WO2024204278A1 - Structural member for automobile body and automobile body - Google Patents

Abstract

This structural member for an automobile body is a hat-shaped member including: a top plate part; a pair of side wall parts; and a pair of flange parts. Two or more longitudinal-direction beads are formed on the top plate part, and a plurality of height-direction beads are formed on the pair of side wall parts. The height-direction beads each include a pair of bead side walls and a bead bottom wall. In a cross-section perpendicular to the longitudinal direction, an angle a1 on the inner side between the bead bottom wall of the height-direction bead and the top plate part is 90-95 degrees.

Description

Automobile body structural members and automobile bodies

The present invention relates to a structural member for an automobile body and an automobile body.
This application claims priority based on Japanese Patent Application No. 2023-049809, filed on March 27, 2023, the contents of which are incorporated herein by reference.

In recent years, the use of high-tensile steel plates in automotive parts has expanded with the aim of improving automobile collision safety performance and reducing vehicle weight. By using high-tensile steel plates, it is possible to obtain parts with better collision safety performance, or to achieve both collision safety performance and weight reduction through thinner parts.

However, when the thickness of the material is reduced, not only does the rigidity of the steel plate before processing decrease, but the rigidity of the parts after processing also decreases, so there are cases where a sufficient increase in strength in terms of collision safety performance cannot be obtained simply by using a high-strength, thin steel plate.

The collision safety performance of automobile body parts includes the bending crush characteristics of side sills and B-pillars in side collisions, and bumpers in frontal collisions. There is a demand for improving the three-point bending characteristics in local buckling mode to achieve higher collision safety performance even when using thin plate materials.

Patent Document 1 discloses a vehicle crashworthiness reinforcement material with excellent buckling resistance that is designed to have a recessed bead extending along the longitudinal direction of the main body portion to the center of the width of the main body portion.
Patent Document 2 discloses a metal vehicle absorber having concave or convex beads that are approximately parallel to the front-rear direction of the vehicle on one or both of an upper web and a lower web.

Japanese Patent No. 5119477 Japanese Patent No. 4330652

However, the techniques of Patent Documents 1 and 2 were unable to fully demonstrate the three-point bending characteristics of the local buckling mode of the more highly bent crushed parts that were required.

The present invention was made in consideration of the above problems, and the object of the present invention is to provide a structural member that can exhibit superior collision safety performance by improving the load-bearing capacity and preferably the impact absorption energy at the beginning of the stroke of deformation in local buckling mode.

Specific aspects of the present invention are as follows:

(1) A first aspect of the present invention is a structural component for an automobile body, which is a hat-shaped component having a top plate portion extending along a longitudinal direction, a pair of side wall portions extending via a pair of first ridge portions formed at both ends of the top plate portion in a width direction, and a pair of flange portions extending via a pair of second ridge portions formed at ends of the pair of side wall portions opposite to the pair of first ridge portions, wherein two or more longitudinal beads extending along the longitudinal direction are formed in the top plate portion in parallel with each other in the width direction, This structural member for an automobile body is characterized in that a plurality of height-direction beads extending along the height direction are formed in parallel in the longitudinal direction on a pair of side wall portions, each of the height-direction beads having a pair of bead side walls extending and bending inward from the side wall portion, and a bead bottom wall connecting the inner ends of the pair of bead side walls, and in that, in a cross section perpendicular to the longitudinal direction, an inner angle a1 between the bead bottom wall of the height-direction bead and the top plate portion is greater than or equal to 90 degrees and less than 95 degrees.
(2) In the structural component of an automobile body described in (1) above, when the top plate portion is subjected to an input load in the height direction, the distance between the pair of second ridge portions may be deformed to become smaller.
(3) In the structural component of an automobile body described in (1) or (2) above, the inner angle a2 between the side wall portion adjacent to the height bead in the longitudinal direction and the top plate portion may be greater than the angle a1.
(4) In the structural component of an automobile body described in any one of (1) to (3) above, the side wall portion adjacent to the height direction bead has a bending point in a cross section perpendicular to the longitudinal direction where it bends halfway in the height direction, and the angle a21 on the inner side between the top plate portion and a side wall portion proximal to the top plate portion, which is a portion of the side wall portion adjacent to the height direction bead that is closer to the top plate portion than the bending point, may be greater than the angle a1.
(5) In the structural component for an automobile body described in any one of (1) to (4) above, a ratio of a bead depth d21 at the first ridge line portion to a maximum value d2max of a bead depth of the height direction bead of the side wall portion may satisfy at least one of d21/d2max≦0.5 and d21≦2 mm.
(6) In a structural component for an automobile body described in any one of (1) to (5) above, in a cross section perpendicular to the longitudinal direction, two longitudinal beads arranged on the outside may be formed in a region from the boundary point between the top plate portion and the first ridge portion to a point spaced apart in the width direction by a distance of 1/4 of the width of the top plate portion, such that the widthwise centers of the two longitudinal beads arranged on the outside are located in the region.
(7) In a structural component for an automobile body described in any one of (1) to (6) above, in a cross section perpendicular to the longitudinal direction, the two longitudinal beads arranged on the outside may be formed in a region from the boundary point between the top plate portion and the first ridge portion to a point spaced 20 mm apart, so that the boundary point between the two longitudinal beads arranged on the outside and the top plate portion is located in the region.
(8) In the structural component for an automobile body described in any one of (1) to (7) above, the hat-shaped component may be formed from a steel plate having a thickness of 1.2 mm or less.
(9) In the structural component for an automobile body described in any one of (1) to (8) above, the hat-shaped component may be formed from a steel plate having a tensile strength of 980 MPa or more.
(10) In the structural component for an automobile body according to any one of (1) to (9) above, the hat-shaped component may be a hardened component.
(11) In the structural component of an automobile body described in any one of (1) to (10) above, the width of the two longitudinal beads arranged on the outside may be 5 mm to 20 mm, and the depth of the two longitudinal beads arranged on the outside may be 5 mm to 20 mm.
(12) In the structural component of an automobile body described in any one of (1) to (11) above, the aspect ratio calculated from the depth/width of the two longitudinal beads arranged on the outside may be 0.25 to 4.0.
(13) In the structural component for an automobile body described in any one of (1) to (12) above, the height direction bead may extend from the first ridge portion.
(14) In the structural component for an automobile body described in any one of (1) to (13) above, the height direction bead may extend from the second ridge portion.
(15) In the structural component for an automobile body described in any one of (1) to (14) above, the height direction bead may extend from the first ridge portion to the second ridge portion.
(16) In the structural component for an automobile body described in any one of (1) to (15) above, the width of the height direction bead may be 10 mm to 60 mm, and the depth of the height direction bead may be 2 mm to 10 mm.
(17) In the structural component for an automobile body according to any one of (1) to (16) above, the aspect ratio calculated by the depth/width of the height direction bead may be 0.05 to 1.0.
(18) In the structural component of an automobile body described in any one of (1) to (17) above, when the top plate portion receives an input load in the height direction, the top plate portion may deform so that the distance between the pair of second ridge portions becomes smaller at the beginning of the stroke.
(19) In the structural component of an automobile body described in any one of (1) to (18) above, the pair of flange portions of the hat-shaped component may not have a component attached to join the pair of flange portions to each other, at least in the longitudinal center portion thereof.
(20) A second aspect of the present invention is an automobile body having a structural member described in any one of (1) to (18) above, characterized in that the pair of flange portions of the hat-shaped member in the structural member do not have any members attached to join the pair of flange portions to each other, at least in their longitudinal central portion.

