JP2009287749A - Energy absorber and energy absorbing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy absorber and an energy absorbing method capable of materializing larger energy absorbing quantity. <P>SOLUTION: The energy absorber 21 is provided with a hollow part 32 surrounded by a wall part 31, and includes a hollow molded body 30 formed of fiber reinforced plastic. The hollow molded body absorbs energy when compression load acts on a wall part by folding a wall part in such a manner that an outer surface 31a of the wall part is folded back to an inside of the hollow part or by folding the wall part in such a manner that an inner surface 31b of the wall part is folded back to an outside to make the outer surfaces face one another. The hollow molded body also absorbs energy by friction force by making folded wall parts contact one another when the wall parts are folded to the inside of the hollow part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an energy absorber and an energy absorbing method.

  For example, vehicles such as automobiles are provided with an energy absorber that absorbs impact energy in the event of a collision. As the energy absorber, for example, a hollow molded body formed of fiber reinforced plastic is used, and impact energy is absorbed by its own destruction (see Patent Documents 1 and 2).

  In an energy absorber using a hollow molded body made of fiber reinforced plastic, in order to absorb energy more efficiently, a method for controlling the fiber cleavage direction (circumferential direction), and a hollow molded body serving as a trigger for cleavage A method of devising the tip shape is employed.

  As for the former method for controlling the cleavage direction, energy is efficiently absorbed by using a pressing member provided with a plurality of concave and convex shapes and controlling the fiber to expand in a plurality in the circumferential direction ( (See Patent Document 1).

  Regarding the method of devising the tip shape of the latter hollow molded body, the tip of the hollow molded body is made into a plurality of tapered irregularities, and the reduction in load at the initial stage of collision is prevented, thereby improving energy absorption efficiency. (See Patent Document 2).

In any of the methods, for energy absorption, delamination force and fiber tensile breaking force are used.
JP 2005-233263 A JP 2006-125531 A

  This type of energy absorber is required to contribute to reducing the weight of the vehicle by realizing a larger amount of energy absorption.

  However, in conventional energy absorbers, the efficiency of energy absorption, that is, the improvement of energy absorption depends on how large the delamination force and fiber tensile breaking force are, and there are limitations on material properties. It is difficult to obtain sufficient efficiency.

  An object of the present invention is to provide an energy absorber and an energy absorption method capable of realizing a larger energy absorption amount.

  In order to achieve the above object, an energy absorber according to the present invention is an energy absorber having a hollow part surrounded by a wall part and having a hollow molded body made of fiber-reinforced plastic. The hollow molded body is formed by bending the wall portion so that the outer surface of the wall portion is folded back into the hollow portion when a compressive load is applied to the wall portion, or inside the wall portion. Energy is absorbed by folding the wall portion so that the outer surface is folded outward and the outer surfaces face each other.

  In order to achieve the above object, an energy absorption method according to the present invention includes a hollow portion surrounded by a wall portion and absorbs energy by a hollow molded body formed of fiber reinforced plastic. Then, when a compressive load is applied to the wall portion of the hollow molded body, energy is absorbed by folding the wall portion so that the outer surface of the wall portion is folded back into the hollow portion. Energy may be absorbed by folding the wall portion so that the inner surface of the wall portion is folded outward and the outer surfaces face each other.

  According to the present invention, energy can be absorbed by fiber breakage using bending energy, in addition to absorbing energy using delamination force and fiber tensile breaking force. Therefore, a larger amount of energy absorption can be realized.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a perspective view showing a main part of a front side member 10 to which an energy absorber 21 according to the present invention is applied, FIG. 2 is a sectional view showing the energy absorber 21 of the first embodiment, and FIG. FIG. 4 is an exploded perspective view showing the hollow molded body 30 and the pressing member 40 shown in FIG. 2, and FIG. 4 is a cross-sectional view showing the pressing member 40.

  Referring to FIG. 1, a front side member 10 as a vehicle body skeleton member is positioned below both sides in the vehicle width direction in front of the vehicle body and has a long shape in the front-rear direction of the vehicle body. In the illustrated front side member 10, an energy absorber 21 is disposed at a tip portion 11 located on the front side of the vehicle body.

