KR20120135314A - Collision energy absorbing structure - Google Patents

Abstract

The structure is not complicated, press work is possible, a stable deformation shape is obtained, and the resistive load in the deformation process is high and stable, thereby providing a collision energy absorbing structure having high energy absorption efficiency. A collision energy absorbing structure which is conventionally deformed in the axial direction and absorbs collision energy, wherein the cross-sectional shape of the cross section perpendicular to the axial direction is point symmetrical with respect to the center of the cross section, and is a non-symmetrical polygon, The aspect ratio at the time of making a rectangle is less than 1.5, and the ratio of the length of the adjacent side among the sides of the polygon which comprises a cross section is 2.3 or less.

Description

Collision energy absorbing structure {COLLISION ENERGY ABSORBING STRUCTURE}

The present invention relates to an impact energy absorbing structure for use in automobiles and the like.

In a vehicle body such as an automobile, a structure that is deformed during a collision and absorbs collision energy is formed in order to alleviate a collision with a crew member or the vehicle body during a collision. As the performance required for such an impact energy absorbing structure, it is required to increase the energy absorption efficiency and to make the cross section compact or thin in view of weight reduction of the vehicle body in consideration of recent environmental problems.

Such an impact energy absorbing structure is required to have a high energy absorption capacity because of high high energy absorption efficiency, that is, the strain resistance load is high and stable even after deformation is started. The impact energy absorbing structure is a large and small tubular structure that is concentric in shape as shown in FIG. 21B, because the deformation at the time of impact cannot sufficiently absorb the collision energy in the unstable strain as shown in FIG. To absorb the impact energy (immersion type; for example, Patent Document 1), or (c) in FIG. 21 by plastic deformation while a small diameter tube is immersed in a large diameter tube with respect to an axial collision load. As shown, the structure is plastically deformed (for example, patent documents 2 to 7) with respect to the axial collision load.

Patent document 2? In Patent Document 2, Patent Document 2 forms a recess in the cross section of the structure to form a polygonal cross section, and Patent Document 3 connects each corner section from the center of the section to have a cross-sectional shape having a radial middle residue, Patent document 4 has an 8-character cross-sectional structure, and both increase the cross-sectional line length and the number of ridges, and obtain a structure having good energy absorption efficiency. Patent document 5 improves a collision absorption performance by providing a filler in a structure inside.

Further, Patent Documents 6 and 7 form irregularities mainly in the direction perpendicular to the axial direction that receives the impact load, and are continuously buckled even when subjected to an axial shock including the inclined load, and is shown in Fig. 22 (c). The deformation shape is controlled so that the plastic deformation of the plain shape occurs.

Japanese Laid-Open Patent Publication No. 48-1676 Japanese Unexamined Patent Publication No. 2008-284931 Japanese Laid-Open Patent Publication 2001-124128 Japanese Unexamined Patent Publication No. 2008-296716 Japanese Laid-Open Patent Publication 2001-182769 Japanese Patent Laid-Open No. 2-175452 Japanese Unexamined Patent Publication No. 2002-104107

However, the immersive type described in Patent Document 1 has a complicated structure, which causes an increase in the molding process, which poses a problem in cost and productivity.

Said patent document 2? The plastic deformation of the structure shown in Fig. 7 has the following problems.

Although the technique of the said patent document 2 is effective as a method of improving energy absorption efficiency while effectively utilizing a limited space, when the axial shock including a gradient load is received, it may be buckled largely and a deformation load may not be stabilized. In such a case, the energy absorption efficiency is lowered.

In the technique disclosed in the above Patent Documents 3 and 4, the cross-sectional shape is very complicated to be forged, which leads to an increase in cost as compared to general press work, and is also disadvantageous in terms of production.

In the technique disclosed in Patent Document 5, the weight and cost of the structure are increased by using the filler.

In the technique disclosed in Patent Documents 6 and 7, the deformed shape is stabilized by forming the uneven portion perpendicularly to the axial direction. However, since the deformation is promoted in the uneven portion, it is difficult to obtain a structure having a low level stability and excellent energy absorption efficiency. .

