JP3360871B2 - 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 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 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 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 a composite material of resin and reinforcing fibers has not only the energy absorbing ability itself but also the smoothness of destruction when the member is locally destroyed at the time of energy absorption. The fact is that it is not fully utilized in practice due to insufficient aspects.

An object of the present invention is to provide an energy absorbing member capable of exhibiting a sufficiently high energy absorbing ability and having a smooth energy absorbing mechanism.

[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 and having at least three reinforcing fiber layers in the thickness direction. In addition, in the reinforcing fiber layer at the central portion in the thickness direction, the reinforcing fiber extends in a direction within a range of 90 ° ± 15 ° with respect to the energy absorption axis direction.

When the energy absorbing member is a tubular member (for example, a cylindrical member), the reinforcing fiber layer at the central portion in the thickness direction is a hoop layer in which the reinforcing fibers extend in the circumferential direction of the tubular member. Is preferred.

In the fiber layers other than the reinforcing fiber layer in the central portion in the thickness direction, that is, in the reinforcing fiber layers located on both sides of the reinforcing fiber layer in the central portion in the thickness direction of the member, the reinforcing fibers are in the energy absorption axis direction. It is preferable that the fiber layer extends in a direction within a range of 0 ° ± 60 ° or includes such a fiber layer.

In such an energy absorbing member, for example, as shown in a cylindrical member 41 in FIG. 1, a reinforcing fiber is provided at a central portion in the thickness direction of the member 41 by 90 ° ± with respect to the energy absorbing axis C direction. Since the reinforcing fiber layer 42 extending inward in the range of 15 ° is provided, the member 41 is easily deformed so as to tear from the center in the thickness direction to both sides when absorbing energy, for example, when the compressive load P acts on the member 41. . That is, when the member is destroyed or plastically deformed, the starting point of the destruction or deformation is determined at the central portion in the thickness direction of the member, and the destruction or deformation is smoothly performed. The reinforcing fiber layer 42 at the central portion in the thickness direction mainly determines the starting point of the destruction in the above-described destruction mechanism, and the energy absorption itself is carried by the reinforcing fiber layer 43 and the matrix resin existing on both sides thereof. .

When the member is broken so as to be split into both sides in the thickness direction, if it is split from the center in the thickness direction, it is possible to absorb a larger amount of energy than if it is split from a position eccentric to either side. Become. Since both side parts of the member to be torn will be destroyed substantially at the same time, all parts in the thickness direction will be used for energy absorption substantially uniformly and effectively, and the energy absorption as a whole member will be most efficient. You can As a result, it becomes possible to maximize the amount of energy absorption in the energy absorbing members having the same shape.

Moreover, since the starting point of the member destruction is set at the center in the thickness direction, the destruction is smoothly started and progressed, and a constant destruction mechanism is always obtained. If the destruction mechanism is constant, there is no variation in the amount of absorbed energy. As a result, the certainty and reliability of the operation of the energy absorbing member are significantly improved.

In order to further promote efficient energy absorption as described above, the reinforcing fiber layers located on both sides of the reinforcing fiber layer at the central portion in the thickness direction are different from the reinforcing fiber layers at the central portion in the thickness direction. It is preferable that they are symmetrical. 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 of both side parts is maximized and efficiently exhibited,
Higher energy absorption is obtained.

In the energy absorbing member of the present invention,
The reinforcing fiber is not limited to carbon fiber, and as the reinforcing fiber other than carbon fiber, for example, glass fiber, aromatic polyamide fiber, alumina fiber, silicon carbide fiber and boron fiber can be selected.

The resin that serves as the matrix of the composite material is not particularly limited, and examples thereof include epoxy resin, unsaturated polyester resin, polyvinyl ester resin, phenol resin, guanamine resin, and bismaleimide.
Examples thereof include polyimide resins such as triazine resins, furan resins, polyurethane resins, polydiallyl phthalate resins, and thermosetting resins such as amino resins such as melanin resins and urea resins. Further, polyamides such as nylon 6, nylon 66, nylon 11, nylon 610 and nylon 612, or copolyamides of these polyamides, polyesters such as polyethylene terephthalate and polybutylene terephthalate, or copolyesters of these polyesters, and Polycarbonate, polyamideimide, polyphenylene sulfide, polyphenylene oxide, polysulfone, polyethersulfone, polyetheretherketone, polyetherimide, polyolefin and the like, and further, thermoplastic elastomer represented by polyester elastomer, polyamide elastomer, and the like. To be 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.