  Referring to FIGS. 2 and 3, the energy absorber 21 of the first embodiment generally includes a hollow portion 32 surrounded by a wall portion 31 and is formed of a fiber reinforced plastic (FRP). It has the hollow molded object 30 which has. The hollow molded body 30 is formed by bending the wall portion 31 so that the outer surface 31a of the wall portion 31 is folded back into the hollow portion 32 when a compressive load is applied to the wall portion 31 from the cylindrical axial direction. Absorbs energy. In this way, the impact due to the compressive load from the axial direction is reduced. The energy absorber 21 further includes a pressing member 40 that is attached to the hollow molded body 30 and applies a load to the wall portion 31 of the hollow molded body 30.

  The magnitude | size of the hollow part 32 of the hollow molded object 30, the thickness of the wall part 31, etc. are suitably selected according to the magnitude | size of the energy which should be absorbed. The hollow molded body 30 of the present embodiment uses the bending energy of the wall portion 31 to break the fiber, and when the wall portion 31 is folded into the hollow portion 32, the folded wall portions 31 are in contact with each other. It is. Energy absorption by fiber breakage utilizing bending energy can be changed by selecting the amount of fiber, the thickness of the wall portion 31, and the shape (for example, rib shape). A frictional force is generated by bringing the folded wall portions 31 into contact with each other, and energy is absorbed by the frictional force. Conversely, energy absorption by frictional force can be changed by selecting the amount of fibers and the shape of the hollow molded body 30.

  The fiber reinforced plastic forming the hollow molded body 30 is a composite material of reinforced fiber and resin. The reinforcing fiber is, for example, carbon fiber, and the resin is, for example, an epoxy resin.

  The reinforcing fiber is not particularly limited as long as it becomes a reinforcing material. As the reinforcing fiber, for example, graphite fiber, glass fiber, organic fiber such as aramid, paraphenylenebenzobisoxazole, polyvinyl alcohol, polyarylate, and the like can be used in addition to the carbon fiber. Furthermore, what used together 2 or more types of the above-mentioned reinforcing fiber can also be used.

  Any resin can be used as the resin as long as it becomes a matrix resin for fiber-reinforced plastic. In addition to the epoxy resin, for example, a thermosetting resin such as an unsaturated polyester resin, a vinyl ester resin, or a phenol resin, or a thermoplastic resin such as polyester, polyolefin, or polyamide resin can be used as the resin. Furthermore, a mixed resin of the above resins can also be used.

  The molding method of the hollow molded body 30 is not particularly limited, and a known production method can be applied. For example, the hollow molded body 30 is applied by applying an RTM (Resin Transfer Molding) molding method in which a molten thermosetting resin is injected into a reinforcing fiber enclosed in a mold and heat-cured, sheet winding molding, press molding, or the like. Can be made. In the hollow molded body 30, layers of reinforcing fibers are laminated in the thickness direction of the wall portion 31.

  Referring also to FIG. 4, the pressing member 40 has a block shape, and is formed with a concave portion 41 for bending the wall portion 31 when the tip portion 33 of the wall portion 31 abuts.

  The pressing member 40 is attached so as to cover the end of the hollow molded body 30. The pressing member 40 is attached to the outer surface 31a of the wall portion 31 of the hollow molded body 30 via an adhesive 42 (see FIG. 2). The adhesive 42 joins the pressing member 40 and the hollow molded body 30 during normal use, and has an adhesive strength that does not hinder the bending of the wall 31 when absorbing energy.

  The front side of the pressing member 40 is fixed to a bumper reinforcement (not shown) via a bolt or the like. The bumper reinforcement and the front side member 10 constitute a crushable zone that absorbs impact.

  As the material of the pressing member 40, an appropriate material can be used as long as a load can act on the wall portion 31 of the hollow molded body 30. For example, iron or aluminum can be used, but a material harder than fiber reinforced plastic, such as iron, is preferable.