The present invention improves the load-bearing capacity and preferably the impact energy absorption capacity at the beginning of the stroke of the local buckling mode deformation, thereby achieving better collision safety performance.

FIG. 1A is a schematic diagram for explaining three-point bending characteristics in local buckling mode, FIG. 1B is a schematic diagram for explaining three-point bending characteristics in wall buckling mode, and FIG. 1C is a schematic diagram for explaining moment bending characteristics. FIG. 2 is a perspective view showing a structural member according to the present embodiment. FIG. 2B is a schematic cross-sectional view of the structural member according to the present embodiment, showing a cross-section along A1-A1' in FIG. 2A. FIG. 2 is a plan view showing a structural member according to the present embodiment. FIG. 4 is a partially enlarged view of a portion B of FIG. 3 . FIG. 4 is a perspective view showing a state after deformation of the structural member according to the embodiment. FIG. 11 is a schematic cross-sectional view showing a structural member according to a first modified example. FIG. 11 is a schematic cross-sectional view showing a structural member according to a second modified example. FIG. 11 is a schematic cross-sectional view showing a structural member according to a third modified example. FIG. 2 is a schematic diagram for explaining three-point bending conditions.

The bending crush characteristics of automobile parts can be broadly divided into three-point bending characteristics, in which the impact of the collision is applied directly to the crushed part of the part, causing deformation, and moment bending characteristics, in which the impact of the collision is applied indirectly to the crushed part of the part, causing deformation.
Among these, the three-point bending characteristics are classified into three-point bending characteristics in a local buckling mode and three-point bending characteristics in a wall buckling mode.
The three-point bending characteristics in the local buckling mode and the three-point bending characteristics in the wall buckling mode are often evaluated based on the three-point bending characteristics obtained by conducting a three-point bending test in which an impactor directly collides with a component, as shown in (a) and (b) of Figure 1.
In the three-point bending characteristic of the local buckling mode, as shown in FIG. 1A, when the distance between the supports supporting the load in the three-point bending test is long, bending deformation occurs mainly at the position where the load is applied by the impactor.
In the three-point bending characteristics of the wall buckling mode, as shown in FIG. 1B, when the distance between the supports supporting the load in the three-point bending test is short, the main deformation is that the side wall is crushed in the part height direction, centered around the position where the load is applied by the impactor.
Furthermore, the moment bending characteristics are often evaluated based on the moment bending characteristics obtained by conducting a moment bending test in which an impactor or the like does not come into contact with the crushed portion of the part, as shown in FIG. 1(c).

The present inventors have studied component shapes for improving collision safety performance against deformation in the local buckling mode as shown in FIG. 1(a) and have obtained the following findings.
(a) In three-point bending where the crushed part comes into contact with the impactor, a combination of compressive stress along the longitudinal direction occurs on the inside of the bent part, compressive stress along the height direction occurs on the side wall of the part, and tensile stress along the longitudinal direction occurs on the outside of the bent part.
(i) Because compressive stress along the height direction occurs in the side walls, the side walls can easily buckle and deform due to compressive stress along the height direction, particularly when the material plate thickness is thin. Even in parts designed to operate in local buckling mode, the deformation state may approach that of wall buckling mode in the early stages of deformation.
(c) When the deformation state approaches the wall buckling mode, if buckling deformation of the side wall easily occurs, not only will good three-point bending characteristics for the wall buckling mode not be obtained, but the crushed side wall will reduce the height of the crushed part, and the bending rigidity in the height direction of the cross section that intersects the longitudinal direction will decrease. Therefore, even if the deformation state reaches the local buckling mode in the subsequent deformation, good three-point bending characteristics for the local buckling mode may not be obtained.
(e) Therefore, by designing a part shape that can simultaneously increase the deformation resistance to compressive stress along the longitudinal direction, the deformation resistance to compressive stress along the height direction, and the deformation resistance to tensile stress along the longitudinal direction, it is possible to improve the load-bearing capacity in deformation in local buckling mode, especially at the beginning of the stroke, and to demonstrate excellent collision safety performance.

The present invention, which was completed based on the above findings, will be described in detail below with reference to the embodiments. Note that in this specification and drawings, components having substantially the same functional configuration are designated by the same reference numerals, and duplicate explanations will be omitted.

In the following description, the axial direction of a structural member, i.e., the direction in which the axis extends, will be referred to as the longitudinal direction Z.
In addition, in a plane perpendicular to the longitudinal direction Z, a direction parallel to the top plate portion is referred to as a width direction X, and a direction perpendicular to the longitudinal direction Z and the width direction X is referred to as a height direction Y.
The direction away from the axis of the structural member is referred to as outward and the opposite direction is referred to as inward.

The following describes a structural member 100 for an automobile body according to an embodiment of the present invention (hereinafter referred to as structural member 100).

First, the schematic configuration of the structural member 100 will be described with reference to FIGS. 2A to 4. FIG.
Fig. 2A is a perspective view of the structural member 100, Fig. 2B is a cross-sectional view taken along the line A1-A1' of Fig. 2A, Fig. 3 is a plan view of the structural member 100, and Fig. 4 is an enlarged partial view of part B of Fig. 3.
2A to 4, the structural member 100 is a member having an open cross-section structure constituted by a hat-shaped member 110. Examples of applications of the structural member 100 include bumper reinforcement bars, door impact bars, and the like.

The structural member 100 in this embodiment is a part that is intended to be installed in an automobile with the top plate portion 111 of the hat-shaped member 110 facing the outside of the vehicle.

Therefore, when an impact load from the outside of the vehicle is input to the hat-shaped member 110 and bending deformation occurs in the structural member 100, as shown in FIG.
A compressive stress (A) along the longitudinal direction Z in the top plate portion 111 of the hat-shaped member 110;
A compressive stress (B) along the height direction Y in the side wall portion 115 of the hat-shaped component 110;
A tensile stress (C) along the longitudinal direction Z in the flange portion 119 of the hat-shaped component 110;
will occur in a complex manner.
Furthermore, the "compressive stress (B) along the height direction Y in the side wall portion 115 of the hat-shaped member 110" can also be rephrased as "compressive stress (B) along a direction perpendicular to the longitudinal direction Z in the side wall portion 115 of the hat-shaped member 110."