The present invention has been made in view of such a point, and the structure is not complicated, press work is possible, light weight and compact, stable deformation shape is obtained, resistance load in the deformation process is high and stable, and energy absorption efficiency An object of this invention is to provide a high collision energy absorbing structure.

The said subject is following (1)? It is solved by the invention of (6).

(1) A collision energy absorbing structure which is normally formed and deforms in the axial direction to absorb collision energy,

The cross-sectional shape of the cross section perpendicular to the axial direction is point symmetrical with respect to the center of the cross section, and is a non-symmetric polygon. The aspect ratio when the outside of the cross section is a quadrangle is less than 1.5, and among the sides of the polygon constituting the cross section. A collision energy absorbing structure, wherein the ratio of the lengths of adjacent sides is 2.3 or less.

(2) The collision energy absorbing structure according to (1), which is tapered in the axial direction.

(3) The collision energy absorbing structure according to (1) or (2), wherein the front end portion has a recess recessed in the axial direction.

(4) The collision energy absorbing structure according to any one of (1) to (3), which is composed of a press molding material formed by pressing a metal plate.

(5) The collision energy absorbing structure according to (4), wherein the impact energy absorbing structure according to (4) is configured by joining at least two of the press-molded materials.

(6) The metal plate constituting the press-molded material is 270? The impact energy absorbing structure according to (4) or (5), which is a steel sheet having a tensile strength of 1500 MPa.

According to the present invention, the cross-sectional shape of the cross section perpendicular to the axial direction is point symmetrical with respect to the center of the cross section and is non-linearly symmetrical. The aspect ratio when the outer edge of the cross section is square is less than 1.5, and the cross-sectional shape of the polygon Since the ratio of the length of an adjacent side among sides is 2.3 or less, a stable deformation | transformation shape is obtained. Therefore, the collision energy absorbing structure with high energy absorption efficiency is obtained by press working without impairing productivity, and the structure can be made compact and light in weight.

1 is a perspective view and a cross-sectional view showing a collision energy absorbing structure according to an embodiment of the present invention.
2 is a perspective view showing a collision energy absorbing structure according to another embodiment of the present invention.
3 is a perspective view showing a collision energy absorbing structure according to still another embodiment of the present invention.
FIG. 4 is a view for explaining an example of a method of manufacturing the collision energy absorbing structure shown in FIG. 1.
FIG. 5 is a view for explaining another example of the method of manufacturing the collision energy absorbing structure shown in FIG. 1.
6 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Example 1 of the present invention.
7 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Example 2 of the present invention.
8 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Example 3 of the present invention.
9 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Example 4 of the present invention.
10 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Example 5 of the present invention.
11 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Example 6 of the present invention.
12 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Example 7 of the present invention.
13 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Comparative Example 1. FIG.
14 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Comparative Example 2. FIG.
15 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Comparative Example 3. FIG.
FIG. 16 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Comparative Example 4. FIG.
17 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Comparative Example 5. FIG.
18 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Comparative Example 6. FIG.
19 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Comparative Example 7. FIG.
20 is a diagram showing a cross-sectional shape, a shape before and after a collision, and a load-stroke curve of the structure of Comparative Example 8. FIG.
21 is a diagram for explaining a modification of the collision energy absorbing structure.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

<Shape of structure>

FIG. 1: shows the collision energy absorption structure which concerns on one Embodiment of this invention, FIG. 1 (a) is a perspective view, FIG. 1 (b) is sectional drawing.

The collision energy absorption structure which concerns on this embodiment consists essentially of a normal body as shown to Fig.1 (a), one end (for example, upper end) becomes a collision tip, and a collision collides with the collision tip. In this case, the collision energy is absorbed by being deformed in the direction of the axis L.

As shown in Fig. 1B, the shape of the cross section perpendicular to the direction of the axis L is point symmetrical with respect to the center O of the cross section and is made of a nonlinear symmetric polygon. The figure has shown the case where the cross-sectional shape is a hexagonal shape containing a recessed part.

By making the shape of the cross section perpendicular to the axis L into a polygon in this manner, it can be produced by press working, and the cross-sectional line length can be made long, so that the collision performance can be improved in a limited space.