  Referring to FIGS. 2 and 4, tip portion 33 of wall portion 31 has a tapered cross section that is inclined so that the inner surface 31 b side is the tip and the outer surface 31 a side is away from the tip. The bottom corner 43 of the recess 41 of the pressing member 40 has a circular arc shape that guides the wall 31 to be bent. The round shape of the bottom corner portion 43 of the pressing member 40 serves as a starting point for breaking the tip portion 33 of the wall portion 31 inward. As for the clearance between the inner surface of the recessed part 41 and the outer surface 31a of the wall part 31, 0.1 mm-0.3 mm are desirable, for example. This is because when the clearance is increased, the deformed form of the wall part 31 does not conform to the rounded shape of the bottom corner part 43.

  FIG. 5 is a cross-sectional view for explaining an energy absorption mechanism by the energy absorber 21 of the first embodiment, and FIG. 6 is a cross-sectional view for explaining a comparative energy absorption mechanism. FIG. 7 is a conceptual diagram showing a broken state of the fiber reinforced plastic fiber in which the wall portion 31 is bent inward, and FIG. 8 shows a broken state of the fiber reinforced plastic fiber in which the wall portion 131 is cleaved in a petal shape. It is a conceptual diagram.

  First, the energy absorption mechanism in the first embodiment will be described.

  With reference to FIG. 5, the pressing member 40 is attached to the hollow molded body 30. The tip 33 of the wall 31 of the hollow molded body 30 is in contact with the bottom of the recess 41 of the pressing member 40 (FIG. 5A). The rear end portion of the hollow molded body 30 is joined to another member 34, and the opening of the hollow portion 32 is closed.

  When the compressive load F from the axial direction acts on the wall portion 31 of the hollow molded body 30 via the pressing member 40, the tip portion 33 of the wall portion 31 is pressed against the bottom portion of the recess 41, and the tip portion 33 is destroyed. Begins (FIG. 5B).

  When the compressive load further acts, the wall portion 31 of the hollow molded body 30 starts to deform along the rounded shape of the bottom corner portion 43 of the pressing member 40 (FIG. 5C). The wall portion 31 is bent inward so that the outer surface 31 a is folded back into the hollow portion 32. When the wall portion 31 is bent suddenly, the bending stress increases on both the tension side (the outer surface 31a side) and the compression side (the inner surface 31b side), and accumulates deformation energy. As release of this energy, fracture occurs at the interface between the reinforced fiber and the matrix resin in the fiber reinforced plastic constituting the hollow molded body 30, and the fiber starts to break. Further, when the wall portion 31 is bent inward, the fracture region is shortened, so that circumferential shear failure occurs, and the bent wall portion 31 is divided.

  When the wall portion 31 is further bent inward while being divided, the bent wall portions 31 come into contact with each other after bending deformation, and a frictional force is generated (FIG. 5D). Again, energy is absorbed by the form of heat or fiber breakage due to frictional forces. The folded wall portion 31 begins to clog in the hollow portion 32. When the fracture state of the fiber-reinforced plastic fiber at the point P1 in FIG. 5 (D) bent inward was confirmed, there was little delamination, while there were many fractured fibers in the layer (see FIG. 7).

  When the wall portion 31 is further bent inward, the bent wall portion 31 is clogged in the hollow portion 32 and has no place to go. The wall portions 31 packed in the hollow portion 32 are pressed against each other, and a frictional force due to compression is generated (FIG. 5E). Again, energy is absorbed by the form of heat or fiber breakage due to the frictional forces of compression.

  Next, a comparative energy absorption mechanism will be described.

  Referring to FIG. 6, the proportional energy absorber 121 includes a hollow molded body 130 and a pressing member 140 that cleaves the tip portion 133 of the wall 131 of the hollow molded body 130 in a petal shape. . The hollow molded body 130 is formed in the same manner as the hollow molded body 30 of the above-described embodiment. The pressing member 140 has a flat surface on which the tip 133 of the wall 131 contacts.

  With reference to FIG. 6, the front-end | tip part 133 of the wall part 131 of the hollow molded object 130 is contacting the flat surface of the press member 40 (FIG. 6 (A)).

