Impact absorbing member

Abstract

To provide an impact absorbing member which can be easily molded by a resin and can efficiently absorb impact energy by properly arranging members different from each other.SOLUTION: A shock-absorbing member made of a resin deformed by receiving a shock load, comprising: a first member having at least a shock-load receiving surface and an internal space opened on a side opposite to the shock-load receiving surface; and a second member mounted in the internal space and having a plate-shaped component extending in a shock-load direction, wherein a plate thickness of the plate-shaped component of the second member is gradually increased from the shock-load receiving surface side toward an opening side of the internal space.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an improved shock absorbing member that efficiently absorbs large impact energy by combining different members against external impacts. [Background technology]

[0002] In transportation equipment such as automobiles or railroad cars, impact absorbing members that absorb impact energy and mitigate shock during a collision are installed at the front, sides, and / or rear of the vehicle. Such vehicle impact absorbing members may employ a structure that combines different members to efficiently absorb the large impact energy during a vehicle collision while maintaining a substantially constant load (making the load-displacement diagram during a collision a rectangular wave).

[0003] In this context, proposed shock absorbing components include one in which a second member is filled into a first member having a hollow portion (Patent Document 1), and another in which members having multiple ribs are stacked and attached inside a hard synthetic resin (Patent Document 2).Further proposed shock absorbing components include one in which a second member having a buckling suppression mechanism is attached to a first member having multiple hollow portions (Patent Document 3), and another in which a resin reinforcing member combining multiple plate-like ribs is attached inside a vehicle frame having a closed cross section (Patent Document 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-349361 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-118670 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-222137 [Patent Document 4] Japanese Patent Application Laid-Open No. 2011-110970 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in any of the prior art documents, it is currently difficult to efficiently absorb impact energy.

[0006] For example, Patent Document 1 discloses that impact-absorbing components mounted under large impact loads, such as those expected in the present application, tend to be large. Therefore, two-shot molding, in which a large resin first component is filled with a second component, is not practical due to the increased cost associated with the larger molding machine and the resulting deterioration of physical properties due to the occurrence of sink marks and voids on the secondary side. Patent Document 2 discloses a rib shape that is thickest on the impact load-receiving side and gradually thins toward the base of the end. However, this shape is prone to buckling at the thinner base, causing the rib to tip over in the direction perpendicular to the impact load, resulting in inefficient energy absorption. Patent Document 3 also discloses a buckling suppression mechanism in which a partition wall molded body or a glass bubble molded body is attached as a restraining member within each hollow portion of a core block. However, it is not practical to mold a molded body with the shape disclosed in Patent Document 3 with the resin expected in the present application with sufficient precision to fit tightly against the inner surface of each hollow portion. Alternatively, in Patent Document 4, a resin reinforcing member is attached to a vehicle frame structure with an open side portion, but if the resin reinforcing member is broken, it will protrude from the open surface and the intended reinforcing effect cannot be obtained.

[0007] Therefore, in view of the problems in the conventional technology described above, the object of the present invention is to provide an impact absorbing component that can be easily molded from resin and that can efficiently absorb impact energy by appropriately arranging different components. [Means for solving the problem]

[0008] In order to solve the above problems, the impact absorbing member of the present invention is a resin impact absorbing member that deforms when subjected to an impact load, and is characterized in that it comprises at least an impact load receiving surface, a first member having an internal space that is open on the side opposite to the impact load receiving surface, and a second member that is mounted within the internal space and has a plate-shaped component extending along the impact load direction, and the plate thickness of the plate-shaped component of the second member gradually increases from the impact load receiving surface side toward the opening side of the internal space.

[0009] In such a shock absorbing member according to the present invention, it is preferable that the first member has ribs extending along the direction of the impact load, and that the internal space of the first member is divided into a plurality of spaces by the ribs.

[0010] It is also preferable that the multiple spaces are formed in line symmetry or point symmetry with respect to the central axis or central point of the first member, and that multiple second members are provided and attached to all of the multiple spaces, respectively.

[0011] It is also preferable that the second member is formed so that the thickness is uniform across the cross section perpendicular to the impact load direction.

[0012] It is also preferable that the second member includes at least two plate-like constituent parts, and that the at least two plate-like constituent parts intersect at least one point when viewed from the impact load direction.

