columnar member

Abstract

Provided is a columnar member which is capable of absorbing more energy in collision without an increase in weight.　A columnar member 100 comprises at least: a top board 12; and two longitudinal walls 14, 16 which are connected to the top board 12 on respective ridges 15 at both side edges 12a, 12b of the top board, and which extend along the respective ridges 15, wherein: at least part of the top board 12 has a bend inducing part 22; the two longitudinal walls 14, 16 have respective soft parts 14b, 16b, at positions that are adjacent to the ridges 15 and that correspond to the bend inducing part 22 in the direction in which the columnar member 100 extends; the bend inducing part 22 has strength lower than that of portions adjacent to the bend inducing part 22 in the top board 12; the soft parts 14b, 16b have yield strength lower than that of portions adjacent to the soft parts 14b, 16b in the longitudinal walls 14, 16; and the maximum lengths of the soft parts 14b, 16b in the direction in which the columnar member 100 extends are 0.01-0.15 times the heights of the longitudinal walls 14, 16.

Description

[Technical Field]

[0001] The present invention relates to a columnar member. [Background technology]

[0002] To reduce the vehicle weight and increase its rigidity, automobile bodies are constructed by welding together columnar members formed by plastically deforming thin plates into a hat-shaped cross section. Furthermore, to ensure a survival space in the passenger compartment in the event of a car collision, these columnar members are required to have high maximum reaction force and absorbed energy during bending deformation.

[0003] For example, Patent Document 1 discloses a columnar member having an upper wall extending along a predetermined main axis, side walls extending along both side edges of the upper wall, and flange portions extending along the edge of the side walls opposite the upper wall, the columnar member having a generally hat-shaped cross section perpendicular to the axis, in which the side walls have low-strength portions adjacent to the side edges connected to the upper wall, the low-strength portions having a strength lower than that of the base material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6268780 Summary of the Invention [Problem to be solved by the invention]

[0005] To ensure the required vehicle crashworthiness while reducing vehicle weight, various innovations are required not only in the materials used in vehicles but also in their design. In particular, there is a strong demand for more compact and efficient components, such as front side members, rear side members, and center pillars, which are primarily responsible for absorbing energy during a collision. These components absorb impact through bending deformation, but bending deformation rapidly weakens the components. For this reason, the addition of reinforcing members to these components is often considered, but adding reinforcing members increases weight. Furthermore, reinforcing members can make the reinforced parts too strong, preventing them from operating in the expected deformation mode and significantly degrading impact absorption performance.

[0006] Recently, the drive source for automobiles has been shifting from the conventional internal combustion engine to smaller drive sources such as electric motors. As the drive source for automobiles becomes smaller, the degree of freedom in vehicle structure, which was previously restricted by the presence of the internal combustion engine, increases. For example, the space previously occupied by the internal combustion engine can now be used as passenger compartment space, making it possible to design vehicles that meet user needs for a larger passenger compartment.

[0007] On the other hand, the space where the internal combustion engine is located has been used to ensure collision safety because even if it were to be crushed during a collision, it would not affect the passengers in the passenger compartment.For this reason, if the space where the internal combustion engine was located were used as a passenger compartment, there is a possibility that the crushing of the vehicle body that occurs during a collision could directly affect the passengers in the passenger compartment, making it impossible to ensure safety during a collision.

[0008] As described above, if the space that was previously occupied by the internal combustion engine is used to enlarge the passenger compartment, the space that was originally used to ensure collision safety will be reduced, and it will be desirable to absorb collision energy in a smaller space.

[0009] The technology described in Patent Document 1 suppresses a sudden decrease in reaction force during bending deformation and increases absorbed energy by providing a low-strength portion adjacent to the side edge connected to the upper wall of the side wall of a columnar member having a hat-shaped cross section, but there is room for further improvement when considering absorbing collision energy in a smaller space.In addition, the technology described in Patent Document 1 is a technology that assumes a side collision of the columnar member, and does not consider bending deformation when a compressive load is applied in the axial direction of the columnar member.

[0010] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a columnar member that is capable of absorbing more energy during a collision without increasing the weight. [Means for solving the problem]

[0011] The gist of the present disclosure is as follows.

[0012] (1) A top plate and Two vertical walls connected to the top plate at ridge portions on both side edges of the top plate and extending along the ridge portions; A columnar member having at least The top plate has a bending induction portion on at least a part thereof, The two vertical walls each have a softened portion formed by softening a material of the vertical wall at a position adjacent to the ridge line portion and corresponding to the bending induction portion in the extending direction of the columnar member, the end of the soft portion on the top plate side is located below the ridge portion connecting the top plate and the vertical wall, or the end of the soft portion on the top plate side is located at the end of the ridge portion connecting the top plate and the vertical wall on the vertical wall side, The bending induction portion is a portion of the top plate having a lower strength than a portion adjacent to the bending induction portion, The soft portion is a portion of the vertical wall having a lower yield strength than a portion adjacent to the soft portion, and the maximum length of the soft portion in the direction in which the columnar member extends is 0.01 to 0.15 times the height of the vertical wall.

[0013] (2) The columnar member according to (1) above, wherein the length of the soft portion in the height direction of the vertical wall is 0.15 to 0.9 times the height of the vertical wall.

[0014] (3) The columnar member according to (1) or (2) above, wherein the ratio of the yield strength of the soft portion to the yield strength of the portion of the vertical wall adjacent to the soft portion is 0.2 to 0.8.

[0016] ( 4 ) The bending induction portion is constituted by a recess, a hole or a protrusion provided on the top plate, 3 ) The columnar member according to any one of the preceding claims.

[0017] ( 5 The top plate has at least two reinforcing portions spaced apart in the direction in which the columnar members extend, The bending induction portion is located between the reinforcing portions spaced apart in the extending direction of the columnar member, 3 ) The columnar member according to any one of the preceding claims.

[0018] ( 6 The bending induction portion includes a recess, a hole, or a protrusion provided in the ridge portion connecting the top plate and the vertical wall, 4 ) The columnar member according to any one of the preceding claims.

[0019] ( 7 ) The above (1) to ( 6 ) The columnar member according to any one of claims 1 to 10. [Effects of the Invention]