As shown in FIGS. 2A to 4, the hat-shaped component 110 has a top plate portion 111 extending along the longitudinal direction Z, a pair of side walls 115, 115, and a pair of flange portions 119, 119.
The hat-shaped member 110 may be a member made of a metal plate such as a steel plate, an aluminum plate, an aluminum alloy plate, a stainless steel plate, or a titanium plate, or further, a resin plate or a CFRP (Carbon Fiber Reinforced Plastic) plate.

(Top plate)
The top plate portion 111 corresponds to a portion that comes into direct contact with an impactor in the three-point bending test of the local buckling mode shown in FIG.
The structural member 100 in this embodiment is installed in an automobile with the top plate portion 111 of the hat-shaped member 110 facing the outside of the vehicle, so that when an impact load from the outside of the vehicle is input to the top plate portion 111, causing bending deformation in the structural member 100, a compressive stress (A) along the longitudinal direction Z is generated in the top plate portion 111.

The width W of the top plate portion 111 may be, for example, 40 mm or more and 200 mm or less. As shown in FIG. 2B, the width W of the top plate portion 111 is the distance in the width direction X between the boundary points of the top plate portion 111 and the first ridge portions 113, 113 at both ends of the top plate portion 111 in a cross section perpendicular to the longitudinal direction Z of the structural member 100. As shown in FIG. 2B, the top plate portion 111 is horizontal, but it may be curved.

(Side wall portion)
The pair of side walls 115, 115 extend via first ridges 113, 113 formed at both ends in the width direction X of the top plate 111. The first ridges 113, 113 have an R portion with a curvature radius of, for example, 1 mm to 10 mm in a cross section perpendicular to the longitudinal direction Z of the structural member 100.
In addition, "through A" means "without through any member other than A." For example, in the above example, only the first ridge portions 113, 113 exist between the pair of side wall portions 115, 115 and the top plate portion 111.
The structural member 100 in this embodiment is installed in an automobile with the top plate portion 111 of the hat-shaped member 110 facing the outside of the vehicle, so that when an impact load from the outside of the vehicle is input to the top plate portion 111, causing bending deformation in the structural member 100, a compressive stress (B) along the height direction Y is generated in the pair of side wall portions 115, 115.

The height H of the side wall 115 may be, for example, 20 mm or more and 150 mm or less. As shown in FIG. 2B, the height H of the side wall 115 is the distance in the height direction Y between the boundary point between the side wall 115 and the first ridge 113 and the boundary point between the side wall 115 and the second ridge 117 in a cross section perpendicular to the longitudinal direction Z of the structural member 100. The second ridges 117, 117 have an R portion with a radius of curvature of, for example, 1 mm to 10 mm in a cross section perpendicular to the longitudinal direction Z of the structural member 100.

(Flange part)
2A , second ridge portions 117, 117 are formed at ends of the pair of side wall portions 115, 115 opposite the first ridge portions 113, 113. The pair of flange portions 119, 119 extend outward via the second ridge portions 117, 117.

(Longitudinal bead)
Two longitudinal beads 150, 150 extending along the longitudinal direction Z are formed in parallel in the width direction X on the top plate portion 111. It should be noted that three or more longitudinal beads 150 may be formed in parallel.
2B, the longitudinal bead 150 is preferably formed so that the center of the longitudinal bead 150 in the width direction X is located in the region from the boundary point between the top plate portion 111 and the first ridge line portion 113 to a point that is a distance of 1/4 of the width W of the top plate portion 111 in the width direction X. More preferably, the longitudinal bead 150 is formed so that the boundary point between the longitudinal bead 150 and the top plate portion 111 is located in the region from the boundary point between the top plate portion 111 and the first ridge line portion 113 to a point that is a distance of 20 mm in a cross section perpendicular to the longitudinal direction.
The longitudinal bead 150 may have an R portion with a predetermined radius of curvature at the end on the top plate portion 111 side. In this case, the longitudinal bead 150 is connected to the top plate portion 111 via the R portion of the longitudinal bead 150.

By providing such a longitudinal bead 150, it is possible to increase the deformation resistance against the compressive stress along the longitudinal direction Z that occurs in the top plate portion 111. As a result, when bending deformation is applied to the structural member 100, the occurrence of early buckling deformation in the top plate portion 111 is suppressed, and the maximum load is increased.

The longitudinal bead 150 may be formed simultaneously using the same mold when the top plate portion 111, the side wall portion 115, and the flange portion 119 are press-molded, or may be formed using a separate mold or tool before the top plate portion 111, the side wall portion 115, and the flange portion 119 are press-molded.

As shown in FIG. 2B , the longitudinal bead 150 is formed by a pair of bead side walls 151 , 151 and a bead bottom wall 152 .
The pair of bead side walls 151, 151 bend and extend inward from the top plate portion 111. In the structural member 100 according to this embodiment, the inward angle θ between the bead side wall 151 and the top plate portion 111 (the inclination angle of the bead side wall 151) is approximately 90 degrees, but the angle θ may be greater than or equal to 90 degrees.
The bead bottom wall 152 extends to connect the ends of the pair of bead side walls 151 , 151 on the opposite side from the top plate portion 111 .

As shown in FIG. 2B, the longitudinal bead 150 has a predetermined depth d1 and a predetermined width w1.

The depth d1 of the longitudinal bead 150 is the distance in the height direction Y from the outer surface of the top plate portion 111 to the outer surface of the bead bottom wall 152 in the longitudinal bead 150. If the longitudinal bead 150 has a shape whose depth changes along the longitudinal direction Z, the maximum value of the distance in the height direction Y from the top plate portion 111 to the bead bottom wall 152 is defined as the depth d1.

The greater the depth d1 of the longitudinal bead 150, the greater the deformation resistance to compressive stress along the longitudinal direction Z that occurs in the top plate portion 111, suppressing early buckling deformation in the top plate portion 111 and increasing the maximum load. Therefore, the depth d1 of the longitudinal bead 150 is preferably 5 mm or more, and more preferably 8 mm or more.

On the other hand, if the depth d1 of the longitudinal bead 150 is too large, the pair of bead side walls 151, 151 may easily collapse in a direction approaching each other immediately after an impact load from the outside of the vehicle is input to the top plate portion 111. If the pair of bead side walls 151, 151 easily collapse in a direction approaching each other, the pair of side wall portions 115, 115 may also easily collapse in a direction approaching each other. In this case, while the pair of bead side walls 151, 151 are collapsing in a direction approaching each other, the time when the deformation resistance against the compressive stress along the longitudinal direction Z generated in the top plate portion 111 increases may be delayed. Furthermore, if the depth d1 of the longitudinal bead 150 is too large, it may be difficult to mold the longitudinal bead 150 if the width w1 of the longitudinal bead 150 is relatively small. Therefore, the depth d1 of the longitudinal bead 150 is preferably 20 mm or less, and more preferably 16 mm or less.

