JPH08177922A - Energy absorbing body of hybridized fiber reinforced compound material - Google Patents

Abstract

PURPOSE: To avoid sudden type load fluctuation in the early stage of deformation of an energy absorbing body and increase total energy absorbing amount as well as to reduce a G value at the time of collision by multiply arranging and/or laminating different kinds of fiber materials along the thickness direction and/or the axis direction. CONSTITUTION: In the early stage of collision, only a ±θ(90 deg.) fiber part 3 acts and a G value can be made small by the action of a low load because of the existence of a taper part 2. Action is then followed by a low strength glass fiber part GF4 and the displacement of the load in an L1 range is nearly regularized. When the displacement comes to an intermediate part, a high strength carbon fiber part CF5 acts and the load of building-up energy absorbing amount increases. The extent of increase varies by the content rate of GF5 and CF5 and the length of L2 -L1 . Because action is followed by a high strength CF5 part, the load in the range of L-L2 further increases and the energy absorbing amount is increased. Thus, reduction of the G value and increase of energy absorbing amount in the early stage of collision can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a hybrid which is arranged at a portion which receives an impact force, can cope with at least two levels of collision speed, has a small initial deceleration (G value), and has a large total energy absorption amount. The present invention relates to an energy absorber of a synthetic fiber reinforced composite material.

[0002]

2. Description of the Related Art For example, an energy absorbing member which is displaced at the time of impact and absorbs energy by being compressed and destroyed (hereinafter, referred to as crushing) is provided in a front and rear portion of an automobile body. Often FIG. 20 shows the most commonly used fiber-reinforced composite cylinder (hereinafter referred to as F
RP cylinder) 8 is shown. The FRP cylinder 8 is formed of a hollow cylindrical body having an inner diameter d, an outer diameter D and a wall thickness t as shown in the drawing, and a tip end portion which receives the impact force thereof is formed with a taper portion 2a having a downward slope by chamfering. In addition, this FRP
For the cylinder 8, see "Energy Absorbtio.
n in Composite Tubes, J. Am. Co
mp. Mat. Vol. 16, (Nov. 198).
2), P521 ”. As shown in FIG. 21, when an impact force is applied to the FRP cylinder 8, a crush deformation 9 is generated at the tip end on the side receiving the impact force to absorb energy. FIG. 22 shows the energy absorption state in this case. That is, in FIG. 22, the horizontal axis represents the displacement δ of the FRP cylinder 8 in the axial direction, and the vertical axis represents the FRP.
When the load P acting on the cylinder 8 is taken, the absorbed energy E is shown by hatching in the figure. Further, in this case, the maximum load Pmax is generated immediately after the collision as shown in the figure, and thereafter, a substantially constant load change (average load Pmax due to crush deformation 9 in FIG. 21).
It is displaced at a value close to mean). Therefore, the FRP cylinder 8
In the case of, the value of Pmean / Pmax is relatively large and the value of absorbed energy E is large. Due to this feature, as described above, the FRP cylinder 8 is widely used as an energy absorber at the time of collision of an automobile or the like.

On the other hand, known techniques relating to FRP cylinders include, for example, JP-A-6-123322 and JP-A-6-123323. The former "energy absorbing member" is composed of a hollow cylindrical body with a bottom, the thickness of which changes from the tip toward the bottom, and the tip side is formed to be the thinnest. Further, the latter "energy absorbing member" is composed of a hollow cylindrical body with a bottom as in the former, but is characterized in that the wall thickness is formed so as to increase in two steps toward at least the bottomed side. It is a thing. All of these energy absorbers do not generate a sudden large load at the time of collision deformation, and are characterized by high energy absorption efficiency thereafter.
In particular, the latter has an energy absorption characteristic corresponding to at least two levels of collision speed, and has a characteristic that it can also function as a tuner of an airbag operation sensor.