[0013] Furthermore, it is preferable that the cross section of the intersection of at least two plate-like constituent parts of the second member in a direction perpendicular to the impact load direction has a cross shape.

[0014] It is also preferable that the second member is formed in line symmetry or point symmetry with respect to the central axis or central point of the second member.

[0015] It is also preferable that the first member has a recess on the inside of a side surface portion that forms the internal space, for guiding the second member when the second member is inserted into the internal space.

[0016] Furthermore, the first and second members are preferably bonded or welded to each other at at least one location.

[0017] Furthermore, it is preferable that the fracture strain ε1 of the first member and the fracture strain ε2 of the second member have the relationship ε1>ε2. [Effects of the Invention]

[0018] According to the impact absorbing member of the present invention, a specific second member is attached to a first member, thereby absorbing large impact energy such as that occurring during a vehicle collision, and the second member is composed of a plate-shaped component extending along the impact load direction, making it easy to mold.The plate-shaped component gradually becomes thicker from the impact load receiving surface side toward the opening side of the internal space, making it possible for the buckling starting point to occur from the impact load receiving surface side, eliminating the risk of tipping over and making it possible to exhibit highly efficient impact energy absorption characteristics. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 shows an impact absorbing member according to a first embodiment (Example 1) of the present invention, where (a) is a perspective view of the impact absorbing member, (b) is a bottom view seen from the opening side of the first member, (c) is a longitudinal cross-sectional view along line A-A' shown in (b), and (d) is a perspective view when the side portion is tilted. [Figure 2] FIG. 2 is a perspective view of a second member in the first embodiment (Example 1) of the present invention. [Figure 3] FIG. 3 is a schematic front view showing a simulation model for a drop weight test of an impact absorbing member according to the first embodiment (Example 1) of the present invention. [Figure 4] FIG. 4 is a load-displacement diagram of Example 1 and Comparative Example 1. [Figure 5] FIG. 5 shows schematic diagrams of deformation of the second member in Example 1 and Comparative Example 1 immediately after the first peak load, where (a) shows Example 1 and (b) shows Comparative Example 1. [Figure 6]FIG. 6 shows an impact absorbing member according to the second embodiment (Example 2) of the present invention and Comparative Example 2, where (a) is a perspective view of the impact absorbing member, (b) is a bottom view of Example 2, (c) is a bottom view of Reference Example 2-1, and (d) is a bottom view of Reference Example 2-2. [Figure 7] FIG. 7 is a load-displacement diagram for Example 2, Reference Example 2-1, and Reference Example 2-2. [Figure 8] FIG. 8 is a schematic diagram showing deformation of the second member in Reference Example 2-1 and Reference Example 2-2 immediately after the first peak load. [Figure 9] 9A and 9B show an impact absorbing member according to the third embodiment (Example 3) of the present invention and Reference Example 3, where (a) is a perspective view of the impact absorbing member, (b) is a bottom view of Example 3, and (c) is a bottom view of Reference Example 3. [Figure 10] FIG. 10 is a load-displacement diagram for Example 3 and Reference Example 3. [Figure 11] FIG. 11 is a schematic diagram of modifications of Example 3 and Reference Example 3 at half the maximum displacement. [Figure 12] FIG. 12 is a bottom view of a shock absorbing member according to a fourth embodiment (Example 4) of the present invention. [Figure 13] FIG. 13 is a bottom view of a shock absorbing member according to the fifth embodiment (Example 5) of the present invention. [Figure 14] FIG. 14 is a load-displacement diagram for Examples 1, 4, and 5. [Figure 15] FIG. 15 is a schematic diagram of deformation of Examples 4 and 5 immediately after the first peak load. [Figure 16] FIG. 16 is a load-displacement diagram for Example 6 and Reference Example 6. [Figure 17] FIG. 17 is a schematic diagram of deformation of Example 6 and Reference Example 6 immediately after the first peak load. [Figure 18] FIG. 18 is a perspective view showing examples of the first member in the impact absorbing member according to the present invention. [Figure 19]FIG. 19 is a bottom view showing examples of the first member in the impact absorbing member according to the present invention. [Figure 20] FIG. 20 is a perspective view showing examples of the second member in the impact absorbing member according to the present invention. [Figure 21] FIG. 21 is a bottom view showing examples of the impact absorbing member according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a shock-absorbing member according to a first embodiment (Example 1) of the present invention, where (a) is a perspective view of the shock-absorbing member, (b) is a bottom view seen from the opening side of the first member, (c) is a longitudinal cross-sectional view along line A-A' shown in (b), and (d) is a perspective view when the side portion is tilted. In FIG. 1, reference numeral 100 denotes the shock-absorbing member, and shock-absorbing member 100 is provided with a first member 101 and a second member 102. Inside first member 101, an internal space 105 is formed by an impact load receiving surface 103 and a side wall portion 104, and second member 102 is attached to internal space 105. On the opening 108 side of internal space 105 of first member 101, a flange portion 106 is provided, extending toward the opposite side of the internal space and having a joint portion for joining to another member, and a fastening portion 107 is provided to flange portion 106. The impact absorbing member 100 is an example of an impact absorbing member produced in this embodiment, and the present invention is not limited to the shape of the impact absorbing member according to this embodiment.