The width w1 of the longitudinal bead 150 is the distance between the intersection of a virtual line extending one bead side wall 151 of the longitudinal bead 150 and a virtual line extending the top plate portion 111, and the intersection of a virtual line extending the other bead side wall 151 of the longitudinal bead 150 and a virtual line extending the top plate portion 111, in a cross section perpendicular to the longitudinal direction Z.
When the longitudinal bead 150 has a shape whose width changes along the longitudinal direction Z, the separation distance in the cross section where the separation distance is maximum is defined as width w1.

The smaller the width w1 of the longitudinal bead 150, the higher the deformation resistance against the compressive stress along the longitudinal direction Z that occurs in the top plate portion 111, suppressing early buckling deformation in the top plate portion 111 and increasing the maximum load. Therefore, the width w1 of the longitudinal bead 150 is preferably 20 mm or less, and more preferably 15 mm or less.

On the other hand, if the width w1 of the longitudinal bead 150 is too small, and the depth d1 of the longitudinal bead 150 is relatively large, it may be difficult to mold the longitudinal bead 150. For this reason, it is preferable that the width w1 of the longitudinal bead 150 is 5 mm or more, and more preferably 8 mm or more.

The longitudinal bead 150 does not necessarily have to be formed over the entire length of the top plate portion 111 in the longitudinal direction Z, but may be formed over a portion of the entire length of the top plate portion 111. The position at which the longitudinal bead 150 is formed may be selected to be the position where the bending crushing characteristics of the structural member 100 should be most strengthened, for example, the position where the impactor comes into contact and its vicinity. The longitudinal bead 150 may also be formed at multiple locations in the longitudinal direction Z.

As described above, the depth d1 and width w1 of the longitudinal bead 150 affect the deformation resistance to the compressive stress along the longitudinal direction Z that occurs in the top plate portion 111. It is preferable that the aspect ratio A1 calculated by the depth d1 relative to the width w1 of the longitudinal bead 150 (depth d1/width w1) is 0.25 or more and 4.0 or less, since this can more reliably achieve the effect of increasing the deformation resistance to the compressive stress along the longitudinal direction Z that occurs in the top plate portion 111. It is even more preferable that the aspect ratio A1 is 0.5 or more and 2.0 or less.

(Height bead)
A plurality of height direction beads 160 extending along the height direction Y are formed in parallel in the longitudinal direction Z on the side wall portion 115 .
In the example shown in Figures 3 and 4, the height direction bead 160 is formed over the entire height of the side wall portion 115 in the height direction Y, but the height direction bead 160 may be formed over only a portion of the entire height direction.
The height direction bead 160 is formed so as to protrude inward from the side wall portion 115 .
The height direction bead 160 may have an R portion with a predetermined radius of curvature at the end portion on the side wall portion 115 side. In this case, the height direction bead 160 is connected to the side wall portion 115 via the R portion of the height direction bead 160.
The provision of such height direction beads 160 can increase the deformation resistance against the compressive stress (B) along the height direction Y generated in the side wall portion 115. As a result, early buckling deformation in the side wall portion 115 is suppressed, and the maximum load is increased.

In the structural member 100 according to this embodiment, the height direction bead 160 is formed so as to extend from the first ridge portion 113 to the second ridge portion 117 .
Since the height direction bead 160 is formed to extend from the first ridge line portion 113, the height direction bead 160 also contributes to the deformation resistance of the first ridge line portion 113 against the compressive stress (B) along the height direction Y, making the first ridge line portion 113 less likely to be crushed. Since the first ridge line portion 113 is less likely to be crushed, the upper part of the side wall portion 115 connected to the first ridge line portion 113 is also less likely to be crushed. Since the first ridge line portion 113 and the side wall portion 115 are less likely to be crushed, a decrease in bending rigidity in the height direction Y of the cross section intersecting the longitudinal direction Z due to a decrease in the height of the structural member 100 is suppressed, and a decrease in the three-point bending characteristics in the local buckling mode can be prevented, which is preferable. Furthermore, in this manner, when the height-direction bead 160 is formed to extend from the first ridge portion 113, a step is formed along the longitudinal direction Z of the first ridge portion 113 between a portion of the bead bottom wall 162 of the height-direction bead 160 and a portion of the side wall portion 115 where the height-direction bead is not formed.

Furthermore, by forming the height direction bead 160 so as to extend from the first ridge portion 113 to the second ridge portion 117, the height direction bead 160 also contributes to the deformation resistance of the second ridge portion 117 against the compressive stress (B) along the height direction Y, making the second ridge portion 117 less likely to be crushed. Therefore, since the first ridge portion 113, the side wall portion 115, and the second ridge portion 117 are less likely to be crushed, the decrease in bending rigidity in the height direction Y of the cross section intersecting the longitudinal direction Z due to the reduction in the height of the structural member 100 is further suppressed, and the decrease in the three-point bending characteristics in the local buckling mode can be further prevented, which is preferable.

The height direction bead 160 is formed by a pair of bead side walls 161 , 161 and a bead bottom wall 162 .
The pair of bead side walls 161 , 161 extend inwardly from the side wall portion 115 while bending.
The bead bottom wall 162 connects the inner ends of the pair of bead side walls 161, 161 to each other.

As shown in FIG. 4, the vertical bead 160 has a predetermined depth d2 and a predetermined width w2.

The depth d2 of the height direction bead 160 is the distance in the width direction X from the outer surface of the side wall portion 115 to the outer surface of the bead bottom wall 162 in the height direction bead 160. If the height direction bead 160 has a shape whose depth changes along the height direction Y, the maximum value of the distance in the width direction X from the side wall portion 115 to the bead bottom wall 162 is defined as the depth d2.

The greater the depth d2 of the height direction bead 160, the greater the deformation resistance to the compressive stress (B) along the height direction Y that occurs in the side wall portion 115. Therefore, the depth d2 of the height direction bead 160 is preferably 2 mm or more, and more preferably 4 mm or more.

On the other hand, if the depth d2 of the height direction bead 160 is too large, the dimension in the width direction X of the structural member 100 becomes locally small, and the bending rigidity in the cross section intersecting the longitudinal direction Z becomes too small, so that the desired three-point bending characteristics may not be obtained. In addition, in a configuration in which the longitudinal bead 150 is formed in the portion near the end of the width direction X of the top plate portion 111, if the depth d2 of the height direction bead 160 is too large, the longitudinal bead 150 may not be formed at the desired position. Furthermore, if the depth d2 of the height direction bead 160 is too large, it may be difficult to mold the height direction bead 160 if the width w2 of the height direction bead 160 is relatively small. Therefore, the depth d2 of the height direction bead 160 is preferably 10 mm or less, and more preferably 8 mm or less.

