Impact absorbing member

Abstract

An impact absorbing member which absorbs an impact by axial crushing, wherein the impact absorbing member has a cylindrical shape extending along the axial direction, in a case where a cross section of the impact absorbing member perpendicular to the axial direction is set as a first cross section and a cross section defined by extension lines of a plurality of sides in the first cross section is set as a second cross section, the second cross section is a polygon, the first cross section includes a common vertex which is a vertex common to the second cross section and a groove which is located at a position corresponding to a vertex of the second cross section, and at least one internal angle of the vertex of the first cross section is 100° or more.

Description

Technical Field

[0001] This disclosure relates to an impact absorbing member. Background Technology

[0002] Shock-absorbing members are known to absorb impacts through axial crushing. When such shock-absorbing members are subjected to axial loads, continuous buckling occurs in a corrugated manner, thereby absorbing the impact. Shock-absorbing members are, for example, disposed at the top of longitudinal beams (front longitudinal beams, rear longitudinal beams) in automobile bodies as collision energy-absorbing boxes.

[0003] For example, Patent Document 1 discloses an impact-absorbing member having a groove recessed inwards in a local area of ​​at least one side of a basic cross-section, excluding the endpoint of that side. Furthermore, Patent Document 2 discloses a die-cast aluminum alloy impact energy-absorbing canister with a material-modified portion on the peripheral wall of a cylindrical section to locally reduce strength relative to compression in the vehicle's longitudinal direction. Furthermore, Patent Document 3 discloses an impact-absorbing member having corner wall portions at the four corners of a first closed cross-section, each forming a rectangular cross-section extending along its length, in cooperation with local portions of the transverse and longitudinal walls. These corner wall portions are separated from each other. Furthermore, Patent Document 4 discloses a collision energy-absorbing structure whose cross-sectional shape perpendicular to the axial direction is a polygon that is point-symmetric and non-axially symmetric with respect to the center of the cross-section. In this energy-absorbing structure, the aspect ratio when the outer contour of the cross-section is a quadrilateral is less than 1.5, and the ratio of the lengths of adjacent sides of the polygon constituting the cross-section is 2.3 or less.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2005-010398

[0007] Patent Document 2: Japanese Patent Application Publication No. 2012-166641

[0008] Patent Document 3: Japanese Patent Application Publication No. 2017-141860

[0009] Patent Document 4: Japanese Patent Application Publication No. 2011-218935 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] Impact absorbing components seek to balance impact absorption performance and lightweight design. This disclosure is made in view of the above-mentioned realities, and its main objective is to provide an impact absorbing component with a good balance between impact absorption performance and lightweight design.

[0012] Solution for solving the problem

[0013] One aspect of this disclosure is an impact-absorbing member that absorbs impacts through axial crushing, characterized in that the impact-absorbing member has a cylindrical shape extending along the axial direction, wherein the first section of the impact-absorbing member perpendicular to the axial direction is designated as a first section, and the second section is designated as a section defined by the extension lines of a plurality of sides in the first section, the second section is a polygon, the first section includes a common vertex sharing a vertex with the second section and a groove located at a position corresponding to the vertex of the second section, and at least one interior angle of the vertex of the first section is 100° or more.

[0014] According to this disclosure, since the first section includes a common vertex and a groove, a shock-absorbing member with a good balance between shock absorption performance and lightweight (shock absorption performance per unit weight) can be obtained.

[0015] In the above disclosure, the first cross section may also include a plurality of common vertices and a plurality of grooves, with the common vertices and grooves alternately arranged along the circumference of the first cross section.

[0016] In the above disclosure, the first cross-section may also include a plurality of shared vertices and a plurality of grooves, with at least two grooves positioned corresponding to vertices on the same diagonal in the second cross-section. The diagonal is the longest of a plurality of diagonals extending from a single vertex.

[0017] In the above disclosure, it is also possible that, in the first section, the lengths of adjacent sides are different.

[0018] In the above disclosure, non-planar portions may also be provided in such a way that the widths of adjacent planar portions are of different lengths.

[0019] In the above disclosure, it is also possible that in the first section, all interior angles less than 180° are 75° or more and 135° or less, and all the angles of the bottom apex of the groove are 75° or more and 135° or less.

[0020] In the above disclosure, the first cross section may not have a flange.

[0021] In the above disclosure, it is also possible that the first section does not have a partition wall inside.

[0022] The effects of the invention

[0023] The impact-absorbing component disclosed herein achieves a good balance between impact absorption performance and lightweight. Attached Figure Description

[0024] Figure 1 This is a schematic perspective view illustrating the impact absorbing component of this disclosure.

[0025] Figure 2 This is a schematic cross-sectional view illustrating the impact absorbing member of this disclosure.

[0026] Figure 3 This is a schematic cross-sectional view illustrating a conventional impact-absorbing component.

[0027] Figure 4 This is a schematic cross-sectional view illustrating the impact absorbing member of this disclosure.

[0028] Figure 5 This is a schematic cross-sectional view illustrating the impact absorbing member of this disclosure.

