Structural members

Abstract

To provide a structural member for vehicle bodies capable of concurrently ensuring axial compression force resistance performance and bending moment resistance performance.SOLUTION: A structural member (10) includes a top plate (11) and two vertical walls (121 and 122). The two vertical walls (121 and 122) are connected to respective side edges of the top plate (11) and are opposed to each other. The structural member (10) satisfies L / W≥1.2 and tL / tW≤0.7, where W is a length of the top plate (11) in a width direction of the structural member (10) on a cross section perpendicular to an axial direction of the structural member (10), L is a length of the vertical walls (121 and 122) in a height direction of the structural member (10), tw is a thickness of the top plate (11), and tL is a thickness of the vertical walls (121 and 122).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This disclosure relates to structural components for vehicle bodies. [Background technology]

[0002] Structural members used in the bodies of automobiles and other vehicles are required to withstand loads applied during vehicle collisions. For example, structural members that can withstand axial compressive forces during a vehicle collision are configured to exhibit high resistance to axial compressive forces. However, when structural members are actually installed in a vehicle body, axial compressive forces may be applied to the structural members at a position offset from the center of gravity axis, for example, in the height direction. In this case, the structural member will be subjected to a bending moment in addition to the axial compressive force.

[0003] For example, Patent Document 1 discloses a vehicle body structure including a rocker frame member and a floor cross member. The floor cross member is a structural member to which an axial compressive force is applied during a side collision of a vehicle. Patent Document 1 explains that conventionally, the centroid of the floor cross member's cross section was significantly displaced downward relative to the centroid of the rocker frame member's cross section, and therefore a bending moment acts on the floor cross member due to the load during a side collision. For this reason, Patent Document 1 proposes forming a convex portion along the vehicle width direction on the floor panel, and bringing the centroid of the closed cross section defined by the floor cross member and the convex portion of the floor panel closer to the centroid of the rocker frame member's cross section in the vehicle's height direction. Patent Document 1 states that with this configuration, the load applied to the vehicle body structure by a side collision acts on the floor cross member as an axial force, not a bending moment. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2010-95218 [Overview of the project] [Problems that the invention aims to solve]

[0005] In recent years, in order to realize lightweight and robust automobiles, high-strength materials such as high-tensile steel and ultra-high-tensile steel have been used for structural members of the vehicle body. When structural members are made thinner as the strength of the material increases, elastic buckling due to axial compressive force is more likely to occur in the structural members. Elastic buckling is more likely to occur as the structural member is made thinner, regardless of the strength of the material. It is preferable that the cross-sectional shape of the structural member be designed in a way that can avoid the occurrence of elastic buckling. Since both axial compressive force and bending moment may be applied to the structural member, it is preferable that the cross-sectional shape of the structural member be designed so that the structural member can exhibit high load-bearing capacity even when both axial compressive force and bending moment are applied simultaneously.

[0006] For example, to improve the resistance to axial compressive force (axial compressive force resistance performance), the parallel section of the structural member's cross-section is generally shortened so that there are no ineffective sections that cannot substantially support the axial compressive force. Shortening the parallel section reduces the size of the structural member's cross-section. However, to improve the resistance to bending moment (bending moment resistance performance), the size of the structural member's cross-section needs to be increased. In other words, in the design of conventional structural member cross-sectional shapes, there is a trade-off between improving axial compressive force resistance performance and improving bending moment resistance performance. Therefore, in order to simultaneously ensure both axial compressive force resistance performance and bending moment resistance performance, it is necessary to devise a new cross-sectional shape for structural members that has not existed before.