The multiple height-direction beads 160 are preferably formed with an inter-bead distance of 50 mm or less in the longitudinal direction Z of the side wall portion 115, and more preferably with an inter-bead distance of 30 mm or less. In this case, it is possible to further increase the deformation resistance against the compressive stress (B) along the height direction Y generated in the side wall portion 115. Note that the inter-bead distance means the distance between one end of the height-direction bead 160 (end in one direction of the longitudinal direction Z) and the other end of the adjacent height-direction bead 160 (end in the other direction of the longitudinal direction Z), as shown in FIG. 4.

The plurality of height-direction beads 160 do not need to be formed over the entire length of the side wall portion 115 in the longitudinal direction Z, but may be formed over a portion of the entire length of the side wall portion 115 in the longitudinal direction Z. The positions at which the plurality of height-direction beads 160 are formed may be selected as positions at which the bending crushing characteristics of the structural member 100 should be most strengthened, for example, the position where the impactor comes into contact and its vicinity.
Furthermore, the multiple height-direction beads 160 do not need to be formed side by side on the side wall portion 115 with equal bead-to-bead distances; for example, when three height-direction beads 160 are formed, the two bead-to-bead distances may be different values.
Furthermore, the plurality of height direction beads 160 do not necessarily have to be formed at the same position in the longitudinal direction Z on the pair of side wall portions 115, 115. For example, at the same position in the longitudinal direction Z as the height direction bead 160 formed on one side wall portion 115, the height direction bead 160 does not have to be formed on the other side wall portion 115.
It is also preferable that the longitudinal bead 150 and the height bead 160 are located at the same position in the longitudinal direction Z. In this case, the load resistance and preferably the impact absorption energy at the beginning of the stroke can be improved more reliably.

The width w2 of the height-wise bead 160 is the distance between the intersection of a virtual line extending the outer surface of one bead side wall 161 of the height-wise bead 160 with a virtual line extending the outer surface of the side wall portion 115, and the intersection of a virtual line extending the outer surface of the other bead side wall 161 of the height-wise bead 160 with a virtual line extending the outer surface of the side wall portion 115, in a cross section perpendicular to the height direction Y.
When the height direction bead 160 has a shape whose width changes along a direction intersecting the longitudinal direction Z, the separation distance in the cross section where the separation distance is maximum is defined as width w2.

The smaller the width w2 of the height direction bead 160, the higher the deformation resistance against the compressive stress (B) along the height direction Y that occurs in the side wall portion 115. Therefore, the width w2 of the height direction bead 160 is preferably 60 mm or less, and more preferably 40 mm or less.

On the other hand, if the width w2 of the height direction bead 160 is too small, and the depth d2 of the height direction bead 160 is relatively large, it may be difficult to mold the height direction bead 160. Therefore, it is preferable that the width w2 of the height direction bead 160 is 10 mm or more, and it is even more preferable that it is 15 mm or more.

As described above, the depth d2 and width w2 of the height direction bead 160 affect the deformation resistance to the compressive stress (B) along the height direction Y that occurs in the side wall portion 115. When the aspect ratio A2 calculated by the depth d2 relative to the width w2 of the height direction bead 160 (depth d2/width w2) is 0.05 or more and 1.0 or less, this is preferable because it can more reliably exert the effect of increasing the deformation resistance to the compressive stress (B) along the height direction Y that occurs in the side wall portion 115. It is even more preferable that the aspect ratio A2 is 0.1 or more and 0.5 or less.

(Height bead angle)
Next, the angle of the height direction bead 160 will be described based on FIG. 2B. As shown in FIG. 2B, in a cross section perpendicular to the longitudinal direction Z, the angle a1 between the bead bottom wall 162 of the height direction bead 160 and the top plate portion 111 is 90 degrees or more and 95 degrees or less. Here, the angle a1 is, more specifically, an inner angle formed by a virtual line extending the outer surface of the top plate portion 111 and a virtual line extending the outer surface of the bead bottom wall 162. In the example of FIG. 2B, the angle a1 is 90 degrees. As shown in the examples described later, by setting the angle a1 to 90 degrees or more and 95 degrees or less, it is possible to increase the deformation resistance against the compressive stress (B) along the height direction Y generated in the side wall portion 115. As a result, it is possible to improve the load capacity and the impact absorption energy at the beginning of the stroke of the deformation in the local buckling mode.
The angle a1 may be constant regardless of the position in the height direction Y of the bead bottom wall 162, or may be varied depending on the position in the height direction Y of the bead bottom wall 162. An example in which the angle a1 varies will be described later.

In a cross section perpendicular to the longitudinal direction Z, the angle a2 between the side wall portion 115 adjacent to the height bead 160 in the longitudinal direction Z and the top plate portion 111 is equal to the angle a1. More specifically, the angle a2 is the inner angle between an imaginary line extending the outer surface of the top plate portion 111 and an imaginary line extending the outer surface of the side wall portion 115. The angle a2 may be constant regardless of the position of the side wall portion 115 in the height direction Y, or may vary depending on the position of the side wall portion 115 in the height direction Y. An example of the variation of the angle a2 will be described later.

From the viewpoint of reducing weight, the hat-shaped component 110 is preferably formed from a steel plate having a thickness of 1.2 mm or less, and more preferably from a steel plate having a thickness of 1.0 mm or less.
The lower limit of the thickness of the hat-shaped component 110 is not particularly limited, and may be 0.3 mm or more.
Furthermore, from the viewpoint of collision safety performance, the hat-shaped member 110 is preferably formed from a steel plate having a tensile strength of 980 MPa or more, and more preferably from a steel plate having a tensile strength of 1470 MPa or more.

The hat-shaped member 110 can be formed, for example, by subjecting a plate material to cold pressing or warm pressing.
The hat-shaped member 110 may also be formed by hot stamping, in which a steel plate is heated to a high temperature in the austenite region, and then press-formed in a die, and simultaneously quenched in the die by a method such as heat extraction into the die or water cooling in the die. Thus, the hat-shaped member 110 may be a quenched member.

According to the structural member 100 of this embodiment, when an impact load from outside the vehicle is input to the top plate portion 111 and bending deformation occurs in the structural member 100, it is possible to exert a combination of deformation resistance to compressive stress (A) along the longitudinal direction Z, deformation resistance to compressive stress (B) along the height direction Y, and deformation resistance to tensile stress (C) along the longitudinal direction Z.
In particular, since the angle a1 is set to be equal to or greater than 90 degrees and equal to or less than 95 degrees, it is possible to increase the deformation resistance against the compressive stress (B) along the height direction Y generated in the side wall portion 115. As a result, it is possible to improve the load resistance and the shock absorption energy in the initial stage of the stroke in the local buckling mode of deformation.

