JPH06307477A - Energy absorbing member - Google Patents

Abstract

PURPOSE:To absorb high energy efficiently with a compound material of resin and reinforced fiber provided with at least three layers of reinforced fiber layers, by disposing the reinforced fiber which is laid on an inner layer in one direction and reinforced fiber fabrics on an outer layer. CONSTITUTION:Compound materials 45a, b provided with reinforced fiber layers 42a, b laid in one direction are disposed at the central side in the thickness direction of a cylindrical energy absorbing member 41, and compound material layers 46a, b provided with reinforced fiber fabrics 43a, b are disposed on the outmost layer in the member thickness direction. When the member 41 tears a compressive load P in a direction along an energy absorbing shaft 44 of the member 41, the member 41 attempts to open so as to tear in the thickness direction at the end part. Tensile strength A works upon the inside surface side of the compound material layers 45a, b, and compression strength works on the outside surface side of the compound material layers 46a, b. Since the compound material layers 45a, b include the reinforced fiber layers 42a, b, the tensile strength in the laid direction is high, so it is possible to absorb a large amount of energy.

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 in particular, it is composed of a composite material of resin and reinforcing fibers,
The present invention relates to the structure of an impact energy absorbing member.

[0002]

2. Description of the Related Art For example, an energy absorbing member that absorbs impact energy is used around the seat of an aircraft, around the seat of an automobile, around a bumper, and various structural members (Japanese Patent Laid-Open No. 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 may be considered in which local destruction is caused from a certain portion of the energy absorbing member, for example, a member end portion, and the energy is absorbed by utilizing the local destruction.

[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. In the case of causing destruction and absorbing energy, there is a problem that the operation of the destruction is not stable and the target energy absorption performance is difficult to obtain stably, and it has not been put to practical use sufficiently. It's a reality.

The present invention provides a structure of an energy absorbing member capable of smoothly starting and advancing a member breaking operation for energy absorption by a predetermined predetermined operation,
An object of the present invention is to provide a highly practical energy-absorbing member with stable performance while efficiently absorbing high energy.

[0005]

The energy absorbing member of the present invention for this purpose comprises a composite material of resin and reinforcing fibers having at least three reinforcing fiber layers, and is unidirectionally aligned in the inner layer. The reinforcing fibers thus obtained are characterized in that reinforcing fiber woven fabrics are respectively arranged in the outer layers.

The reinforcing fibers aligned in one direction (hereinafter also referred to as UD reinforcing fibers) are 0 ° ± 60 ° with respect to the energy absorbing direction axis of the energy absorbing member.
It is arranged in the range of. If the angle is too large, the reinforcing fibers are not effectively used for absorbing the impact energy acting in the compression direction.

The form of the reinforcing fiber woven fabric arranged on the outer layer side is not particularly limited, but at least the warp yarn or the weft yarn of the woven fabric is in the range of 0 ° ± 60 ° with respect to the energy absorption direction axis as described above. It is preferably arranged.

In the energy absorbing member of the present invention,
The UD reinforcing fiber layer as described above is arranged on the inner layer side in the member thickness direction, and the reinforcing fiber fabric is arranged on the outer layer side in the member thickness direction. For example, as shown in FIGS. 1 and 2 showing the cross section of the end portion of the cylindrical energy absorbing member 41, composite material layers 45a and 45b having UD reinforcing fiber layers 42a and 42b are arranged on both sides in the center of the thickness direction of the member 41. Composite material layers 46a and 46b having reinforcing fiber woven fabrics 43a and 43b are provided on both outermost layers in the member thickness direction. Each reinforcing fiber layer may be a single layer or may have a laminated structure. Also, between the composite layers 45a and 46a, and between 45b and 4a.
Between 6b and other reinforcing fiber (regardless of form)
A layer containing a may be interposed.

In the energy absorbing member of the present invention having such a structure, for example, when absorbing impact energy in the compression direction, as shown in an enlarged view in FIG. 2, a direction along the energy absorbing axis 44 (FIG. 1). When the member 41 is destroyed by the compressive load P, the member 41 tries to open at the end of the member 41 so as to tear in the thickness direction. At that time, tensile stress A acts on the inner surface side of the composite material layers 45a, 45b having the inner layer side UD reinforcing fibers 42a, 42b, and the composite material layers 46a, 46b having the outer layer side reinforcing fiber fabrics 43a, 43b Compressive stress B on the outer surface
Works.

The composite material layers 45a, 45b on the inner layer side are U
Since the D reinforcing fiber layers 42a and 42b are included, the tensile strength in the aligning direction is extremely high, and a large resistance force is exhibited when the end portions of the member try to spread to both sides. As a result, the energy absorbing member can absorb a large amount of energy.

On the other hand, the composite material layers 46a and 46b on the outer layer side
Has reinforcing fiber fabrics 43a, 43b. The reinforcing fiber fabrics 43a and 43b have crimps to a greater or lesser degree, except for a special form (so-called non-crimp fabric), and are structurally weak against compression. Therefore, as shown in FIG. 2, when the energy absorbing member 41 breaks so as to expand to both sides at the member end portion, the expanding is performed smoothly, and the breaking always occurs on the outer surface side, that is, the reinforcing fiber. It occurs from the side of the layers 46a and 46b including the fabrics 43a and 43b, and a stable and constant destruction mechanism is obtained.

That is, in the energy absorbing member according to the present invention, a layer mainly including the UD reinforcing fiber layer on the inner layer side exerts a high resistance against deformation of the member, and thus a high energy absorbing performance, and the reinforcing fiber on the outer layer side. The layer containing the woven fabric stabilizes the mechanism particularly when the member is broken, so that a predetermined constant breaking operation is performed stably and smoothly. As a result, both a high absorbed energy amount of the energy absorbing member and stable performance and operation are simultaneously achieved.

