JP3360872B2 - Energy absorbing member - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energy absorbing member, and more particularly to a structure of an energy absorbing member made of a composite material of resin and reinforcing fibers having a plurality of reinforcing fiber layers.

[0002]

2. Description of the Related Art For example, an energy absorbing member that absorbs impact energy is used for a seat around an aircraft, a seat around an automobile, a bumper, and various structural members (JP-A-60-109630). 62-17
No. 438, etc.). In addition to the ability to absorb impact energy well, this energy absorbing member is generally lightweight,
Since high rigidity is required, a composite material of a resin and reinforcing fibers, so-called fiber reinforced plastic (hereinafter sometimes referred to as FRP), especially carbon fiber reinforced plastic (hereinafter also referred to as CFRP) There is) is said to be suitable. In such an energy absorbing member, an energy absorbing mechanism is considered in which local destruction or deformation is caused from a site of the energy absorbing member, for example, a member end, and the local destruction or deformation is used to absorb energy. To be

[0003]

However, the conventional energy absorbing member made of the composite material of the resin and the reinforcing fiber has a surface with insufficient energy absorbing ability and, for example, as described above, the end portion of the member is not formed. When energy is absorbed by causing destruction or deformation, there is a problem that the operation of destruction or deformation is not stable, and it is difficult to obtain the target energy absorption performance in a stable manner. The reality is not.

The present invention provides a structure of an energy absorbing member capable of smoothly starting and advancing the destruction or deformation of the member for absorbing energy by a predetermined predetermined operation and efficiently absorbing high energy. In addition to the above, it is an object of the present invention to provide an energy absorbing member having stable performance and high practicality.

[0005]

The energy absorbing member of the present invention for this purpose is an energy absorbing member made of a composite material of resin and reinforcing fibers having a plurality of reinforcing fiber layers, wherein the reinforcing fiber layers are A resin having a higher elongation than the resin compounded with the reinforcing fiber layer is arranged between the layers.

The energy absorbing member of the present invention is manufactured in a structure having a plurality of reinforcing fiber layers by laminating a plurality of layers of prepreg in which reinforcing fibers are impregnated with resin. The laminated structure of the reinforcing fiber layer may be two or more layers and is not particularly limited.

A resin having a higher elongation than the resin compounded with the reinforcing fiber layer is disposed between the reinforcing fiber layers. This resin layer is arranged when the prepregs are laminated one by one.

For example, as shown in FIG. 1, there is a cylindrical energy absorbing member 41 made of a composite material of resin and reinforcing fibers, which is produced by laminating four layers of prepreg.
Between the reinforcing fiber layers 42a, 42b, 42c, 42d, resin layers 43a, 43b, 43c having a higher elongation than the resin compounded with the reinforcing fiber layers are arranged, respectively, and these layers are laminated. It is molded as a composite material in the state.

In the energy absorbing member of the present invention having such a structure, when absorbing the impact energy in the compression direction, as shown in the enlarged view of the member 41 of FIG. When the member 41 is destroyed,
At the end of the member 41, for example, the member 41 bends so as to tear in the thickness direction and tries to open. Layers 42a and 42b, layer 4
Since 2c and 42d tend to bend with different radii of curvature, a shearing force acts between these layers due to the shear deformation of the adjacent layers. This shearing force is effectively absorbed by the high elongation resin layers 43a and 43c interposed between the layers. That is, since the resin layers 43a and 43c have high elongation,
The shear deformation due to the difference in the radius of curvature between the layers 42a and 42b and between the layers 42c and 42d is reduced by the respective layers 42a, 42b, 42c and 42d.
Resin layers 43a, 4
Absorbs at 3c. As a result, each layer 42a, 42
b, 42c, and 42d can exhibit the high bending resistance of each layer itself (that is, the high bending strength of each composite material layer reinforced with the reinforcing fiber itself), and the expansion as shown in FIG. Bending and even destruction start and proceed smoothly.

Further, when the resin layer 43b is also arranged in the central portion of the member 41 in the thickness direction, since the resin layer 43b is not reinforced with reinforcing fibers, the adjacent composite material layer 42
It is weaker in strength than b and 42c, and becomes a starting point of bending deformation or breakage from the central portion to both sides as shown in FIG. 2, and the bending deformation or breakage starts smoothly. Further, if a trigger is provided at the central portion in the member thickness direction, smoother operation can be obtained. Note that the resin layer 43b at the central portion does not necessarily have to have a high elongation as long as the bending deformation and the breakage as shown in FIG. 2 are always caused. When other forms of bending deformation or destruction occur, for example, when the member bends to the left or right side over the entire thickness direction instead of expanding to both sides as shown in FIG. 2, the resin at the center The layer 43b also exhibits the shear deformation absorbing function as described above.

