JP3520959B2 - Energy absorbing member for automotive frame structure made of extruded aluminum alloy with excellent axial crush characteristics - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a hollow extruded aluminum alloy material, which absorbs the impact load and the static load when it receives a compressive impact load or a compressive static load in its extrusion axis direction. The present invention relates to an energy absorbing member having the action of

[0002]

2. Description of the Related Art In a frame structure of an automobile, application of an aluminum alloy hollow extruded shape member as an energy absorbing member such as a side member or a bumper stay has been studied (for example, Japanese Patent Laid-Open Nos. Hei 7-310156 and Hei 7). -118782, JP-A-8-216917, JP-A-6-247338). One of the characteristics required of these energy absorbing members that are subjected to a compressive impact load in the axial direction is that, as described in the above publication, when the members are subjected to a load in the axial direction of extrusion, the entire profile is It is to obtain stable energy absorption by causing Euler's buckling (buckling in which the whole shape member bends in a dogleg shape) and contracting and deforming like a bellows without causing crush cracking.

Among the above publications, for example, JP-A-6-247.
In Japanese Patent No. 338, in order to suppress Euler buckling and to cause a bellows-shaped contraction deformation in a side member made of a hollow section having a rectangular cross section, a cross-sectional second moment (rigidity) about the X axis and a Y axis about the cross section are generated. The cross-sectional shape of the panel is set so that the panel that has a high probability of buckling like a bellows of the side member will buckle earlier than other panels at the beginning of a collision by intentionally making a difference in the second moment of inertia of the section. . Then, once one of the panels buckles, bellows-like buckling propagates to the other panels one after another, and even if the length of the side member becomes long, the bellows-like buckling stably occurs over the entire length. ing.

[0004]

SUMMARY OF THE INVENTION According to the present invention, in an energy absorbing member such as a side member of an automobile which receives a compressive load in the axial direction, a cross-sectional shape is devised in the same manner as the technique disclosed in JP-A-6-247338. The purpose is to suppress Euler buckling, induce bellows-like contraction deformation, and obtain stable energy absorption.

[0005]

According to the present invention, there is provided an energy absorbing member having an excellent shaft crushing property in an outer peripheral portion and an outer peripheral portion thereof.
An array of inner ribs that connect and intersect each other.
Made of hollow extruded aluminum alloy, ribs and outer circumference
The corner R of the part to be connected is less than 1/2 of the rib thickness.
1m at the corner R below and where multiple ribs intersect
It is characterized in that it is m or less. This hollow extruded profile
And preferably the thickness of the inner rib is the thickness of the outer circumference.
To be thin.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the hollow extruded shape member having an outer peripheral portion and an inner rib connected to the outer peripheral portion, the present inventors separately grasp the cross-sectional shape of the outer peripheral portion and the inner rib to determine the outer peripheral portion. The Euler buckling or accordion-like deformation is likely to occur due to the rigidity of the connecting portion between the plates that form the inner rib and the rigidity of the intersection of the plates that form the inner rib, or the rigidity of the inner rib. It was found that when the rigidity of this portion is small, buckling of the plate forming the outer peripheral portion or the rib is likely to occur, and a bellows-like deformation is easily induced. The present invention has been made based on this finding.

FIG . 1 exemplifies a hollow extruded profile according to the present invention, which has a rectangular outer peripheral portion having a basically uniform thickness a in cross-sectional shape, and a basically uniform thickness. It has a rib with b. Here, the basically uniform thickness means that the outer peripheral portion and the rib each have a uniform thickness other than the connecting portion, the intersecting portion, and the corner portion. However, the hollow extruded profile according to the present invention is not limited to such a specific cross-sectional shape.

If the corner R (Ra) of the connecting portion between the outer peripheral portion of the hollow extruded shape member and the rib is smaller than 1/2 of the rib thickness b (Ra≤b / 2), the rigidity of the connecting portion becomes low. The plates forming the outer peripheral portion or the ribs are likely to buckle, and a bellows-shaped deformation is likely to be induced. Here, the thickness of the rib may change in the plate width direction, but in that case, the thickness b of the rib is the thickness of the thickest portion in the portion excluding the connecting portion or the intersecting portion. Further, when the corner R (Rb) of the intersection between the ribs is smaller than 1 mm (Rb ≦ 1), the rigidity of the intersection becomes low, buckling of the plate forming the rib easily occurs, and a bellows-like deformation occurs. Easy to be triggered. Regarding the thickness of each of the outer peripheral portion and the rib of the hollow extruded shape member which satisfy these two requirements, it is desirable to form the rib thickness b to be equal to or smaller than the outer peripheral portion thickness a (b ≦ a). Further, when the rib thickness b is formed to be thinner (b <a) than the plate thickness a of the outer peripheral portion of the hollow extruded shape member, the rigidity is reduced and the rib is likely to buckle, resulting in a bellows-like deformation. Easy to be triggered. By forming the rib thickness b to be thinner, the bellows-shaped deformation is further stabilized. Hollow extruded profile made of aluminum alloy is Ra ≦ b /
2 and Rb ≦ 1 are satisfied, and more preferably
When b ≦ a is satisfied, part of the plate that constitutes the outer peripheral portion or rib buckles, which causes the buckling of other plates, which suppresses Euler buckling and tends to cause bellows-shaped deformation. Become.