[0020] According to the present invention, a columnar member is provided that is capable of absorbing more energy during a collision without increasing the weight. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram for explaining the structure of a vehicle body floor of an automobile according to an embodiment of the present invention, and is a plan view of the vehicle body floor as seen from above. FIG. [Figure 2] FIG. [Figure 3]FIG. 2 is a perspective view showing the configuration of a columnar member according to an embodiment of the present invention. [Figure 4] 1 is a cross-sectional view showing a cross section (transverse cross section) cut at a position of a breakage inducing bead by a plane perpendicular to the longitudinal direction, which is the direction of the main axis of the columnar member. [Figure 5] FIG. 10 is a perspective view showing the configuration of a columnar member of a base member model in which a bead portion is not provided. [Figure 6A] 1A to 1C are schematic diagrams showing, in time series, how bending deformation of a columnar member progresses when a compressive load is applied to the columnar member in the direction of the main axis. [Figure 6B] 1A to 1C are schematic diagrams showing, in time series, how bending deformation of a columnar member progresses when a compressive load is applied to the columnar member in the direction of the main axis. [Figure 6C] 1A to 1C are schematic diagrams showing, in time series, how bending deformation of a columnar member progresses when a compressive load is applied to the columnar member in the direction of the main axis. [Figure 7] 6D is a schematic diagram showing the vicinity of the folding inducing bead on the top plate of the columnar member as viewed from above at the timing shown in FIG. 6C. FIG. [Figure 8] 6A to 6C. This is a schematic diagram showing the top view of the vicinity of the breakage-inducing bead on the top plate of a columnar member when a compressive load is applied under the same conditions as in FIGS. 6A to 6C to a columnar member in which the length I of the soft part in the direction along the main axis Om is not set to 0.01 to 0.15 times the height H of the vertical wall, at the same timing as in FIG. 6C. [Figure 9] FIG. 10 is a characteristic diagram showing the relationship between stroke (horizontal axis) and reaction force (vertical axis) when a compressive load is applied in the direction of the main axis Om to the columnar member according to this embodiment and the columnar member of the base member model. [Figure 10A] FIG. 10 is a diagram showing the state of bending deformation of the columnar member of this embodiment at the timing of stroke S1 in the stroke and reaction force characteristics shown in FIG. [Figure 10B] 10B is a cross-sectional view showing the state in which the columnar member is cut along the dashed line II-II' shown in FIG. 10A. FIG. [Figure 10C]FIG. 10 is a diagram showing the state of bending deformation of the columnar member of this embodiment at the timing of stroke S2 ​​in the stroke and reaction force characteristics shown in FIG. [Figure 11A] FIG. 10 is a diagram showing the state of bending deformation of the columnar member of the base member model at the timing of stroke S1 in the stroke and reaction force characteristics shown in FIG. [Figure 11B] FIG. 10 is a diagram showing the state of bending deformation of the columnar member of the base member model at the timing of stroke S2 ​​in the stroke and reaction force characteristics shown in FIG. [Figure 11C] FIG. 10 is a diagram showing the state of bending deformation of the columnar member of the base member model at the timing of stroke S3 in the stroke and reaction force characteristics shown in FIG. 9. [Figure 12] FIG. 10 is a schematic diagram showing in detail a soft portion provided on a vertical wall. [Figure 13] FIG. 4 is an enlarged cross-sectional view of the vicinity of the soft part in FIG. 3. [Figure 14] FIG. 10 is a characteristic diagram showing the relationship between stroke and reaction force for each variation in the shape of the soft portion. [Figure 15] FIG. 10 is a characteristic diagram showing the relationship between stroke and reaction force for each variation in the strength of the soft portion. [Figure 16A] FIG. 2 is a characteristic diagram showing the relationship between the length I of the soft portion and the energy absorption ratio. [Figure 16B] FIG. 4 is a characteristic diagram showing the relationship between the height h of the soft portion and the energy absorption ratio. [Figure 16C] FIG. 10 is a characteristic diagram showing the relationship between the vertical wall angle and the energy absorption ratio. [Figure 16D] FIG. 10 is a characteristic diagram showing the relationship between the vertical wall angle and the energy absorption ratio. [Figure 17] Similar to Figure 12, this is a schematic diagram showing in detail the soft portion provided on the vertical wall, and is a diagram showing an example in which a gap is provided between the position of the upper end of the soft portion and the position of the lower end of the ridge portion. [Figure 18]17. This is a characteristic diagram showing the relationship between the stroke and reaction force of the columnar member, similar to FIG. 14, and is a characteristic diagram showing the characteristic C11 for the columnar member with the interval s of 5 mm shown in FIG. 17, together with the characteristic C1 and characteristic C2 of FIG. [Figure 19] FIG. 10 is a perspective view showing an example in which the bending induction portion is configured as a hole provided in the top plate. [Figure 20] FIG. 10 is a perspective view showing an example in which the bending inducement portion is composed of four concave beads extending in the direction of the main axis. [Figure 21] FIG. 10 is a schematic diagram showing an example in which a columnar member is composed of two hat-shaped members, and is a schematic diagram showing a cross section along a direction perpendicular to the direction of the main axis of the columnar member. [Figure 22] FIG. 10 is a perspective view showing an example in which the bending induction portion is composed of a V-shaped bending induction bead that spans from the top plate to both side edges. [Figure 23] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 24] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 25] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 26] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 27] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 28] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 29] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 30] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 31] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 32] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 33] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 34] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 35] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 36]FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 37] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 38] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 39] FIG. 10 is a perspective view showing another example of the bending induction portion. [Figure 40] FIG. 10 is a perspective view showing another example of the bending induction portion. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, a columnar member according to one embodiment of the present invention will be described with reference to the drawings. First, the configuration of a vehicle body floor 110 of an automobile to which a columnar member according to one embodiment of the present invention is applied will be described with reference to Figs. 1 and 2. Fig. 1 is a schematic diagram for explaining the structure of the vehicle body floor 110 of an automobile according to this embodiment, and is a plan view of the vehicle body floor 110 as viewed from above. Fig. 2 is a view of the vehicle body floor 110 as viewed from below.

[0023] As shown in FIG. 1, a vehicle body floor 110 includes a floor panel 112, floor cross members 114a to 114f, a front bumper 115, front side members 116a and 116b, rear side members 117a and 117b, a rear bumper 119, and side sills 120.

[0024] The side sills 120 extend in the front-to-rear direction (vehicle length direction) of the vehicle along the left and right sides of the vehicle. The floor cross members 114a to 114f extend in the left-to-right direction (vehicle width direction) of the vehicle. Each of the floor cross members 114a to 114f is joined at both ends to the left and right side sills 120, respectively, by welding, riveting, bolting, etc. (hereinafter referred to as welding, etc.).

[0025] The floor cross members 114b to 114e are arranged to extend in the vehicle width direction within an area surrounded by the left and right side sills 120, the floor cross member 114a, and the floor cross member 114f.

[0026] A floor panel 112 is disposed below the floor cross members 114b to 114e. The floor panel 112 is fixed to the floor cross members 114a to 114f and the side sill 120 by welding or the like.

[0027] The floor cross members 114a to 114f may all be made of hat material (members with a hat-shaped cross section).Furthermore, the floor cross members 114a to 114f may be made of hollow tubular members, and may have a rectangular cross section perpendicular to the longitudinal direction.

[0028] Two front side members 116a, 116b extend in the vehicle length direction on the vehicle widthwise inner side of the side sill 120. The rear ends of the front side members 116a, 116b abut against a floor cross member 114f and are fixed to the floor cross member 114f by welding or the like.

[0029] The upper surfaces of the front side members 116a, 116b may be in contact with the floor panel 112, or may be fixed to the floor panel 112 by welding or the like.

[0030] Two rear side members 117a, 117b extend in the vehicle length direction behind the floor cross member 114f. The front ends of the rear side members 117a, 117b are fixed to the floor cross member 114f by welding or the like. A rear bumper 119 is fixed to the rear ends of the rear side members 117a, 117b. In addition, a cross member 117c that connects the rear side member 117a and the rear side member 117b is disposed midway between the rear side members 117a, 117b in the fore-and-aft direction. The ends of the cross member 117c are fixed to the rear side member 117a and the rear side member 117b, respectively, by welding or the like.

[0031] As mentioned above, components such as the front side members 116a, 116b and rear side members 117a, 117b are primarily responsible for absorbing energy during a vehicle collision, and there is a strong demand for them to be more compact and efficient.

[0032] The inventors discovered that in order to simultaneously eliminate weakening of components due to bending deformation and avoid weight increase, it is possible to provide soft sections in areas close to the bending-induced sections of these components. This invention makes it possible to reduce weakening of these components due to bending deformation without adding reinforcing members.