Since the thinner the plate material, the lower the deformation resistance, the conventional method has been one of the barriers to weight reduction by using thin, high-strength materials. That is, even if the deformation resistance of the top plate 111 against the compressive stress (A) along the longitudinal direction Z is increased by increasing the strength or designing the part shape, the structural member 100 cannot exhibit good three-point bending characteristics if the side wall 115 is easily buckled due to bending deformation or the like due to the thinning. Conversely, even if the deformation resistance of the side wall 115 against the compressive stress (B) in the direction intersecting the longitudinal direction Z is increased by increasing the strength or designing the part shape, the structural member cannot exhibit good three-point bending characteristics if the top plate 111 is easily buckled due to bending deformation or the like due to the thinning.
As described above, the structural member 100 of this embodiment can exert a composite deformation resistance at each portion, making it possible to exert excellent collision safety performance even when using a thin-walled, high-strength material.

(First Modification)
Next, a first modified example of the structural member 100 (structural member 100A) will be described based on FIG. 6. FIG. 6 is a cross-sectional view perpendicular to the longitudinal direction Z of the structural member 100A. In this structural member 100A, the angle a2 is larger than the angle a1. Furthermore, the ratio d21/d2 max of the depth d21 of the height direction bead 160 at the first ridge line portion 113 to the maximum value d2 _max of the depth d2 of _the height direction bead 160 is 0.5 or less. Note that d21 may be 2 mm or less. The lower limit of d21 is not particularly limited and may be 0 mm. Therefore, in the first modified example, the depth d2 of the height direction bead 160 gradually changes (gradually increases in the height direction (more specifically, in the direction from the top plate side to the flange side)). According to the first modified example, the load capacity and impact absorption energy at the beginning of the stroke of the deformation in the local buckling mode can be improved. In order to obtain this effect more stably, it is preferable that angle a2 is larger than angle a1 by 2° or more, and angle a2 is preferably equal to or smaller than 100°. In other words, it is preferable that angle a1 and angle a2 satisfy a1+2°≦a2≦100°.

(Second Modification)
Next, a second modified example of the structural member 100 (structural member 100B) will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view perpendicular to the longitudinal direction Z of the structural member 100B. In this structural member 100B, the bead bottom wall 162 has a bending point b1 at which the bead bottom wall 162 bends midway in the height direction Y. The bead bottom wall 162 is divided into a top plate proximal bead bottom wall 162a, which is a portion closer to the top plate 111 than the bending point b1, and a top plate distal bead bottom wall 162b, which is opposite to the top plate proximal bead bottom wall 162a. The angle a11 between the top plate proximal bead bottom wall 162a and the top plate 111 is 90 degrees or more and 95 degrees or less. Here, the angle a11 is, more specifically, the inner angle formed by a virtual line extending the outer surface of the top plate portion 111 and a virtual line extending the outer surface of the top plate portion proximal bead bottom wall 162a. The angle a12 between the top plate portion distal bead bottom wall 162b and the top plate portion 111 is larger than the angle a11. Here, the angle a12 is, more specifically, the inner angle formed by a virtual line extending the outer surface of the top plate portion 111 and a virtual line extending the outer surface of the top plate portion distal bead bottom wall 162b. In addition, in FIG. 7, the angle a12 is drawn as the angle formed by a two-dot chain line (corresponding to a virtual line extending the outer surface of the top plate portion 111) that passes through the bending point b1 and is parallel to the top plate portion 111 and a virtual line extending the outer surface of the top plate portion distal bead bottom wall 162b. The angle a2 is equal to the angle a12, but the two may be different. Furthermore, the ratio d21/d2 _max of the depth d21 of the height direction bead 160 at the first ridge portion 113 to the maximum value d2 _max of the depth d2 of the height direction bead 160 is 0.5 or less. Note that d21 may be 2 mm or less. The lower limit of d21 is not particularly limited and may be 0 mm. Therefore, in the second modified example, the depth d2 of the height direction bead 160 gradually changes (gradually increases in the height direction (more specifically, in the direction from the top plate side to the flange side)) above the bending point b1. According to the second modified example, the load capacity and the shock absorption energy at the beginning of the stroke of the deformation in the local buckling mode can be improved.

(Third Modification)
Next, a third modified example of the structural member 100 (structural member 100C) will be described with reference to FIG. 8. FIG. 8 is a cross-sectional view perpendicular to the longitudinal direction Z of the structural member 100C. In this structural member 100C, the side wall portion 115 adjacent to the height direction bead 160 has a bending point b2 that bends in the middle of the height direction Y in a cross-section perpendicular to the longitudinal direction Z. The side wall portion 115 adjacent to the height direction bead 160 is divided into a proximal side wall portion 115a of the top plate portion, which is a portion closer to the top plate portion 111 than the bending point b2, and a distal side wall portion 115b of the top plate portion opposite the proximal side wall portion 115a of the top plate portion. The angle a21 between the proximal side wall portion 115a of the top plate portion and the top plate portion 111 is larger than the angle a1. Here, the angle a21 is, more specifically, the inner angle formed by a virtual line extending the outer surface of the top plate 111 and a virtual line extending the outer surface of the top plate proximal sidewall 115a. The angle a22 between the top plate distal sidewall 115b and the top plate 111 is equal to the angle a1, but the two may be different. Here, the angle a22 is, more specifically, the inner angle formed by a virtual line extending the outer surface of the top plate 111 and a virtual line extending the outer surface of the top plate distal sidewall 115b. In FIG. 8, the angle a22 is depicted as the inner angle formed by a two-dot chain line (corresponding to a virtual line extending the outer surface of the top plate 111) that passes through the bending point b2 and is parallel to the top plate 111, and a virtual line extending the outer surface of the top plate distal sidewall 115b. Furthermore, the ratio d21/d2 _max of the depth d2 of the height bead 160 at the first ridge portion 113 to the maximum value d2 _max of the depth d2 of the height bead 160 is 0.5 or less. Note that d21 may be 2 mm or less. The lower limit of d21 is not particularly limited and may be 0 mm. Therefore, in the third modified example, the depth d2 of the height bead 160 gradually changes (gradually increases in the height direction (more specifically, in the direction from the top plate side to the flange side)) above the bending point b2. According to the third modified example, the load capacity and impact absorption energy at the beginning of the stroke of the deformation in the local buckling mode can be improved. In order to obtain this effect more stably, it is preferable that the angle a21 is 4° or more larger than the angle a1, and the angle a21 is preferably 105° or less. That is, it is preferable that the angle a1 and the angle a21 satisfy a1+4°≦a21≦105°.