[0021] The first component 101 has at least an impact load receiving surface 103 and an internal space 105 that is open on the side opposite the impact load receiving surface. The impact load receiving surface 103 is preferably formed so that the impact load can be evenly distributed throughout the component when an impact load is applied. A sidewall 104 formed to form the internal space 105 may extend in the impact load direction or in a direction angled from the impact load direction. Preferably, the sidewall 104 extends along the impact load direction. However, to provide a draft angle when forming the first component 101 by injection molding, the sidewall 104 may extend in a direction angled from the impact load direction, as shown in FIG. 1(d). Providing a flange 106 on the opening 108 side of the internal space 105 of the first component 101 that extends toward the opposite internal space and has a joint for connection to another component is preferable because it facilitates joining to another component when the shock absorbing component 100 is installed in a vehicle or the like. Examples of joining methods include fastening with bolts or screws, bonding with adhesive, heat welding, and fitting, but other joining methods may also be used.

[0022] 2 shows the second member 102 in the first embodiment (Example 1) of the present invention. In this embodiment, the second member 102 is formed of a single plate-shaped component 200. The plate thickness of the second member 102 gradually increases from the impact load receiving surface side toward the opening side of the internal space. The plate thickness of the second member 102 is formed so as to gradually increase from the impact load receiving surface 103 side of the first member 101 toward the opening 108 side of the internal space 105, which allows the center of gravity of the second member 102 to be located away from the impact load receiving surface 103, thereby maintaining a more mechanically stable state.

[0023] Here, the effects of the structure of the impact absorbing member 100 according to Example 1 will be explained based on the results of a simulation of a drop weight test using the finite element method (FEM). Figure 3 shows a simulation model for performing analysis using the finite element method. The simulation software used was LS-DYNA (Version 971 R10.2.0) manufactured by ANSYS, Inc., which is widely used in academia and industry. However, other analysis software and programs that can take into account the deformation of the impact absorbing member due to impact may also be used.

[0024] In the simulation model, the dimensions of the shock absorbing member 100 were 57 mm × 57 mm × 80 mm (x direction × y direction × z direction) for the first member 101 and 37 mm × 37 mm (x direction × y direction) for the impact load receiving surface 103. The thickness of the first member 101 was 3 mm. The second member 102 had a plate thickness of 1.7 mm on the impact load receiving surface 103 side and a plate thickness of 3 mm on the opening 108 side, and had a gradient of 0.5 degrees widening from the impact load receiving surface 103 side to the opening 108 side. Furthermore, as a comparative example, Comparative Example 1 was carried out with reference to Patent Document 2, in which the second member had a plate thickness of 3 mm on the impact load receiving surface and a plate thickness of 1.7 mm on the opening side.

[0025] FIG. 3 is a schematic front view showing a simulation model for a drop weight test of the impact absorbing member 100 according to the first embodiment (Example 1). As shown in FIG. 3, the impact absorbing member 100 is erected on a base portion 300, and a predetermined weight 301 is dropped from above in a collision direction 302 to crush the impact absorbing member 100 in the z direction in FIG. 3. The drop weight test was conducted under the following conditions: the weight of the weight 301 was 150 kg, the height of the falling weight was 1 m, and the fastening portion was fully restrained. The displacement of the impact absorbing member 100 from the start of compressive deformation and the load generated by the compressive deformation were output. The resin used for the impact absorbing member 100 was 8207X01B (elastic modulus: 1.8 GPa, strength: 135 MPa) manufactured by Toray Industries, Inc. The embodiment of Comparative Example 1 was the same as Example 1 except for the thickness configuration of the second member.