[0033] 3 is a perspective view showing the configuration of a pillar member 100 according to one embodiment of the present invention. The pillar member 100 is particularly suitable for use as front side members 116a, 116b or rear side members 117a, 117b among the components constituting the vehicle body floor 110. The pillar member 100 may also be used as other components of the vehicle body floor 110 shown in FIG. 1, such as floor cross members 114a to 114f or side sills 120. Furthermore, the pillar member 100 may also be used as other components of the vehicle body floor 110, such as a center pillar, A pillar, or B pillar of the vehicle.

[0034] 3, the columnar member 100 has at least a top plate 12 and two vertical walls 14, 16 that are connected to the top plate 12 at ridges on both side edges 12a, 12b of the top plate 12 and extend along the ridges. The following description will be given taking as an example a case where the columnar member 100 has a hat-shaped member 10 and a plate-shaped member 30. The hat-shaped member 10 and the plate-shaped member 30 are formed, for example, from steel plates.

[0035] The hat-shaped member 10 includes a flat top plate 12, vertical walls 14, 16 connected to the top plate 12 at ridges on both side edges 12a, 12b of the top plate 12 and extending along the ridges, respectively, and flanges 18, 20 extending along opposite edges 14a, 16a of each vertical wall 14, 16. The direction of the main axis Om shown in FIG. 3 indicates the longitudinal direction in which the columnar member 100 extends. The main axis Om may also be a line passing through the center of gravity of a cross section of the columnar member 100 that is perpendicular to the longitudinal direction. Note that the extension direction of the columnar member 100 is not limited to a linear direction, and the columnar member 100 may extend in any curved direction.

[0036] A bend induction portion 22 is formed in at least a part of the top plate 12 of the hat-shaped member 10. A soft portion 14b is formed in the vertical wall 14. Similarly, a soft portion 16b is formed in the vertical wall 16. The soft portions 14b, 16b are provided at positions corresponding to the bend induction portion 22 in the direction along the main axis Om, i.e., in the direction in which the columnar member 100 extends (the longitudinal direction of the columnar member 100). Here, "provided at a corresponding position" includes a case in which the soft portions 14b, 16b are provided at the same position as the bend induction portion 22 in the direction in which the columnar member 100 extends, and a case in which at least a part of the range in which the soft portions 14b, 16b are provided overlaps with the range in which the bend induction portion 22 is provided in the direction in which the columnar member 100 extends.

[0037] Fig. 4 is a cross-sectional view showing a cross section (transverse section) cut at the position of the bending induction portion 22 by a plane perpendicular to the longitudinal direction, which is the direction of the main axis Om of the columnar member 100. As shown in Fig. 4, the transverse section of the hat-shaped member 10 is generally hat-shaped. The plate-shaped member 30 is joined to the flange portions 18, 20 of the hat-shaped member 10 by spot welding, line welding, or the like.

[0038] The bending induced portion 22 is a portion of the top plate 12 having lower strength than the portion adjacent to the bending induced portion 22. Here, "lower strength than the adjacent portion" means that the columnar member 100 is the first to deform when subjected to a compressive load in the longitudinal direction. Therefore, when a load is applied to the columnar member 100 in the longitudinal direction, the columnar member 100 undergoes bending deformation at the position of the bending induced portion 22. In the example shown in FIGS. 3 and 4, the bending induced portion 22 is composed of a bending bead (recess) that makes the front side of the top plate 12 (the upper side of the top plate 12 in FIG. 1) concave. The bending induced portion 22 is formed by press-forming a steel plate, which is the base material of the hat-shaped member 10. The bending induced portion 22 may be formed simultaneously with the formation of the hat-shaped member 10 during press-forming, in which a steel plate is bent to press-form the hat-shaped member 10.

[0039] When a vehicle collides, the front side members 116a, 116b or rear side members 117a, 117b that make up the vehicle body floor 110 receive a large impact force in the vehicle length direction and undergo compressive deformation. When the columnar members 100 are applied to the front side members 116a, 116b or rear side members 117a, 117b and a large impact force is applied in the vehicle length direction due to a collision, a compressive load is applied in the direction of the main axis Om of the columnar members 100, causing bending deformation of the columnar members 100. The bending deformation of the columnar members 100 absorbs the energy of the collision.

[0040] The bending inducing portions 22 are formed to provide the columnar member 100 with locations that are prone to breaking, and serve as the starting points for bending of the columnar member 100 when the columnar member 100 receives a compressive load in the direction of the main axis Om. As a result, when a compressive load is applied to the columnar member 100, the columnar member 100 undergoes bending deformation in a predetermined, predetermined deformation mode. Therefore, when a compressive load is applied to the columnar member 100, unexpected deformation of the columnar member 100 is suppressed, ensuring safety.

[0041] By providing the bending induction portion 22, when a compressive load is applied to the columnar member 100 in the direction of the principal axis Om, bending deformation occurs in the columnar member 100 at the position of the bending induction portion 22, and the columnar member 100 bends at the position of the bending induction portion 22. When a compressive load is applied, the reaction force in the direction of the principal axis Om of the columnar member 100 increases until the columnar member 100 bends due to bending deformation, and then decreases once the columnar member 100 bends.

[0042] When the columnar member 100 bends, a groove-shaped depression is formed in the top plate 12 at the position of the bending induction portion 22 on the inside of the bend, in a direction perpendicular to the main axis Om. As the deformation of the columnar member 100 progresses and the bending becomes greater, the width of the groove-shaped depression becomes narrower and the distance between the opposing inner walls of the groove-shaped depression becomes closer. When the opposing inner walls of the groove-shaped depression collide, the bending of the columnar member 100 temporarily stops, and the reaction force, which had been decreasing, begins to increase.

[0043] The soft portions 14b, 16b are provided in the two vertical walls 14, 16 of the hat-shaped member 10 at positions adjacent to the ridge line portion in a direction perpendicular to the top plate 12 and corresponding to the bending-induced portion in the direction in which the columnar member 100 extends. The soft portions 14b, 16b are configured as portions of the vertical walls 14, 16 of the hat-shaped member 10 that have lower yield strength (or tensile strength) than portions adjacent to the soft portions 14b, 16b. The soft portions 14b, 16b are provided to generate groove-shaped depressions earlier in the process in which the columnar member 100 bends and deforms, causing opposing groove-shaped inner walls to collide with each other early in the bending deformation, thereby suppressing a decrease in the reaction force of the columnar member 100. The soft portions 14b, 16b are formed by softening parts of the vertical walls 14, 16 by selective annealing during hot stamping or partial tempering. The soft portions 14b, 16b have a strength that is 0.2 to 0.8 times, preferably 0.2 to 0.6 times, the base material strength (yield strength) of the other portions of the steel plate.

[0044] As an example, the soft portions 14b, 16b have a rectangular shape in a plan view seen from a field of view perpendicular to the vertical walls 14, 16, and the maximum length I of the soft portions 14b, 16b in the direction in which the columnar member 100 extends (the direction along the main axis Om) is set to 0.01 to 0.15 times the height H of the vertical walls 14, 16. By setting the length I of the soft portions 14b, 16b in the direction along the main axis Om to 0.01 to 0.15 times the height H of the vertical walls 14, 16, after bending deformation of the columnar member 100 starts at the position of the bend induction portion 22, the opposing groove-shaped inner walls collide with each other early in the bending deformation, and the opposing groove-shaped inner walls collide with each other stepwise multiple times, thereby suppressing a decrease in reaction force and increasing the amount of collision energy absorption.