[0004]

As an energy absorber, in order to reduce damage to the occupant during a collision, the energy of the collision is absorbed and the initial deceleration (G value) applied to the occupant is reduced. First of all, it is necessary. Also,
As a whole, a material having a high energy absorption rate is required to sufficiently absorb the energy of collision. In order to reduce the G value, it is necessary to avoid a sudden load such as the load Pmax shown in FIG. 22 from occurring in the initial stage of the collision, and the load gradually increases as the displacement progresses and the absorbed energy increases. It is necessary to transform so as to increase. Further, in an automobile or the like, an airbag is provided for protection of an occupant, but the energy absorber is provided in order to allow the energy absorber to function as a tuner of an operation sensor that issues an operation command to operate the airbag. It is also necessary to have an energy absorption mode corresponding to collision speeds of at least two levels or more. Judging from this necessity, the FRP cylinder 8 of FIGS. 20 to 22 does not satisfy the above requirements. Further, in the case of the above-mentioned known technique, the above request is met for the time being.
The energy absorbing member of Japanese Patent Laid-Open No. 2 has a problem in that it is difficult to mount it between structures due to its tapered wall thickness, and the amount of energy absorbed is small because only short fiber materials are used. Further, in the case of the energy absorbing member disclosed in Japanese Patent Laid-Open No. 6-123323, the wall thickness changes stepwise in order to achieve two levels of speed correspondence. Therefore, there is a problem that it is difficult to mount it between the structures as in the former case, and the energy absorption amount is small because only the short fiber material is used.

The present invention was devised in view of the above circumstances and reduces the G value at the time of collision and
Thereafter, a large amount of energy can be absorbed to improve the energy absorption efficiency, and the energy absorption body of the hybridized fiber reinforced composite material that can function as a tuner of an airbag operation sensor by absorbing energy corresponding to at least two levels of collision speed. The purpose is to provide.

[0006]

In order to achieve the above object, the present invention is an energy absorber made of a fiber reinforced composite material for absorbing impact energy, wherein the fiber reinforced composite material is thick. And / or stacking different types of fibrous materials in multiple directions along the axial direction and / or the axial direction, and hybridizing the fibrous materials. A hybrid consisting of an appropriate combination group of ± θ fibers arranged in parallel, 90 ° fibers with an θ angle of 90 °, short fiber reinforced composite material, long fiber reinforced composite material, glass fiber, carbon fiber, etc. It constitutes an energy absorber of a synthetic fiber reinforced composite material. More specifically, the energy absorber has a layer in which a plurality of high-strength fiber materials are arranged in order from the crush start end side to the other end side, or the energy absorber has the energy A portion in which the relatively high strength fiber material continuously increases and / or a portion in which the relatively low strength fiber material continuously decreases from the crush start end side to the other end side along the axis of the absorber. Is provided, or the end of the energy absorber on the side where the crush starts is chamfered.

[0007]

The energy absorber of the present invention is not composed of only one kind of fiber material, but is composed of various kinds arranged and / or laminated in the thickness direction and / or axial direction. Thereby, a desired load-displacement change can be obtained. Therefore, it is possible to form an energy absorber having a desired energy absorption efficiency. Further, in order to reduce the G value at the initial stage of the collision, it is possible to cope with the use of the above-mentioned various kinds of fiber materials and the tapered tip portion. Further, energy absorption corresponding to two levels of collision speed can be performed depending on the content of the fibrous material to be used, the arrangement thereof, and the laminated form, and it can function as a tuner of an airbag operation sensor. Further, since the energy absorber of the present invention has a constant thickness along the axial direction and the outer and inner diameters are straight, there is no problem that it is difficult to mount the energy absorber between structures as in the above-mentioned known technique.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 is an axial sectional view showing an energy absorber of the most general form of the present invention, FIG. 2 is a schematic perspective view showing its external shape,
FIG. 3 is a load-displacement diagram of the energy absorber of FIG. 1, and FIGS. 4 to 10 are partial axial sectional views showing another embodiment of the present invention in which the wall thickness of the fiber material does not continuously change along the axial direction. FIG. 11, FIG. 12, FIG. 12, and FIG. 14 to FIG. 19 are partial axial sectional views showing another embodiment of the present invention in which the wall thickness of the fibrous material continuously changes along the axial direction, and FIG. It is what shows the load-displacement diagram etc. of the energy absorber shown.

