JP2002067693A - Safety member for automobile and section design method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safety member arranged in a door in parallel with the front and back direction of automobile and made of an extruded aluminum alloy in order to secure the existence space for crews against heat-on collision, and to design a section shape for lightening with satisfying the necessary performance. SOLUTION: Concerning the extruded aluminum alloy material with given proof stress σ0.2 and Young's modulus E, when the length is L and the required maximum resisting load is Pcr, the section shape is designed that k value defined by the equation k=Pcr/(σ0.2×A) (A; cross section (mm2), λ; effective slenderness ratio (=L/r), λ0; reference slenderness ratio (=π(2E/σ0.2)1/2), r; section quadratic radius (mm)) is in the range of 2 lines of Fig. 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety member located on the side of a passenger compartment of a motor vehicle or in a door, and particularly for securing strength against a collision from the front of a truck or a car.

[0002]

2. Description of the Related Art A safety member called a door beam, a side impact beam, or the like for protecting an occupant from a side collision or ensuring the strength of a door is mounted in a door of an automobile. Iron is used, and some aluminum alloy extruded materials are used. The door beam is assumed to have a side collision, and the evaluation also specifies the maximum load and the amount of energy absorption by a bending test of a beam supported at both ends (JP-A-5-246242, JP-A-5-246242). 247575, etc.).

[0003] In addition, various studies have been conducted on the use of aluminum (a crushable material) such as a side member that absorbs energy by being crushed in the axial direction as a member against a frontal collision. These members absorb the impact at the time of collision by the regular buckling in the longitudinal direction against the collision load in the axial direction, suppress the long column buckling, induce bellows-like contraction deformation, and achieve stable energy absorption. (JP-A-8-310440, JP-A-6-24)
7338, JP-A-11-29064, etc.).

Further, Japanese Patent Application Laid-Open No. 10-138756 and Japanese Patent Application Laid-Open No. 10-138575 disclose the same function as the door beam in the case of a side collision, and receive the collision load in the case of a head-on collision, and The impact beam which secures is described. In the event of a head-on collision, the impact beam does not deform if the axial compression load applied to the impact beam is less than the buckling load (if the buckling load is greater than the buckling load, the occupant survives space). It has a different characteristic from the crushable material that absorbs collision energy by contracting and deforming in a bellows shape. The head-on collision includes a full-face collision and an offset collision from the front-back direction.

[0005]

Since these safety members increase the vehicle weight, it is desired to reduce the weight as much as possible. For the door beam material and the crushable material described above, an aluminum alloy extruded material is used. In order to satisfy the required performance and reduce the weight, various cross-sectional shapes have been proposed. However, regarding a safety member that receives a collision load in the axial direction in the event of a collision from the front of the vehicle and secures an occupant survival space, Japanese Patent Laid-Open No. 10-1387 discloses the above-mentioned safety member.
No. 56 or JP-A-10-138575 merely discloses a butt pipe formed by pressing a steel plate into a cylindrical shape.

SUMMARY OF THE INVENTION Accordingly, the present invention relates to a safety member which receives a collision load in an axial direction when a collision occurs from the front of a vehicle and secures an occupant survival space. It is an object of the present invention to provide a cross-sectional shape or a design method of the cross-sectional shape that can reduce the weight while satisfying the required performance when configured with.

[0007]

SUMMARY OF THE INVENTION The present invention is arranged substantially parallel to the front-rear direction of a vehicle on the side or inside a door of a passenger compartment of the vehicle, and has a predetermined maximum load P _{cr with} respect to axial compression in the member axial direction. After that, it is an automotive safety member that buckles in a long column in the off-axis direction, and that k defined by the following formula (1) is made of an extruded aluminum alloy material that satisfies the following formulas (2) and (3). Features.

(Equation 3) The secondary radius r of the cross section is calculated by the following equation as is well known.

(Equation 4) In this equation, the second moment of area I is perpendicular to the long column buckling direction and is the second moment of area around an axis passing through the centroid.

