JPH04252754A - Hybrid bumper beam - Google Patents

Abstract

PURPOSE:To obtain a light hybrid bumper beam of high strength and rigidity by covering an area in question of buckling strength with a large specific buckling strength parameter of material and an area in question of bending strength with a large specific bending rigidity strength of material for hybridization. CONSTITUTION:For hybridizing a bumper beam, an area 3 in question of buckling strength is covered with a large specific buckling strength parameter of material and an area 4 in question of bending strength is covered with a large specific bending rigidity strength of material. As a large specific buckling strength parameter of material, a glass fiber reinforcing sheet (stampable sheet) of resin unit is used, and as a large specific bending rigidity strength of material steal, high strength steal or one-way reinforcing material is used. This one-way reinforcing material includes a combination of glass fiber, carbon fiber or aramide fiber and resin.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to bumper beams for automobiles.

0002

[Prior Art] The basic structure of a conventional bumper beam for automobiles is shown in Fig. 10 (Japanese Unexamined Patent Publication No. 62-240514)
Figure 1 (Unexamined Japanese Patent Publication No. 2-92756) and Figure 12 (Unexamined Japanese Patent Publication No. 5
9-160448), the main body 10 has a U-shaped cross section, and the ribs 11 are vertically and vertically aligned for reinforcement.
Some are installed horizontally. All of these are made of a single material.

0003

[Problems to be Solved by the Invention] As mentioned above, conventional bumper beams are made of a single material, so within the limited space of the bumper, thick walls are required to maintain strength and rigidity. However, there is a problem in that the weight of the bumper beam increases.

As a measure to avoid this, efforts are being made to increase the strength of metal materials (SAE Technical Paper 90).
0737). However, the buckling strength is significantly lower than the bending rigidity, and the required plate thickness is determined by the buckling strength, making it difficult to reduce weight.

On the other hand, when resin materials are used, there is a problem that bending rigidity is insufficient and deformation becomes large (Journal of the Japan Society for Composite Materials, No. 14 (1988), p. 101). , the desired weight reduction cannot be achieved.

[0006] Furthermore, in some cases, materials with high specific buckling strength have poor deformability and cannot absorb deformation energy (SAE Technical Paper 890339).

An object of the present invention is to provide a hybrid bumper beam that can solve the above problems.

[0008]

[Means for Solving the Problems] In the hybrid bumper beam of the present invention, a material with a large specific buckling strength parameter is used in the part where the buckling strength is a problem, and a material with a large specific buckling strength parameter is used in the part where the bending strength is a problem. It is a hybrid made by using large materials.

[0009]

[Operation] By hybridizing a material with a large specific buckling strength parameter and a material with a large specific bending stiffness strength, it is possible to achieve an appropriate distribution of strength.

Energy absorption is determined by the product of loading capacity and deformability. If the rigidity is increased more than necessary, excessive load will be transmitted to the vehicle body, causing problems. On the other hand, if the rigidity is too low, excessive deformation will occur, causing problems in vehicle body design. Therefore, appropriate rigidity and deformability can be achieved by hybridization.

Specifically, with respect to bending deformation upon impact, the buckling load is set to be smaller than the limit bending load, the impact surface side is buckled, and deformation on the vehicle body attachment side is suppressed.

[0012] This makes it possible to prevent the load generated upon impact from becoming excessive and to suppress displacement on the side to which the vehicle body is attached.

[0013]

[Embodiment] First, the basic idea of the present invention will be explained with reference to FIG. A material having a large specific buckling strength parameter is applied to the part 3 where the buckling strength is a problem, and a material having a large specific bending stiffness strength is applied to the part 4 where the bending strength is a problem to create a hybrid. As a result, a hybrid bumper beam that is lightweight and has increased rigidity can be obtained.

A specific example will be explained below with reference to the drawings.

In FIG. 2, the hybrid bumper beam 1 has a U-shaped cross section with a side wall 1c connecting an impact receiving portion 1a and a mounting portion 1b to the vehicle body.