As shown in FIG. 1, this energy absorber 1
Is a hollow cylindrical body having a constant wall thickness and a constant outer and inner diameter along the axial direction, and a tapered portion 2 having a downward slope is formed on the tip end side that receives an impact force. This energy absorber 1 includes a ± θ fiber portion (or 90 ° fiber portion) 3 and a glass fiber portion (hereinafter,
It is composed of a GF) 4 and a carbon fiber portion (hereinafter referred to as CF) 5. In order to clearly distinguish these, ± θ (90 °) fiber portion 3 is indicated by □, GF4 (90 °) is indicated by ◯, and CF5 (90 °) is indicated by ● in the figure. As shown in FIG. 2, the ± θ (90 °) fiber portion 3 is made of a fiber-reinforced composite material in which the fiber direction is arranged at a θ angle of 90 degrees or positive and negative directions with respect to the axial direction,
For example, it is made of filament winding.
Further, GF4 and CF5 are also preferably made of general glass and carbon fibers and have an orientation angle of 90 ° with respect to the axis, but the content thereof is not particularly limited. Note that CF5 has higher strength than GF4. In this energy absorber 1, ± θ (90 °) fiber portions 3 are arranged on the innermost side as shown in the drawing, GF4 is arranged on the upper side in the axial direction on the outer side, and GF4 and CF5 are arranged in parallel in the middle. , CF5 is arranged on the lower side. Therefore, the upper part of the energy absorber 1 (range of L _{1 in} the figure) is ± θ (90
°) Composed of fiber part 3 and GF4, middle part (L ₂ -L in the figure)
₁ range) is ± θ (90 °) fiber part 3 and GF4 and C
It consists of F5, and the lower part (range of L-L _{2 in} the figure) is ± θ
It consists of (90 °) fiber part 3 and CF5. As described above, the energy absorber 1 according to the present embodiment has the hybridized array and the laminated structure. Further, in FIG. 1, there is a taper portion 2 at the tip portion, and the thickness of the ± θ (90 °) fiber portion 3 and GF4 increases along the inclined surface in the range of the taper portion 2. The energy absorption state at the time of collision of the hybridized energy absorber 1 having the above structure is shown by the load-displacement diagram of FIG. In FIG. 3, a curve A is a load-displacement diagram of the energy absorber 1 of this embodiment, and a curve B is shown in FIG.
An intermediate portion of the (L ₂ range of -L ₁₎ and lower part (L-L ₂
The range C) is composed entirely of GF4, and the curve C is composed of only ± θ (90 °) fiber portions 3. The curves B and C have changes similar to those of FIG. 22 of the prior art described above, but the energy absorber 1 of the present embodiment shows changes corresponding to at least two levels of collision speed as shown by the curve A, and the displacement is The form in which the energy absorption efficiency is increased by advancing is shown. This is because at the initial stage of the collision, only the fiber portion 3 of ± θ (90 °) acts, and since the taper portion 2 exists, a low load acts and the G value can be reduced. GF4 having a low strength continues to act, and the load is almost constant and displaced in the L ₁ range. CF with high strength when displaced in the middle
5, the load rises and the amount of energy absorbed increases. The degree of this increase depends on the content ratio of GF4 and CF5,
It changes depending on the length of (L ₂ −L ₁ ). Next, since the CF5 portion having high strength acts, the load further increases and the energy absorption amount increases as shown in the figure. As described above, the G value at the initial stage of the collision can be reduced, the energy absorption amount can be increased, and the load can be changed stepwise, so that it can function as a tuner of the airbag operation sensor. In this embodiment, ± θ (90 °) fiber portion 3 and GF4, CF
Various load-displacement diagrams can be obtained by varying the arrangement of 5 and the degree of stacking, and a desired energy absorption form and energy absorption amount can be obtained.

4 and other figures show another embodiment. The energy absorber 1a of the embodiment shown in FIG. 4 is obtained by changing the stacking order of GF4 and CF5 in the intermediate portion (range of L ₂ -L ₁ ) of FIG. 1 and has substantially the same effect as that of FIG. Have.

FIG. 5 shows an energy absorber 1 using a short fiber reinforced composite material 6 instead of the ± θ (90 °) fiber portion 3 of FIG.
b is shown. The short fiber reinforced composite material 6 is made of a fiber reinforced composite material in which short fibers are dispersed, and is manufactured by, for example, SMC (sheet molding compound) or injection molding.