[0045] On the other hand, if the length I of the soft portions 14b, 16b in the direction along the main axis Om is not set to 0.01 to 0.15 times the height H of the vertical walls 14, 16, the opposing groove-shaped inner walls will not collide with each other in the early stages of bending deformation, and the opposing groove-shaped inner walls will not collide with each other in stages multiple times, which will reduce the reaction force of the columnar member 100 and reduce the amount of collision energy absorbed.

[0046] 6A to 6C are schematic diagrams showing, in time series, how bending deformation of the columnar member 100 progresses when a compressive load is applied in the direction of the main axis Om to the columnar member 100 in which the length I of the soft portions 14b, 16b in the direction along the main axis Om is set to 0.01 to 0.15 times the height H of the vertical walls 14, 16. In Figs. 6A to 6C, the positions of the dashed dotted lines indicate the positions of the bending induction portions 22.

[0047] 6A shows a jig 40 for applying a compressive load to a columnar member 100. To analyze how bending deformation progresses in the columnar member 100, rotating shafts are inserted into holes 42 in the jig 40 at both ends of the columnar member 100, and deformation is analyzed when the rotating shafts are brought closer to each other.

[0048] 6A shows the state where a compressive load is beginning to be applied in the longitudinal direction of the columnar member 100. In this state, although a compressive load is being applied in the longitudinal direction of the columnar member 100, the surface of the top plate 12 of the hat-shaped member 10 and the surface of the plate-shaped member 30 remain flat, and the columnar member 100 has not yet bent. As described above, the reaction force of the columnar member 100 when a compressive load is applied increases until the columnar member 100 bends.

[0049] 6B, as the rotation axes inserted into the holes 42 approach each other, a compressive load is applied to the columnar member 100 in the longitudinal direction, and the columnar member 100 begins to bend at the position of the bending induced portion 22, causing wrinkle-like bulges 14d and 16d in the vertical walls 14 and 16, and a groove-like depression 13d in the top plate 12 at the position of the bending induced portion 22 on the inside of the bending. In addition, a protrusion 13c is formed on the upper part of the soft portions 14b and 16b.

[0050] Next, as shown in FIG. 6C, when the rotation shaft inserted into the hole 42 approaches further, the columnar member 100 bends further, and the opposing groove-shaped inner walls collide with each other on the back side of the protrusion 13c.

[0051] FIG. 7 is a schematic diagram showing the vicinity of the bending induction portion 22 of the top plate 12 of the columnar member 100 as viewed from above at the timing shown in FIG. 6C. As shown in FIG. 7, convex portions 13c are formed on the upper portions of the vertical walls 14 and 16 at the positions of the soft portions 14b and 16b. At the timing shown in FIG. 6C, the opposing inner walls on the back sides of the convex portions 13c collide with each other. The collision of the opposing groove-shaped inner walls on the back sides of the convex portions 13c suppresses a decrease in the reaction force of the columnar member 100. As the bending deformation of the columnar member 100 further progresses, the opposing inner walls 13e of the groove-shaped recesses 13d collide with each other. This further suppresses a decrease in the reaction force of the columnar member 100. Furthermore, the collision between the opposing groove-shaped inner walls on the back side of the convex portion 13c and the collision between the opposing inner walls 13e of the groove-shaped recess 13d on the front side of the top plate 12 occur in stages at different times, thereby suppressing the decrease in reaction force due to multiple collisions and increasing the amount of collision energy absorbed.

[0052] On the other hand, when a compressive load is applied under the same conditions as in Figures 6A to 6C to a columnar member 104 in which the length I of the soft portions 14b, 16b in the direction along the main axis Om is not 0.01 to 0.15 times the height H of the vertical walls 14, 16, the opposing groove-like inner walls do not collide early or multiple times, and the reaction force of the columnar member 104 decreases as the compression stroke increases.

[0053] Figure 8 is a schematic diagram showing the state of the vicinity of the bending induction portion 22 of the top plate 12 of the columnar member 104 viewed from above at the same timing as in Figure 6C (after a certain time T has elapsed since the start of application of the compressive load) when a compressive load is applied under the same conditions as in Figures 6A to 6C to a columnar member 104 in which the length I of the soft portions 14b, 16b in the direction along the main axis Om is not 0.01 to 0.15 times the height H of the vertical walls 14, 16.

[0054] 8, even in a columnar member 104 in which the length I of the soft portions 14b, 16b in the direction along the main axis Om is not 0.01 to 0.15 times the height H of the vertical walls 14, 16, wrinkle-like bulges 14c, 16c occur in the vertical walls 14, 16, and a depression 13a occurs in the top plate 12 at the position of the bending induced portion 22. However, if the length I of the soft portions 14b, 16b in the direction along the main axis Om is not 0.01 to 0.15 times the height H of the vertical walls 14, 16, the soft portions 14b, 16b as a whole will be deformed into a concave shape, and convex portions 13c will not be formed at the tops of the soft portions 14b, 16b, and therefore the opposing groove-like inner walls will not collide with each other on the back sides of the convex portions 13c. Furthermore, opposing inner walls 13b of groove-like recess 13a are spaced apart by width d1, and at this point, the opposing inner walls 13b do not collide with each other. Therefore, in a columnar member 104 in which the length I of soft portions 14b, 16b in the direction along main axis Om is not 0.01 to 0.15 times the height H of vertical walls 14, 16, no collision occurs between the opposing groove-like inner walls at the bent portion at the time shown in Figure 8, so no force resisting bending is applied, and it is not possible to suppress a decrease in reaction force.

[0055] Next, the characteristics showing the relationship between the stroke and reaction force of the pillar-shaped member 100 according to this embodiment, in which the length I of the soft portions 14b, 16b in the direction along the main axis Om is set to 0.01 to 0.15 times the height H of the vertical walls 14, 16, will be described while comparing it with the characteristics of a pillar-shaped member 102 of a base member model that does not have the soft portions 14b, 16b. FIG. 5 is a perspective view showing the configuration of the pillar-shaped member 102 of the base member model that does not have the soft portions 14b, 16b. The configuration of the pillar-shaped member 102 shown in FIG. 5 is the same as that of the pillar-shaped member 100 according to this embodiment shown in FIG. 3, except that the soft portions 14b, 16b are not provided.

[0056] 9 is a characteristic diagram showing the relationship between stroke (horizontal axis) and reaction force (vertical axis) when a compressive load is applied in the direction of the main axis Om to the columnar member 100 according to this embodiment, in which the length I of the soft portions 14b, 16b in the direction along the main axis Om is 0.1 times the height H of the vertical walls 14, 16, and to the columnar member 102 of the base member model. In FIG. 9, the characteristic C1 shown by the solid line indicates the characteristic between stroke and reaction force in the columnar member 100 according to this embodiment, in which the length I of the soft portions 14b, 16b in the direction along the main axis Om is 0.1 times the height H of the vertical walls 14, 16. Furthermore, the characteristic C2 shown by the dashed line indicates the characteristic between stroke and reaction force in the columnar member 102 of the base member model.

[0057] 10A to 10C and 11A to 11C are diagrams showing the bending deformation of the columnar members 100, 102 at stroke timings S1, S2, and S3 in the stroke-reaction force characteristics shown in FIG. 9. FIGS. 10A to 10C show the bending deformation of the columnar member 100 of this embodiment in which the length I of the soft portions 14b, 16b in the direction along the main axis Om is set to 0.1 times the height H of the vertical walls 14, 16. FIGS. 11A to 11C also show the bending deformation of the columnar member 102 of the base member model. FIGS. 10A, 10C, and 11A to 11C show the state of the columnar members 100, 102 broken along the dashed-dotted line I-I' shown in FIGS. 3 and 5 at the respective timings. FIG. 10B is a cross-sectional view showing the columnar member 100 cut along the dashed line II-II' shown in FIG. 10A.