[0026] FIG. 4 is a load-displacement diagram for Example 1 and Comparative Example 1, with 400 being the load-displacement diagram for Example 1 and 401 being the load-displacement diagram for Comparative Example 1. In both Example 1 and Comparative Example 1, the load increases as the displacement increases in the initial stage of displacement, but then decreases midway, resulting in primary peak loads 402 and 403, respectively. This is because the plate thickness of the impact load-receiving surface 103 side of the plate-like component of the second member in Comparative Example 1 is thicker than in Example 1. Meanwhile, with regard to the respective maximum displacements 404 and 405 in Example 1 and Comparative Example 1, the length of the maximum displacement range is shorter for maximum displacement 404 in Example 1 than for maximum displacement 405 in Comparative Example 1.

[0027] FIG. 5 shows schematic diagrams of deformation of the second member according to Example 1 and Comparative Example 1 immediately after the first peak load, with (a) being Example 1 and (b) being Comparative Example 1. While Example 1 buckles from the impact load-receiving surface side immediately after the first peak load, Comparative Example 1 buckles from the opening side, causing the second member 500 to tilt. This is because the load generated in the second member 500 should normally be supported by the opening side, which is the base side. However, because the opening side buckles, the load cannot be fully supported, resulting in tilting. Therefore, Example 1 according to this embodiment suppresses the first peak load, which is the maximum load, compared to Comparative Example 1 based on Patent Document 2, and is able to absorb the desired impact energy within a short displacement range, thereby achieving highly efficient impact energy absorption characteristics.

[0028] In order to enable a plurality of second components to be mounted in the internal space 105, the first component 101 preferably has ribs extending along the impact load direction, and the internal space 105 of the first component 101 is preferably divided into a plurality of spaces by the ribs. More preferably, the plurality of spaces provided in the first component 101 are formed in line symmetry or point symmetry with respect to the central axis or center point of the first component 101, and a plurality of second components are provided and mounted in all of the plurality of spaces, respectively. Even more preferably, the plurality of second components are desirably formed to have the same plate thickness in a cross section perpendicular to the impact load direction.

[0029] The effects of the above were confirmed by a weight drop simulation. Figure 6 shows impact-absorbing members according to a second embodiment (Example 2) of the present invention and Reference Examples 2-1 and 2-2, where (a) is a perspective view of the impact-absorbing member, (b) is a bottom view of Example 2, (c) is a bottom view of Reference Example 2-1, and (d) is a bottom view of Reference Example 2-2. Example 2 is a more preferred embodiment of the present invention, and in a first member 101 substantially identical to Example 1, a rib 600 forms a plurality of spaces that are line-symmetric and point-symmetric with respect to the central axis or center point of the first member 101. A plurality of second members 601, 602, 603, and 604 are provided, and the plurality of second members 601, 602, 603, and 604 are attached to all of the spaces, respectively. On the other hand, in Reference Example 2-1, the same number of internal spaces as in Example 2 are defined by rib 605, but the multiple internal spaces are formed asymmetrically with respect to the central axis of the first member, and second members 606, 607, 608, and 609 are respectively attached to each internal space. Alternatively, in Reference Example 2-2, multiple internal spaces similar to those in Example 2 are defined by rib 610, and second members 611, 612, 613, and 614 are respectively attached to each internal space, and the plate thickness of each second member is formed to vary in a cross section perpendicular to the impact load direction. Note that Example 2, Reference Example 2-1, and Reference Example 2-2 use the same amount of resin, and the plate thickness of each second member gradually increases from the impact load receiving surface side toward the opening side of the internal space.

[0030] 7 is a load-displacement diagram for Example 2, Reference Example 2-1, and Reference Example 2-2, with 700 being the load-displacement diagram for Example 2, 701 being the load-displacement diagram for Reference Example 2-1, and 702 being the load-displacement diagram for Reference Example 2-2. The maximum displacement 703 for Example 2, the maximum displacement 704 for Reference Example 2-1, and the maximum displacement 705 for Reference Example 2-2 show that the length of the maximum displacement range shortens in the order Example 2 < Reference Example 2-1 < Reference Example 2-2, with Example 2 absorbing impact energy most efficiently.