FIG. 6 shows an energy absorber 1c using a long fiber reinforced composite material 7 (for example, woven fabric reinforced composite material) instead of the ± θ (90 °) fiber portion 3 of FIG. It is formed by a sheet winding method or the like.

FIG. 7 shows still another embodiment. This energy absorber 1d is ± θ on the outside of the hollow cylinder.
(90 °) The fiber part 3 is provided, and the upper part (L ₁
In the middle part (L ₂ -L)
GF4 and CF5 are installed side by side in the range ( ₁ ) and the lower part (L-
CF5 is arranged in the range of L ₂ .

FIG. 8 shows an energy absorber 1e of another embodiment having a slightly complicated construction. This energy absorber 1e has ± θ (90 °) fiber portions 3 arranged at the center of the thick portion. Inside, GF4 is arranged in the range of L ₁ ,
L ₂ -L ₁ of the intermediate portion GF4 and juxtaposed to CF5, disposing CF5 the lower portion (the range of L-L _2). Further, GF4 is in the outer L ₁ range, GF4 and CF5 are in the middle part (L ₂ -L ₁ range), and CF5 is in the lower part (L-L ₂ range).
Are arranged respectively.

The energy absorber 1f shown in FIG. 9 is one in which ± θ (90 °) fiber portions 3 are arranged both inside and outside the hollow cylindrical body. G in the range of L _{1 in} the center of the thick part
Disposed to F4, the intermediate section (L ₂ -L ₁ range) to GF4 and CF5, is lower portions (L-L ₂ range) in a CF5 those disposed respectively.

FIG. 10 shows an energy absorber 1g which does not use the ± θ (90 °) fiber portion 3. Upper part (range of L ₁ )
Is provided with GF4, and the middle part (range of L ₂ −L ₁ ) is G
Juxtaposed the F4 and CF5, the lower portion (the range of L-L ₂₎ to dispose the CF5 respectively.

Although the various types of energy absorbers 1 to 1g have been described above, of course, the present invention is not limited to these, and any type of energy absorber whose strength gradually increases from the upper part to the lower part can be used. The arrangement and stacking form may be arbitrary. Also, each part may be formed by integral molding or secondary molding. Further, GF4 and CF5 may be manufactured by the filament winding method or other manufacturing methods.

11 to 19 show various embodiments of the energy absorber in which at least one of the fiber materials constituting the energy absorber is such that its wall thickness continuously changes along the axial direction. Energy absorber 1h of FIG.
Is a structure in which the ± θ (90 °) fiber portion 3 is arranged inside the hollow cylindrical body, CF5 is arranged in the center of the wall thickness, and GF4 is arranged outside. The tapered portion 2 is formed at the tip. As shown in the figure, the CF5 at the center is provided with a thickness of almost zero at the position of the tapered portion 2, and is arranged in such a manner that the thickness increases as it goes downward along the axial direction. On the contrary, GF4 has the maximum wall thickness at the position of the tapered portion 2, the wall thickness becomes smaller as it goes downward, and it is arranged so that it becomes almost zero at the lowermost surface. Of course, the entire thickness of the thick portion is constant. With the above structure, the strength of the tip portion is low, and the strength is increased as it goes downward.

FIG. 13 is a load-displacement diagram showing the energy absorption form of the energy absorber 1h of FIG. In the figure, the curve A shows the case of FIG. 11, the curve B shows the case where the CF5 part in the center of FIG. 11 is also formed of GF4, and the curve C does not have the parts of GF4 and CF5 of FIG. The case of an energy absorber formed of only ± θ (90 °) fiber portions 3 is shown. The curves B and C are almost similar to those of the prior art shown in FIG. 22, but the curve A can obtain a large energy absorption. In this case, the load −
The displacement curve changes gradually from beginning to end, and there is no sudden change, and the maximum load appears at the end of displacement. As a result, the G value of the occupant is reduced, and large energy absorption can be secured.

FIG. 12 shows the energy absorber 1i excluding the taper portion 2 of FIG. As described above, since the strength continuously changes along the axial direction, crushing occurs even without the tapered portion 2, and a large amount of energy can be absorbed.

