JP2001132788A - Energy-absorbing member formed of aluminum alloy extruded section having superior axial pressure crush characteristics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To induce bellows-form shrinkage deformation by suppressing the occurrence of Euler buckling and to perform stable absorption of energy, in an energy absorbing member such as a side member of an automobile, on which a compression load is axially exerted. SOLUTION: This energy-absorbing member is formed of a hollow extruded section of an aluminum alloy having an outer peripheral part and an inside rib connected to the outer peripheral part. Its sectional shape satisfies one or a plurality of conditions of (1) the corner R (Ra) of a portion, to which a rib and an outer peripheral part are connected is set to a value not larger than 1/2 of the thickness (b) of the rib, (2) the corner R (Rb) of a portion, where a plurality of the ribs cross each other is set to 1 mm or less, and (3) the thickness of the inside rib is decreased to a value smaller than the thickness of the outer peripheral part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow extruded member made of an aluminum alloy and, when subjected to a compression impact load or a compression static load in the axial direction of the extrusion, absorbs the impact load and the static load. The present invention relates to an energy absorbing member having a function of acting.

[0002]

2. Description of the Related Art In an automobile frame structure, the use of a hollow extruded aluminum alloy as an energy absorbing member such as a side member or a bumper stay has been studied (for example, JP-A-7-310156, JP-A-7-310156). -118782, JP-A-8-216917, JP-A-6-247338). One of the properties required of these energy absorbing members that receive a compressive impact load in the axial direction is, as described in the above-mentioned publication, that when the member is subjected to a load in the extrusion axial direction, Euler buckling (buckling in which the entire shape bends in a U-shape) does not occur, and shrinks and deforms in a bellows shape without generating crushing cracks, thereby obtaining stable energy absorption.

[0003] Of the above publications, for example,
In Japanese Patent No. 338, in order to suppress Euler buckling and cause bellows-like contraction deformation of a side member made of a hollow section having a rectangular cross section, a cross-sectional secondary moment (rigidity) around the X-axis and Y-axis The cross-sectional shape is set so that the panel that has a high probability of buckling in the bellows shape of the side members buckles earlier than the other panels at the beginning of the collision, by intentionally making a difference in the second moment of area . Then, once any panel buckles, bellows-like buckling propagates to other panels one after another, and even if the total length of the side members becomes longer, bellows-like buckling occurs stably over the entire length. ing.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to an energy absorbing member such as a side member of an automobile which receives a compressive load in the axial direction by devising the cross-sectional shape in the same manner as in the technique of Japanese Patent Application Laid-Open No. 6-247338. An object of the present invention is to suppress the buckling of Euler, induce bellows-like contraction deformation, and obtain stable energy absorption.

[0005]

The energy absorbing member having excellent axial crushing characteristics according to the present invention comprises a hollow extruded aluminum alloy member having an outer peripheral portion and an inner rib connected to the outer peripheral portion. A corner extruded section of an aluminum alloy having a corner R at a portion where the outer peripheral portion is connected is set to not more than の of the thickness of the rib, and an outer peripheral portion and a plurality of inner ribs connected to the outer peripheral portion and crossing each other. And a corner extruded from an aluminum alloy having an outer peripheral portion and an inner rib connected to the outer peripheral portion. The thickness is formed smaller than the thickness of the outer peripheral portion. Two or more of these features may be provided simultaneously.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have found that in a hollow extruded profile having an outer peripheral portion and an inner rib connected to the outer peripheral portion, the sectional shape of the hollow extruded material is divided into an outer peripheral portion and an inner rib, and the outer peripheral portion is taken into account. The rigidity of the connecting portion between the plates constituting the inner ribs and the rigidity of the intersections between the plates constituting the inner ribs, or the rigidity of the inner ribs is likely to cause Euler buckling or bellows deformation. And that if the rigidity of this portion is small, buckling of the plate constituting the outer peripheral portion or the rib is likely to occur, and bellows-like deformation is likely to be induced. The present invention has been made based on this finding.

FIGS. 1 (a) and 1 (b) illustrate 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. It is provided with ribs having a basically uniform thickness b. here,
Basically, the uniform thickness means that the thickness of the outer peripheral portion and the rib is uniform except for the connection portion, the intersection 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.