The kind of the reinforcing fiber in the composite material constituting the energy absorbing member of the present invention is not particularly limited, and examples thereof include carbon fiber, glass fiber, aromatic polyamide fiber, alumina fiber, silicon carbide fiber, boron fiber and the like. You can choose from. However, the tensile strength of the reinforcing fiber is 4
It is preferably 50 kgf / mm ² or more. Since the strength of the composite material layer is improved by using the high-strength fiber, a high-strength energy absorbing member can be realized and a high energy absorbing capacity can be obtained at the same time as the smooth bending mechanism described above.

The arrangement of these reinforcing fibers is different from that of the energy absorbing member 4 unless a special combination arrangement is performed.
0 with respect to the energy absorption axis 44 (shown in FIG. 1) of 1
It may be performed in the range of ± 60 °. If the angle is too large, the reinforcing fibers are not effectively used for absorbing the impact energy acting in the compression direction.

Further, each reinforcing fiber layer may be a single layer, or may have a laminated structure (for example, one having ± 25 ° layers,
A layer having ± 25 ° layers and ± 15 ° layers). Further, the form of the reinforcing fiber is not particularly limited, and a woven fabric of the reinforcing fiber can be used in addition to ordinary filaments.

The resin forming the matrix of the composite material of the present invention is not particularly limited, and examples thereof include epoxy resin and
Unsaturated polyester resin, polyvinyl ester resin, phenol resin, guanamine resin, polyimide resin such as bismaleimide / triazine resin, furan resin, polyurethane resin, polydiallyl phthalate resin, and amino resin such as melanin resin and urea resin. A thermosetting resin may be used. Also, nylon 6, nylon 66,
Polyamides such as nylon 11, nylon 610 and nylon 612, copolyamides of these polyamides, polyesters such as polyethylene terephthalate and polybutylene terephthalate, copolyesters of these polyesters, and further polycarbonates, polyamide imides and polyphenylene sulfides. , Polyphenylene oxide, polysulfone, polyether sulfone, polyether ether ketone, polyether imide, polyolefin, and the like, and thermoplastic elastomers typified by polyester elastomer, polyamide elastomer and the like. Furthermore, as the resin satisfying the above range, acrylic rubber,
It is also possible to use rubber such as acrylonitrile butadiene rubber, urethane rubber, silicone rubber, styrene butadiene rubber, and fluororubber. Furthermore, it is also possible to use a resin obtained by blending a plurality of the above-mentioned thermosetting resins, thermoplastic resins, and rubber. The resin arranged between the prepreg layers is selected to have a higher elongation than that according to the setting of the matrix resin of the prepreg as described above,
Just set it. The form of the resin placed between the layers is
In addition to the continuous layered form, for example, particles or flakes may be dispersed, or a fibrous form or a non-woven form.

Further, in the present invention, it is preferable that the reinforcing fibers have a surface relief of 1.08 or more. When the surface undulation degree of the reinforcing fiber is 1.08 or more, the so-called anchor effect due to the undulation of the surface is improved, so the adhesiveness between the reinforcing fiber and the resin is improved, and an interface that is extremely difficult to peel or break can be achieved. . By improving the adhesiveness, the strength of the reinforcing fibers in the composite material can be utilized very effectively, the strength of each composite material layer itself as shown in FIG. 1 can be increased, and the rigidity of the composite material as a whole can be improved. Can be improved, so that a large amount of energy can be absorbed. If the surface undulation degree is less than 1.08, the anchor effect as described above cannot be expected, or even if there is, it is slight.

When the reinforcing fiber is made of carbon fiber, the surface functional group amount (O / C), which is the atomic number ratio of oxygen (O) and carbon (C) on the surface of the reinforcing fiber, is 0.08 or more. Is preferred. When the amount of surface functional groups (O / C) is 0.08 or more, the activated O enhances the adhesiveness of the surface of the reinforcing fiber, and the adhesive strength between the resin and the reinforcing fiber is increased to make it more difficult to break. Therefore, each composite material layer, and by extension, the energy absorbing member as a whole can exhibit extremely high rigidity and energy absorbing ability. If the amount of surface functional groups (O / C) is less than 0.08, the adhesiveness between the resin and the reinforcing fiber becomes insufficient, and peeling or breakage easily occurs at the interface between the resin and the reinforcing fiber during energy absorption. , The energy absorption capacity is reduced accordingly.