The present invention also relates to a method for designing a cross section of an extruded aluminum alloy used for the safety member for an automobile,
For an aluminum alloy extruded material having a predetermined proof stress σ _0.2 and a Young's modulus E, the length is L, and the required value of the maximum load when buckling a long column in the off-axis direction with respect to the axial compression is P _cr Then, the geometrical shape of the cross section of the extruded material is designed so that k defined by the expression (1) satisfies the expressions (2) and (3).

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS When an impact is applied to a vehicle from the front (or rear), the impact is transmitted to the space (occupant room) where the occupant is present through a side frame or the like in a normal vehicle. At this time, the above-mentioned crushable material has a purpose of absorbing the impact energy by plastic deformation. The crushable material is arranged in the crushable zones A and C shown in FIG. 2, and contracts and deforms into a regular bellows shape in response to an impact load in the axial direction to absorb energy. On the other hand, the safety member 1 according to the present invention is disposed in the safety zone B shown in FIG. 2, that is, in the side of the occupant compartment or in the door (see FIG. 3). The purpose is to secure the crew's living space.
Therefore, the mechanical behavior and role are different from those of the crushable material.

The main characteristics required for such a safety member are:
It is the maximum resistance load that indicates how much it can withstand an impact from the axial direction. We have various cross-sectional shapes,
In many experiments on alloy types and tempered aluminum alloy extruded materials, it is necessary to consider not only elastic buckling of long columns but also plastic buckling in order to predict the maximum resistance load. Further, it has been found that there is a certain experimental relationship between the slenderness ratio and the maximum resistance load, and a design equation (Equations (1) to (3)) for predicting the maximum resistance load of the member is obtained. It was constructed.

This design equation is derived from the results of the following experiment. 6000 series and 700 shown in Table 1
After extruding a zero-series aluminum alloy into various cross-sectional shapes (hollow), each extruded material is subjected to an aging treatment so as to give predetermined mechanical properties (proof stress), and cut into a length of about 800 mm. Samples were used. Table 1 shows the length (span), geometric data of cross section, and proof stress of each test material. In addition, proof strength was cut out from JIS No. 5 tensile test piece from extruded material after aging treatment,
It was determined by conducting a tensile test.

[0012]

[Table 1]

As shown in FIG. 4, for each specimen 2,
Movable jigs 5 and 5 fixed to pins 4 and 4 on fixed jigs 3 and 3
The vertical compression is fixed to the axis, and the static compressive load (P) is applied in the axial direction.
In addition, measure the displacement-load curve up to 30mm
And the obtained maximum resistance load P _crAnd the geometric shape of the member
The relationship was plotted. Note that the maximum resistance load P_crMore than
When a load is applied, the test material becomes large in the plane perpendicular to the pin 4.
Long column buckling. At this time, the vertical axis represents the maximum load P_crThe proof stress
σ_0.2Use the k value divided by × A (see the above formula (1))
The horizontal axis is the effective slenderness ratio λ and the reference slenderness ratio λ₀Divided by
The original one was used. Slenderness ratio represents the geometric dimensions of the column
The basic parameter, the effective slenderness ratio λ is
The buckling length l taking into account different coefficients depending on the support conditions of
The value is divided by the secondary radius r of the cross section (λ = 1 / r). This
In the case of, the support condition at both ends is pin support (movement is restricted, rotation
Is free), and l = L, λ = L / r.
You. The secondary radius r of the cross section is calculated by the above equation (4), and
The surface second moment I is parallel to the axial direction of the pin 4 and
The second moment of area around the axis passing through the centroid was used. Ma
The reference slenderness ratio λ₀As Euler's buckling stress formula,

(Equation 5) Against

(Equation 6) Is set to λ ₀ . That is,

(Equation 7) And The Young's modulus was determined by the tensile test.

The k value obtained from each test material and (λ / λ₀)
1 is shown in FIG. Surround plot
, A polynomial approximation is performed to obtain the equation (2),
(3) was determined. Note that λ / λ₀The larger the
Λ / λ as a practical range₀≤2.5
Was. For this safety member, the required maximum resistance load
Given mechanical properties (proof strength σ _0.2, Young's modulus E)
When using an extruded aluminum alloy,
The geometry of the cross section of the extruded material is determined from this. Conversely, the cross section of the extruded material
Once the geometry is determined, the maximum resistance required for the extruded material
It can be determined whether the load resistance is satisfied. And this cheap
Do not install all components in a narrow door, for example
To avoid interference with other members.
Therefore, there is a large restriction on the cross-sectional shape.
Satisfies the required maximum resistance load
This facilitates the cross-sectional design to reduce the weight.