  When the compressive load F from the axial direction acts on the wall portion 131 of the hollow molded body 130 via the pressing member 140, the tip portion 133 of the wall portion 131 is pressed against the flat surface, and the tip portion 133 starts to break. (FIG. 6B). The front end portion 133 of the wall portion 131 is cleaved in a petal shape. The fiber reinforced plastic constituting the hollow molded body 130 absorbs energy mainly by delamination. Energy absorption by delamination is relatively small.

  When the compressive load is further applied, the layer cleaved outward is released as it is, and the layer cleaved inward is bent inward so as to be folded back into the hollow portion 132 (FIG. 6C). The layers that are cleaved inward are in contact with each other, but the absolute amount of fiber reinforced plastic is small relative to the cross-sectional area and volume of the hollow portion 132, so that the effect of absorbing energy by frictional force is relatively small. When the fracture state of the fiber-reinforced plastic fiber at the point P2 in FIG. 6C where the wall 131 is cleaved in a petal shape was confirmed, delamination progressed, while the fiber fractured in the layer (See FIG. 8).

  FIG. 9 is a load displacement diagram obtained by an energy absorption experiment of the energy absorber 21 and the proportional energy absorber 121 of the present embodiment. In FIG. 9, the load displacement curve of the present embodiment is represented using a solid line, and the proportional load displacement curve is represented using a broken line.

  The energy absorption experiment was performed using a falling weight tester. As shown in the drawing, the initial rise of the load is substantially the same in the present embodiment and the comparison. Thereafter, in the proportionality, the load slightly decreases and the load changes at a certain level. In the present embodiment, the load changes at a level higher than the proportionality without the load decreasing. In the present embodiment, the load increases rapidly in the region indicated by reference numeral Z1 in the figure. In this region Z1, the bent wall portions 31 are in contact with each other and absorb energy by the generated frictional force. Further, the load further increases in the region indicated by the reference symbol Z2. In this region Z2, the wall portions 31 that have been packed in the hollow portion 32 and have lost their place are pressed against each other, and energy is absorbed by the generated frictional force due to compression. The maximum displacement of the present embodiment is smaller than the proportional maximum displacement.

  The proportional energy absorber 121 has a petal-like fracture mode, and absorbs energy by using only the delamination force and the fiber tensile breaking force.

  In the first embodiment, in addition to energy absorption in comparison, firstly, energy is absorbed by fiber breakage utilizing bending energy, and secondly, the energy is absorbed inside the hollow molded body 30. Energy is absorbed by the frictional force generated when the wall portions 31 are pressed against each other. Therefore, according to the energy absorption method of this embodiment and the energy absorber 21 that embodies this, it is possible to realize a larger amount of energy absorption. As shown in FIG. 9, the present embodiment can absorb about twice as much energy as the comparative example in which the destruction form is a petal shape. Furthermore, this embodiment can absorb more energy with the same amount of displacement compared to the proportionality.

  By providing the pressing member 40, a load can be reliably applied to the wall portion 31 of the hollow molded body 30, and by providing the concave portion 41, the wall portion 31 can be bent.

  The leading edge 33 of the wall 31 has a tapered cross section, and the bottom corner 43 of the recess 41 has a circular arc shape, so that the cross sectional arc shape of the bottom corner 43 destroys the leading edge 33 of the wall 31. Thus, the wall 31 can be guided and bent.

  The pressing member 40 only needs to be provided with a recess 41 at a portion where the hollow molded body 30 contacts. Compared with a mode in which a plurality of concave and convex shapes are provided on the pressing member to control the cleavage direction, the pressing member 40 can be processed more easily.

  The tip 33 of the wall 31 of the hollow molded body 30 only needs to be provided with one taper. The processing of the tip portion 33 of the wall portion 31 is facilitated as compared with a configuration in which a plurality of uneven shapes are provided at the tip portion of the wall portion and the shape of the trigger portion is devised.

  Since the energy absorber 21 of the present embodiment can realize a larger amount of energy absorption, the amount of fibers of the hollow molded body 30 can be reduced and the energy absorber 21 can be reduced in size and weight if the energy absorption amount is the same. Can be achieved. Through this, it is possible to contribute to weight reduction of the vehicle.