[0007] The object of this disclosure is to provide a structural member for a vehicle body that can simultaneously ensure axial compressive force resistance and bending moment resistance. [Means for solving the problem]

[0008] The structural member for a vehicle body according to this disclosure comprises a top plate and two vertical walls. The two vertical walls are connected to both side edges of the top plate and face each other. In a cross section perpendicular to the axial direction of the structural member, the length of the top plate in the width direction of the structural member is W, the length of the vertical walls in the height direction of the structural member is L, and the thickness of the top plate is t w The thickness of the vertical wall boards is t L In this case, the structural members have L / W ≥ 1.2 and t L / t W It satisfies ≤0.7. [Effects of the Invention]

[0009] The structural member for the vehicle body according to this disclosure makes it possible to simultaneously ensure both axial compressive force resistance and bending moment resistance. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a perspective view of a structural member according to an embodiment. [Figure 2] Figure 2 is a cross-sectional view of the structural member shown in Figure 1. [Figure 3] Figure 3 shows the relationship between tL / tW and the ratio of the axial force at the time of maximum moment generation relative to a reference structural member, for a structural member made of steel plate having a tensile strength of 2500 MPa or more. [Figure 4] Figure 4 shows the relationship between L / W and the ratio of the axial force at the time of maximum moment generation relative to a reference structural member, for a structural member made of steel plate having a tensile strength of 2500 MPa or more. [Figure 5] Figure 5 shows the relationship between tL / tW and the ratio of the axial force at the time of maximum moment generation relative to a reference structural member, for a structural member made of steel plate having a tensile strength of 1470 MPa or more. [Figure 6] Figure 6 shows the relationship between L / W and the ratio of the axial force at the time of maximum moment generation relative to a reference structural member, for a structural member made of steel plate having a tensile strength of 1470 MPa or more. [Modes for carrying out the invention]

[0011] The structural member for a vehicle body according to the embodiment includes a top plate and two vertical walls. The two vertical walls are connected to both side edges of the top plate and face each other. In a cross-section perpendicular to the axial direction of the structural member, the length of the top plate in the width direction of the structural member is denoted as W, the length of the vertical wall in the height direction of the structural member is denoted as L, and the plate thickness of the top plate is t w , and the plate thickness of the vertical wall is t L . When this is the case, the structural member satisfies L / W≧1.2 and t L / t W ≦0.7 (the first configuration).

[0012] When an axial compressive force is input to the structural member including the top plate and the two vertical walls, for example, at a position shifted toward the top plate side from the centroid axis, compressive deformation occurs in the top plate, and tensile deformation occurs in the portion of each vertical wall away from the top plate. The top plate may undergo elastic buckling due to the generated compressive stress. When elastic buckling occurs, it becomes difficult for the structural member to exhibit the desired axial compressive force resistance performance and bending moment resistance performance. Therefore, in the structural member according to the embodiment, the plate thickness t W of the top plate where elastic buckling is likely to occur is made larger than the plate thickness t L of the vertical wall, and the length W of the top plate in the width direction is made smaller than the length L of the vertical wall in the height direction. More specifically, in a cross-section perpendicular to the axial direction of the structural member, the plate thickness t W of the top plate and the plate thickness t L of the vertical wall are set so as to satisfy t L / t W ≦0.7. Also, in a cross-section perpendicular to the axial direction of the structural member, the length W of the top plate and the length L of the vertical wall are set so as to satisfy L / W≧1.2. With such a configuration, when an axial compressive force is input to the structural member, elastic buckling of the top plate is less likely to occur, and both the axial compressive force resistance performance and the resistance to bending moment can be simultaneously exhibited by the structural member. That is, the axial compressive force resistance performance and the bending moment resistance performance can be ensured simultaneously.

[0013] The top plate and vertical walls are preferably made of steel plates having a tensile strength of 1470 MPa or more (second configuration), and more preferably made of steel plates having a tensile strength of 2500 MPa or more (third configuration).