The shape of the energy absorbing member made of the composite material of the present invention is not particularly limited, and may be cylindrical, columnar, or
Various shapes such as a plate shape can be adopted. Representative shapes or applicable shapes are illustrated in FIGS. 3 to 12.

As a typical shape of the energy absorbing member, first, a cylindrical shape can be mentioned. The most typical shape as a cylindrical shape is a cylinder 1 as shown in FIG. The direction of the arrow in the figure is the compressive load acting direction as impact energy. Further, as shown in FIG. 4, a cylinder 2 in which the top of the cylinder is formed in a conical shape or a spherical shape can also be applied. Further, although not shown, a prism, a cone, a pyramid, a truncated cone, a truncated pyramid, or a cylinder having an elliptical cross section, and further, as shown in FIG. A tubular shape 4 such as a tube) can also be adopted.

The shape is not limited to the cylindrical shape, but may be a columnar shape. For example, a columnar shape or a prismatic shape can be mentioned.

Further, it is possible to adopt a plate shape. For example, a corrugated plate-shaped member can be used as an energy absorbing member because it is strong against buckling. Also,
As shown in FIG. 6, for example, a cross section T having a rib 5 is provided.
The shape 6 may be a V shape, or may be a shape 7 having a U-shaped cross section as shown in FIG. 7. In the shape 7 having a U-shaped cross section shown in FIG. 7, the lid member 8 can be provided as shown by a two-dot chain line. Further, as shown in FIG. 8, a cross-shaped cross section 9 may be used.

Furthermore, it is also possible to adopt a structure in which members of various shapes are combined. For example, FIG. 9 and FIG.
As shown in FIG. 0, small elongated cylinders 12 and 13 are put in a large cylinder 10 and a large truncated cone 11 and are made of a composite material, so that an energy absorbing member that is less likely to buckle can be obtained. it can.

Further, the energy absorbing member may be composed of one member, or may be composed of a plurality of members stacked or combined. For example, in FIG.
As shown in FIG. 12, the energy absorbing members 16 and 17 may be configured by vertically stacking members 14, 15a, 15b and 15c made of a composite material having the same or similar shapes. In the configuration of FIG. 12, each member may be alternately laminated inside and outside.

In the energy absorbing member as described above, it is desirable to form a trigger shape for sequentially destroying the energy absorbing member from the end, and this trigger is a pressing member for pressing the energy absorbing member. It may be provided on the side.

[Method of measuring characteristics and method of evaluating effects]
The method of measuring the characteristics used in the description of the present invention will be described below. (1) Tensile elongation of resin Measured according to ASTM-D-638.

(2) Tensile strength of fiber Measured according to the resin-impregnated strand test method specified in JIS-R7601. The resin formulation and curing conditions used in the test are shown below. Resin Formulation: "Bakelite" ERL-4221 100 parts of 3 boron trifluoride monoethylamine (BF ₃ · MEA) ₃ parts acetone 4 parts Curing conditions: 130 ° C., 30 minutes

(3) Surface relief The composite material is cut perpendicularly to the fiber direction, and the cut surface is mirror-polished by metal phase polishing. Here, the cross-sectional shape of the single fiber perpendicular to the polishing surface was measured by a scanning electron microscope (JSM manufactured by JSM Co., Ltd.).
-T300 type) is used to photograph a backscattered electron composition image at an accelerating voltage of 15 kV and a photographing magnification of 10,000 times on a film. The backscattered electron composition image photograph thus obtained was further stretched to 2 times at the time of printing, that is, the magnification was 2 in total.
It is taken as a photograph for surface undulation analysis with a magnification of 0000. Here, from the photograph for surface undulation analysis, the area S (m
m ² ) and the outer peripheral length L (mm) are measured. The surface undulation degree is obtained according to the following formula as a ratio of the above L and the outer peripheral length of a virtual perfect circle having the same S. Surface relief = L · (πS) ^−1/2 / 2 L is measured at 20000 times. After accurately sticking a non-stretchable cotton thread on the outer periphery of the single fiber cross-sectional image in the photograph, Can be removed and the length of the straight line can be measured. Further, S was measured by placing a trace paper of known weight per unit area on a photograph printed at 20000 times, accurately tracing the outer periphery of the single fiber cross-sectional image, and accurately cutting the trace line. The weight can be converted from the weight of the cut single fiber cross-sectional image and the weight per unit area of the trace paper. The measurement is carried out on 10 monofilaments, and the average value is taken as the surface relief. There is no limitation on the method of measuring L and S as long as it can be accurately measured, and an image analyzer can be used in addition to the above method.