In order to further promote efficient energy absorption as described above, the reinforcing fiber layers on both sides of the central portion in the member thickness direction are symmetrical with respect to the reinforcing fiber layer in the central portion in the member thickness direction. It is preferable to be laminated on. By adopting such a symmetrical laminated structure, when the member breaks so as to tear from the center in the thickness direction to both sides, the strength possessed by both sides is maximized efficiently and a higher energy absorption amount is obtained. To be

In the present invention, the kind of the reinforcing fiber is not particularly limited and can be appropriately selected from carbon fiber, glass fiber, aromatic polyamide fiber, alumina fiber, silicon carbide fiber, boron fiber and the like.

The resin which serves as the matrix of the composite material of the present invention is not particularly limited, and examples thereof include epoxy resin, unsaturated polyester resin, polyvinyl ester resin, phenol resin, guanamine resin, and bismaleimide triazine resin. Such as polyimide resin, furan resin, polyurethane resin, polydiallyl phthalate resin,
Further, thermosetting resins such as amino resins such as melanin resin and urea resin may be mentioned. Also, nylon 6, nylon 66, nylon 11, nylon 610, nylon 612
Polyamides such as, or copolyamides of these polyamides, polyesters such as polyethylene terephthalate and polybutylene terephthalate, or copolyesters of these polyesters, and further polycarbonates, polyamide imides, polyphenylene sulfides, polyphenylene oxides, polysulfones, polyethers Examples thereof include sulfone, polyether ether ketone, polyether imide, and polyolefin, and thermoplastic elastomers typified by polyester elastomer and polyamide elastomer.
Furthermore, as the resin satisfying the above range, acrylic rubber, acrylonitrile butadiene rubber, urethane rubber,
Rubber such as silicone rubber, styrene-butadiene rubber, and fluororubber can also be used. Furthermore, it is also possible to use a resin obtained by blending a plurality of the above-mentioned thermosetting resins, thermoplastic resins, and rubber.

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, the composite material as a whole can exhibit extremely high rigidity and energy absorption capability. 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.

When the reinforcing fiber is made of carbon fiber,
The crystal size of the reinforcing fiber is preferably 20 Å or more. This crystal size particularly affects the tensile elastic modulus, and when the crystal size is 20 Å or more, a high tensile elastic modulus can be easily achieved. The higher the tensile modulus, the better the energy absorption capacity.

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 in the drawings, 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 above description will be described below. (1) Tensile elastic modulus of fiber It was measured according to the resin-impregnated strand test method defined 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

(2) 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).

(3) Crystal Size (Lc) The crystal size Lc is a value obtained by wide-angle X-ray diffraction according to the following procedure. That is, as the X-ray source, Cu Kα rays monochromated by the Ni filter are used, and 2θ = 2
The half width of the peak of the plane index (002) observed around 6.0 ° is scanned in the equatorial direction to find the half-value width, and the value calculated by the following formula is defined as the crystal size Lc. Lc = λ / (β ₀ cos θ) Here, λ: wavelength of X-ray (1.5418 angstrom in this case), θ: diffraction angle, β ₀ : true half width.
Note that β ₀ uses a value calculated by the following equation. ^{_{β 0 = (β A 2 -β}} 1 2) 1/2 where, β _A ^2: Apparent half width, beta ₁ ^2: apparatus constant (output Rigaku Denki Co. 4036A2 type X-ray generator 35
1.05 × 10 ^-2 ra when used at kV, 15 mA
d).

[0028]

As described above, according to the energy absorbing member of the present invention, the energy absorbing member is made of a composite material of resin and reinforcing fibers having at least three reinforcing fiber layers, and has an inner layer. The reinforcing fibers arranged in one direction and the reinforcing fiber woven fabric are arranged in the outer layer, respectively. The UD reinforcing fibers increase the strength against member destruction, and the reinforcing fiber fabric prevents destruction of the member during energy absorption. Start smoothly with a certain mechanism,
Since it was made to proceed, energy absorption performance is high,
Further, it is possible to realize a highly practical energy absorbing member having stable performance and high reliability, which can be suitably used in various fields.

[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 having T-shaped cross section 7 Energy absorbing member 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 member 12, 13 Elongated members 14, 15a, 15b, 15c Energy absorption member members 16, 17 Energy absorption of combined configuration Member 41 Energy absorbing member 42a, 42b Reinforcing fiber 43a, 43b unidirectionally aligned Reinforcing fiber fabric 44 Energy absorbing shaft 45a, 45b Composite material layer having unidirectionally aligning reinforcing fiber 46a, 46b Reinforcing fiber woven fabric Composite material layer having

Claims (3)

[Claims] 1. Having at least three reinforcing fiber layers,
An energy absorbing member comprising a composite material of resin and reinforcing fibers, wherein reinforcing fibers arranged in one direction are arranged in an inner layer, and reinforcing fiber fabric is arranged in an outer layer. 2. The energy absorbing member according to claim 1, wherein reinforcing fiber layers aligned in one direction are disposed on both sides in the center of the thickness direction, and reinforcing fiber woven layers are disposed on both outermost sides. 3. The energy according to claim 1, wherein the reinforcing fiber layers located on both sides of the reinforcing fiber layer in the central portion in the thickness direction are symmetrical with respect to the reinforcing fiber layer in the central portion in the thickness direction. Absorbing member.