[0014] The structural member according to the embodiment is particularly effective when the top plate and vertical walls are formed from high-strength material, as in the second or third configuration. Specifically, when steel plates (high-strength material) having a tensile strength of 1470 MPa or more or 2500 MPa or more are used for the structural member, the structural member is usually made thinner overall in order to reduce weight. However, when the structural member is made thinner, elastic buckling is more likely to occur when axial compressive force is applied to the structural member. When elastic buckling occurs, the structural member cannot exhibit the axial compressive force resistance and bending moment resistance performance expected of high-strength material. In contrast, in the structural member according to the embodiment, as described above, the plate thickness t of the top plate, which is prone to elastic buckling, w As the strength increases and the length W of the top plate decreases, elastic buckling is suppressed. As a result, the structural member can exhibit excellent resistance to axial compressive force and bending moment. On the other hand, in the structural member according to the embodiment, the vertical walls, which are less prone to elastic buckling, are made thinner, thereby reducing the weight. Therefore, the structural member according to the embodiment can achieve both the improvement in axial compressive force resistance and bending moment resistance expected of high-strength materials and the weight reduction of the structural member due to the adoption of high-strength materials.

[0015] Embodiments of this disclosure will be described below with reference to the drawings. In each drawing, the same or equivalent components are denoted by the same reference numerals, and the same description will not be repeated.

[0016] [Structural Member Composition] Figure 1 is a perspective view of a structural member 10 for a vehicle body according to an embodiment. The structural member 10 is used, for example, in the body of an automobile. The structural member 10 may be, for example, a floor cross member, roof cross member, dash cross member, lower floor cross member, side sill, or tunnel of an automobile.

[0017] As shown in Figure 1, the structural member 10 has an elongated shape. The structural member 10 comprises a top plate 11 and two vertical walls 121 and 122. The structural member 10 further comprises two flanges 131 and 132, two first ridge sections 141 and 142, and two second ridge sections 151 and 152.

[0018] The top plate 11 extends in the axial direction (longitudinal direction) of the structural member 10. The vertical walls 121 and 122 face each other. The vertical walls 121 and 122 are connected to both side edges of the top plate 11. One vertical wall 121 is connected to one of the two side edges of the top plate 11 that extend in the axial direction of the structural member 10. The other vertical wall 122 is connected to the other side edge of the top plate 11. The vertical wall 121 is connected to the top plate 11 via the first ridge section 141. The vertical wall 122 is connected to the top plate 11 via the first ridge section 142. The vertical walls 121 and 122 and the first ridge sections 141 and 142 extend along the top plate 11 in the axial direction of the structural member 10.

[0019] The flanges 131 and 132 project outward from the vertical walls 121 and 122, respectively, toward the outside of the structural member 10. One flange 131 is connected to one vertical wall 121 on the opposite side of the top plate 11. Flange 131 is connected to the vertical wall 121 via a second ridge portion 151. The other flange 132 is connected to the other vertical wall 122 on the opposite side of the top plate 11. Flange 132 is connected to the vertical wall 122 via a second ridge portion 152. The flanges 131 and 132 and the second ridge portions 151 and 152 extend axially along the structural member 10, similar to the vertical walls 121 and 122.

[0020] The structural member 10 is typically formed from a metal plate. The structural member 10, including the top plate 11 and vertical walls 121 and 122, may be formed from a steel plate. From the viewpoint of increasing the strength of the structural member 10, the steel plate preferably has a tensile strength of 1470 MPa or more, and more preferably has a tensile strength of 2500 MPa or more. The structural member 10 can be manufactured, for example, by press-forming a metal plate such as a steel plate. This press-forming may be cold pressing or hot pressing (hot stamping).

[0021] Structural member 10 is fixed to other structural members 20 when installed on the vehicle body. In the example shown in Figure 1, structural member 20 has a flat plate shape. Structural member 20 seals the openings of structural member 10 on the flange 131, 132 side. Structural member 20 is joined to flange 131, 132, for example, by welding.

[0022] Structural member 20, like structural member 10, is typically formed from a metal plate. Structural member 20 may also be formed from a steel plate. If structural members 10 and 20 are formed from steel plates, the tensile strength of the steel plate used for structural member 20 may be less than or equal to the tensile strength of the steel plate used for structural member 10, or it may be greater than the tensile strength of the steel plate used for structural member 10.