The energy absorber 1j shown in FIG.
(90 °) Fiber part 3 is provided, GF4 is in the center and CF is on the outside
5 is provided. The central GF4 has the maximum wall thickness on the upper side of the taper portion 2 and becomes almost zero at the lower end.
On the other hand, CF5 is arranged such that the taper portion 2 has a thickness of almost zero and the CF5 has a maximum thickness at the lower end. Also, FIG.
Also in the case of 4, the energy absorber without the tapered portion 2 may be used.

FIG. 15 shows the ± θ (90 °) fiber portion 3 of FIG.
The energy absorber 1k in the case of using the short fiber reinforced composite material 6 instead of is shown.

FIG. 16 shows the ± θ (90 °) fiber portion 3 of FIG.
An energy absorber 1m using a long fiber reinforced composite material 7 (for example, a woven fabric reinforced composite material) instead of is shown.

FIG. 17 shows an energy absorber 1n in which the ± θ (90 °) fiber portions 3 are arranged outside the hollow cylindrical body. In this case, GF4 is arranged inside and CF5 is arranged in the center. As shown in the figure, GF4 is arranged such that the tip end portion on the taper portion 2 side has the thickest wall thickness and the bottom end portion has almost zero thickness. It is arranged to have a wall thickness.

FIG. 18 shows an energy absorber 1p having a slightly complicated structure. This one has ± θ (90 °) in the center
The fiber part 3 is provided, and GF4 and CF5 are superposed on the inside so that the wall thickness continuously changes in mutually opposite directions.
Also on the outer side, GF4 and CF5 are arranged such that their wall thicknesses continuously change in opposite directions. In this case, GF4 has the largest thickness portion on the tapered portion 2 side both on the inside and the outside. The energy absorber 1 of the embodiment shown in FIG.
From j to the energy absorber 1p of this embodiment, the taper portion 2 is formed on the tip end side that receives the impact force, but of course, the taper portion 2 having no taper portion 2 is also used as in the case of FIGS. 11 and 12. It

FIG. 19 shows ± θ (90) inside and outside the hollow cylinder.
°) An energy absorber 1q in which the fiber portion 3 is arranged and GF4 and CF5 are arranged in the center. In this case, the tip may have no tapered portion. Also, as shown in the figure, GF
4 has the maximum wall thickness in the upper part and becomes almost zero at the lower end, and CF5 is arranged so as to have the maximum wall thickness in the lower end part.

Although various embodiments have been described above, the embodiment is limited to the above embodiments as long as the strength is increased from the upper part toward the lower part like the above-mentioned embodiments. Not a thing.

[0028]

According to the present invention, the following remarkable effects are obtained. 1) By arranging and / or laminating various fiber materials in the thickness direction and the axial direction to form a hybridized fiber layer, an energy absorbing function based on a desired curve can be formed, and a collision side can be formed. By arranging the fibers so that the strength is lowered and the strength is increased toward the base end side, it is possible to reduce the G value at the time of collision and increase the energy absorption amount as a whole. 2) By devising the arrangement and / or laminated structure of various fibers, it is possible to form a load displacement curve that can correspond to at least two levels of collision speed. As a result, it is possible to provide a function as a tuner of the airbag operation sensor. 3) By forming a taper portion on the tip side where impact force acts, the G value at the time of collision can be further reduced. 4) The load change can be moderated by continuously changing the wall thickness of GF and CF. As a result, the impact force applied to the occupant can be mitigated. 5) It can be easily manufactured by known techniques such as integral molding, secondary molding, filament winding manufacturing method, and SMC, and can be carried out relatively easily and at low cost.

[Brief description of drawings]

FIG. 1 is an axial sectional view of an energy absorber according to an embodiment of the present invention in which a ± θ (90 °) fiber portion is disposed inside.

FIG. 2 is a schematic perspective view showing the appearance of FIG.

FIG. 3 is a load-displacement diagram of the energy absorber of FIG.

FIG. 4 is a partial axial sectional view of another embodiment of the present invention.

FIG. 5 is a partial axial sectional view of another embodiment of the present invention in which a short fiber composite material is used on the inside.

FIG. 6 is a partial axial sectional view of another embodiment of the present invention in which a long fiber composite material is used for the inside.

FIG. 7 is a partial axial sectional view of another embodiment of the present invention in which ± θ (90 °) fiber portions are arranged outside.