  10 (A) and 10 (B) are cross-sectional views showing pressing members 40 with different rounded shapes at the bottom corners 43, and FIG. 11 shows pressing members 40 with different rounded shapes at the bottom corners 43. It is a load displacement diagram obtained by the energy absorption experiment used. In FIG. 10, the size of the round shape of the bottom corner 43 is exaggerated for easy understanding. Further, in FIG. 11, the load displacement curve when the pressing member 40 (FIG. 10A) having the smaller radius shape is used is represented by a solid line, and the pressing force having the larger radius shape is pressed. A load displacement curve when the member 40 (FIG. 10B) is used is represented by a broken line.

  The pressing member 40 in FIG. 10A has a round shape of the bottom corner 43, for example, R2, and the pressing member 40 in FIG. 10B has a round shape of the bottom corner 43, for example, R5. is there. For convenience of explanation, the pressing member 40 having a smaller radius shape is referred to as a “small R pressing member 40”, and the pressing member 40 having a larger radius shape is referred to as a “large R pressing member 40”. To tell.

  The energy absorption experiment was performed using a falling weight tester. As shown in FIG. 11, the rise of the initial load is larger when the small R pressing member 40 is used. Thereafter, the load changes at a certain level both when the small R pressing member 40 is used and when the large R pressing member 40 is used. When the small R pressing member 40 is used, the load changes at a higher level than when the large R pressing member 40 is used. Regardless of which pressing member 40 is used, the point that the load increases rapidly is the same although there is a difference in level. Energy is absorbed by the generated frictional force. The maximum displacement when the small R pressing member 40 is used is smaller than the maximum displacement when the large R pressing member 40 is used.

  Thus, the amount of energy absorption can be changed by the size of the round shape of the bottom corner portion 43 of the pressing member 40, and the size of the round shape may be set according to the required amount of energy absorption. .

(Second Embodiment)
FIG. 12 is a cross-sectional view showing the energy absorber 22 of the second embodiment, and FIG. 13 is a cross-sectional view for explaining an energy absorption mechanism by the energy absorber 22 of the second embodiment. In addition, the same code | symbol is attached | subjected to the site | part which is common in 1st Embodiment, and the description is partially abbreviate | omitted.

  The second embodiment is different from the first embodiment in which the direction in which the wall portion 31 of the hollow molded body 30 is bent is the outside, and the second embodiment is bent inward. Since the direction in which the wall portion 31 is bent is different, the shape of the pressing member 40 is also slightly different.

  Referring to FIG. 12, the energy absorber 22 of the second embodiment includes a hollow portion 32 surrounded by a wall portion 31 and is formed of fiber reinforced plastic (FRP), as in the first embodiment. A hollow molded body 30 having a cylindrical shape is provided. The hollow molded body 30 has the wall 31 so that the inner surface 31b of the wall 31 is folded outward and the outer surfaces 31a face each other when a compressive load is applied to the wall 31 from the cylindrical axial direction. Energy is absorbed by bending. In this way, the impact due to the compressive load from the axial direction is reduced. The energy absorber 22 further includes a pressing member 40 that is attached to the hollow molded body 30 and applies a load to the wall portion 31 of the hollow molded body 30.

  The pressing member 40 of the second embodiment also has a block shape, and is formed with a recess 45 for bending the wall portion 31 when the tip portion 33 of the wall portion 31 abuts. However, in order to bend the wall portion 31 outward, an insertion portion 46 that fits into the hollow portion 32 of the hollow molded body 30 protrudes from the center of the pressing member 40, and the concave portion 45 is formed in a ring shape. . Further, in order to bend the wall portion 31 so that the inner surface 31b of the wall portion 31 is folded outward and the outer surfaces 31a face each other, the ring-shaped recess 45 has a bottom corner portion 47 on the inner peripheral side and an outer peripheral side corner portion 47. The bottom corner 47 faces each other. The vertical wall on the outer peripheral side of the recess 45 faces the outer surface 31a of the wall 31 and extends downward from the bottom corner 47 on the outer peripheral side in the drawing.