When the reinforcing fibers are made of carbon fibers, oxygen (O) and carbon (C) on the surface of the reinforcing fibers of the fiber layers located on both sides of the reinforcing fiber layer at the central portion in the thickness direction are particularly preferable. The amount of surface functional groups (O / C), which is the atomic ratio of 0.
It is preferably 08 or more. Surface functional group amount (O /
When C) is 0.08 or more, the activated O enhances the adhesiveness of the reinforcing fiber surface, and the adhesive strength between the resin and the reinforcing fiber is enhanced, resulting in extremely high rigidity and energy absorption of the composite material as a whole. You can demonstrate your 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.

Further, in the reinforcing fiber of the carbon fiber, it is preferable that the crystal size is 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.

In the energy absorbing member of the present invention,
In the composite material, the arrangement of the reinforcing fibers other than the reinforcing fiber layer at the central portion in the thickness direction is 0 ° to the axis of the energy absorbing member in the compression direction as described above, unless a special combination arrangement is performed. It may be performed within a 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, 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 shape of the energy absorbing member made of the composite material of the present invention is not particularly limited, and various shapes such as a cylindrical shape, a columnar shape, and a plate shape can be adopted. Representative shapes or applicable shapes are illustrated in FIGS. 2 to 11.

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. 3, a cylinder 2 in which the top of the cylinder is formed into 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. 5, for example, a cross section T having ribs 5 is provided.
The shape 6 may be a V shape, or a shape 7 having a U-shaped cross section as shown in FIG. In the shape 7 having a U-shaped cross section shown in FIG. 6, the lid member 8 can be provided as shown by a chain double-dashed line. Further, as shown in FIG. 7, a cross-shaped cross section 9 may be used.

Furthermore, the energy absorbing member is composed of one member, and a plurality of members are superposed,
Alternatively, they may be configured in combination. For example, as shown in FIGS. 8 and 9, 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. 9, 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 is as follows. (1) 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).

(2) 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).

[0025]

As described above, in the case of the energy absorbing member of the present invention, the energy absorbing member is made of a composite material of resin and reinforcing fibers, and the energy absorbing axial direction is formed at the central portion in the thickness direction. 90 ° ± 1
Since the reinforcing fiber layer extending in the direction of 5 ° is provided,
It is possible to provide a stable and highly reliable energy absorbing member, which has high rigidity, can set the starting point of member destruction at the time of energy absorption, and can start and progress the destruction smoothly. Then, the energy absorbing ability of the composite material can be maximized when the member is destroyed, and an energy absorbing member having high energy absorbing performance can be realized.

[Brief description of drawings]

FIG. 1 shows a structural example of an energy absorbing member of the present invention,
It is a partial longitudinal cross-sectional view of a member.

FIG. 2 is a perspective view showing an example of the shape of the energy absorbing member of the present invention.

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

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

FIG. 9 is a perspective 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 absorbing members 14, 15a, 15b, 15c Members 16 and 17 constituting the energy absorbing member Energy absorbing member 41 in a combined configuration Energy absorbing member 42 Reinforcing fiber layer 43 at the central portion in the thickness direction Reinforcing fiber layers C on both sides Energy absorption axis

Front Page Continuation (56) References JP-A-5-332386 (JP, A) JP-A-57-124142 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16F 7 / 12

Claims (4)

(57) [Claims] 1. A composite material of resin and reinforcing fibers,
An energy absorbing member having at least three reinforcing fiber layers in the thickness direction, and in the reinforcing fiber layer at the central portion in the thickness direction, the reinforcing fibers are 90 ° ± 15 ° with respect to the energy absorbing axis direction. An energy absorbing member, characterized in that it extends in a direction within the range. 2. The energy absorbing member is formed of a tubular member, and the reinforcing fiber layer at the central portion in the thickness direction is a hoop layer in which the reinforcing fiber extends in the circumferential direction of the tubular member.
Energy absorption member. 3. In the reinforcing fiber layers located on both sides of the reinforcing fiber layer at the central portion in the thickness direction, the reinforcing fibers extend in a direction within a range of 0 ° ± 60 ° with respect to the energy absorption axis direction. The energy absorbing member according to claim 1 or 2. 4. The reinforcing fiber layer located on both sides of the reinforcing fiber layer at the central portion in the thickness direction is symmetrical with respect to the reinforcing fiber layer at the central portion in the thickness direction. The energy absorbing member as described in 1.