(4) Surface Functional Group Amount (O / C) It was determined by the following procedure by X-ray photoelectron spectroscopy. First, carbon fiber (bundle) from which sizing agents have been removed with a solvent
After cutting and arranging them on a copper sample support, the photoelectron escape angle was set to 90 °, and MgKα1, X-ray source was used.
2 is used and the sample chamber is kept at 1 × 10 ⁻⁸ Torr. The kinetic energy value (KE) of the main peak of C _1S is set to 969 eV as a correction of the peak associated with charging during measurement. The C _1S peak area was calculated as K. E. As 958-97
It is obtained by drawing a linear baseline in the range of 2 eV. The O _1S peak area was measured by K.K. E. As 714-726
It is determined by drawing a straight baseline in the range of eV. Here, the amount of surface functional groups (O / C) is calculated as an atomic number ratio from the ratio of the O _1S peak area and the C _1S peak area using a sensitivity correction value specific to the apparatus. The inventors of the present invention used a model ESCA-75 manufactured by Shimadzu Corporation.
0 was used to measure the ratio of the O _1S peak area to the C _1S peak area, and the ratio was divided by the sensitivity correction value of 2.85 to obtain the surface functional group amount (O / C).

[0028]

As described above, according to the energy absorbing member of the present invention, the energy absorbing member has a structure having a plurality of reinforcing fiber layers, and a resin layer having a high elongation is provided between the reinforcing fiber layers. Since the high elongation resin layer absorbs the shear deformation between the adjacent composite material layers when the member is bent and deformed, the composite material layers can efficiently exhibit their strength. Bending deformation and breakage for energy absorption can be started and progressed smoothly, and a highly practical energy absorption member with stable operation while having high energy absorption capacity can be realized.

[Brief description of drawings]

FIG. 1 is a partial vertical sectional view of an energy absorbing member according to the present invention.

FIG. 2 is an enlarged partial vertical sectional view of the member of FIG.

FIG. 3 is a perspective view showing an example of the shape of the energy absorbing member of the present invention.

FIG. 4 is a perspective view showing another example of the shape of the energy absorbing member of the present invention.

FIG. 5 is a perspective view showing still another example of the shape of the energy absorbing member of the present invention.

FIG. 6 is a perspective view showing still another example of the shape of the energy absorbing member of the present invention.

FIG. 7 is a perspective view showing still another example of the shape of the energy absorbing member of the present invention.

FIG. 8 is a perspective view showing still another example of the shape of the energy absorbing member of the present invention.

FIG. 9 is a perspective view showing another structural example of the energy absorbing member of the present invention.

FIG. 10 is a perspective view showing still another structural example of the energy absorbing member of the present invention.

FIG. 11 is a vertical sectional view showing still another structural example of the energy absorbing member of the present invention.

FIG. 12 is a vertical sectional view showing still another structural example of the energy absorbing member of the present invention.

[Explanation of symbols]

1, 2 Cylindrical energy absorbing member 3 Flange portion 4 Cylindrical energy absorbing member having a flange portion 5 Rib 6 Energy absorbing member 7 having T-shaped cross section 7 Energy absorbing member 8 having U-shaped cross section 8 Lid member 9 Cross section Cross-shaped energy absorption member 10 Cylindrical energy absorption member 11 Frustum-shaped energy absorption members 12, 13 Elongated members 14, 15a, 15b, 15c Energy absorption member members 16, 17 Combination energy absorption Member 41 Energy absorbing members 42a, 42b, 42c, 42d Reinforcing fiber layers 43a, 43b, 43c High elongation resin layer 44 Energy absorbing shaft

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Claims (4)

(57) [Claims] 1. An energy absorbing member comprising a composite material of a resin and a reinforcing fiber, which has a plurality of reinforcing fiber layers, wherein between the layers of the reinforcing fiber layer, a resin compounded with the reinforcing fiber layer is used. An energy absorbing member characterized in that a resin having a high elongation is also arranged. 2. The tensile strength of the reinforcing fiber is 450 kgf.
/ Mm ² or more, the energy absorbing member according to claim 1. 3. The energy absorbing member according to claim 1, wherein the surface relief of the reinforcing fibers is 1.08 or more. 4. The carbon fiber having a surface functional group content (O / C) of 0.08 or more, which is the atomic number ratio of oxygen (O) to carbon (C), on the surface of the reinforcing fiber. The energy absorbing member according to any one of 1 to 3.