[0029] Figure 6 This is a schematic cross-sectional view illustrating the impact absorbing member of this disclosure.

[0030] Figure 7 These are schematic perspective views and schematic cross-sectional views illustrating the impact absorbing component of this disclosure.

[0031] Figure 8 This is a schematic cross-sectional view illustrating the impact absorbing member of Example 1 and Comparative Examples 1 and 2.

[0032] Figure 9 These are the results of FEM analysis of Example 1 and Comparative Examples 1 and 2.

[0033] Figure 10 This is the result of FEM analysis in Example 2.

[0034] Figure 11 This is the result of FEM analysis in Example 3.

[0035] Figure 12 This is a schematic front view illustrating the deformation pattern of compression.

[0036] Figure 13 This is a schematic cross-sectional view illustrating the impact-absorbing components of Examples 4, 5 and Comparative Example 3.

[0037] Figure 14 These are the results of FEM analysis of Examples 4, 5 and Comparative Example 3. Detailed Implementation

[0038] The impact-absorbing component of this disclosure is described in detail below. To facilitate understanding, the size and shape of the parts are appropriately exaggerated in the following figures. Furthermore, for convenience, shading lines or reference numerals are sometimes omitted in the figures.

[0039] Furthermore, when expressing the configuration of other components relative to a certain component, the configuration described as "above" or "below" includes both the configuration of other components being configured directly above or below a certain component in a manner that is in contact with a certain component, and the configuration of other components being configured above or below a certain component with another component in between.

[0040] Figure 1 This is a schematic perspective view illustrating the impact-absorbing component of this disclosure. Furthermore, Figure 2 This is a schematic cross-sectional view illustrating the impact absorbing member of this disclosure, specifically representing... Figure 1 and axial D A A sectional view with a vertical cutting plane. Figure 1 The impact absorbing member 10 shown passes through axial D A The impact is absorbed by crushing. The impact absorbing member 10 has a diameter along the axial direction D. A An extended cylindrical shape. Furthermore, as... Figure 2 As shown, the impact absorbing member 10 is aligned with the axial direction D. A The vertical section is designated as section 11. Figure 2 In this diagram, the first section 11 is depicted using a thicker solid line. On the other hand, the section defined by the extensions of the multiple sides (line segments connecting the vertices) of the first section 11 is designated as the second section 12. Figure 2 In the middle, section 12 is the section marked with a dashed line.

[0041] like Figure 2 As shown, the second section 12 is a polygon. Specifically, the second section 12 is an octagon with eight vertices along its circumference, from vertex A to vertex H. The first section 11 shares vertices with the second section 12. Figure 2 In the diagram, the first section 11 and the second section 12 share vertices A, C, E, and G, which are equivalent to common vertices. On the other hand, the first section 11 and the second section 12 do not share vertices B, D, F, and H. The first section 11 has grooves spanning vertices B, D, F, and H. These grooves have vertices B′, D′, F′, and H′ at their bottoms, respectively.

[0042] According to this disclosure, since the first section has a common vertex and a groove, a shock-absorbing member with a good balance between shock absorption performance and lightweight (shock absorption performance per unit weight) is obtained.

[0043] use Figure 3This explains the differences from previous impact-absorbing components. Figure 3 (a) is related to Patent Document 1. Figure 3 A considerable cross-section. Figure 3 In section 11 shown in (a), the first section 11 has grooves in portions of edge HA and edge DE in the second section 12. For example, edge HA is divided into edge HM and edge PA by the grooves, but these edges are on the same straight line. When considering the axial direction, the planar portion containing edge HM and the planar portion containing edge PA are on the same plane. Therefore, there is room for improvement in the balance between impact absorption performance and lightweight.

[0044] also, Figure 3 (b) is the cross section studied in Comparative Example 2 described later, but it is different from... Figure 3 Similarly, in (a), the two sides divided by the groove are on the same straight line, so there is room for improvement in the balance between shock absorption performance and lightweight.

[0045] In contrast, the first section of this disclosure has a groove located at a position corresponding to the vertex of the second section. The two sides obtained by dividing the section by such a groove are... Figure 3 of (a), Figure 3 (b) are different and not on the same straight line. For example, in Figure 2 In the design, the bottom is divided into sides AI and JC by a groove with a vertex B′ corresponding to vertex B, but these sides are not on the same straight line. When considering the axial direction, the planar portion containing side AI and the planar portion containing side JC are not on the same plane. Therefore, a good balance between shock absorption performance and lightweight can be achieved.

[0046] Figure 3 (c) is related to Patent Document 2. Figure 3 A considerable cross-section. Figure 3 As shown in (c), the first section 11 has grooves at all vertices (vertices A to D) of the second section 12. That is, Figure 3 The first section 11 shown in (c) does not have a common vertex with the second section 12. When bending stress is generated in the impact absorbing member in the axial direction, the common vertex becomes the main resistance point. Therefore, when the first section does not have a common vertex, the resistance relative to bending stress is low. In contrast, since the first section of this disclosure has a common vertex, it has the advantage of higher resistance relative to bending stress.