[0058] Figures 10A and 11A show the bending deformation of the columnar members 100, 102 at the timing of stroke S1 shown in Figure 9. Figures 10C and 11B show the bending deformation of the columnar members 100, 102 at the timing of stroke S2 ​​shown in Figure 9. Figure 11C shows the bending deformation of the columnar member 102 at the timing of stroke S3 shown in Figure 9.

[0059] 9, when a compressive load is applied to the columnar members 100, 102 in the direction of the principal axis Om, the reaction force increases with the increase in stroke until the stroke reaches S0, at which point the columnar members 100, 102 bend at the positions of the bending induction portions 22.

[0060] After stroke S0, bending deformation of the columnar member 100 progresses, and the reaction force decreases as the stroke increases. In the columnar member 100 of this embodiment, a groove-shaped recess 13d is formed in the top plate 12, and the length I of the soft portions 14b, 16b in the direction along the main axis Om is set to 0.1 times the height H of the vertical walls 14, 16. Therefore, the vertical walls 14, 16 buckle at the positions of the soft portions 14b, 16b, forming convex portions 13c that bulge outward at the tops of the vertical walls 14, 16. On the other hand, in the columnar member 102 of the base member model, a groove-shaped recess 13a is formed in the top plate 12, but the columnar member 102 does not have the soft portions 14b, 16b with the length I set to 0.01 to 0.15 times the height H of the vertical walls 14, 16. Therefore, the convex portions 13c in the columnar member 100 of this embodiment are not formed. Until the stroke reaches S1, the reaction force continuously decreases as the stroke increases in both the characteristic C1 and the characteristic C2.

[0061] When the stroke reaches S1, in the columnar member 100 of this embodiment, as shown in FIGS. 10A and 10B, the backsides of the convex portions 13c formed on the upper portions of the vertical walls 14 and 16 are groove-shaped, and the opposing inner walls 13f of these groove-shaped portions collide with each other (first collision). In this manner, in the columnar member 100 of this embodiment, the length I of the soft portions 14b and 16b is set to 0.1 times the height H of the vertical walls 14 and 16. Therefore, the convex portions 13c bulge outward at the upper portions of the vertical walls 14 and 16. When the stroke reaches S1, the opposing inner walls 13f of the convex portions 13c collide with each other on the backsides of the convex portions 13c, thereby enabling an early collision. As a result, the reaction force temporarily increases after stroke S1 in the characteristic C1 indicated by the solid line in FIG. 9. Thereafter, the reaction force of characteristic C1 gradually decreases until stroke S2.

[0062] On the other hand, in the pillar-shaped member 100 of the base member model, as shown in Fig. 11A, even when the stroke reaches S1, there is no equivalent to the convex portion 13c in the pillar-shaped member 100 of this embodiment, and a relatively large space exists between the opposing inner walls 13b of the groove-like recess 13a, so no collision occurs at this stage. Therefore, in the dashed line characteristic C2 shown in Fig. 9, the reaction force continues to decrease even after the stroke S1.

[0063] When the stroke reaches S2, in the columnar member 100 of this embodiment, as shown in Fig. 10C, the opposing inner walls 13e of the groove-like recess 13d collide with each other (second collision). As a result, in the characteristic C1 indicated by the solid line in Fig. 9, the reaction force temporarily increases after the stroke S2. Thereafter, the reaction force of the characteristic C1 remains at a substantially constant value even if the stroke increases.

[0064] On the other hand, in the case of the columnar member 102 of the base member model, even when the stroke reaches S2, the opposing inner walls 13b of the groove-like recess 13a still do not collide, and a space exists between the opposing inner walls 13b, as shown in Fig. 9. Therefore, in the characteristic C2 indicated by the dashed line in Fig. 9, the reaction force continues to decrease even after the stroke S2.

[0065] When the stroke reaches S3, the opposing inner walls 13b of the groove-like recess 13a finally collide with each other in the columnar member 102 of the base member model, as shown in Fig. 11C. As a result, in the dashed line characteristic C2 shown in Fig. 9, the reaction force increases after the stroke S3, and thereafter, similar to the solid line characteristic C1, the reaction force remains at an approximately constant value even when the stroke increases.

[0066] As described above, in the characteristic C1 of the columnar member 100 according to this embodiment, in which the length I of the soft portions 14b, 16b in the direction along the main axis Om is set to 0.1 times the height H of the vertical walls 14, 16, the inner walls 13f, 13e collide a total of two times, at the timing of stroke S1 and stroke S2, and therefore the decrease in reaction force after stroke S1 is suppressed. This makes it possible to generate a large reaction force with a small stroke, and therefore makes it possible to efficiently absorb energy during a collision in a smaller space.

[0067] On the other hand, in the case of the columnar member 102 of the base member model, the opposing inner walls 13b do not collide until stroke S3 is reached, and so the reaction force continues to decrease until the inner walls 13b collide. Therefore, in the columnar member 102 of the base member model, the reaction force generated at the same stroke is lower than in the columnar member 100 of this embodiment, and a larger space is required to absorb the same collision energy as the columnar member 100 of this embodiment.

[0068] 9, the area of ​​the region surrounded by the characteristic C1 or characteristic C2 and the horizontal axis indicates the magnitude of collision energy absorbed by bending deformation of the columnar member 100. According to the characteristic C1 of the columnar member 100 of this embodiment, in which the vertical walls 14, 16 are provided with the soft portions 14b, 16b and the length I of the soft portions 14b, 16b in the direction along the main axis Om is 0.1 times the height H of the vertical walls 14, 16, a larger amount of collision energy is absorbed by the hatched area than the characteristic C2 of the columnar member 102 of the base member model in which the vertical walls 14, 16 are not provided with the soft portions 14b, 16b.

[0069] In the above-described embodiment, the bend inducing portion 22 is formed of a concave bead, but the bend inducing portion 22 may be formed of any portion that is the starting point of bending of the columnar member 100 and has lower strength than the portion of the top plate 12 adjacent to the bend inducing portion 22, and may be formed of a convex portion or hole provided in the top plate 12, or a point of change in the curvature of the columnar member 100. The bend inducing portion 22 may also be formed of a portion of the columnar member 100 where the material strength is locally reduced.

[0070] For example, FIG. 19 is a perspective view showing an example in which the bend induced portion 22 is formed by a hole provided in the top plate 12. FIG. 20 is a perspective view showing an example in which the bend induced portion 22 is formed between four concave beads 23 extending in the direction of the principal axis Om. The bending rigidity of the columnar member 100 is determined by the shape of the cross section perpendicular to the principal axis Om. Bending deformation is likely to occur at the point where the second moment of area changes. In both the examples shown in FIGS. 19 and 20, the second moment of area of ​​the cross section perpendicular to the principal axis Om changes at the position of the bend induced portion 22. Therefore, when a compressive load is applied to the columnar member 100 in the direction of the principal axis Om, the bend induced portion 22 becomes the starting point of bending. FIG. 19 shows an example in which the second moment of area decreases at the bend induced portion 22, while FIG. 20 shows an example in which the second moment of area increases at the concave beads 23, resulting in the second moment of area decreasing at the bend induced portion 22. 20, the recessed bead 23 provided on the top plate 12 is one form of the reinforcing portion. In the example of Fig. 20, instead of providing the recessed bead 23 on the top plate 12, a resin material or the like may be bonded to the area where the bead 23 is provided to form the reinforcing portion. As shown in Fig. 20, the top plate 12 may have at least two reinforcing portions (beads 23) spaced apart in the extension direction of the columnar member 100, and the bend inducing portion 22 may be located between the reinforcing portions spaced apart in the extension direction of the columnar member 100.