As the cross-sectional shape of the aluminum alloy extruded, a hollow cross-section is generally desirable for weight reduction. For example, various cross-sections such as a round cross-section, a polygonal cross-section, and a symmetric or asymmetric cross-section including a plurality of flanges and webs are preferable. Things are conceivable. However, it is not necessarily limited to a hollow section.
In the experiment, the extruded material was stopped after applying a constant displacement to give a certain displacement, but at the time of an actual collision, the magnitude of the load differs depending on the collision speed, form, and vehicle weight.
If the collision load applied to the safety member is equal to or less than the maximum resistance load, the collision load is received and the occupant survival space is secured. When a collision load exceeding the maximum load is applied, the safety member buckles the long column. Even in such a case, it is desirable that the bending direction is not directed toward the passenger compartment. Further, a material that does not break due to bending is desirable.

As the safety member, aluminum alloy extruded materials of various compositions can be used. In particular, 6000 series (Al-Mg-
A Si-based or 7000-based (Al-Zn-Mg-based) aluminum alloy is preferable. If it is an Al-Mg-Si based aluminum alloy, Si: 0.2 to 1.5%, Mg;
The one containing 0.4 to 1.3% is desirable, and Al-Z
If it is an n-Mg based aluminum alloy, Mg;
It is desirable to contain 2%, Zn; 4 to 9%. In addition, in both systems, Cu: 0.05 to 0.6%, M
n: 0.05 to 0.6%, Cr: 0.05 to 0.2%,
Any one or more of Zr: 0.05 to 0.2%, and any one or two or more of Ti: 0.005 to 0.2%, or more can be contained. The balance is Al
And unavoidable impurities.

Hereinafter, the composition of the aluminum alloy will be described. (Al-Mg-Si) Si, Mg Si, Mg are elements necessary for maintaining the strength (proof stress) of the aluminum alloy. Si is less than 0.2%, Mg
Is less than 0.4%, the desired strength cannot be obtained. On the other hand, S
If i exceeds 1.5% and Mg exceeds 1.3%, the extrudability of the aluminum alloy decreases and elongation also decreases. Therefore, Si: 0.2 to 1.5%, Mg: 0.4 to 1.3%
And

Cu Cu enhances the strength (proof stress) of the aluminum alloy. Further, Cu has an effect of improving the stress corrosion cracking resistance of the aluminum alloy. The preferred range is Cu: 0.05 to 0.6.
%, The effect is insufficient when the amount is less than the lower limit, and when the amount exceeds the upper limit, extrudability deteriorates and general corrosion resistance also decreases. Mn, Cr, Zr These elements have the effect of increasing the strength (proof stress) of the aluminum alloy, and one or more of these elements are added as appropriate. A preferable range is Mn: 0.05 to 0.6.
%, Cr: 0.05-0.2%, Zr: 0.05-0.
2%. If the respective amounts are less than the lower limits, the above-mentioned effects are insufficient. If the amounts are more than the upper limits, extrudability deteriorates, quenching sensitivity becomes sharp, and quenching becomes difficult.

Ti Ti has the effect of refining the ingot structure. But,
If less than 0.005%, the effect of miniaturization is not sufficient,
If it is more than 0.2%, it is saturated and a huge compound is generated. Therefore, the content of Ti is set to 0.005 to 0.2%. Inevitable impurities Fe is the most inevitable impurity contained in aluminum ingots. If it exceeds 0.35% in the alloy, coarse intermetallic compounds are crystallized during casting and the mechanical properties of the alloy are impaired. . Therefore, the content of Fe is 0.35
% Or less. Further, when casting an aluminum alloy, impurities are mixed from various routes such as a base metal and an intermediate alloy of an additive element. There are various elements to be mixed, but impurities other than Fe alone have 0.05% or less, and if the total amount is 0.15% or less, it hardly affects the properties of the alloy. Therefore, these impurities are set to 0.05% or less in a simple substance, and 0.15% or less in total. In addition, B among impurities is mixed into the alloy in an amount of about 1/5 of the Ti content with the addition of Ti, but a more preferable range is 0.02% or less.
Further, it is desirably 0.01% or less.