[0047] also, Figure 3 (d) is a cross-section with a honeycomb structure, but with Figure 3 Similarly, in section (c), section 11 does not share a vertex with section 12. Therefore, its resistance to bending stress is lower. Furthermore, Figure 3 The first section 11 shown in (d) has an internal partition wall. In the axial direction, the planar portions P1 and P2 constituting the outer edge of the first section 11 and the planar portion P3 constituting the partition wall form a robust joint structure, which acts as a resistance structure, thus achieving a good balance between impact absorption performance and lightweight. However, during axial crushing, high stress is generated in the joint structure, therefore, complex countermeasures are required to avoid damage to the joint structure caused by this stress. In contrast, the impact-absorbing member of this disclosure has the advantage that even when the first section does not have an internal partition wall, a good balance between impact absorption performance and lightweight is achieved.

[0048] The impact absorbing component of this disclosure is described in more detail below.

[0049] In this disclosure, the section perpendicular to the axial direction of the impact-absorbing member is defined as the first section. For example... Figure 1 and Figure 2 As shown, the first section 11 is achieved by utilizing the axial direction D A In the case of a cylindrical impact-absorbing member 10 being cut in the normal direction, the cross section is typically a closed cross section defined by the outer edge of the cylindrical shape.

[0050] On the other hand, in this disclosure, the section defined by the extensions of the plurality of sides of the first section is defined as the second section. Specifically, as Figure 2 As shown, the section defined by the extensions of the multiple edges (edges AI, JC, CK, LE, EM, NG, GO, and PA) of the first section 11 is defined as the second section 12. The multiple edges are set to be the maximum number that can constitute the second section 12. For example, in... Figure 2 In the second section 12, when edges AI, CK, EM, and GO are used as multiple edges constituting the second section 12, their extensions define a larger quadrilateral, but this is not equivalent to the second section 12 (because other edges such as JC are not considered). Furthermore, the second section 12 is defined as having no interior angles greater than 180°. For example, when edges IB′ and B′J are used as multiple edges constituting the second section 12, a figure with vertex B′ is defined, but this is not equivalent to the second section 12 (because the interior angle of vertex B′ is greater than 180°). The second section 12 is generally defined as the outer edge enclosing the first section 11.

[0051] In this disclosure, the second cross-section is a polygon. The second cross-section can be either a quadrilateral or a 2n-sided polygon (n is an integer greater than or equal to 2), or a triangle or a 2n+1-sided polygon (n is an integer greater than or equal to 1). The former has higher graphical symmetry, thus providing a shock-absorbing member with uniform resistance to bending stress in the axial direction. Such a shock-absorbing member is useful, for example, as a member requiring strong resistance to impacts (bending stress) from any direction. Compared to the former, the latter has lower graphical symmetry, thus providing a shock-absorbing member with non-uniform resistance to bending stress in the axial direction. Such a shock-absorbing member is useful, for example, as a member requiring strong resistance to impacts (bending stress) from a specific direction. n is not particularly limited and can be 2 or more, 3 or more, or 4 or more. On the other hand, n is, for example, 10 or less.

[0052] Figure 4 This is a schematic cross-sectional view illustrating the impact absorbing member of this disclosure, showing... Figure 2 A partial view of section 11 and section 12. In Figure 4 In the first section 11, there are shared vertices (vertices A and C) with the second section 12. On the other hand, the first section 11 has a groove X located at a position corresponding to the vertex of the second section 12. The following steps are used to determine whether the first section 11 has a groove X.

[0053] First, identify the vertices in the second section that are not shared with the first section (non-shared vertices). Figure 4 In the diagram, vertex B is equivalent to a non-shared vertex. Then, determine the boundary point (the boundary vertex of the first section) that exists in the middle of the edge connecting the non-shared and shared vertices and serves as the boundary between whether the first and second sections share that edge. Figure 4 In the diagram, vertex I, located in the middle of edge BA, and vertex J, located in the middle of edge BC, of ​​the first section are respectively equivalent to boundary vertices. Finally, considering a straight line connecting the two boundary vertices spanning the non-shared vertices, if the first section has an inflection point (foldback vertex) on the inner side of the second section (opposite to the non-shared vertex) closer to the outer edge of the second section than this line, it is determined that the first section possesses a groove. Figure 4 In the diagram, imagine a straight line IJ connecting vertices I and J, which serve as the dividing vertices. Since the first section 11 has a folded vertex (vertices B′) located on the inner side of the second section 12 (opposite to vertex B, which is a non-shared vertex) closer to the outer edge of the straight line IJ, it is determined that the first section 11 possesses a groove X. The groove X can have a single folded vertex or multiple folded vertices. Furthermore, the folded vertex can also be called the bottom vertex of the groove X.