[0071] 22 is a perspective view showing an example in which the bend inducing portion 22 is formed from a V-shaped fold inducing bead formed so as to extend from the top plate 12 to the ridges of both side edges 12a, 12b. As shown in FIG. 22, the bend inducing portion 22 may be formed in an area including the top plate 12 and the ridges of both side edges 12a, 12b of the top plate 12.

[0072] 23 to 40, the bend inducing portion 22 may be configured as disclosed in Japanese Patent Application Laid-Open No. 2018-149912. FIGS. 23 to 40 are schematic diagrams showing other examples of the bend inducing portion 22 provided in the columnar member 100 according to this embodiment. As shown in FIG. 23, the bend inducing portion 22 may be formed by a circular hole provided in the top plate 12. As shown in FIG. 24, the bend inducing portion 22 may be formed by multiple holes provided in the top plate 12. In this case, for example, the multiple holes may be arranged in a direction perpendicular to the longitudinal direction of the columnar member 100. As shown in FIG. 25, the bend inducing portion 22 may be formed by a hole provided in the ridge portion of the side edge 12a or 12b. As shown in FIG. 26, the bend inducing portion 22 may be formed by a circular recess provided in the top plate 12. 27, the bend inducing portion 22 may be composed of a plurality of circular recesses provided in the top plate 12. In this case, for example, a plurality of recesses may be arranged side by side in a direction perpendicular to the longitudinal direction of the columnar member 100. As shown in FIG. 28, the bend inducing portion 22 may be composed of a rounded rectangular bead (recess) extending in a direction perpendicular to the longitudinal direction of the columnar member 100. As shown in FIG. 29, the bend inducing portion 22 may be composed of a recess provided in the ridge portion of the side edge 12a or 12b. As shown in FIG. 30, two rectangular recesses 24 extending along the longitudinal direction of the columnar member 100 may be provided, and the bend inducing portion 22 may be formed between the two recesses 24. In the example of FIG. 30, the recesses 24 are one example of a reinforcing portion. As shown in FIG. 31, the bend inducing portion 22 may be composed of a circular protrusion provided in the top plate 12. 32, the bending inducing portion 22 may be composed of a plurality of protrusions provided on the top plate 12. In this case, for example, the plurality of protrusions may be arranged side by side in a direction perpendicular to the longitudinal direction of the columnar member 100. As shown in FIG. 33, the bending inducing portion 22 may be composed of a protrusion provided on the top plate 12 and extending in a direction perpendicular to the longitudinal direction of the columnar member 100. As shown in FIG. 34, the bending inducing portion 22 may be composed of a protrusion provided on the ridge portion of the side edge 12a or 12b.35, two protrusions 26 extending along the longitudinal direction of the columnar member 100 may be provided, and the bending inducing portion 22 may be configured between the two protrusions 26. In the example of FIG. 35, the protrusions 26 are one form of a reinforcing portion. As shown in FIG. 36, the hat-shaped member 10 of the columnar member 100 may include a first thickness portion 12c and a second thickness portion 12d, and the thickness of the steel plate may be different between the first thickness portion 12c and the second thickness portion 12d. The bending inducing portion 22 may be located on the thinner side of the boundary between the first thickness portion 12c and the second thickness portion 12d (the portion between the boundary and the dashed line shown in FIG. 36). The thickness of the first thickness portion 12c is assumed to be thinner than that of the second thickness portion 12d. 37, a thin-walled portion having a relatively thinner plate thickness than other portions may be provided in the circumferential direction of the hat-shaped member 10, and the bending inducing portion 22 may be formed from this thin-walled portion. Also, as shown in FIG. 38, the bending inducing portion 22 may be formed from a different strength portion provided along the circumferential direction of the hat-shaped member 10 and having a different (lower) yield strength than other portions of the hat-shaped member 10. Also, as shown in FIG. 39, the bending inducing portion 22 formed from a different strength portion may be partially provided on the top plate 12. Also, as shown in FIG. 40, the hat-shaped member 10 of the columnar member 100 may include a first strength portion 12e and a second strength portion 12f, and the yield strength of the steel plate may differ between the first strength portion 12e and the second strength portion 12f. The bending inducing portion 22 may be formed in the portion on the lower strength side of the boundary between the first strength portion 12e and the second strength portion 12f (the portion between the boundary and the dashed line in FIG. 40). The first strength portion 12e has a lower strength than the second strength portion 12f.

[0073] Furthermore, in the above-described embodiment, an example has been shown in which the bending induction portion 22 is provided on the top plate 12, but the bending induction portion 22 may also be provided on the plate-shaped member 30 on the opposite side of the top plate 12.

[0074] Furthermore, in the above-described embodiment, an example in which the columnar member 100 is composed of a hat-shaped member 10 and a plate-shaped member 30 has been described. However, the columnar member 100 may be composed of two hat-shaped members. FIG. 21 is a schematic diagram illustrating an example in which the columnar member 100 is composed of a hat-shaped member 10 and a hat-shaped member 50, and is a schematic diagram illustrating a cross section along a direction perpendicular to the direction of the principal axis Om of the columnar member 100. In the columnar member 100 shown in FIG. 21, the flange portions 52 and 54 of the hat-shaped member 50 are joined to the flange portions 18 and 20 of the hat-shaped member 10 by spot welding, line welding, or the like. The top plate 56 of the hat-shaped member 50 may be located on the hat-shaped member 10 side or on the opposite side from the hat-shaped member 10. Note that FIG. 21 illustrates a cross section at a position in the direction of the principal axis Om where no recesses or holes corresponding to the bending induction portions 22 are provided.

[0075] As described above, according to this embodiment, the soft portions 14b, 16b are provided in the vertical wall 14 at the position of the bending induction portion 22, and the length I of the soft portions 14b, 16b in the direction along the main axis Om is set to 0.01 to 0.15 times the height H of the vertical walls 14, 16, thereby suppressing a decrease in reaction force due to bending deformation when a compressive load is applied to the columnar member 100. This improves the impact absorption performance of the columnar member 100 without increasing its weight. [Example]

[0076] A specific example of this embodiment will be described below.

[0077] The columnar member 100 is a structure in which a hat-shaped member 10 including the bending-induced portion 22 and the soft portions 14b, 16b is spot-welded to a plate-shaped member 30 at flange portions 18, 20. The hat-shaped member 10 is made of a steel plate with a tensile strength of 1180 MPa and a thickness of 1.6 mm, and the plate-shaped member 30 is made of a steel plate with a tensile strength of 980 MPa and a thickness of 1.2 mm.

[0078] The spot welding pitch was 30 mm, and the diameter of the spot welds was 6 mm. The member length (L1 shown in FIG. 6A) was 340 mm, the height (H shown in FIG. 4) of the hat-shaped member 10 was 72 mm, and the width (W shown in FIG. 4) of the plate-shaped member 30 was 160 mm, all of which were common to all of the columnar members 100 and the columnar member 102 of the base member model.

[0079] As a result of extensive research by the present inventors, it was found that the reaction force against the base member model and the amount of energy absorption differ depending on the shape (aspect ratio) and strength ratio of the soft portions 14b and 16b.