[0009]

Embodiments of the present invention will be described below with reference to FIGS. A compressive load was applied in the axial direction to a 6063-T5 aluminum alloy hollow extruded shape having a cross section shown in FIGS. 2A to 2C and having a total length of 200 mm, and the relationship between the load and the displacement amount was investigated. The shapes of the outer peripheral portions A to C are all the same, and the outer shape is 45 mm × 55 mm and the thickness is 2 mm.
Further, in A, Ra and Rb are all 6 mm, and rib thickness b is 2
mm and B, Ra and Rb are all 1 mm, and rib thickness b is 2
In mm and C, Ra and Rb are all 1 mm, and the rib thickness b is 1.5 mm.

The load-displacement curves of A to C are shown in FIG.
5 and the maximum load, energy absorption amount, effective displacement, and respective buckling modes read from FIGS.
Shown in. In addition, the effective displacement in Table 1 means the displacement amount when the embodiment is crushed in a bellows shape in the axial direction and the load is increased again to reach a load value equivalent to the initial maximum load, The energy absorption amount in Table 1 means the energy absorption amount until the effective displacement is reached. Same reference example
is there. On the other hand, in the comparative example, since Euler buckling starts and the load monotonically decreases, it is not possible to define the effective displacement in the same meaning as in the example, so the test is stopped at an appropriate displacement and this is displayed. In the column of effective displacement of 1 was described as a reference value, and in the column of energy absorption amount, the energy absorption amount until the displacement was reached was described as a reference value.

[0011]

[Table 1]

In Comparative Example A, the corner R (Ra) at the connecting portion between the outer peripheral portion and the rib is 6 mm and the corner R (Rb) at the intersection between the ribs is 6 mm, and the maximum load is large because of the large cross-sectional area. However, due to Euler buckling, the effective displacement (reference value) is small and the energy absorption amount (reference value) is small. On the other hand, in Example B, the corner R (Ra) of the connecting portion between the outer peripheral portion and the rib was 1 mm, and the corner R (Rb) between the ribs was 1 mm, both of which satisfied the regulations of the present invention and were compressed and deformed in a bellows shape. And the effective displacement and the amount of energy absorption are increased. In addition, participants
Consideration C is a corner R (Ra) at the connecting portion between the outer peripheral portion and the rib.
Is 1 mm and does not satisfy a part of the regulations of the present invention (Ra> b
/ 2), the provision of this meet some of the provisions of the invention, the present invention is formed further plate thickness of the rib is thinner than the thickness of the outer peripheral portion at the corner R (Rb) is 1mm ribs between It is filled and is compressed and deformed like a bellows . Reference example C
When compared with Example B, the maximum load is considered to be small because the cross-sectional area is small.

[0013]

According to the present invention, when a compressive impact load or a compressive static load is applied in the axial direction, it contracts and deforms in a bellows shape without causing Euler buckling, and the effective displacement and the energy absorption amount are reduced. It is possible to obtain a large energy absorbing member having excellent axial crushing characteristics.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a cross-sectional shape of a hollow extruded shape member according to the present invention.

FIG. 2 is a cross-sectional shape of hollow extruded profiles of Comparative Example A, Example B, and Reference Example C.

FIG. 3 is a load-displacement curve of Comparative Example A.

4 is a load-displacement curve of Example B. FIG.

5 is a load-displacement curve of Reference Example C. FIG.

─────────────────────────────────────────────────── ───Continued from the front page (56) References: Kaihei 7-35252 (JP, U) JP 8-216916 (JP, A) JP 6-127428 (JP, A) JP 6- 247338 (JP, A) JP-A-7-310156 (JP, A) JP-A-8-216917 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B62D 21/15 B62D 21 / 00

Claims (2)

(57) [Claims] 1. A hollow extruded shape member of an aluminum alloy having an outer peripheral portion and a plurality of inner ribs connected to the outer peripheral portion and intersecting each other .
An energy absorbing member in a frame structure of an automobile having excellent axial crushing characteristics, characterized in that a corner R has a thickness of 1/2 or less of a rib and a corner R of a portion where a plurality of ribs intersect is 1 mm or less. Wherein the outer peripheral portion and the rib has an essentially uniform thickness, respectively, and the thickness of the outer peripheral portion is set forth in claim 1, wherein the larger of the same or the thickness of the ribs Energy absorbing member for automobile frame structure with excellent axial crushing property.