[0054] The first cross-section can have either a single shared vertex or multiple shared vertices as described above. Similarly, the first cross-section can have either a single groove or multiple grooves as described above. The number of shared vertices and grooves can be arbitrarily combined. Furthermore, it is preferable that, as Figure 2 As shown, vertices and grooves are alternately arranged along the circumference of the first section 11. This is to ensure stable buckling. The second section 12 is a 2n-sided polygon (n is an integer greater than 2). Figure 2 In the case where the middle section is an octagon, the vertices and grooves are arranged alternately along the circumferential direction in a discontinuous manner. Furthermore, although not shown, in the case where the second section 12 is a 2n+1 gon (n is an integer greater than 1), the vertices and grooves along the circumferential direction produce a continuous portion, except for the continuous portion, which is arranged alternately.

[0055] Figure 5 This is a schematic cross-sectional view illustrating the impact absorbing member of this disclosure, showing... Figure 2 A portion of the first section 11 and the second section 12. In the impact absorbing member 10, at least one of the interior angles of the vertex of the first section 11 has an interior angle of 100° or more. As shown in the embodiments described later, if the interior angle of at least one vertex of the first section 11 is 100° or more, the resistance to bending stress is improved compared to the case where the interior angle of the vertex is 90° or less.

[0056] Furthermore, if the interior angle of at least one vertex of the first section 11 is 100° or greater, then the interior angles of the other vertices are not particularly limited. Here, as... Figure 5 As shown, the interior angle of vertex B′, which is the bottom vertex, is usually 180° or more. Therefore, for convenience, we assume that such an interior angle is not considered. In this case, in addition to the vertices with interior angles of 100° or more as described above, the interior angles of the vertices of the first section that are less than 180° are, for example, 75° or more, 90° or more, or 105° or more. Furthermore, the interior angle of at least one vertex of the first section 11 may also be 105° or more, or 110° or more.

[0057] When considering the axial direction, the interior angle in the first section corresponds to the edge angle of the adjacent planar portion. Since the edge angle of the adjacent planar portions is above an appropriate angle determined according to the shape and plate thickness of the impact-absorbing member, the out-of-plane deformation of adjacent planar portions easily generates a phase difference during axial crushing. Therefore, the out-of-plane deformations of planar portions with different phases interfere with each other, thereby increasing the resistance of each planar portion and making it easier to create a member with a good balance between impact absorption performance and lightweight.

[0058] On the other hand, interior angles less than 180° in the first section (e.g.) Figure 5The interior angle θ shown A and interior angle θ I The angle of the first section is, for example, 135° or less, preferably 130° or less. The interior angle in the first section corresponds to the edge angle of the adjacent planar portion of the impact absorbing member 10. If the angle of the interior angle (the edge angle of the adjacent planar portion) is within the above-mentioned range, the stability of buckling can be improved. Furthermore, all interior angles in the first section that are less than 180° are preferably within the above-mentioned range.

[0059] The angle of the outer corner of the bottom vertex of the groove (e.g.) Figure 5 The exterior angle θ shown B′ There are no particular limitations. The angle of the outer angle of the bottom vertex can be, for example, 75° or more, 90° or more, or 105° or more. The angle of the bottom vertex is also equivalent to the edge angle of the adjacent planar portion, just like the inner angle in the first section. Therefore, by using an appropriate angle or higher determined according to the shape, plate thickness, etc., of the edge angle of the adjacent planar portions, the out-of-plane deformations of different phases interfere with each other, and the resistance of the planar portions is easily improved.

[0060] On the other hand, the angle of the bottom apex can be, for example, 135° or less, or even 130° or less. This improves the stability of buckling. Furthermore, the angles of all bottom apexes of the groove are preferably within the above-mentioned range.

[0061] In the first section 11, the lengths of adjacent sides are preferably different. This is because the stability of buckling is improved. Here, considering the axial direction, the sides in the first section 11 correspond to the widths of the planar portions. Different lengths of adjacent sides mean that the widths of adjacent planar portions are different. If the widths of adjacent planar portions are different, the out-of-plane deformation of adjacent planar portions is more likely to produce a phase difference during axial crushing. When adjacent planar portions buckle in opposite phases due to the phase difference, buckling proceeds stably. "Different lengths" means that the absolute value of the difference between the lengths of two sides is 0.5 mm or more, or it can be 1.0 mm or more, or it can be 2.0 mm or more. On the other hand, the absolute value of the difference between the lengths of two sides is, for example, 2.0 cm or less. Furthermore, in the first section 11, the lengths of adjacent sides can also be the same. "The same lengths" means that the absolute value of the difference between the lengths of two sides is less than 0.5 mm.

[0062] The condition that "adjacent sides in the first cross section have different lengths" can be categorized into several forms. Specific examples include (i) the two sides forming a common vertex have different lengths, (ii) the two sides forming a bottom vertex have different lengths, and (iii) the two sides forming a dividing vertex have different lengths. The first cross section preferably satisfies at least one of (i) to (iii). This is because the stability of buckling is improved.

