japanese Industrial Standards. That is, a testing machine (not shown) is used which includes a crosshead of a indenter that moves in the Y direction with respect to the collision energy absorption structure 1 and two supports spaced a predetermined distance in the Z direction. The test specimen for bending rigidity is placed on the two supports and pressed by the indenter at a position intermediate between these supports. The testing machine measures the load applied to the indenter and its displacement, and ends the test at the time when an arbitrary displacement is given. Note that the indenter may be divided into two spaced in the Z direction. In this case, the two indenters are separated from each other by an equal distance in the Z direction from the midpoint between the two supports. Note that the dimensions of the test piece, the supports (lower jigs), and the indenter (upper jigs), as well as the span between the supports, etc. are not limited to those specified in JIS Z 2248.

[0030] Regarding condition (2), whether only the "breaking moment of the reinforcing part 20" is selected or the "sum of the breaking moment of the reinforcing part 20 and the full plastic moment of the reinforcing part 20" is selected depends on the constituent material of the reinforcing part 20. For example, when the reinforcing part 20 is formed of a synthetic resin without a yield point or the like, only the "breaking moment of the reinforcing part 20" is selected. On the other hand, in the case of a composite member in which the reinforcing part 20 is formed of a synthetic resin without a yield point or the like and a metal with a yield point, the "sum of the breaking moment of the reinforcing part 20 and the full plastic moment of the reinforcing part 20" is selected.

[0031] Since the collision energy absorption structure 1 satisfies the above two conditions, when an excessive load due to the collision of an object or the like is applied to the load assumption surface 11, excessive deformation of the yielded part is suppressed by the reaction force from the reinforcing part 20, and the stress at that part is two-dimensionally dispersed. Therefore, the location where yielding occurs can be expanded two-dimensionally (for example, in the X direction and the Z direction), and local crushing due to bending limited to the vicinity of the load point (collision point) can be suppressed. That is, plastic deformation on the load assumption surface 11 can be expanded two-dimensionally, and the amount of collision energy absorption can be increased as compared with at least the case where the above two conditions are not satisfied. Further, at least since the second plate member that increases the bending rigidity is made of resin, the weight of the collision energy absorption structure 1 can also be reduced. That is, the collision energy absorption rate per unit weight of the collision energy absorption structure 1 can be improved.

[0032] Note that the outer shape of the collision energy absorption structure 1 and the cross-sectional shape of the cavity 13 inside thereof can be appropriately deformed according to the shape of the vehicle body or the like to which it is applied as long as the above conditions regarding the bending rigidity and the full plastic moment are satisfied. For example, the cross-sectional shape of the cavity 13 may be a shape defined by a closed curve, and the shape may also change along the Z direction.

[0033] Further, the first plate member 17 of the first part 15 and the second part 16 of the shell part 10 may be integrally formed from a single base material. In this case, for example, the shell part 10 is a hollow structure formed by a single metal plate, a reinforcing part 20 is provided inside the structure, and a second member is adhered to the outer surface of the structure.

[0034] Note that the present disclosure is not limited to the above-described embodiments, is shown by the description of the claims, and further includes all changes within the meaning and scope equivalent to the description of the claims.

Description of Reference Numerals

[0035] 1... Collision energy absorption structure, 10... Shell part, 11... Load assumption surface, 12... Outer surface, 13... Cavity, 14... Inner surface, 15... First part, 15a... End part, 16... Second part, 17... First plate member, 18... Second plate member, 19... Third part, 20... Reinforcing part, 20a... Surface, 21... Auxiliary plate, 22... Resin part

Claims

1. A collision energy absorption structure, having an outer surface including a load assumption surface and an inner surface defining a cavity with a closed cross-section, a shell portion extending in one direction, a reinforcing portion extending in the extending direction of the shell portion and attached to a position on the inner surface of the shell portion facing the load assumption surface and comprising, the shell portion includes a first portion including the load assumption surface and formed of a metal plate, and a second portion provided separately from the first portion at a position facing the load assumption surface through the cavity and joined to the first portion, the second portion is composed of a metal plate or an FRP plate, and includes a first plate member to which the reinforcing portion is attached and joined to the first portion, and a second plate member provided on the opposite side of the load assumption surface across the cavity, formed of FRP, and adhered to the first portion at a location different from the first plate member in a state separated from the first plate member at a position farther from the cavity than the first plate member, the bending rigidity of the reinforcing portion is set to be equal to or less than the bending rigidity of the shell portion, the breaking moment of the reinforcing portion, or the sum of the breaking moment of the reinforcing portion and the full plastic moment of the reinforcing portion, is set to be equal to or less than the sum of the full plastic moment of the shell portion and the breaking moment of the shell portion A collision energy absorption structure.

2. the reinforcing portion is separated from the load assumption surface of the first portion The collision energy absorption structure according to claim 1.

3. the reinforcing portion is in contact with the load assumption surface of the first portion The collision energy absorption structure according to claim 1.

4. the shell portion further includes a third portion located between the load assumption surface and the reinforcing portion and formed of a metal plate The collision energy absorption structure according to any one of claims 1 to 3.

5. The length of the reinforcing part is set to 1 / 10 to 1 / 2 of the length of the shell part. The collision energy absorption structure according to claim 1.

6. The reinforcing part is formed of foamed plastic or steel wool. The collision energy absorption structure according to claim 1.

Images