[0031] FIG. 8 shows schematic diagrams of deformation of the second members according to Reference Example 2-1 and Reference Example 2-2 immediately after the first peak load. (a) shows the deformation of the second members 608 and 609 according to Reference Example 2-1, and (b) shows the deformation of the second member 614 according to Reference Example 2-2. In Example 2, deformation similar to that shown in FIG. 5(a) was observed in all the attached second members. However, in Reference Example 2-1, the buckling deformation was different in the second members 608 and 609. This is because the multiple internal spaces were formed asymmetrically with respect to the central axis of the first member, which resulted in the impact load not being evenly distributed among the four attached second members. Therefore, it is preferable that the multiple spaces provided in the first member be formed with line symmetry and point symmetry with respect to the central axis or center point of the first member. Alternatively, in Reference Example 2-2, torsional deformation in addition to buckling was observed in the second member 614. This is because the thickness of the second member is formed to vary within the cross section in the impact load direction, resulting in variations in buckling strength within the cross section. Therefore, it is preferable that the thickness of the second member is the same across the cross section in the direction perpendicular to the impact load direction.

[0032] In order to improve the buckling strength of the plate-like constituent parts, the second member preferably has at least two plate-like constituent parts that intersect at least one location when viewed from the impact load direction. More preferably, the cross section of the intersection of the at least two plate-like constituent parts of the second member in a direction perpendicular to the impact load direction has a cross shape. Alternatively, the second member is preferably formed with line symmetry and point symmetry with respect to the central axis or center point of the second member.

[0033] The effects of the above were confirmed by a weight drop simulation. Figure 9 shows impact absorbing members according to a third embodiment (Example 3) of the present invention and Reference Example 3, where (a) is a perspective view of the impact absorbing member, (b) is a bottom view of Example 3, and (c) is a bottom view of Reference Example 3. Example 3 is a more preferred embodiment, in which the cross section of the intersection of at least two plate-like components of the second member 900 in a direction perpendicular to the impact load direction has a cross shape. Meanwhile, Reference Example 3 uses two second members 102 of Example 1 arranged side by side.

[0034] Fig. 10 is a load-displacement diagram for Example 3 and Reference Example 3, with 1000 being the load-displacement diagram for Example 3 and 1001 being the load-displacement diagram for Reference Example 3. With regard to the ranges of maximum displacements 1002 and 1003 in Example 3 and Reference Example 3, respectively, the maximum displacement 1002 in Example 3 is shorter than the maximum displacement 1003 in Reference Example 3, and Example 3 absorbs impact energy more efficiently.

[0035] FIG. 11 shows schematic diagrams of deformation in Example 3 and Reference Example 3 at a displacement of half the maximum displacement, where (a) shows the deformation of the second member 900 in Example 3 and (b) shows the deformation of the two second members 102 in Reference Example 3. In Example 3, the second member buckles only at a location close to the impact load receiving surface, while in Reference Example 3, bending due to buckling can be seen overall. This is due to the fact that the buckling strength of the second member is improved by intersecting the plate-like components of the second member. In this regard, it is preferable that at least two plate-like components intersect at at least one location when viewed from the impact load direction, and more preferably, the cross section of the intersection of the two plate-like components in a direction perpendicular to the impact load direction has a cross shape.

[0036] As confirmed with the first member, it is preferable that the second member be formed with line symmetry and point symmetry with respect to the central axis or central point of the second member, since this allows the impact load to be distributed evenly across the second member.

[0037] 12 is a bottom view of a shock-absorbing member according to a fourth embodiment (Example 4) of the present invention. In this embodiment, a first member 1200 has a recess 1202 on the inside of its side surface, which can guide a second member 1201 when the second member is inserted into the internal space.

[0038] 13 is a bottom view of a shock-absorbing member according to a fifth embodiment (Example 5) of the present invention. In this embodiment, a first member 1300 and a second member 1301 are bonded together at a contact point 1302.

[0039] The above effects were confirmed by a weight drop simulation. Fig. 14 shows load-displacement diagrams for Examples 1, 4, and 5, with 400 being the load-displacement diagram for Example 1, 1400 being the load-displacement diagram for Example 4, and 1401 being the load-displacement diagram for Example 5. The ranges of maximum displacement 1402 for Example 4 and maximum displacement 1403 for Example 5 are shorter than maximum displacement 404 for Example 1, and Examples 4 and 5 absorb impact energy more efficiently.