[0063] use Figure 5 Explain the morphology of (i) to (iii). In Figure 5 In the equation, vertex A, which is a shared vertex, is connected by edge α. A and edge β A The vertex B′, which forms the bottom vertex of the groove X, is formed by edge γ. B′ and edge δ B′ The boundary vertex I is formed by edge β. A and edge γ B′ The form of (i) is equivalent to edge α. A and edge β A Different shapes with varying lengths, (ii) is equivalent to edge γ. B′ and edge δ B′ The shapes with different lengths, (iii) is equivalent to edge β. A and edge γ B′ Different shapes with varying lengths.

[0064] In this disclosure, it is preferred that the lengths of the sides are repeated along the circumference of the first cross-section. For example, in Figure 5 In the first section 11, edges AI, IB′, B′J, and JC are arranged circumferentially. However, along the circumferential direction of the first section 11, edge IB′ is shorter than edge AI, edge B′J is longer than edge IB′, and edge JC is shorter than edge B′J. In particular, consider the case where the first section is a 2n-sided polygon (n is an integer greater than 2), with edges 1 to 2n along the circumferential direction. When the second edge is longer than the first edge, it is preferable that the 2m-1 edge (m = 2 to n) is shorter than the 2m-2 edge, the 2m edge is longer than the 2m-1 edge, and the first edge is shorter than the 2n edge. Conversely, when the second edge is shorter than the first edge, it is preferable that the 2m-1 edge (m = 2 to n) is longer than the 2m-2 edge, the 2m edge is shorter than the 2m-1 edge, and the first edge is longer than the 2n edge. Alternatively, the lengths of all sides of the 2m-1th edge (m = 2 to n) can be the same as the length of the first edge, and the lengths of all sides of the 2mth edge (m = 2 to n) can be the same as the length of the second edge. Furthermore, as... Figure 8 As shown in (a), in Embodiment 1 described later, the first cross section is a hexagon, and the lengths of the sides (Wp1, Wp2) repeat along the circumference of the first cross section.

[0065] Furthermore, when the first section is a 2n-sided polygon (n is an integer greater than 2) and is arranged alternately along the circumferential long side L (width Wp1 of the planar portion) and short side S (width Wp2 of the planar portion), it is preferable to satisfy the following condition (1).

[0066] 1.01 <L / S (1)

[0067] In impact-absorbing members that satisfy the conditions described in (1) above, even when high-strength steel plates are used as the material, the phase difference in out-of-plane deformation of adjacent planar portions during axial crushing is easily generated. When adjacent planar portions buckle in opposite phases due to this phase difference, buckling is easily and stably carried out. In addition, the length of the side (width of the planar portion) in this specification is the length from the rounded corner node (the boundary between the curve and the straight line in the cross section) of one of the two edge portions separated by a planar portion to the rounded corner node of the other edge portion.

[0068] In this disclosure, the first cross-section may also not have a flange. When the first cross-section does not have a flange, it is possible to suppress the disorder of buckling (deformation) caused by the flange. A flange refers to a portion that protrudes outward from the outer edge of the first cross-section. Furthermore, as a conventional impact-absorbing member, an impact-absorbing member such as that disclosed in Japanese Patent Publication No. Hei 8-128487 is known, in which a back plate and a flange provided on a member having a cap-shaped cross-section are welded together to form a box-shaped member.

[0069] In this disclosure, the first section may also not have a partition wall portion internally. Like the method described above... Figure 3 As explained in (d), a robust bonding structure is formed by providing partition walls, which acts as a structural support, thus achieving a good balance between impact absorption performance and lightweight. However, during axial crushing, high stress is generated in the bonding structure, requiring complex countermeasures to prevent damage to the bonding structure caused by this stress. In contrast, the impact-absorbing member of this disclosure has the advantage of maintaining a good balance between impact absorption performance and lightweight even when the first section does not have partition walls internally.

[0070] Figure 6 This is a schematic cross-sectional view illustrating the impact-absorbing member of this disclosure. Figure 6 In (a), the second section 12 is a hexagon with six vertices, A to F, along its circumference. The first section 11 and the second section 12 share vertices C and F, which are equivalent to common vertices. However, the first section 11 and the second section 12 do not share vertices A, B, D, and E. The first section 11 has grooves X spanning vertices A, B, D, and E. These grooves X have vertices A′, B′, D′, and E′ at their bottoms, respectively. Alternatively, as... Figure 6 As shown in (a), the number of vertices is less than the number of grooves X.

[0071] Preferably, at least two grooves X are positioned corresponding to vertices on the same diagonal in the second section 12. In this case, the diagonal is the longest of several diagonals extending from a single vertex (hereinafter referred to as the "longest diagonal"). With such an impact-absorbing member, the symmetry of the shared vertex and groove configuration is improved, and buckling stability is enhanced. Figure 6 In the example shown in (a), there are three longest diagonals: Y1 extending from vertex A, Y2 extending from vertex B, and Y3 extending from vertex C. Furthermore, the groove X is positioned corresponding to the vertices of vertices A and D that are endpoints of diagonal Y1, and the vertices of vertices B and E that are endpoints of diagonal Y2.