[0023] Figure 2 is a cross-sectional view of the structural member 10. The cross-section of the structural member 10 is a cross-section obtained by cutting the structural member 10 with a plane perpendicular to its axial direction. Hereinafter, in the cross-section of the structural member 10, the direction in which the vertical walls 121 and 122 face each other is called the width direction of the structural member 10, and the direction perpendicular to the axial direction and the width direction is called the height direction of the structural member 10.

[0024] Referring to Figure 2, the top plate 11 extends substantially in the width direction in a cross-sectional view of the structural member 10. In the example shown in Figure 2, the top plate 11 is positioned parallel to the width direction in a cross-sectional view of the structural member 10. However, the top plate 11 may be slightly inclined with respect to the width direction in a cross-sectional view of the structural member 10.

[0025] The vertical walls 121 and 122 each extend generally in the height direction in a cross-sectional view of the structural member 10. In the example shown in Figure 2, the vertical walls 121 and 122 are inclined with respect to the height direction of the structural member 10 such that they move further apart from each other as you move from the top plate 11 side toward the flanges 131 and 132 side. However, in a cross-sectional view of the structural member 10, at least one of the vertical walls 121 and 122 may be parallel to the height direction. The angle of vertical wall 121 relative to the top plate 11 may be the same as or different from the angle of vertical wall 122 relative to the top plate 11.

[0026] The first ridge sections 141 and 142 have a substantially or generally arc shape in cross-sectional view of the structural member 10. The first ridge section 141 is positioned between the top plate 11 and one vertical wall 121, forming a corner between the top plate 11 and the vertical wall 121. The first ridge section 142 is positioned between the top plate 11 and the other vertical wall 122, forming a corner between the top plate 11 and the vertical wall 122.

[0027] The second ridge sections 151 and 152 have a substantially or generally arc shape in a cross-sectional view of the structural member 10. The second ridge section 151 is positioned between the vertical wall 121 and the flange 131 and constitutes the corner between the vertical wall 121 and the flange 131. The second ridge section 152 is positioned between the vertical wall 122 and the flange 132 and constitutes the corner between the vertical wall 122 and the flange 132.

[0028] In the cross-section of the structural member 10, when the length of the top plate 11 in the width direction is the width W of the structural member 10, and the lengths of the vertical walls 121 and 122 in the height direction are the height L of the structural member 10, the height L is greater than the width W. More specifically, the structural member 10 satisfies L / W ≥ 1.2 in its cross-section. It is more preferable that the structural member 10 satisfies L / W ≥ 1.5 in its cross-section.

[0029] The width W is the distance in the width direction from the intersection i1 of the extension line of the outer surface of the top plate 11 and the extension line of the outer surface of one vertical wall 121 to the intersection i2 of the extension line of the outer surface of the other vertical wall 122 in the cross-section of the structural member 10. The height L is the distance in the height direction from the R-end on the flange 131,132 side on the outer surface of the second ridge sections 151,152 to the intersections i1,i2 in the cross-section of the structural member 10, for example. In the example shown in Figure 2, the distance in the height direction from the R-end on the flange 131 side on the outer surface of the second ridge section 151 to the intersection i1 (height on the vertical wall 121 side) is substantially equal to the distance in the height direction from the R-end on the flange 132 side on the outer surface of the second ridge section 152 to the intersection i2 (height on the vertical wall 122 side). If the height of vertical wall 121 differs from the height of vertical wall 122, the greater of the two will be the height L of the structural member 10.

[0030] The width W can be determined, for example, using the following equation based on Kármán's effective width theory. In the following equation, t is the plate thickness (t=t w ), k is the buckling coefficient, E is Young's modulus, ν is Poisson's ratio, σ y This is the yield stress. The width W of the cross-section of the structural member 10 is preferably less than or equal to the effective width be calculated by the following formula. In calculating the effective width be, compression of the surrounding simply supported plate is assumed, and k can be set to 4.