In addition, the load at the time of a collision is not limited to the case where it is input in an axial direction, for example, It is also assumed that it receives the inclination load which has an angle with respect to an axial direction, and when a collision containing such inclination load is received, When the deformation of the member becomes unstable due to buckling or local bending, the deformation load is lowered and the energy absorption capacity is remarkably lowered.By symmetrical or nonlinear symmetry of the cross section perpendicular to the axis L of the ordinary body, Including such an inclined load, the deformation | transformation form at the time of collapse can be stabilized, and stable collision performance can be obtained. It is considered that this is because the point symmetry and the non-linear symmetry cause deviations in the progression of the buckling of the sides facing each other, and it is difficult to cause a large deformation such as a buckling with a long period of time or a fall or buckling.

The rectangle R that forms the outline of the cross section has an aspect ratio of less than 1.5. Here, the aspect ratio is a value of long side / short side (a / b in the example of the drawing). When the square R is square (a = b), the aspect ratio is 1, and the aspect ratio is necessarily 1 or more.

The aspect ratio of the rectangle forming the cross section of the polygon is less than 1.5 to obtain a stable deformation, because the aspect ratio becomes large, that is, it becomes easy to bend during collapse as the elongated rectangle becomes large.

Moreover, the ratio of the length of the adjacent side among the sides of the polygon which comprises a cross section is 2.3 or less. Here, the ratio of the lengths of the adjacent sides is taken as the value of the long side / short side. When the lengths of two adjacent sides are the same, the ratio of the length of the adjacent side is 1, and the ratio of the length of the adjacent side is necessarily 1 or more. In the example of a figure, the combination whose ratio of the length of an adjacent side is maximum is combination (L1> L2) of the side L1 and the side L2, and L1 / L2 <= 2.3.

The ratio of the length of the adjacent side among the sides of the polygon which comprises a cross section is 2.3 or less is because the deformation | transformation form becomes stable by this. This is likely to cause large deformation on the longer side of the adjacent sides, and in order to suppress such large deformation, the side length of the side of the adjacent side that is shorter is important, and is optimal between these adjacent sides. It is thought that due to the existence of the human factor.

It is preferable to set it as the structure which tapered the collision energy absorbing structure in the axial direction from a viewpoint of stabilizing a deformation | transformation form. It is preferable that the taper in this case is formed so that it may spread from the front end (collision front end) to the rear end as shown. This is considered to be because the taper can be used to specify the site where the deformation is started, and the deformation is stably started.

As shown in Fig. 3, by forming the same recessed shape N at the tip (collision tip), it is possible to specify the site where the deformation is started in the same way, and the deformation can be started stably.

Moreover, you may form the recessed shape N like FIG. 3 in the structure in which the taper like FIG. 2 was formed.

<Applicable material of the structure>

It is preferable that the collision energy absorption structure of this embodiment is comprised by press-molding a metal plate. Examples of the metal sheet to be applied include a hot rolled steel sheet, a cold rolled steel sheet, or a plated steel sheet which is plated with electrolytic zinc plating or hot dip galvanizing, or further, a stainless steel sheet (SUS). In the case of a hot-dip galvanized steel plate, you may perform alloying process. In addition, the plated steel sheet may further be subjected to an organic film treatment after plating. 270? It is desirable to have a tensile strength of 1500 MPa. Moreover, other metal materials, such as aluminum, magnesium, these alloys, can also be used as a metal plate.

<Manufacturing Method>

Next, an example of the manufacturing method of such an impact energy absorbing structure is demonstrated.

Here, the case where a collision energy absorber is manufactured by press molding is shown. In the example of FIG. 4, as shown to Fig.4 (a), two metal plates are prepared, these are shape | molded as shown to Fig.4 (b) using the metal mold | die which consists of a die and a punch, The structure shown to Fig.4 (d) is obtained by joining the cross sections of the molded articles obtained as shown to c). Specifically, in order to manufacture the structure of FIG. 1, the molded article of the same shape is manufactured by press molding from two metal plates, and these are joined. In the example of FIG. 5, one metal plate shown to Fig.5 (a) is shape | molded as shown to Fig.5 (b) using the metal mold | die which consists of a die and a punch, this is closed-sectioned by bending process, and edges are comrades By joining, the structure shown in FIG.5 (c) is obtained. The dies (die and punch) used for press molding are polygons of the cross-sectional shape (point symmetry with respect to the center of the cross-section and non-symmetrical polygons, having an aspect ratio of less than 1.5 when the outer edge of the cross section is square, The ratio of the length of the adjacent side among the sides of the polygon which comprises is designed in consideration of 2.3 or less).