[0072] exist Figure 6 In (b), the second section 12 is a decagon with 10 vertices A to J along the circumferential direction. The first section 11 and the second section 12 share vertices B, C, E, G, H, and J, which are equivalent to common vertices. On the other hand, the first section 11 and the second section 12 do not share vertices A, D, F, and I. The first section 11 has grooves X spanning vertices A, D, F, and I. These grooves X have vertices A′, D′, F′, and I′ at their bottoms, respectively. Alternatively, as... Figure 6 As shown in (b), the number of shared vertices is greater than the number of grooves X. Furthermore, in Figure 6 In the example shown in (b), there are four diagonals Y1 to Y5 as the longest diagonals, and the groove X is positioned at the corresponding vertices of vertices A and F that become the endpoints of diagonal Y1 and vertices D and I that become the endpoints of diagonal Y4.

[0073] In addition, Figure 6 In (c), the second section 12 is a hexagon with six vertices, A to F, along its circumference. The first section 11 and the second section 12 share vertices A, C, and E, which are equivalent to common vertices. However, the first section 11 and the second section 12 do not share vertices B, D, and F. The first section 11 has grooves X spanning vertices B, D, and F. These grooves X have vertices B′, D′, and F′ at their bottoms, respectively. Alternatively, as shown... Figure 6 As shown in (c), the number of vertices is the same as the number of grooves X.

[0074] In addition, Figure 6In (d), the second section 12 is a pentagon with five vertices, A to E, along its circumference. The first section 11 and the second section 12 share vertices A and D, which are equivalent to shared vertices. On the other hand, the first section 11 and the second section 12 do not share vertices B, C, and E. The first section 11 has grooves X spanning vertices B, C, and E. These grooves X have vertices B′, D′, and F′ at their bottoms, respectively.

[0075] The impact absorbing member disclosed herein may also have a non-planar portion in such a way that the lengths of adjacent planar portions are different from each other. According to the impact absorbing member having such a non-planar portion, similar to the case where the lengths of adjacent sides in the first section described above are different, the stability of buckling that may occur when an axial load is applied is improved. Furthermore, in order to improve this effect, the relationship between the lengths of adjacent planar portions preferably satisfies the condition described above (1).

[0076] A non-planar portion refers to a discontinuous portion of material within the plane of a planar portion constituting an impact-absorbing member, or a portion that is recessed inward or protrudes outward relative to that planar portion. Examples of non-planar portions with material discontinuities include openings such as round or elongated holes, and notches. Furthermore, examples of non-planar portions that are recessed inward or protruding outward relative to the planar portion include concave reinforcing ribs that are recessed inward relative to the planar portion, convex reinforcing ribs that protrude outward relative to the planar portion, or embossed portions with irregularities created through embossing. The specific shape of the non-planar portion is not particularly limited. For example, if the non-planar portion is a hole, it can be either a circular or square hole. Similarly, if the non-planar portion is a reinforcing rib, it can be either a circular or square reinforcing rib.

[0077] Furthermore, when a planar portion is sandwiched between an edge portion and a non-planar portion, the width of the planar portion of the impact-absorbing member having a non-planar portion refers to the length from the rounded corner of the edge portion to the non-planar portion. Additionally, when a planar portion is sandwiched between two non-planar portions, the length from one non-planar portion to the other is the width of the planar portion.

[0078] Here, refer to Figure 7 Examples of the shape and arrangement of the non-planar parts described above. Figure 7 This is a perspective view of the axial end of an impact-absorbing member having a non-planar portion and a schematic diagram showing a cross-section cut along a direction perpendicular to the axial direction. Figure 7 In the example shown in (a), notches are formed in the planar portion at the axial end of the impact-absorbing member 10 as a plurality of non-planar portions 13. Figure 7 In the example shown in (b), a ratio is formed. Figure 7The notch shown in (a) is a wide notch as multiple non-planar parts 13. Figure 7 (c) is an example of a non-planar portion 13 having a notch and an elongated hole. The elongated hole is formed on a planar portion that is different from the planar portion with the notch, and the positions of the elongated hole and the notch in the axial direction are different from each other.

[0079] Materials for the impact-absorbing member disclosed herein include, for example, metals such as steel and aluminum alloys. Furthermore, the tensile strength of the aforementioned metals is preferably 780 MPa or higher, more preferably 980 MPa or higher, and even more preferably 1180 MPa or higher. Furthermore, the plate thickness of the impact-absorbing member is not particularly limited, for example, it is 0.5 mm or more and 5 mm or less, or it can be 0.5 mm or more and 1.6 mm or less. While materials with a tensile strength of 780 MPa or higher are advantageous for impact absorption performance, there is room for improvement in terms of suppressing the decrease in stability caused by deformation due to material fracture. It can be concluded that fracture occurs due to bending deformation, and the thinner the plate, the more advantageous the strain generated by bending deformation with the same radius of curvature. From this perspective, the plate thickness of the impact-absorbing member is preferably 1.6 mm or less. Furthermore, the impact-absorbing member can be used for any application of absorbing impacts through axial crushing, but a typical application is a collision energy-absorbing box for automobiles.