Here, it is preferable that the structural member 100 deforms so that the distance between the pair of second ridge portions 117 becomes smaller when the top plate portion 111 receives an input load in the height direction Y. More specifically, the "input load" referred to here means an input load caused by pressing an impactor against the center of the top plate portion 111 in the longitudinal direction Z at 60 mm/min with the flange portion 119 of the structural member 100 in the vicinity of both longitudinal ends placed on a pair of supports as shown in Fig. 9 .
More specifically, "near both ends of the flange portion 119 of the structural member 100 in the longitudinal direction" refers to a position 50 mm away from the end in the longitudinal direction Z, and each of the "pair of support bases" is a long member with a semicircular cross section with a radius of curvature of 30 mm, and the impactor is a long member with a semicircular cross section with a radius of curvature of 50 mm. In addition, assuming that the structural member 100 is assembled as an automobile part, in order to simulate the end of the structural member 100 being restrained by being connected to another part, in the portion placed on the pair of support bases near both ends of the structural member 100, a plate-shaped mild steel with a thickness of 15 mm is fitted inside the cross section, thereby maintaining the cross-sectional shape of both ends of the structural member 100 during the three-point bending test. The distance between the pair of support bases is 700 mm. However, if the total length of the structural member 100 is less than 800 mm, the distance between the pair of support bases is the total length of the structural member 100 minus 100 mm.
Under these conditions, when an input load is applied in the height direction Y, it is preferable that the deformation occurs so that the distance between the pair of second ridge portions 117 becomes smaller at least until the initial stroke of 10 mm is reached.
When deformation progresses such that the distance between the pair of second ridges 117 increases, the sidewalls 115 open in the width direction X, reducing the height of the structural member 100 and reducing the bending rigidity in the height direction Y of the cross section perpendicular to the longitudinal direction Z. This is because the three-point bending characteristics of the local buckling mode may decrease. In this regard, in the first to third modified examples described above, the depth d2 of the height direction bead 160 in the vicinity of the top plate 111 is reduced. Therefore, in the initial stroke, the sidewalls 115 in the vicinity of the top plate 111 are crushed while bulging outward. However, thereafter, the height direction bead 160 is deformed so that the distance between the second ridges 117 decreases while withstanding the input load. Or, even if the distance between the second ridges 117 increases, the timing of this can be delayed. As a result, in the first to third modified examples, the load resistance and impact absorption energy in the initial stroke of the deformation in the local buckling mode can be further improved.

In the above-described embodiment and each modified example, the top plate portion 111, the side wall portion 115, and the bead bottom wall 162 are linear in a cross section perpendicular to the longitudinal direction Z, but they may be curved. In addition, the shape (broken line) at the bending point may also be curved.
The curved shape here is not limited to a curve in a cross section perpendicular to the longitudinal direction Z, but also includes a curve in the longitudinal direction of the member, i.e., a curve in the height direction (up and down direction) and width direction (left and right direction). In this case, the shape of the top plate portion 111, the side wall portion 115, and the bead bottom wall 162 in a cross section perpendicular to the longitudinal direction Z is a straight line connecting both ends of the length direction of each part in the cross section (for example, a straight line is drawn connecting both ends of the width direction (length direction of the top plate portion 111) of the top plate portion 111 in a cross section perpendicular to the longitudinal direction Z, and this straight line is assumed to be the top plate portion 111), and the above-mentioned parameters (for example, angle a1) may be defined.

(Automobile body)
The automobile body according to this embodiment includes any one of the above-mentioned structural members 100, 100A to 100C. In the structural members 100, 100A to 100C, the pair of flange portions 119 of the hat-shaped member 110 do not have a member attached to join the pair of flange portions 119 to each other at least in the longitudinal center portion.

(Example)
The effects of the present invention will be specifically described below with reference to examples. Note that the examples described below are merely examples of the present invention and do not limit the present invention.

A simulation model of a structural member composed of hat-shaped members using steel plates with a thickness of 0.8 mm and a tensile strength of 2.5 GPa was prepared.
A simulation model of the structural member was appropriately given longitudinal and height beads, and a simulation was performed assuming three-point bending to evaluate the maximum load at the beginning of the stroke and the impact absorption energy up to a stroke of 100 mm. In addition, a three-point bending simulation was also performed on a structural member that did not have longitudinal and height beads as a standard or comparative example. The basic conditions, the conditions of the comparative example, and the conditions of each example of the invention are as follows. In this example, the inclination angle of the bead side wall of the longitudinal bead placed on the top plate was set to 95 degrees with respect to the top plate.
(Basic conditions)
Width of top plate W = 70 mm
Side wall height H = 50 mm
Radius of curvature of first ridge (inner bend) = 5 mm
Radius of curvature of the second ridge (inner bend) = 5 mm
Total length of structural member L = 800 mm
Longitudinal bead depth d1 = 10 mm
Width of longitudinal bead w1 = 10 mm
Height direction bead width w2 = 24 mm
Distance between beads in the height direction = 16 mm
Comparative Example
Angle between the side wall and the top plate on the inner side = 95 degrees Formation of height direction bead and longitudinal direction bead: None (corresponding to invention example 1: embodiment)
Angle a1 = Angle a2 = 95 degrees Height direction bead depth d2 = 4 mm (constant)
(Example 2: Corresponding to the embodiment)
Angle a1 = Angle a2 = 90 degrees Height direction bead depth d2 = 4 mm (constant)
(Example 3: Corresponding to the third modified example)
Angle a1 = 90.9 degrees Angle a21 = 99.8 degrees > Angle a1
Angle a22 = Angle a1
Bend point b2: Located in the middle of the height H of the side wall portion Maximum value of height direction bead depth d2 d2 _max = 4 mm
(Example 4: Corresponding to the first modified example)
Angle a1 = 90.9 degrees Angle a2 = 95 degrees > Angle a1
Maximum value of height direction bead depth d2 d2 _max = 3.6 mm