[0031]

number

[0032] In the cross-section of the structural member 10, the top plate 11 has a plate thickness t. W The top plate 11 has a plate thickness t over substantially its entire length in a cross-sectional view of the structural member 10. W It has the following characteristics. In the cross-section of the structural member 10, the vertical walls 121 and 122 each have a plate thickness t L The vertical walls 121 and 122 have a plate thickness t over substantially the entire cross-sectional view of the structural member 10. L It has the following: The thickness of the top plate 11 is t W The thickness t of the vertical walls 121, 122 LIt is larger than . More specifically, the structural member 10 has a cross-section of t L / t W The condition ≤0.7 is satisfied. In this embodiment, the plate thickness t of the vertical wall 121 L The vertical wall 122 has a plate thickness t L It is equal to the plate thickness t of the vertical wall 121. L and the thickness t of the vertical wall 122 L They may be different. The plate thickness t of the vertical wall 121 L and the thickness t of the vertical wall 122 L If they are different, the plate thickness t of the vertical wall 121 L and the plate thickness t of the vertical wall 122 L Both of them L / t W The condition ≤ 0.7 may be satisfied, and the plate thickness t of only one of the vertical walls 121, 122 may be satisfied. L ga t L / t W The condition ≤0.7 may also be satisfied. The plate thickness t of the vertical wall 121. L and the plate thickness t of the vertical wall 122 L If they are different, at least the thickness t of the vertical wall with the greater height among the vertical walls 121 and 122 L ga t L / t W The condition ≤ 0.7 must be satisfied. The thickness t of the vertical wall with the smaller height among vertical walls 121 and 122. L The thickness of the top plate 11 is t W It may be equal to . The structural member 10 has a cross-section of t L / t W It is more preferable that the value be ≤0.5.

[0033] By using, for example, a patchwork blank or a tailored blank as the material for the structural member 10, the thickness t of the tabletop 11 can be reduced. W The plate thickness t of the vertical wall 121, 122 LIt can be made larger than that. A patchwork blank is a material formed by layering a metal plate as a reinforcing material on top of a metal plate that is the blank body and joining the two by welding or the like. A tailored blank may be a tailored welded blank or a tailored rolled blank. A tailored welded blank is a material formed by butting together metal plates of different thicknesses and welding them. A tailored rolled blank is a material in which a metal plate is rolled to form parts with different thicknesses. For example, the thickness t of both vertical walls 121 and 122 L The thickness of the top plate 11 is t L When manufacturing a structural member 10 smaller than the above, if a tailor-welded blank is used as the material, a metal plate corresponding to the vertical wall 121, a metal plate corresponding to the top plate 11, and a metal plate corresponding to the vertical wall 122 are joined together. On the other hand, if one of the vertical walls 121 and 122 has a plate thickness smaller than the top plate 11, and the other of the vertical walls 121 and 122 has the same plate thickness as the top plate 11, then it is sufficient to join the metal plate corresponding to one of the vertical walls 121 and 122 with the metal plate corresponding to the top plate 11 and the other of the vertical walls 121 and 122, thereby reducing the number of joints between metal plates.

[0034] In the cross-section of the structural member 10, the thickness of the first ridge sections 141 and 142 that are continuous with the top plate 11 is equal to the thickness t of the top plate 11. W It may be the same or different. Preferably, the thickness of at least a portion of the first ridge portions 141, 142 is the same as the thickness t of the top plate 11. W It is equal to the thickness t of the top plate 11. In the cross-section of the structural member 10, the first ridges 141 and 142 are equal to the thickness t of the top plate 11 throughout their entire length. W It is preferable that the plate thickness be the same, but only a portion of the first ridge sections 141 and 142 has the plate thickness t of the top plate 11. W It may have the same plate thickness as the other. For example, in a cross-sectional view of the structural member 10, the portion of the first ridges 141 and 142 on the side of the top plate 11 has the same plate thickness t as the top plate 11. W It has the same plate thickness, and the portion on the vertical wall 121, 122 side has the same plate thickness t as the vertical wall 121, 122. L It may have the same plate thickness as the other.