When the corner R (Ra) of the connecting portion between the outer peripheral portion of the hollow extruded profile and the rib is smaller than 1/2 of the thickness b of the rib (Ra ≦ b / 2), the rigidity of the connecting portion decreases. In addition, the plate constituting the outer peripheral portion or the rib is easily buckled, and bellows-like deformation is easily induced. Here, the thickness of the rib may change in the width direction of the plate. In such a case, the thickness b of the rib is the thickness of the thickest part except for the connection part or the intersection. If the corner R (Rb) of the intersection of the ribs is smaller than 1 mm (Rb ≦ 1), the rigidity of the intersection is reduced, the buckling of the plate constituting the rib is likely to occur, and the bellows-like deformation is caused. Easily induced. Regarding the thickness of each of the outer peripheral portion and the rib of the hollow extruded shape member that satisfies either of these two requirements, the thickness b of the rib is equal to or smaller than the thickness a of the outer peripheral portion (b ≦ a). It is desirable. Furthermore, if the thickness b of the rib is smaller than the thickness a of the outer peripheral portion of the hollow extruded profile (b <a), rigidity is reduced and buckling of the rib is likely to occur, and bellows-like deformation is caused. Easily induced. By forming the rib thickness b to be thinner, the bellows-like deformation is further stabilized. When the hollow extruded profile made of an aluminum alloy satisfies one or more of the above three requirements, a part of the plate constituting the outer peripheral portion or the rib buckles, and buckling of the other plate is induced accordingly. Thus, Euler buckling is suppressed and bellows-like deformation is likely to occur.

[0009]

An embodiment 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 total length of 200 mm and a cross-sectional shape shown in FIGS. 2A to 2C, and the relationship between the load and the amount of displacement was investigated. The shapes of the outer peripheral portions A to C are all the same, the outer size is 45 mm × 55 mm, and the thickness is 2 mm.
A is Ra and Rb are all 6 mm, and the rib thickness b is 2
mm, 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 thickness b of the rib is 1.5 mm.

The load-displacement curves for each of A to C are shown in FIGS.
Table 1 shows the maximum load, the energy absorption, the effective displacement, and the respective buckling forms read from FIG. 3 to FIG. 5. Note that the effective displacement in Table 1 means the displacement amount when the load of the example is completely collapsed in a bellows shape in the axial direction and the load rises again and reaches a load value equivalent to the initial maximum load. The amount of energy absorption in Table 1 means the amount of energy absorption until the effective displacement is reached. On the other hand, in the case of the comparative example, Euler buckling started and the load monotonously decreased, so that the effective displacement in the same meaning as in the example could not be defined, so the test was stopped at an appropriate displacement, and this was displayed. In Table 1, the effective displacement column is described as a reference value, and in the column of energy absorption, the amount of energy absorbed until the displacement is reached is described as a reference value.

[0011]

[Table 1]

In Comparative Example A, the corner R (Ra) of the connecting portion between the outer peripheral portion and the rib was 6 mm, and the corner R (Rb) of the intersection of the ribs was 6 mm. Since the cross-sectional area was large, the maximum load was large. However, due to Euler buckling, the effective displacement (reference value) is small and the energy absorption (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 satisfying the requirements 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 Example C, the corner R (Ra) of the connecting portion between the outer peripheral portion and the rib was used.
Is 1 mm and does not satisfy the requirements of the present invention (Ra> b / 2)
However, the corner R (Rb) of the ribs is 1 mm, which satisfies the requirements of the present invention, and the thickness of the rib is smaller than the thickness of the outer peripheral portion, which satisfies the requirements of the present invention. , Effective displacement and energy absorption are increased. In addition, when Example C is compared with Example B, it is considered that the reason why the maximum load is small is that the cross-sectional area is small.

[0013]

According to the present invention, when an impact load of compression or a static load of compression is applied in the axial direction, it contracts and deforms in a bellows shape without causing Euler buckling, and the effective displacement and energy absorption amount are reduced. A large energy absorbing member having excellent axial crushing characteristics can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional shape of a hollow extruded material of Comparative Example A, Example B, or C.

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

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

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

Claims (3)

[Claims] 1. An aluminum alloy hollow extruded shape having an outer peripheral portion and an inner rib connected to the outer peripheral portion,
An energy absorbing member having excellent axial crushing characteristics, wherein a corner R at a portion where a rib and an outer peripheral portion are connected is set to be equal to or less than 1/2 of a thickness of the rib. 2. An aluminum alloy hollow extruded shape having an outer peripheral portion and a plurality of inner ribs connected to the outer peripheral portion and intersecting with each other, and a corner R at a portion where the plurality of ribs intersect is 1 mm or less. An energy absorbing member having excellent axial crushing characteristics. 3. An aluminum alloy hollow extruded shape having an outer peripheral portion and an inner rib connected to the outer peripheral portion,
An energy absorbing member having excellent axial crushing characteristics, characterized in that the thickness of the inner rib is formed smaller than the thickness of the outer peripheral portion.