[0080] The method for manufacturing the impact-absorbing component disclosed herein is not particularly limited, but examples include one or more methods such as extrusion, hydroforming (liquid sealing), and roll forming of raw materials having a cylindrical shape. Another example of a method for manufacturing the impact-absorbing component is a method in which a cylindrical shape having a first cross-section is formed by one or more processes such as stamping, bending, drawing, winding, and roll forming of a steel plate. To make the cylindrical shape a closed cross-section, appropriate joining may be performed. Examples of joining methods include intermittent joining such as spot welding, riveting, and friction stir spot welding, and continuous joining such as arc (plasma) welding, laser welding, and friction stir joining.

[0081] This disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and any embodiment having a structure that is substantially the same as the technical concept described in the claims of this disclosure and achieving the same effect is included within the protection scope of this disclosure.

[0082] Example

[0083] [Example 1]

[0084] The buckling deformation behavior was evaluated using FEM analysis. In Example 1, the buckling deformation behavior was evaluated using FEM analysis. Figure 8The buckling deformation behavior of the impact absorbing member in section 1 shown in (a) was evaluated. Figure 8 The first section shown in (a) defines Wp1 (11 mm) and Wp2 (9 mm) as the width Wp (forming the edge of the first section) of the axially extending planar portion P. Additionally, although not shown, Figure 8 The second section of the impact absorbing member shown in (a) is... Figure 2 It is also an octagon. Furthermore, all interior angles (edge ​​angles) less than 180° in the first section are set to θ1 = 120°, and the angles (edge ​​angles) at the bottom vertices of the four grooves are all set to θ2 = 90°. Additionally, the radius of curvature Rr of the edges is set to 5 mm, and the axial length is set to 200 mm. The FEM analysis uses the material properties of a 1180 MPa grade steel plate with a thickness of 1.0 mm. The strain rate dependence is considered according to the Cowper-Symonds model, and the deformation rate (impact velocity) during buckling deformation is set to 5 m / s.

[0085] [Comparative Example 1]

[0086] In Comparative Example 1, for those with Figure 8 The buckling deformation behavior of the impact absorbing member in section 1 shown in (b) was evaluated. Figure 8 In the first section shown in (b), Wp1 (10 mm), Wp2 (12 mm), and Wp3 (8 mm) are defined as the width Wp of the axially extending planar portion P. Furthermore, all interior angles (edge ​​angles) less than 180° in the first section are set to θ1 = 90°, and the angles (edge ​​angles) of the bottom vertices of the four grooves are also set to θ1 = 90°. Other conditions are the same as in Example 1.

[0087] [Comparative Example 2]

[0088] In Comparative Example 2, for those with Figure 8 The buckling deformation behavior of the impact absorbing member in section 1 shown in (c) was evaluated. Figure 8 The first section shown in (c) is defined with Wp1 (12 mm), Wp2 (8 mm), Wp3 (9 mm), and Wp4 (12 mm) as the width Wp of the axially extending planar portion P. Furthermore, all interior angles (edge ​​angles) less than 180° in the first section are set to θ1 = 90°, and the angles (edge ​​angles) of the bottom vertices of the four grooves are also set to θ1 = 90°. Other conditions are the same as in Example 1. The setting conditions of Example 1 and Comparative Examples 1 and 2 are shown in Table 1.

[0089] [Table 1]

[0090]

[0091] [evaluate]

[0092] The results of FEM analysis of Example 1 and Comparative Examples 1 and 2 are presented in... Figure 9 In. Figure 9 In the graph, the horizontal axis represents the displacement δ [mm] at the load point, and the vertical axis represents the load F / Lt [kN / mm] per unit cross-sectional area, obtained by dividing the load F by the cross-sectional area Lt of the component. 2 ].like Figure 9 As shown, it can be confirmed that Example 1 has a higher load level throughout the entire crushing stroke compared to Comparative Examples 1 and 2. Specifically, the average load F, which represents the displacement from 0 mm to 125 mm, is... ave / Lt[kN / mm 2 In Example 1, it was 0.53 kN / mm. 2 In Comparative Example 1, it was 0.44 kN / mm. 2 In Comparative Example 2, it was 0.46 kN / mm. 2 That is, compared with Comparative Examples 1 and 2, Example 1 has a good balance between shock absorption performance and lightweight (shock absorption performance per unit weight).

[0093] [Examples 2 and 3]

[0094] The buckling deformation behavior was evaluated using FEM analysis. In Examples 2 and 3, similar to Example 1, the buckling deformation behavior was evaluated using FEM analysis. Figure 8 The buckling deformation behavior of the impact absorbing member at the first cross section shown in (a) was evaluated. The setting conditions for Examples 2 and 3 are shown in Table 2.