[0035] In the cross-section of the structural member 10, the thickness of the second ridge sections 151 and 152 that are continuous with the vertical walls 121 and 122, respectively, is equal to the thickness t of the top plate 11. W Or the plate thickness t of the vertical walls 121, 122 L It may be the same or different. In the cross-section of the structural member 10, the plate thickness of the flanges 131 and 132 that are continuous with the second ridge sections 151 and 152, respectively, is the same as the plate thickness t of the top plate 11. W Or the plate thickness t of the vertical walls 121, 122 L It may be the same as, or it may be different from,

[0036] Other structural members 20 are joined to flanges 131 and 132 of structural member 10, and together with structural member 10, form a closed cross section. Structural members 20 extend substantially or generally in the width direction in a cross-sectional view of structural members 10 and 20. The thickness of structural member 20 is, for example, the thickness t of the top plate 11. W It is less than t. However, the thickness of the structural member 20 is the thickness of the top plate 11 t W It may be greater than or equal to the above. Also, the plate thickness of the structural member 20 is the plate thickness t of the vertical walls 121, 122. L It may be the same as, or it may be different from,

[0037] [effect] In this embodiment, the structural member 10, when formed together with other structural members 20, has a closed cross-section, and the plate thickness t of the vertical walls 121, 122 L / Top plate thickness t W The structure is configured such that the ratio is 0.7 or less. Furthermore, the structural member 10 is configured such that, in the closed cross-section, the ratio of the length L of the vertical walls 121 and 122 in the height direction to the length W of the top plate 11 in the width direction is 1.2 or more. As a result, even if, for example, an axial compressive force is applied to the structural member 10 at a position shifted from the center of gravity axis toward the top plate 11 due to a collision with the vehicle body, and both the axial compressive force and bending moment are applied to the structural member 10 simultaneously, elastic buckling of the top plate 11 becomes less likely. Therefore, the structural member 10 can exhibit high resistance to axial compressive force and bending moment, and the axial compressive force resistance and bending moment resistance performance of the structural member 10 can be improved simultaneously.

[0038] In this embodiment, the structural member 10 is preferably made of a steel plate having a tensile strength of 1470 MPa or more, and more preferably made of a steel plate having a tensile strength of 2500 MPa or more. In this case, while achieving weight reduction of the structural member 10, the axial compressive strength resistance and bending moment resistance performance expected of a high-strength material such as ultra-high-tensile steel can be obtained. Specifically, in the structural member 10, the plate thickness t of the top plate 11, which is prone to elastic buckling, w The plate thickness t between the vertical walls 121 and 122 L Compared to the previous configuration, the length W of the top plate 11 is made larger compared to the length L of the vertical walls 121 and 122. This makes it possible to suppress elastic buckling of the top plate 11 when an axial compressive force is applied to the structural member 10 at a position offset from the center of gravity axis toward the top plate 11. Therefore, the structural member 10 can achieve the axial compressive force resistance and bending moment resistance performance expected of high-strength materials. On the other hand, the plate thickness t of the vertical walls 121 and 122 is less prone to elastic buckling. L Because it is smaller, it is also possible to reduce the weight of the structural member 10.

[0039] In this embodiment, the structural member 10 has a ratio of L / W ≥ 1.2 and t over its entire axial length. L / t W It may have a cross-section that satisfies ≤0.7, or it may have such a cross-section in a portion of the axial direction. For example, L / W ≥ 1.2 and t L / t W The structural member 10 can be constructed such that the axial length of the cross-section satisfying ≤0.7 is 10 mm or more. The structural member 10 has a cross-section in which L / W ≥ 1.2 and t in a range of at least 1 / 6 of the total length in the axial direction of the structural member 10. L / t W It is preferable that the configuration satisfies ≤0.7. In this case, t obtained at multiple equally spaced locations within a range of at least 1 / 6 of the total axial length of the structural member 10. L ,t W The mean of L and W is L / W ≥ 1.2 and t L / t W It is sufficient if ≤0.7 is satisfied. L / W ≥ 1.2 and t L / tW It is preferable that a cross-section satisfying ≤0.7 is provided at least on the axial end side of the structural member 10, i.e., on the side where axial compressive force is applied.