[0080] FIG. 12 is a schematic diagram showing the details of the flexible portion 14b provided on the vertical wall 14. FIG. 13 is an enlarged cross-sectional view of the flexible portion 14b and its vicinity in FIG. 3. In FIGS. 12 and 13, h1 indicates the distance from the surface of the table top 12 to the lower end of the ridge portion (the bent R portion) 15 at the boundary between the table top 12 and the vertical walls 14 and 16. The ends of the flexible portions 14b and 16b on the table top 12 side (the upper ends of the flexible portions 14b and 16b) are located at the end (lower end) of the ridge portion 15 (the ridge portion 15 that is a distance of h1 from the table top 12) that connects the table top 12 and the vertical walls 14 and 16. As shown in FIG. 12, the shapes of the flexible portions 14b and 16b are determined by the length I [mm] in the direction of the main axis Om and the height h [mm]. The lower end of the ridge portion 15 corresponds to the upper edge of the vertical walls 14 and 16.

[0081] (Relationship between the shape of the soft part and the reaction force) First, we will show the results of an investigation into the relationship between the reaction force and variations in the shape of the soft portions 14b and 16b according to the length I and height h. Using a base member model columnar member 102 with a bending induction portion 22 formed in the longitudinal center of the web surface as shown in Figure 5 as a reference, we used CAE to compare the reaction force with that of a columnar member 100 with soft portions 14b and 16b.

[0082] In examining the reaction force, several variations were prepared for the length I [mm] of the soft parts 14b and 16b in the direction of the main axis Om shown in Figure 12 and the height h [mm] of the soft parts 14b and 16b, and for each variation in the size of the soft parts 14b and 16b, characteristics showing the relationship between the stroke and the reaction force similar to those shown in Figure 9 were obtained.

[0083] 6A, deformation was analyzed when the rotating shafts inserted into the holes 42 of the jigs 40 at both ends of the columnar member 100 were brought closer to each other. In Fig. 6A, a rotating shaft with its axis in the width direction of the columnar member 100 was inserted into the hole 42 provided at a position L2 = 67 mm from the end of the columnar member 100 in the longitudinal direction and L3 = 15 mm from the top plate 12 in the height direction. These rotating shafts were brought closer to each other at a speed of 500 mm / s to impart a forced displacement, and the bending deformation of the columnar members 100, 102 was analyzed.

[0084] FIG. 14 is a characteristic diagram showing the relationship between stroke and reaction force for each variation in the shape of the flexible portions 14b and 16b. A number of variations in the shape of the flexible portions 14b and 16b, each with a different length I [mm] and height h [mm] in the direction of the main axis Om, were prepared, and characteristics C1 to C6 of the stroke and reaction force shown in FIG. 14 were measured. For characteristics C1 to C6, the ratios of the length I [mm] and height h [mm] to the height H are as shown in Table 1 below. Note that characteristics C1 and C2 shown in FIG. 14 are the same as characteristics C1 and C2 shown in FIG. 9. Among the pillar-shaped members 100 provided with the flexible portions 14b and 16b, those that had a higher reaction force than the pillar-shaped member 102 of the base member model during the process of decreasing reaction force were designated as invention examples, and those that had a lower reaction force than the pillar-shaped member 102 of the base member model were designated as comparative examples.

[0085] [Table 1]

[0086] As shown in Figure 14, in comparison with the base member model (characteristic C2), immediately after the initial collision, the reaction force of characteristic C1 was the largest, followed by characteristic C3 and characteristic C4. From these results, it can be seen that if I / H is 0.1 or more and 0.33 or less, the decrease in reaction force can be suppressed regardless of the height h [mm] of soft portions 14b, 16b. Furthermore, when I / H is 0.4, the length I in the direction of main axis Om is not set to 0.01 to 0.15 times the height H of vertical walls 14, 16, so when a compressive load is applied, soft portions 14b, 16b easily deform, and the reaction force became lower than that of the base member model immediately after stroke S0.

[0087] (Relationship between the strength of the soft part and the reaction force) Next, we present the results of an investigation into the relationship between variations in the strength of the soft portions 14b and 16b and the reaction force. Figure 15 is a characteristic diagram showing the relationship between stroke and reaction force for each variation in the strength of the soft portions 14b and 16b. As shown in Table 2 below, the values ​​of I / H and h / H were fixed at 0.10 and 0.33, respectively, and the ratios of the yield strength of the soft portions 14b and 16b to the yield strength of the base material other than the soft portions 14b and 16b were set to 0.2, 0.4, 0.6, 0.8, and 0.9. Forced displacement was applied to the columnar member 100 under the same conditions as above. Among the columnar members 100 provided with the soft portions 14b and 16b, those with a higher reaction force than the columnar member 102 of the base member model during the reaction force decrease process were designated as examples of the invention, and those with a lower reaction force than the columnar member 102 of the base member model were designated as comparative examples.

[0088] [Table 2]

[0089] As shown in Figure 15, in comparison with the base member model (characteristic C2), the maximum reaction force of characteristic C1 (the peak reaction force that occurs first, corresponding to the reaction force at stroke S0 when the columnar members 100 and 102 bend) was the smallest, followed by characteristics C7, C8, C9, and C10 in order of maximum reaction force. When the length I of the soft portions 14b and 16b was set to 0.01 to 0.15 times the height H of the vertical walls 14 and 16, the smaller the strength ratio, the smaller the initial peak reaction force. Therefore, it can be seen that the larger the strength ratio, the higher the initial peak reaction force, and therefore the greater the amount of energy absorption. Furthermore, immediately after the initial collision (stroke S1), the reaction force of characteristic C1 was the largest, followed by characteristics C7, C8, C9, and C10 in order of maximum reaction force. This shows that when the intensity ratio is small, the initial peak reaction force decreases, but the reaction force immediately after the initial collision increases, causing the first and second collisions to occur earlier, resulting in an increased amount of energy absorption.

[0090] (Amount of energy absorbed) In addition, a forced displacement was applied to the columnar member 100 under the same conditions as above, and the relationship between the size (length I, height h) of the soft parts 14b and 16b, their strength ratio to the base material, and the angle (θ shown in Figure 4) of the vertical walls 14 and 16 and the energy absorption performance of the columnar member 100 was investigated by comparing it with the amount of energy absorption in the base member model.

[0091] As in the above, the size of the flexible portions 14b and 16b was expressed as a ratio to the height H of the vertical walls 14 and 16, and variations in ratios of 0.1, 0.2, 0.25, 0.33, 0.4, 0.5, 0.75, and 1.0 were prepared for the length I and height h. Five variations in the vertical wall angle were available: 50°, 60°, 70°, 80°, and 90°. Furthermore, variations in the strength ratio were available: 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9.

[0092] When considering length I, the ratio of height h to height H was set to 0.33, the vertical wall angle was set to 80 degrees, and the strength ratio was set to 0.2. When considering height h, the ratio of length I to height H was set to 0.1, the vertical wall angle was set to 80 degrees, and the strength ratio was set to 0.2. When considering the vertical wall angle, the ratio of length I to height H was set to 0.1, the ratio of height h to height H was set to 0.33, and the strength ratio was set to 0.2. When considering the strength ratio, the ratio of length I to height H was set to 0.1, the ratio of height h to height H was set to 0.33, and the vertical wall angle was set to 80 degrees. Each level is shown in Table 3 below.