The hybrid bumper beam 1 is made of a stampable sheet made of polypropylene and glass fiber, which are materials with a large specific buckling strength parameter. A thin steel plate 2 serving as a reinforcing material is combined with the lower surface of the mounting portion 1b to the vehicle body.

[0017] Table 1 shows the absorbed energy at load point displacements of 25, 50, and 75 mm when a three-point bending test was conducted on this hybrid bumper beam, in comparison with a bumper beam made only of stampable sheets. .

Compared to the comparative example, although there is no difference in unit length and weight, the absorbed energy is significantly greater. Moreover, Comparative Examples 1 and 2 were damaged by a displacement of 50 mm and 75 mm, respectively.

[0019]
Table 1 Height Thickness
Weight per unit length E25 E50
E75mm
mm g/mm
kgf-m Example 1 90
5 2.36
16.7 35.7 46.6 Example 2 110 4
1.63 14.4 31.5
42.6 Comparative Example 1 90 5.
5 1.98 1
7.6 22.6 Comparative example 2 110
4 1.53
12.5 27.1 28.3 FIGS. 3 to 5 show the case of FIG. 2 with reinforcing ribs 5 attached respectively.

FIG. 6 shows a hybrid bumper beam in which, unlike the case shown in FIG. 2, a reinforcing member 2 is attached to the attachment portion 1b to the vehicle body over the entire lower surface.

Note that the method of attaching the reinforcing member 2 to the attachment portion 1b to the vehicle body is not limited to the case shown in FIGS. 3 to 5, but also the method shown in FIG.
As in the case of , the reinforcing material 2 may be attached over the entire lower surface of the bumper beam.

In FIGS. 7 and 8, reinforcing members 2 are attached to the attachment portion 1b to the vehicle body and the side wall 1c to increase buckling strength and bending strength. By changing the height h of the side wall reinforcement, the buckling strength can be adjusted. Furthermore, the reinforcing material 2 may be attached to the side wall 1c by either embedding or pasting.

FIG. 9 shows a structure in which a reinforcing member 2 is attached to the impact receiving portion 1a and the attachment portion 1b to the vehicle body to increase rigidity.

[0024] In the above embodiment, the case where steel was used as the reinforcing material was explained, but a combination of glass fiber, carbon fiber, aramid fiber, etc., and resin may also be used as the reinforcing material. .

[0025]

[Effects of the Invention] The hybrid bumper beam of the present invention is as described above, and by hybridizing a material with a large specific buckling strength parameter and a material with a large specific bending stiffness strength, it has high strength and high rigidity. A lightweight hybrid bumper beam can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the basic idea of the present invention.

FIG. 2 is an explanatory diagram of one embodiment.

FIG. 3 is an explanatory diagram of a modification of FIG. 2;

FIG. 4 is an explanatory diagram of a modification of FIG. 2;

FIG. 5 is an explanatory diagram of a modification of FIG. 2;

FIG. 6 is an explanatory diagram of another embodiment.

FIG. 7 is an explanatory diagram of another embodiment.

FIG. 8 is an explanatory diagram of another embodiment.

FIG. 9 is an explanatory diagram of another embodiment.

FIG. 10 is an explanatory diagram of a conventional bumper beam.

FIG. 11 is an explanatory diagram of a conventional bumper beam.

FIG. 12 is an explanatory diagram of a conventional bumper beam.

[Explanation of symbols]

Claims (3)

[Claims] 1. A hybrid bumper beam in which a material with a large specific buckling strength parameter is used in the part where the buckling strength is an issue, and a material with a large specific bending stiffness strength is used in the part where the bending strength is an issue. [Claim 2] The material with a large specific buckling strength parameter is a resin alone or a glass fiber reinforced sheet (stampable sheet), and the material with a large specific flexural rigidity is steel, high-strength steel, or unidirectionally reinforced material. A hybrid pumper beam according to claim 1. 3. The hybrid bumper beam according to claim 2, wherein the unidirectional reinforcing material is a combination material of glass fiber, carbon fiber, aramid fiber, etc., and resin.