[0040] FIG. 15 shows schematic diagrams of deformation in Examples 4 and 5 immediately after the first peak load. (a) shows the deformation of the second member 1201 in Example 4, and (b) shows the deformation of the second member 1301 in Example 5. Compared to Example 1, the degree of buckling is suppressed in the second member 1201 in Example 4 and the second member 1301 in Example 5. This is because the second member is guided when inserted into a recess formed on the inside of the side surface of the first member, or the contact points between the first and second members are bonded, thereby transmitting load between the first and second members and distributing the impact load throughout the entire shock-absorbing member. In this regard, it is preferable that the inside of the side surface forming the internal space of the first member has a recess that guides the second member when the second member is inserted into the internal space. Alternatively, it is preferable that the first and second members are bonded or welded to each other at at least one location.

[0041] The resin material for the first and second members is not particularly limited, but from the viewpoint of lightness, it is preferable that the resin be composed of any of a thermoplastic resin, a thermosetting resin, and a fiber-reinforced resin composition containing a resin and reinforcing fibers. Examples of thermoplastic resins include polyethylene terephthalate resin, polybutylene terephthalate resin, polytrimethylene terephthalate resin, polyethylene naphthalate resin, other polyester resins, polyethylene resin, polypropylene resin, other polyolefin resins, polyoxymethylene resin, polyamide resin, polyphenylene sulfide resin, polyketone resin, polyether ketone resin, polyether ether ketone resin, polyether ketone ketone resin, polyether nitrile resin, fluorine-based resins such as polytetrafluoroethylene, liquid crystal polymer, styrene-based resin, polycarbonate resin, polymethyl methacrylate resin, polyvinyl chloride resin, polyphenylene ether resin, polyimide resin, polyamide imide resin, polyether imide resin, polysulfone resin, polyether sulfone resin, polyarylate resin, phenoxy resin, copolymers and modified products thereof, and blends of two or more selected from the copolymers and modified products thereof. Examples of thermosetting resins include epoxy resins, unsaturated polyester resins, phenolic resins, melamine resins, polyurethane resins, silicone resins, maleimide resins, vinyl ester resins, cyanate ester resins, and resins obtained by prepolymerizing maleimide and cyanate ester resins. Alternatively, a fiber-reinforced resin composition containing a resin and reinforcing fibers can be prepared by combining the thermoplastic or thermosetting resins listed above with reinforcing fibers such as glass fiber, carbon fiber, aramid fiber, polyethylene fiber, Zylon fiber, and boron fiber. A reinforcing fiber content of 10% to 80% by weight of the fiber-reinforced resin composition is preferred from the perspective of achieving the desired effects. A more preferred reinforcing fiber content is 20% to 50% by weight. The fracture strain ε1 of the first member and the fracture strain ε2 of the second member can be selected so that they satisfy the relationship ε1 > ε2.

[0042] The effects of the above were confirmed by a falling weight simulation. The shape was the same as in Example 1, and in the sixth embodiment (Example 6), the first member was 8207X01B manufactured by Toray Industries, Inc., and the second member was PBT / PC / GF (elastic modulus: 12 GPa, strength: 164 MPa) manufactured by Toray Industries, Inc., while in Reference Example 6, the first member was PBT / PC / GF manufactured by Toray Industries, Inc., and the second member was 8207X01B manufactured by Toray Industries, Inc.

[0043] 16 is a load-displacement diagram for Example 6 and Reference Example 6, with 1600 being the load-displacement diagram for Example 6 and 1601 being the load-displacement diagram for Reference Example 6. In Example 6, the load transition is relatively stable even after the first peak load, whereas in Reference Example 6, the load drops sharply after the first peak load.

[0044] FIG. 17 shows schematic diagrams of deformation in Example 6 and Reference Example 6 immediately after the first peak load, with (a) showing the first member in Example 6 and (b) showing the deformation of the first member in Reference Example 6. While no cracks were observed in the first member in Example 6, as in Example 1, a crack 1700 occurred in the first member in Reference Example 6, and a sudden drop in load occurred along with the crack. Furthermore, a phenomenon in which the second member protruded outward was observed following the crack in the first member. Therefore, it is preferable to select materials such that the fracture strain ε1 of the first member and the fracture strain ε2 of the second member satisfy the relationship ε1 > ε2.

