JP2002012165A - Energy absorbing member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high energy absorbing capacity in limited space and weight in an energy absorbing member composed of an aluminum alloy extruded section having a hollow rectangular cross section. SOLUTION: This energy absorbing member for arranging a rectangular cross-sectional projecting part outside a wall surface part, can be used for a side member of an automobile.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energy absorbing member, such as a side member at a front portion of an automobile, for preventing an entire structure from being broken by converting an impact load applied from an axial direction into deformation energy.

[0002]

2. Description of the Related Art As shown in FIG. 6, an energy absorbing member at a front portion of an automobile includes a bumper 1, a front side member (hereinafter referred to as a side member) 2, and the like. It is mainly the side member 2 that absorbs energy. Therefore, the side member 2 is required to absorb more energy in a limited space.

[0003] As a side member of an automobile, a rectangular steel plate having a rectangular cross section made of a steel plate press is often used, but a light alloy such as an aluminum alloy which can be expected to be lighter in light of recent demands for a lighter weight can be considered. It has become These side members have a hollow columnar shape as a whole, and FIG.
As schematically shown in FIG. 2, when compressed in the axial direction, the wall surface deforms while forming a bellows shape, and absorbs energy by converting impact energy into plastic deformation energy of metal. In addition, in the case of aluminum alloy, since it has low strength and rigidity as compared with steel, it easily collapses plastically and has good energy absorbing ability.

A conventional energy absorbing member used for a side member or the like has a problem in that when it collapses plastically by receiving a compressive force in the axial direction as disclosed in Japanese Patent Application Laid-Open No. 4-50083 or Japanese Patent Application Laid-Open No. 02-175452. The main focus is on whether to collapse the bellows. That is, by intentionally disintegrating in a bellows shape, Euler buckling (the side member itself is broken) is prevented, and stable energy absorption is obtained. However, these technologies can stabilize energy absorption but cannot increase the amount of energy absorption itself, and in order to increase the energy absorption, it is inevitable to increase the diameter and thickness of the cross section. Therefore, in order to secure a larger amount of energy absorption in a limited space and a limited weight like an automobile, these conventional technologies are not enough.

In order to reduce the weight, use of a light metal such as aluminum is conceivable. However, a light metal mainly made of an aluminum alloy has a drawback that it has a smaller elongation than steel and that even a small amount of deformation causes cracking. . In particular, when trying to give a large amount of energy absorption capacity with a small volume, a treatment to increase the material strength by heat treatment or adjustment of alloy components is performed, but such a treatment loses the ductility (elongation) of the material. In many cases, the material may be broken at the time of crushing and energy may not be absorbed effectively. Also, when not using a high-strength material, it is necessary to increase the thickness of the energy absorbing member, and when the profile wall deforms in a bellows shape during crushing, the wall surface distortion due to the thickening becomes too large,
There is a disadvantage that the energy absorption ability is reduced due to cracks.

[0006]

The use of an extruded aluminum alloy material makes it possible to reduce the weight and obtain a good energy-absorbing capacity. May be broken and a predetermined energy absorbing ability may not be obtained. An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide an energy absorbing member made of an extruded aluminum alloy having a high energy absorbing capacity in a limited space and weight. It is to get.

[0007]

The energy absorbing member according to the present invention is an extruded aluminum alloy material having a hollow rectangular cross section, wherein a convex portion having a rectangular cross section is provided outside a wall surface portion. (See FIG. 1). Here, the profile having a rectangular cross section refers to a profile having a rectangular or square cross section. This includes not only a mouth shape in cross section, but also a shape material having a web inside such as an eye shape, a Japanese shape, and a Tagata shape. In the case of this profile, it is preferable that a convex portion is provided outside the facing wall portion. This energy absorbing member is formed using an extruded aluminum alloy material, and is particularly applied to a use such as a side member of an automobile in which an impact load applied from an axial direction is converted into deformation energy to prevent the entire structure from being destroyed. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction and operation of an energy absorbing member according to the present invention will be described more specifically with reference to FIGS.