[0093] [Table 3]

[0094] The results of the study are shown in Figures 16A to 16D. In Figures 16A to 16D, the vertical axis shows the ratio (energy absorption ratio) of the energy absorption amount of the columnar member 100 under study to the energy absorption amount of the base member model. When this ratio is greater than 1, the energy absorption amount is greater than that of the base member model.

[0095] FIG. 16A shows the relationship between the length I of the soft portions 14b, 16b and the energy absorption ratio. In FIG. 16A, the horizontal axis shows the ratio I / H of the length I [mm] to the height H. As shown in FIG. 16A, when I / H was 0.01 or more and 0.15 or less, the energy absorption ratio with respect to the base member model was greater than 1. On the other hand, when I / H was greater than 0.15, the length I of the soft portions 14b, 16b in the direction of the main axis Om was not set to 0.01 to 0.15 times the height H of the vertical walls 14, 16, and therefore the energy absorption ratio with respect to the base member was less than 1. More preferably, when I / H was 0.01 or more and 0.11 or less, the energy absorption ratio with respect to the base member was significantly greater.

[0096] Fig. 16B shows the relationship between the height h of the soft portions 14b, 16b and the energy absorption ratio. In Fig. 16A, the horizontal axis shows the ratio h / H of the height h [mm] to the height H. As shown in Fig. 16B, when h / H was 0.15 or more and 0.9 or less, the energy absorption ratio with respect to the base member was greater than 1. More preferably, when h / H was 0.15 or more and 0.4 or less, the energy absorption ratio with respect to the base member was significantly greater.

[0097] Figure 16C shows the relationship between the vertical wall angle and the energy absorption ratio. In Figure 16C, the horizontal axis represents the vertical wall angle. As shown in Figure 16C, the energy absorption ratio for the base member model was greater than 1 at all vertical wall angles.

[0098] Figure 16D shows the relationship between the intensity ratio and the energy absorption ratio. In Figure 16D, the horizontal axis represents the intensity ratio. As shown in Figure 16D, when the intensity ratio was 0.9, no first collision occurred, and as a result, no improvement in energy absorption was observed. However, when the intensity ratio was 0.2 or more and 0.8 or less, the energy absorption ratio relative to the base member model was greater than 1. More preferably, when the intensity ratio was 0.3 or more and 0.7 or less, the energy absorption ratio relative to the base member was significantly increased.

[0099] In addition, in Figures 16A and 16B, the data on the energy absorption ratio when the ratio (I / H, h / H) on the horizontal axis is 0.0 shows the results for a base member model that does not have soft portions 14b, 16b.

[0100] (Distance from the ridge to the top of the bead) When the columnar member 100 is subjected to a compressive load in the direction of the main axis Om, a relatively large reaction force is generated at the ridge line portion 15. For this reason, if the soft portions 14b, 16b extend up to the ridge line portion 15, the reaction force generated at the ridge line portion 15 decreases, and the collision energy absorption capacity of the columnar member 100 decreases. For this reason, it is preferable that the upper ends of the soft portions 14b, 16b are positioned below the ridge line portion 15.

[0101] More preferably, the positions of the upper ends of the soft portions 14b and 16b coincide with the position of the lower end of the ridge portion 15, which is a distance h1 from the top plate 12. With this configuration, when a compressive load is applied to the columnar member 100, a large reaction force is generated at the ridge portion 15, and the protrusion 13c can quickly collide with the opposing inner wall 13f on the back side thereof.

[0102] On the other hand, even if the positions of the upper ends of the soft portions 14b and 16b are located below the position of the lower end of the ridge portion 15, it is possible to increase the reaction force to the base member model.

[0103] Like Figure 12, Figure 17 is a schematic diagram showing in detail the soft portion 14b provided on the vertical wall 14, and shows an example in which a gap s is provided between the upper ends of the soft portions 14b and 16b and the lower end of the ridge portion 15.

[0104] Fig. 18 is a characteristic diagram showing the relationship between the stroke and reaction force of the columnar members 100, 102, similar to Fig. 9, and shows characteristic C11 of the columnar member 100 in which the interval s shown in Fig. 17 is 5 mm, along with characteristic C1 and characteristic C2 of Fig. 9. The I / H of the columnar member 100 in which the interval s is 5 mm, the length of the soft portions 14b, 16b in the height H direction of the vertical walls 14, 16, the strength ratio, and the vertical wall angle were the same as those of the columnar member 100 from which characteristic C1 was obtained.

[0105] 18, characteristic C11 of columnar member 100 in which a gap of 5 mm is provided between the positions of the upper ends of soft portions 14b, 16b and the position of the lower end of ridge portion 15 shows a lower reaction force immediately after stroke S1 at which the initial collision occurs than characteristic C1, but the reaction force is still significantly higher than characteristic C2 of the base member model. Therefore, as shown in FIG. 17, a gap s may be provided between the positions of the upper ends of soft portions 14b, 16b and the position of the lower end of ridge portion 15. In this case, the positions of the upper ends of soft portions 14b, 16b do not necessarily have to coincide with the position of the lower end of ridge portion 15, which increases the degree of freedom in designing soft portions 14b, 16b and is expected to reduce manufacturing costs. [Explanation of symbols]

[0106] 10,50 Hat-shaped member 12,56 Top plate 12a,12b side edge 13a, 13d recesses 13b,13e,13f Inner wall 13c Convex part 14 Vertical Wall 14a,16a Edge 14b,16b Soft part 15 Ridgeline 16 Vertical Wall 18, 20, 52, 54 Flange section 22 Bending induction section 30 Plate-shaped members 40 Jig 42 holes 100, 102, 104 Column members 110 Body floor

Claims

1. The top plate and Two vertical walls connected to the top plate at ridge portions on both side edges of the top plate and extending along the ridge portions; A columnar member having at least The top plate has a bending induction portion on at least a part thereof, the two vertical walls each have a softened portion formed by softening a material of the vertical wall at a position adjacent to the ridge line portion and corresponding to the bending induction portion in the extending direction of the columnar member, the end of the soft portion on the top plate side is located below the ridge portion connecting the top plate and the vertical wall, or the end of the soft portion on the top plate side is located at the end of the ridge portion connecting the top plate and the vertical wall on the vertical wall side, The bending induction portion is a portion of the top plate having a lower strength than a portion adjacent to the bending induction portion, The soft portion is a portion of the vertical wall having a lower yield strength than a portion adjacent to the soft portion, and the maximum length of the soft portion in the direction in which the columnar member extends is 0.01 to 0.15 times the height of the vertical wall.

2. 2. The columnar member according to claim 1, wherein the length of the soft portion in the height direction of the vertical wall is 0.15 to 0.9 times the height of the vertical wall.

3. 3. The columnar member according to claim 1, wherein a ratio of the yield strength of the soft portion to the yield strength of the portion of the vertical wall adjacent to the soft portion is 0.2 to 0.

8.

4. A columnar member described in any one of claims 1 to 3, wherein the bending-inducing portion is composed of a recess, hole or protrusion provided in the top plate.

5. The top plate has at least two reinforcing parts spaced apart in the direction in which the columnar members extend, The columnar member according to any one of claims 1 to 3, wherein the bending induction portion is located between the reinforcing portions spaced apart in the extending direction of the columnar member.

6. A columnar member described in any one of claims 1 to 4, wherein the bending-inducing portion includes a recess, hole or protrusion provided in the ridge portion connecting the top plate and the vertical wall.

7. A columnar member described in any one of claims 1 to 6 constituting a front side member or a rear side member of a vehicle.

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