FIG. 8 is a partial axial sectional view of another embodiment of the present invention in which a ± θ (90 °) fiber portion is arranged in the center of the wall thickness.

FIG. 9 is a partial axial cross-sectional view of another embodiment of the present invention in which ± θ (90 °) fiber portions are arranged inside and outside.

FIG. 10 is a partial axial sectional view of another embodiment of the present invention consisting of GF and CF only.

FIG. 11: GF in which ± θ (90 °) fiber portion is arranged inside
And a partial axial cross-sectional view of an embodiment of the present invention in which the wall thickness of CF continuously changes along the axial direction.

12 is a partial axial cross-sectional view of an embodiment in which the taper portion on the side receiving the impact force in FIG. 11 is removed.

13 is a load-displacement diagram of the energy absorber of FIG.

14 is a partial axial sectional view of another embodiment of the present invention in which the arrangements of GF and CF in FIG. 11 are reversed.

FIG. 15: GF and C with a short fiber composite material disposed inside
The partial axial sectional view of the other Example of this invention which the thickness of F changes continuously along an axial direction.

16 is a partial axial sectional view of another embodiment of the present invention in which a long fiber composite material is used inside instead of the short fiber composite material of FIG.

FIG. 17: GF with ± θ (90 °) fiber portion arranged outside
FIG. 6 is a partial axial sectional view of another embodiment of the present invention in which the thickness of CF continuously changes.

FIG. 18 is a partial axial cross-section of another embodiment of the present invention in which a ± θ (90 °) fiber portion is arranged in the center and a fiber layer whose wall thickness of GF and CF is continuously variable is provided inside and outside. Fig.

FIG. 19 shows another embodiment of the present invention in which fiber layers of GF and CF having a ± θ (90 °) fiber portion on the inner and outer sides and a continuously changing wall thickness are arranged in the center, and having no taper portion. The partial axial sectional view of an Example.

FIG. 20 is an axial sectional view of an FRP cylinder.

FIG. 21 is an axial cross-sectional view showing a collapsed deformation state of the FRP cylinder of FIG.

22 is a load-displacement diagram showing the energy absorption amount of the FRP cylinder of FIG.

[Explanation of symbols]

 1 Energy Absorber 1a Energy Absorber 1b Energy Absorber 1c Energy Absorber 1d Energy Absorber 1e Energy Absorber 1f Energy Absorber 1g Energy Absorber 1h Energy Absorber 1i Energy Absorber 1j Energy Absorber 1k Energy Absorber 1m Energy Absorber 1n Energy absorber 1p Energy absorber 1q Energy absorber 2 Tapered part 2a Tapered part 3 ± θ (90 °) Fiber part 4 Glass fiber part (GF) 5 Carbon fiber part (CF) 6 Short fiber reinforced composite material 7 Long fiber reinforced composite material 8 FRP cylinder (fiber reinforced composite material cylinder) 9 Crush deformation

Claims (4)

[Claims] 1. An energy absorber made of a fiber-reinforced composite material for absorbing energy of impact, wherein the fiber-reinforced composite material comprises a plurality of different kinds of fiber materials along a thickness direction and / or an axial direction. The fiber material is a hybrid material formed by arranging and / or laminating, and the fiber material is ± θ fibers in which the fibers are arranged in the positive and negative directions by an angle of θ with respect to the axial direction, and 90 of the θ angle of 90 °. An energy absorber for a hybrid fiber-reinforced composite material, which comprises an appropriate combination of fibers, short fiber-reinforced composite materials, long fiber-reinforced composite materials, glass fibers, carbon fibers and the like. 2. The hybridized fiber according to claim 1, wherein the energy absorber has a layer in which a plurality of fibrous materials having high strength are arranged in order from the crush start end side to the other end side. Energy absorber for reinforced composite materials. 3. A portion and / or comparison in which the fibrous material having relatively high strength continuously increases in the energy absorber from the crush start end side to the other end side along the axis of the energy absorber. The energy absorber of the hybridized fiber-reinforced composite material according to claim 1, wherein the fiber material having low dynamic strength is provided with a continuously decreasing portion. 4. The energy absorber of the hybridized fiber-reinforced composite material according to claim 1, wherein an end portion of the energy absorber on the crush start end side is chamfered.