(Al-Zn-Mg) Zn, Mg Zn and Mg are elements necessary for maintaining the strength of the aluminum alloy. Zn is less than 4% by weight, Mg is 0.5
%, The desired strength cannot be obtained. Further, when Zn is 9
%, Mg exceeds 2%, the extrudability of the aluminum alloy decreases and elongation also decreases. Therefore, Zn: 4 ~
9%, Mg: 0.5 to 2%. Cu, Mn, Cr, Zr, Ti These elements are added within the above range as needed for the same reason as the Al-Mg-Si system. Inevitable impurities Inevitable impurities are limited to the above range for the same reason as in the Al-Mg-Si system.

[0021]

According to the present invention, the maximum resistance load required for the safety member is determined by a relational expression incorporating the proof stress σ _{0.2 of the} extruded material, the Young's modulus E, and the geometrical shape of the extruded material. This relational expression was derived based on the actually measured values of various aluminum alloy extruded materials, and based on this relational expression, the cross-sectional design of the aluminum alloy extruded material constituting the safety member that satisfies the required maximum resistance load Can be easily performed. And among the geometric shapes satisfying the required maximum resistance load, it is possible to easily obtain a geometrical shape that satisfies the restrictions on the cross-sectional shape for arranging in a narrow space and that can be reduced in weight.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a k value obtained in a compression test and (λ / λ ₀ ).

FIG. 2 is a diagram illustrating an arrangement position of a safety member according to the present invention.

FIG. 3 is a diagram illustrating an arrangement position of a safety member according to the present invention.

FIG. 4 is a view for explaining a compression test method of the present invention, and is a diagram (a) before a long column buckling occurs and a diagram (b) when a long column buckling occurs.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Safety member 2 Test material 3 Fixing jig 4 Pin 5 Movable jig A, C Crushable zone B Safety zone

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masakazu Hirano 14-1, Chofu Minatomachi, Shimonoseki City, Yamaguchi Prefecture Inside the Kofu Steel Works Chofu Works (72) Inventor Toru Hashimura 1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture No. 5 Kobe Steel, Ltd. Kobe Research Institute

Claims (5)

[Claims] 1. A vehicle which is disposed substantially parallel to the front-rear direction of a vehicle on a side surface or a door of a passenger compartment of the vehicle. A safety member for a vehicle that buckles a column, wherein k defined by the following formula (1) is made of an extruded aluminum alloy satisfying the following formulas (2) and (3). (Equation 1) 2. The extruded aluminum alloy is composed of Si;
2 to 1.5% (mass%, the same applies hereinafter), Mg;
The automobile safety member according to claim 1, comprising an Al-Mg-Si aluminum alloy containing 1.3%. 3. The extruded aluminum alloy material is Mg;
Al-Zn-Mg containing 5 to 2%, Zn; 4 to 9%
2. The method according to claim 1, wherein the alloy is made of an aluminum alloy.
An automotive safety member according to claim 1. 4. An aluminum alloy extruded material having a predetermined proof stress σ _0.2 and a Young's modulus E has a length L,
_Assuming that the required value of the maximum load when buckling the long column in the off-axis direction with respect to the compression in the axial direction is P _cr , k defined by the following equation (1) is expressed by the following equations (2) and (3). A cross-sectional design method of an aluminum alloy extruded material, wherein a cross-sectional geometrical shape of the extruded material is designed so as to satisfy. (Equation 2) 5. The aluminum alloy extruded material is disposed substantially parallel to the front-rear direction of the vehicle on the side surface or in the door of a passenger compartment of the vehicle, and has obtained a predetermined maximum load with respect to axial compression in the member axial direction. The method for designing a cross section of an aluminum alloy extruded material according to claim 4, wherein the method is used as a safety member for an automobile that subsequently buckles in a long column in an off-axis direction.