[0045] The structure of the impact absorbing member according to the present invention is not limited to those shown in Figures 1, 6, 9, 12, and 13, and various structures can be adopted as long as they satisfy the requirements specified in the present invention.

[0046] Figure 18 shows examples of the first member in the shock-absorbing member according to the present invention. For example, as shown in Figures 18(a) and 18(b), the shock load receiving surfaces 1802 and 1803 of the first members 1800 and 1801 in the shock-absorbing member may be triangular or hexagonal, or may be polygonal other than triangular or hexagonal. Alternatively, as shown in Figure 18(c), the shock load receiving surface 1805 of the first member 1804 may be circular. Furthermore, a flange portion extending toward the opposite side of the internal space and having a joint portion for joining to another member may be provided on the opening side of the internal space of the first member, and a fastening portion may be provided on the flange portion.

[0047] FIG. 19 shows examples of the first component in the shock-absorbing component according to the present invention. When the impact load-receiving surface of the first component to which the second component is attached is rectangular, the internal space of the first component may be divided into two parts by providing a rib 1901 that divides the internal space equally in the y direction of the drawing, as shown in first component 1900 of FIG. 19(a). Alternatively, the internal space may be divided unevenly in the y direction by a rib 1903, as shown in first component 1902 of FIG. 19(b). Furthermore, as shown in first component 1904 of FIG. 19(c), a rib 1905 may be provided to divide the internal space equally or unevenly in the x direction of the drawing. Alternatively, a rib 1907 may be provided diagonally in the xy plane, as shown in first component 1906 of FIG. 19(d). In this case, the angle θ between the rib 1907 and the x-axis may be 0°<θ<90° or 90°<θ<180°, and the space divided by the slanted rib 1907 may be either equally or unequal. Alternatively, the internal space may be divided into two by arranging ribs 1909 that intersect or bend, as shown in first member 1908 in Figure 19(e). Furthermore, when the internal space is divided into three or more parts, the rib arrangement method can be the same as in the case of two parts.

[0048] FIG. 20 shows examples of the second member in the impact-absorbing member according to the present invention. In the second member, as shown in FIG. 20(a) as a second member 2000, the plate-like components may extend bifurcated from their intersections. Alternatively, as shown in FIG. 20(b) as a second member 2001, the plate-like components may extend trifurcated from their intersections. Alternatively, the plate-like components may extend quadruple or more from their intersections. Alternatively, the plate-like components may intersect at two points, as shown in FIG. 20(c) as a second member 2002. Alternatively, the intersects may be formed at three or more points. Alternatively, while the example in FIG. 20(c) shows a plate-like component provided so that each intersection is quadrupled, the plate-like components may be provided bifurcated, trifurcated, or quintuple or more from their intersections. Furthermore, as shown in FIG. 20(d) as a second member 2003, the impact-receiving side may be formed into a rectangular shape by combining plate-like components. The shape of the impact receiving side may be a triangle or a polygon with pentagons or more. A top surface may be provided on the impact load receiving side, as long as the thickness of the plate-like component of the second member gradually increases from the impact load receiving surface side toward the opening side of the internal space. The plate-like component constituting the second member may be a solid cylinder, a cone, a pyramidal shape such as a triangle or a rectangle when viewed from the impact load direction, or a prism shape such as a triangle or a rectangle when viewed from the impact load direction, as shown in second members 2004, 2005, 2006, and 2007 in Figures 20(e), (f), (g), and (h). In this case, the cross section (circular or polygonal) viewed from a direction perpendicular to the impact load direction should have the smallest area on the impact load receiving surface side and gradually increase in cross-sectional area toward the opening side of the first member.

[0049] FIG. 21 shows examples of bottom views of the shock-absorbing member according to the present invention. As shown in FIG. 21(a), a second member 2101 consisting of two plate-like components may be attached to a first member 2100. Alternatively, as shown in FIG. 21(b), a second member 2104 consisting of one plate-like component 2103 and two plate-like components may be attached to a first member 2102. In this case, the number of plate-like components may be the same or different, and is not limited. Furthermore, as shown in FIG. 21(c), second members 2107 and 2108 attached to the internal space formed by rib 2106 of first member 2105 may have different shapes. [Industrial Applicability]

[0050] The impact absorbing member of the present invention can be used in any application where impact absorption is desired, particularly in any part of a vehicle, and is particularly suitable for use in the rear and side parts of an automobile body in addition to the front part. [Explanation of symbols]