[0040] In the structural member 10 according to this embodiment, the length W of the top plate 11 in the width direction can be less than or equal to the effective width be calculated based on Karman's effective width theory. In this case, when an axial compressive force is applied to the structural member 10, the top plate 11 can support the load along its entire length in the width direction, and buckling of the top plate 11 can be prevented.

[0041] In the structural member 10 according to this embodiment, the first ridge portions 141 and 142 that are continuous with the top plate 11 can have a plate thickness greater than that of the vertical walls 121 and 122, similar to the top plate 11. The first ridge portions 141 and 142 have a plate thickness t of the top plate 11, at least in the portion on the top plate 11 side. W It is preferable that the plate thickness is the same as that of the top plate 11, and the plate thickness t of the top plate 11 is the same throughout. W It is more preferable that the plate thickness be the same as that of the first ridge sections 141 and 142. By increasing the thickness of the first ridge sections 141 and 142, when an axial compressive force is applied to the structural member 10 at a position offset from the center of gravity axis toward the top plate 11, elastic buckling of the top plate 11 and its vicinity becomes less likely. Therefore, the axial compressive force resistance and bending moment resistance of the structural member 10 can be further improved.

[0042] While embodiments relating to this disclosure have been described above, this disclosure is not limited to the embodiments described above, and various modifications are possible as long as they do not deviate from its spirit. [Examples]

[0043] The present disclosure will be further described below with reference to examples. However, the present disclosure is not limited to the following examples.

[0044] To confirm the effects of the structural member according to the present disclosure, structural analysis was performed on the behavior of the structural member when an axial compressive force was input, using commercially available analysis software (LS-DYNA, manufactured by Livermore Software Technology Corporation (LSTC)). In the analysis, regarding the structural member 10 described in the above embodiment, displacements in the axial direction (z-direction), width direction (y-direction), and height direction (x-direction) were constrained for one end side in the axial direction, and rotations around the x and z axes were constrained. With respect to the other end side in the axial direction, while constraining displacements in the x and y directions and rotations around the x and z axes, an axial compressive load was input from the other end side at a position offset 40 mm from the center of gravity toward the top plate 11 side. Then, the axial force (axial direction load resistance) and the moment around the y-axis at the cross section at the central position in the axial direction of the structural member 10 were confirmed.

[0045] In this analysis, t L / t W and the conditions of L / W were changed, and the influence of t L / t W and L / W on the axial force and moment was investigated. Table 1 shows the conditions of t L / t W and L / W.

[0046]

Table 1

[0047] In this analysis, t L / t WBased on the structural members with L / W, the axial force and moment were evaluated as ratios to the reference structural member. For the reference structural member, based on the existing floor cross member, a steel plate with a tensile strength (TS) of 980 MPa class (tensile strength: 980 MPa or more) was used as the material, and its plate thickness was made constant throughout. On the other hand, the material of the structural member 10 other than the reference was a steel plate of TS2500 MPa class (tensile strength: 2500 MPa or more) or TS1470 MPa class (tensile strength: 1470 MPa or more). For the other structural member 20 that forms a closed cross section together with each structural member, a steel plate with a tensile strength of 1470 MPa was used as the material, and its plate thickness was set to 1 / 2 of the plate thickness of the reference structural member.

[0048] Figure 3 shows the relationship between t L / t W and the ratio of the axial force at the time of the maximum moment to the reference structural member (No. 1) for the structural members 10 of TS2500 MPa class (No. 2 to No. 6). Figure 4 shows the relationship between L / W and the ratio of the axial force at the time of the maximum moment to the reference structural member for the structural members 10 of TS2500 MPa class. Since it is normal that it becomes difficult to obtain a high axial force when a bending moment acts on a structural member and bending deformation occurs, in this analysis, the axial force at the time of the maximum moment was evaluated, and it was judged that the axial compression resistance performance and bending moment resistance performance were better as the axial force at the time of the maximum moment became larger.