  The pressing member 40 is attached so that the insertion portion 46 is fitted into the hollow portion 32 and covered with the end portion of the hollow molded body 30. The pressing member 40 is attached to the inner surface 31b of the wall portion 31 of the hollow molded body 30 via an adhesive.

  The front end portion 33 of the wall portion 31 has a tapered cross section that is inclined so that the inner surface 31b side is the front end and the outer surface 31a side is away from the front end. The bottom corner 47 of the recess 45 of the pressing member 40 has a circular arc shape that guides the wall 31 to be bent on both the inner and outer peripheral sides. The rounded shape of the bottom corner portion 47 on the inner peripheral side serves as an induction starting point for breaking the tip portion 33 of the wall portion 31 inward. As for the clearance between the insertion part 46 and the inner surface 31b of the wall part 31, 0.1 mm-0.3 mm are desirable, for example. This is because when the clearance is increased, the deformed form of the wall part 31 does not conform to the rounded shape of the bottom corner part 47.

  With reference to FIG. 13, the energy absorption mechanism in 2nd Embodiment is demonstrated.

  The tip 33 of the wall 31 of the hollow molded body 30 is in contact with the bottom of the recess 45 of the pressing member 40 (FIG. 13A).

  When the compressive load F from the axial direction acts on the wall portion 31 of the hollow molded body 30 via the pressing member 40, the distal end portion 33 of the wall portion 31 is pressed against the bottom portion of the concave portion 45, and the distal end portion 33 is destroyed. Begins (FIG. 13B).

  When the compressive load further acts, the wall portion 31 of the hollow molded body 30 starts to deform along the round shape of the bottom corner portion 47 of the pressing member 40 (FIG. 13C). The wall 31 is bent outward so that the inner surface 31b is folded outward and the outer surfaces 31a face each other. When the wall portion 31 is bent suddenly, the bending stress increases on both the tension side (the inner surface 31b side) and the compression side (the outer surface 31a side), and accumulates deformation energy. As release of this energy, fracture occurs at the interface between the reinforced fiber and the matrix resin in the fiber reinforced plastic constituting the hollow molded body 30, and the fiber starts to break. Further, when the wall portion 31 is bent outward, the fracture region is enlarged, so that circumferential shear failure occurs, and the bent wall portion 31 is divided.

  In the second embodiment, the wall portion 31 is released from the pressing member 40 after bending deformation. For this reason, energy absorption due to frictional force does not occur.

  In the second embodiment, energy is not absorbed by frictional force, but energy is absorbed by fiber breakage using bending energy in addition to energy absorption utilizing delamination force and fiber tensile breaking force. is doing. Therefore, according to the energy absorbing method of the second embodiment and the energy absorber 22 embodying the energy absorbing method, although the energy absorption amount is smaller than that of the first embodiment, it is larger than the above-described comparison. Energy absorption can be realized.

(Third embodiment)
FIG. 14 is a cross-sectional view showing the energy absorber 23 of the third embodiment. In addition, the same code | symbol is attached | subjected to the site | part which is common in 2nd Embodiment, and the description is partially abbreviate | omitted.

  The third embodiment is different from the second embodiment in which energy absorption by frictional force is not performed in that energy absorption by frictional force is also performed.

  Referring to FIG. 14, the energy absorber 23 of the third embodiment further includes a ring member 50 that is attached to the pressing member 40 and forms a space 51 into which the wall portion 31 that is bent outward is packed. . By attaching the ring member 50 to the pressing member 40, the wall portion 31 is not released from the pressing member 40 after bending deformation, and is clogged in the space 51 and has no place to go. The wall portions 31 packed in the space 51 are pressed against each other, and a frictional force due to compression is generated. Energy is absorbed in the form of heat or fiber breakage due to this frictional force of compression.

  In the third embodiment, in addition to the second embodiment, energy is absorbed by the frictional force generated by the wall portions 31 bent to the outside of the hollow molded body 30 pressing each other. . Accordingly, it is possible to realize a larger amount of energy absorption as in the first embodiment.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. For example, the present invention is not limited to the case where the energy absorbers 21, 22, and 23 of the present invention are applied to the front side member 10 as a vehicle body skeleton member. Needless to say, the energy absorbers 21, 22, and 23 can be applied to any portion that needs to absorb energy.