[0095] [Table 2]

[0096]

[0097] [evaluate]

[0098] The results of FEM analysis in Examples 2 and 3 are presented in... Figure 10 , Figure 11 In the middle. For example Figure 10 , Figure 11 As shown, the larger the edge angle θ1 becomes, the more likely it is to reach 130°. F ave A higher / Lt value is better. On the other hand, such as Figure 11 As shown, when the edge angle θ1 is 135°, F ave The value of / Lt decreases slightly. Here, as... Figure 12 As shown in (a), Figure 10 and Figure 11 The quadrilateral markings shown represent a deformation mode (Type I) where buckling occurs stably. On the other hand, as... Figure 12 As shown in (b), Figure 11 The triangles shown represent deformation modes that occur unstablely during buckling (“unstable”). Figure 11 As shown, when the edge angle θ1 is 130°, although the deformation mode becomes "unstable", F ave The value of / Lt is the highest, thus showing that the edge angle θ1 is particularly preferably below 130°.

[0099] [Example 4]

[0100] In Example 4, for those having Figure 13 The buckling deformation behavior of the impact absorbing member in section 1 shown in (a) was evaluated. Figure 13 The first cross-section shown in (a) has Wp1 (16 mm) and Wp2 (14 mm) as the width Wp of the planar portion P. The second cross-section is a quadrilateral. Furthermore, the interior angles (edge ​​angles) of the common vertices B and D of the first cross-section are all set to θ1 = 90°, the interior angles (edge ​​angles) of the dividing vertices I, J, K, and L are all set to θ2 = 100°, and the angles (edge ​​angles) of the bottom vertices A′ and C′ are all set to θ3 = 110°. Other conditions are the same as in Example 1.

[0101] [Example 5]

[0102] In Example 5, for those having Figure 13 The buckling deformation behavior of the impact absorbing member in section 1 shown in (b) was evaluated. Figure 13 The first cross-section shown in (b) has Wp1 (16 mm) and Wp2 (14 mm) as the width Wp of the planar portion P. The second cross-section is a quadrilateral. Furthermore, the interior angles (edge ​​angles) of the common vertices B and D of the first cross-section are all set to θ1 = 110°, the interior angles (edge ​​angles) of the dividing vertices I, J, K, and L are all set to θ2 = 90°, and the angles (edge ​​angles) of the bottom vertices A′ and C′ are all set to θ3 = 110°. Other conditions are the same as in Example 1.

[0103] [Comparative Example 3]

[0104] In Comparative Example 3, for those with Figure 13 The buckling deformation behavior of the impact absorbing member in section 1 shown in (c) was evaluated. Figure 13 The first cross-section shown in (c) has Wp1 (16 mm) and Wp2 (14 mm) as the width Wp of the planar portion P. The second cross-section is a quadrilateral. Furthermore, the interior angles (edge ​​angles) of the common vertices B and D, the interior angles (edge ​​angles) of the boundary vertices I, J, K, and L, and the angles (edge ​​angles) of the bottom vertices A′ and C′ of the first cross-section are all set to 110°. Other conditions are the same as in Example 1. The setting conditions of Examples 4, 5, and Comparative Example 3 are shown in Table 1.

[0105] [Table 3]

[0106]

[0107] [evaluate]

[0108] The results of FEM analysis of Examples 4, 5 and Comparative Example 3 are presented in... Figure 14 In the middle. For example Figure 14 As shown, it can be confirmed that Examples 4 and 5, compared to Comparative Example 3, exhibit higher load levels throughout the entire crushing stroke. Specifically, considering the average F load as a displacement of 0 mm to 125 mm... ave / Lt[kN / mm 2 When, in Examples 4 and 5, F ave / Lt was improved by about 10% compared to Comparative Example 3. That is, compared with Comparative Example 3, Examples 4 and 5 showed a good balance between shock absorption performance and lightweight (shock absorption performance per unit weight).

[0109] Explanation of reference numerals in the attached figures

[0110] 10. Impact absorbing component; 11. First section; 12. Second section; X, groove.

Claims

1. An impact-absorbing member that absorbs impact through axial crushing, wherein, The impact-absorbing member has a cylindrical shape extending along the axial direction. When the section perpendicular to the axial direction of the impact-absorbing member is designated as the first section, and the section defined by the extensions of the multiple sides of the first section is designated as the second section, The second cross section is polygonal. The first cross section includes a common vertex that shares a vertex with the second cross section and a groove located at a position corresponding to the vertex of the second cross section. At least one interior angle of the vertex of the first section is 100° or more. The first cross section includes a plurality of common vertices and a plurality of grooves. The common vertices and the grooves are arranged alternately along the circumference of the first cross section. In any adjacent side of the first section, the lengths of the two adjacent sides are not the same. At least two of the grooves are positioned at locations corresponding to the vertices on the same diagonal line in the second section. The diagonal is the longest of a plurality of diagonals extending from a single vertex. Non-planar portions are provided in such a way that the widths of adjacent planar portions are of different lengths.

2. The impact absorbing member according to claim 1, wherein, In the first section, All interior angles less than 180° are between 75° and 135°. The angle of the bottom apex of the groove is all above 75° and below 135°.

3. The impact absorbing member according to claim 1, wherein, The first cross section does not have a flange.

4. The impact absorbing member according to claim 1, wherein, The first section does not have a partition wall inside.

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