[0049] The structural members 10 of No. 2 to No. 6 are configured to be approximately 50% lighter than the reference structural member No. 1. As shown in Figures 3 and 4, among these structural members 10, for the structural members 10 of No. 2 and No. 3 where t L / t W was set to 0.7 or less and L / W was set to 1.2 or more, the axial force at the time of the maximum moment became larger compared to the reference structural member. From Figures 3 and 4, it can be seen that the axial force at the time of the maximum moment becomes larger as t L / t W decreases and as L / W increases.

[0050] Figure 5 shows the structural members 10 (No. 7 to No. 11) of the TS1470MPa class, t L / t W Figure 6 shows the relationship between L / W and the ratio of axial force at the time of maximum moment generation relative to the standard structural member (No. 1).

[0051] Structural members 10 No. 7 to No. 11 are constructed to be approximately 30% lighter than the standard structural member No. 1. As shown in Figures 5 and 6, even when the tensile strength of the material is 1470 MPa or higher, t L / t W In structural members 10 No. 7 and No. 8, where t was set to 0.7 or less and L / W was set to 1.2 or more, the axial force at the time of maximum moment generation was greater compared to the standard structural member. As shown in Figures 5 and 6, similar to the case where the tensile strength of the material was 2500 MPa or more, the axial force at the time of maximum moment generation was t L / t W It can be seen that the value tends to increase as the decrease in [value] and the increase in L / W.

[0052] Based on the above analysis results, even if the material of the structural member 10 is made stronger and the structural member 10 is made lighter as a result, t L / t W When ≤0.7 and L / W ≤1.2 are satisfied, it can be said that good axial compressive strength resistance and bending moment resistance can be ensured. In particular, when the structural member 10 is formed from a steel plate with a tensile strength of 2500 MPa or more, it is possible to significantly reduce the weight of the structural member 10 while ensuring excellent axial compressive strength resistance and bending moment resistance.

[0053] In this analysis, the thickness of the first ridge sections 141 and 142 that are continuous with the top plate 11, specifically the portion on the top plate 11 side from the center, is defined as the thickness t of the top plate 11. W This was made identical. Furthermore, the plate thickness of flanges 131 and 132, and the plate thickness of the second ridge sections 151 and 152, specifically the portion on the flange 131 and 132 side from the center, were set to the plate thickness t of the top plate 11. WThis was treated as the same. However, under the condition that an axial compressive force is applied to the structural member 10 at a position shifted toward the top plate 11 from the center of gravity, tensile deformation occurs in the flanges 131, 132 and the second ridge sections 151, 152, so the plate thickness of the flanges 131, 132 and the second ridge sections 151, 152 does not substantially affect the axial compressive force resistance and bending moment resistance. [Explanation of Symbols]

[0054] 10: Structural members 11: Top plate 121,122: Vertical wall

Claims

1. A structural component for the vehicle body, The tabletop and Two vertical walls, which are connected to both side edges of the aforementioned top plate and face each other, Equipped with, The aforementioned structural member is a hot-stamped structural member formed from a steel plate. In a cross-section perpendicular to the axial direction of the structural member, Let W be the length of the top plate in the width direction of the structural member, and L be the length of the vertical wall in the height direction of the structural member. Let the thickness of the top plate be tW, and the thickness of the vertical wall be t Ｌ In that case, L / W ≥ 1.2 and t Ｌ / t Ｗ A structural member that satisfies ≤ 0.

7.

2. A structural member according to claim 1, The top plate and the vertical wall are structural members formed from steel plates having a tensile strength of 1470 MPa or more.

3. A structural member according to claim 2, The top plate and the vertical wall are structural members formed from steel plates having a tensile strength of 2500 MPa or more.

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