FIG. 1 shows a hollow rectangular cross section formed with a rectangular cross section having a height αt and a width (B / β) outside the wall. (A) of FIG.
(B) is an example in which a convex portion is provided on two facing wall portions, (c) is an example in which three wall portions are provided, and (d) is a case where a convex portion is provided in four wall portions. As an example, (b) or (d) in which a convex portion is provided on the outside of the facing wall portion is more preferable from the viewpoint of the balance of the load distribution that the profile receives during crushing.

When a conventional profile having a rectangular cross section is crushed in the axial direction, energy absorption due to the movement of a plastic hinge line at a corner portion (circled portion) shown in FIG. It is known that the amount of bending deformation energy consumed when a wall surface (a portion sandwiched between corners) is folded in a bellows shape is not so large. This indicates that increasing the number of corners increases the amount of energy absorption. In other words, in this energy absorbing member, a plastic hinge line is formed there by providing a convex corner portion on a wall surface portion that has not conventionally contributed much to energy absorption, and the impact energy is absorbed by the movement of the hinge line. As a result, it is possible to absorb more impact energy than a simple rectangular cross-section member without causing a significant increase in weight.

(Embodiment) Next, the operation and effect of this type of energy absorbing member will be described more specifically based on the results of simulation analysis. As shown in FIGS. 1A to 1D, a cross section B × H, a plate thickness t, and a height h (= 180 mm)
Of aluminum extruded profile of height αt on the outside of the wall,
Each of the projections having a rectangular cross section with a width (B / β) is compressed 80% of the height h at a speed of 1 mm / s in the axial direction, respectively.
A relationship diagram between the energy absorption amount and the convex portion height parameter α or the convex portion width parameter β shown in FIGS. 3 and 4 was obtained. The vertical axis of FIG. 3 and FIG. 4 is a ratio of the energy absorption amount E ₁ of the present invention type (FIG. 1 (a) ~ (d)) of the energy absorption amount E ₂ and conventional (having no protrusions), Also, in FIG. 3, the convex portion width parameter β = 3 is set, and in FIG. 4, the convex portion height parameter α is set.
= 5. The extruded aluminum material is 6N01-T
It was set to 5.

As shown in FIGS. 3 and 4, the shapes (a) to (d) of the type according to the present invention have energy absorption in all the regions α and β compared to the conventional type by providing a convex portion on the wall surface. The amount is increasing. FIG. 5 shows the energy absorption ratio (E ₂
/ E ₁₎ and, shows the relationship between the ratio of A ₁ of the cross-sectional area of the cross-sectional area A ₂ and the conventional profile of the present invention type profiles of (A 2 _{/ A 1),} the form of the present invention type It can be seen that the material has an increased actual energy absorption at a rate greater than the area of the protrusions. That is, a larger increase in energy absorption can be achieved with a small weight increase.

[0013]

According to the present invention, a rectangular cross-section convex portion is provided outside a wall portion of an aluminum alloy extruded profile having a hollow rectangular cross-section, thereby achieving a larger increase in energy absorption with a small increase in weight. Can be.

[Brief description of the drawings]

FIG. 1 is a view showing various forms of a cross-sectional shape of an energy absorbing member having a rectangular cross-section according to the present invention.

FIG. 2 is a diagram illustrating a cross-sectional shape of a conventional energy absorbing member having a rectangular cross section.

FIG. 3 shows the energy absorption amount and the height parameter α of the convex portion.
FIG.

[FIG. 4] Similarly, energy absorption amount and convex part width parameter β
FIG.

FIG. 5 is a diagram showing a relationship between an absorption energy ratio (E ₂ / E ₁ ) and a sectional area ratio (A ₂ / A ₁ ).

FIG. 6 is a diagram showing a structure of a front part of the automobile.

FIG. 7 is a schematic diagram of axial compression deformation of a rectangular cross-sectional shape member.

[Explanation of symbols]

 1 Bumper reinforcement 2 Front side member

Claims (3)

[Claims] 1. An energy absorbing member comprising an aluminum alloy extruded shape having a hollow rectangular cross section, wherein a convex portion having a rectangular cross section is provided outside a wall portion. 2. The energy absorbing member according to claim 1, wherein a convex portion is provided outside the facing wall surface portion. 3. The energy absorbing member according to claim 1, which is used for a side member of an automobile.