It is a perspective view which shows the principal part of the front side member to which the energy absorber which concerns on this invention is applied. It is sectional drawing which shows the energy absorber of 1st Embodiment. It is a disassembled perspective view which shows the hollow molded object and press member which are shown by FIG. It is sectional drawing which shows a pressing member. It is sectional drawing for demonstrating the energy absorption mechanism by the energy absorber of 1st Embodiment. It is sectional drawing for demonstrating a comparative energy absorption mechanism. It is a conceptual diagram which shows the fracture state of the fiber of the fiber reinforced plastic by which a wall part is bend | folded inside. It is a conceptual diagram which shows the fracture state of the fiber of the fiber reinforced plastic which the wall part has cleaved in the shape of a petal. It is the load displacement diagram obtained by the energy absorption experiment of the energy absorber of this embodiment and the comparative energy absorber. 10A and 10B are cross-sectional views showing pressing members having different round shapes at the bottom corners. It is the load displacement diagram obtained by the energy absorption experiment using the press member from which the magnitude | size of the round shape of a bottom corner | angular part differs. It is sectional drawing which shows the energy absorber of 2nd Embodiment. It is sectional drawing for demonstrating the energy absorption mechanism by the energy absorber of 2nd Embodiment. It is sectional drawing which shows the energy absorber of 3rd Embodiment.

Explanation of symbols

10 Front side member,
21, 22, 23 Energy absorber,
30 hollow molded body,
31 walls,
31a The outer surface of the wall,
31b The inner surface of the wall,
32 hollow part,
33 The tip of the wall,
40 pressing member,
41, 45 recess,
42 adhesives,
43, 47 The bottom corners of the recesses,
46 Insertion part,
50 ring member,
51 space.

Claims (8)

An energy absorber comprising a hollow part surrounded by a wall part and having a hollow molded body formed from fiber-reinforced plastic,
The hollow molded body is formed by bending the wall portion so that the outer surface of the wall portion is folded back into the hollow portion when a compressive load is applied to the wall portion, or inside the wall portion. An energy absorber that absorbs energy by folding the wall portion so that the outer surface is turned back and the outer surfaces face each other.   The energy absorber according to claim 1, wherein when the wall portion is folded into the hollow portion, the folded wall portions are in contact with each other. A pressing member that is attached to the hollow molded body and causes a compressive load to act on the wall portion of the hollow molded body;
The energy absorber according to claim 1, wherein the pressing member is formed with a concave portion for bending the wall portion by abutting a tip portion of the wall portion. The tip portion of the wall portion has a tapered cross-sectional shape that is inclined so that the inner surface side is the tip and the outer surface side is away from the tip,
The energy absorber according to claim 3, wherein a bottom corner portion of the concave portion of the pressing member has a cross-sectional arc shape that guides the wall portion to be bent. An energy absorption method comprising a hollow portion surrounded by a wall portion and absorbing energy by a hollow molded body formed of fiber reinforced plastic,
When a compressive load is applied to the wall part of the hollow molded body, the wall part is folded so that the outer surface of the wall part is folded back into the hollow part, or the inner surface of the wall part An energy absorption method for absorbing energy by folding the wall portion so that the outer surface faces each other by being folded outward.   The energy absorbing method according to claim 5, wherein when the wall portion is folded into the hollow portion, the folded wall portions are brought into contact with each other.   By causing a compressive load to act on the wall portion of the hollow molded body via a pressing member attached to the hollow molded body, the wall portion is brought into contact with a concave portion formed in the pressing member, whereby the wall portion The energy absorption method of Claim 5 or Claim 6 which bends. The tip portion of the wall portion has a tapered cross-sectional shape that is inclined so that the inner surface side is the tip and the outer surface side is away from the tip,
The energy absorbing method according to claim 7, wherein a bottom corner portion of the concave portion of the pressing member has a cross-sectional arc shape that guides the tip portion of the wall portion to be bent.