The three-point bending conditions were set as follows: the impactor radius of curvature was 50 mm, and the support stand separation distance was 700 mm, as shown in Fig. 9. The maximum load at the beginning of the stroke and the impact energy absorption up to a stroke of 100 mm are shown in Table 1. The reference ratios in Table 1 are values expressed as percentages relative to the values (maximum load and impact energy absorption amount) of the comparative example.
In the comparative example, the side wall portion buckled early from the beginning of the stroke, and the structural members were significantly deformed, so that the maximum load and the impact absorption energy at the beginning of the stroke were low.
In Examples 1 and 2, the maximum load at the beginning of the stroke was significantly improved compared to the Comparative Example. This is believed to be because the height-direction bead increased the rigidity of the side wall, suppressing buckling of the side wall at the beginning of the stroke, and the longitudinal bead increased the deformation resistance against compressive stress along the longitudinal direction that occurs in the top plate. However, after the beginning of the stroke, the side wall deformed in the outward direction, reducing the load capacity, and the impact absorption energy of Example 1 was slightly reduced. In Example 2, the impact absorption energy was only slightly improved from the Comparative Example.
In the invention examples 3 and 4, the maximum load at the beginning of the stroke was also significantly improved compared to the comparative example. This is believed to be because the height direction bead increased the rigidity of the side wall, suppressing buckling of the side wall at the beginning of the stroke, and the longitudinal direction bead increased the deformation resistance against the compressive stress along the longitudinal direction generated in the top plate. However, since the depth d2 of the height direction bead at the upper part of the side wall is small, the upper part of the side wall is slightly more likely to buckle at the beginning of the stroke than the invention examples 1 and 2. Therefore, the maximum load at the beginning of the stroke was slightly lower than the invention examples 1 and 2. After the beginning of the stroke, the buckling of the upper part of the side wall suppressed the side wall from opening outward, so the height direction bead and the longitudinal direction bead fully functioned, and the load capacity was higher than the invention examples 1 and 2. As a result, the impact absorption energy was higher than the invention examples 1 and 2.

The present invention provides a structural member that can exhibit superior collision safety performance by improving the load-bearing capacity and preferably the impact energy absorption capacity at the beginning of the stroke of deformation in local buckling mode.

100, 100A, 100B, 100C Structural member 110 Hat-shaped member 111 Top plate portion 113 First ridge portion 115 Side wall portion 117 Second ridge portion 119 Flange portion 150 Longitudinal bead 151 Bead side wall 152 Bead bottom wall 160 Height direction bead 161 Bead side wall 162 Bead bottom wall X Width direction Y Height direction Z Longitudinal direction

Claims (20)

A top plate portion extending along a longitudinal direction;
A pair of side walls extending through a pair of first ridges formed at both ends of the top plate in a width direction;
a pair of flange portions extending via a pair of second ridge portions formed at ends of the pair of side wall portions opposite to the pair of first ridge portions;
A structural member of an automobile body which is a hat-shaped member having
Two or more longitudinal beads extending along the longitudinal direction are formed in parallel in the width direction on the top plate portion,
A plurality of height-direction beads extending along a height direction are formed in the pair of side wall portions and are arranged in parallel in the longitudinal direction,
Each of the height beads is
A pair of bead side walls extending inwardly from the side wall portion;
a bead bottom wall connecting inner ends of the pair of bead side walls;
Equipped with
A structural member for an automobile body, characterized in that in a cross section perpendicular to the longitudinal direction, an inner angle a1 between the bead bottom wall of the height direction bead and the top plate portion is 90 degrees or more and 95 degrees or less. The structural member of an automobile body according to claim 1, characterized in that when the top plate portion receives an input load in the height direction, it deforms so that the distance between the pair of second ridge portions becomes smaller. 2. A structural member for an automobile body according to claim 1, wherein an inner angle a2 between the side wall portion adjacent to the height direction bead in the longitudinal direction and the top plate portion is larger than the angle a1. A structural member of an automobile body as described in claim 1, characterized in that the side wall portion adjacent to the height direction bead in the longitudinal direction has a bending point where it bends halfway in the height direction in a cross section perpendicular to the longitudinal direction, and the inner angle a21 between the top plate portion and a side wall portion proximal to the top plate portion, which is a portion of the side wall portion adjacent to the height direction bead that is closer to the top plate portion than the bending point, is greater than the angle a1. 2. The structural member of an automobile body according to claim 1, wherein a ratio of a bead depth d21 at the first ridge line portion to a maximum value _d2max of a bead depth of the height direction bead of the side wall portion satisfies at least one of d21/ _d2max ≦0.5 and d21≦2 mm. A structural member of an automobile body as described in any one of claims 1 to 5, characterized in that in a cross section perpendicular to the longitudinal direction, two longitudinal beads arranged on the outside are formed in an area from the boundary point between the top plate portion and the first ridge portion to a point that is spaced apart in the width direction by a distance of 1/4 of the width of the top plate portion, such that the widthwise centers of the two longitudinal beads arranged on the outside are located in the area. A structural member of an automobile body as described in any one of claims 1 to 5, characterized in that in a cross section perpendicular to the longitudinal direction, two longitudinal beads arranged on the outside are formed in an area from the boundary point between the top plate portion and the first ridge portion to a point spaced 20 mm apart, such that the boundary point between the two longitudinal beads arranged on the outside and the top plate portion is located. 6. A structural member for an automobile body according to claim 1, wherein the hat-shaped member is formed from a steel plate having a thickness of 1.2 mm or less. 6. A structural member for an automobile body according to claim 1, wherein the hat-shaped member is formed from a steel plate having a tensile strength of 980 MPa or more. 6. The structural member for an automobile body according to claim 1, wherein the hat-shaped member is a hardened member. The width of the two longitudinal beads arranged on the outside is 5 mm to 20 mm,
6. A structural member for an automobile body according to claim 1, characterized in that the depth of the two longitudinal beads arranged on the outside is 5 mm to 20 mm. A structural member for an automobile body according to any one of claims 1 to 5, characterized in that the aspect ratio calculated by the depth/width of the two longitudinal beads arranged on the outside is 0.25 to 4.0. 6. The structural component for an automobile body according to claim 1, wherein the height direction bead extends from the first ridge line portion. 6. The structural component for an automobile body according to claim 1, wherein the height direction bead extends from the second ridge line portion. 6. The structural component for an automobile body according to claim 1, wherein the height direction bead extends from the first ridge line portion to the second ridge line portion. The width of the height direction bead is 10 mm to 60 mm,
6. The structural member for an automobile body according to claim 1, wherein the depth of the bead in the height direction is 2 mm to 10 mm. 6. The structural member for an automobile body according to claim 1, wherein an aspect ratio calculated by dividing the height direction bead by its depth/width is 0.05 to 1.0. A structural member for an automobile body as described in any one of claims 1 to 5, characterized in that when the top plate portion is subjected to an input load in the height direction, at the beginning of the stroke, the distance between the pair of second ridge portions is deformed to become smaller. A structural member of an automobile body as described in any one of claims 1 to 5, characterized in that the pair of flange portions of the hat-shaped member do not have any members attached to join the pair of flange portions to each other, at least in their longitudinal central portion. An automobile body having a structural member according to any one of claims 1 to 5,
An automobile body, characterized in that in the structural component, the pair of flange portions of the hat-shaped component do not have any members attached to join the pair of flange portions to each other, at least in their longitudinal central portion.

Images