[0051] 100 Impact absorbing member 101 First member 102 Second member 103 Impact load bearing surface 104 Side wall portion provided on first member 105 Internal space formed in first member 106 Flange portion provided on first member 107 Fastening part 108 Aperture 200 Plate-shaped component 300 Base used in simulation of drop weight test 301 Weights used in simulation of drop weight tests 302 Impact direction of weight 400 Load-displacement diagram in Example 1 401 Load-displacement diagram for Comparative Example 1 402 First peak load of Example 1 403 First peak load of Comparative Example 1 404 Maximum Displacement in Example 1 405 Maximum displacement of Comparative Example 1 500 Second member in Comparative Example 1 600 Rib provided on the first member in the second embodiment 601, 602, 603, 604 Second member in Example 2 605 Rib provided on the first member in Reference Example 2-1 606, 607, 608, 609 Second member in Reference Example 2-1 610 Rib provided on the first member in Reference Example 2-2 611, 612, 613, 614: Second member in Reference Example 2-2 700 Load-displacement diagram in Example 2 701 Load-displacement diagram for Reference Example 2-1 702 Load-displacement diagram for Reference Example 2-2 703 Maximum displacement of Example 2 704 Maximum displacement of Reference Example 2-1 705 Maximum displacement of Reference Example 2-2 900 Second member of Example 3 1000 Load-displacement diagram for Example 3 1001 Load-displacement diagram for Reference Example 3 1002 Maximum displacement of Example 3 1003 Maximum displacement of Example 3 1200 First member of Example 4 1201 Second member of Example 4 1202 recess 1300 First member of Example 5 1301 Second member of Example 5 1302 Contact point between the first and second members 1400 Load-displacement diagram for Example 4 1401 Load-displacement diagram for Example 5 1402 Maximum displacement of Example 4 1403 Maximum displacement of Example 5 1600 Load-displacement diagram for Example 6 1601 Load-displacement diagram for Reference Example 6 1700 Cracks occurring in the first component 1800, 1801, 1804 First member 1802, 1803, 1805 Impact load bearing surface 1900, 1902, 1904, 1906, 1908 First member 1901, 1903, 1905, 1907, 1909 Ribs 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 Second member 2100, 2102, 2105 First member 2106 Rib 2101, 2103, 2104, 2107, 2108 Second member

Claims

1. A resin shock absorbing member that deforms when subjected to an impact load, a first member having at least an impact load receiving surface and an internal space that is open on the side opposite to the impact load receiving surface; a second member that is mounted in the internal space and has a plate-shaped component that extends along the impact load direction; An impact absorbing member characterized in that the thickness of the plate-shaped constituent portion of the second member gradually increases from the impact load receiving surface side toward the opening side of the internal space.

2. 2. The shock absorbing member according to claim 1, wherein the first member has ribs extending in the direction of the impact load, and the internal space of the first member is divided into a plurality of spaces by the ribs.

3. 3. The impact absorbing member according to claim 2, wherein the plurality of spaces are formed in line symmetry or point symmetry with respect to the central axis or central point of the first member, and a plurality of the second members are provided, and the plurality of second members are respectively attached to all of the plurality of spaces.

4. 4. The impact absorbing member according to claim 3, wherein the second member is formed so that all of its plate thicknesses are uniform in cross section in a direction perpendicular to the impact load direction.

5. The impact absorbing member according to claim 1, wherein the second member includes at least two plate-shaped constituent parts, and the at least two plate-shaped constituent parts intersect at least one point when viewed from the impact load direction.

6. The impact absorbing member according to claim 5 , wherein a cross section of the intersection of the at least two plate-like constituent parts of the second member in a direction perpendicular to the impact load direction has a cross shape.

7. 2. The impact absorbing member according to claim 1, wherein the second member is formed in line symmetry or point symmetry with respect to a central axis or a central point of the second member.

8. 2. The impact absorbing member according to claim 1, wherein the first member has a recess on the inside of a side surface portion that defines the internal space, the recess providing a guide for the second member when the second member is inserted into the internal space.

9. The impact absorbing member according to claim 1 , wherein the first and second members are bonded or welded to each other at at least one location.

10. 10. The impact absorbing member according to claim 1, wherein the breaking strain ε1 of the first member and the breaking strain ε2 of the second member have a relationship of ε1>ε2.

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