In the example of FIG. 4, FIG. 5, the case where the structural body was manufactured by manufacturing and joining the molded part of predetermined cross-sectional shape from the 1 to 2 metal plate was demonstrated, Each site | part is shape | molded using 3 or more metal plate, These are It is also possible to produce a structure by bonding. As a method for joining cross sections, various methods such as spot welding, laser welding, arc welding, caulking, rivet bonding, and adhesive application can be adopted.

Example

Here, the characteristics of the collision energy absorbing structures of various shapes were grasped by simulation.

Simulation is a general-purpose dynamic understanding software LS-DYNA ver. 971 was used. The applied material was a steel sheet having a tensile strength of 440 MPa and a plate thickness of 1.6 mm. Inventive Example 1 having a shape within the scope of the present invention. 7 structures, and Comparative Example 1? The collapse performance of the structure of 8 when the indenter on the plane without curvature was collided at 15 km / h was simulated. Since the collapse performance was evaluated by the deformation resistance load after the start of deformation, the average load was determined from the load-stroke curve at the collapse distance of 20 mm to 70 mm, and the average load per unit weight and the shape after deformation were evaluated. The result is put together in Table 1 and shown. Inventive Example 1? The cross-sectional shape, the shape before and after the collision and the load-stroke curve of the structure of FIG. It shows in 12. Comparative Example 1? The cross-sectional shape, the shape before and after the collision and the load-stroke curve of the structure of Fig. It shows in 20. In Table 1, as for the deformation | transformation shape column, (circle) is deformed continuously in the form of a tetrahedron, and x is bending and buckling with a big period generate | occur | produced. 6,? In 20, (a) is a cross-sectional shape, (b) is the shape before and behind a collision, and (c) is a load-stroke curve. As shown to these, this invention example 1 which exists in the scope of the present invention. In 7, it was confirmed that plastic deformation was carried out stably and continuously in crushing at the time of collapse, and the average load per unit weight at the time of collapse was high, and the absorption energy efficiency was high. On the other hand, Comparative Example 1? In 8, buckling and a large buckling occurred in the axial direction, and it was confirmed that the deformation shape was unstable and the average load per unit weight was low.

As described above, the cross-sectional shape of the cross section perpendicular to the axial direction is point symmetrical with respect to the center of the cross section as in the present invention, and the non-symmetrical polygon has an aspect ratio of less than 1.5 when the outside of the cross section is a quadrangle. It was confirmed that stable deformation shape was obtained by setting ratio of the length of the adjacent edge | side among the polygonal edges which make the structure into 2.3, resistance load became high stable, and the collision energy absorbing structure with high energy absorption efficiency was obtained.

Claims (6)

A collision energy absorbing structure which is normally formed and deforms in the axial direction and absorbs collision energy,
The cross-sectional shape of the cross section perpendicular to the axial direction is point symmetrical with respect to the center of the cross section, and is a non-symmetrical polygon. A collision energy absorbing structure, wherein the ratio of the lengths of adjacent sides is 2.3 or less. The method of claim 1,
A collision energy absorbing structure, which is tapered in the axial direction. 3. The method according to claim 1 or 2,
An impingement energy absorbing structure, having a concave portion recessed in the axial direction at a distal end portion. The method according to any one of claims 1 to 3,
An impact energy absorbing structure comprising: a press molding material formed by pressing a metal plate. The method of claim 4, wherein
A collision energy absorbing structure comprising at least two press-molded materials joined together. The method according to claim 4 or 5,
The metal plate constituting the press-forming material is 270? A collision energy absorbing structure, which is a steel sheet having a tensile strength of 1500 MPa.

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