JPH05124120A - Fiber-reinforced resin structure - Google Patents

Abstract

PURPOSE:To provide an FRP structure, in which elastic deformation in the other direction can be increased while keeping rigidity in the specific direction. CONSTITUTION:An FRP structure 1 is manufactured by impregnating a fiber base material 2 for reinforcement, in which a first base material 20, in which fibers 22 having a high Young's modulus are extended in the longitudinal direction, is held by second base materials 10 knitted by warp 12 elongated in the short direction and weft 14 elongated in the longitudinal direction and having a low Young's modulus, with a synthetic resin 4 and solidifying the synthetic resin. Upper and lower FRP layers reinforced by the second base material 10 display large elastic deformation to stress in the vertical direction. When bending stress works from the vertical direction of the FRP structure 1, the FRP structure 1 also displays large elastic deformation because the upper and lower layers, to which large stress is applied, indicate large elastic deformation. When bending stress works from the longitudinal or horizontal direction, there is an FRP layer reinforced by the first base material 20 composed of the fibers 22 having the high Young's modulus even on a surface section, to which large distortion is applied, thus acquiring large rigidity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to a fiber reinforced resin (FiberReinforced) obtained by impregnating a reinforcing fiber base material such as aramid fiber, glass fiber or carbon fiber with a synthetic resin such as a thermoplastic resin or a thermosetting resin. Plastics; hereinafter also abbreviated as FRP) structure, particularly FRP structure exhibiting elastic deformation characteristics that differ depending on the direction in which stress is applied.

[0002]

2. Description of the Related Art For the purpose of improving the vibration absorbing characteristics of a vehicle suspension leaf spring and reducing its weight, the FRP is used.
A leaf spring made of (fiber reinforced resin) material has been developed and disclosed in Japanese Patent Laid-Open No. 60-208642. This leaf spring has a structure in which a carbon fiber reinforced FRP material having a large elastic modulus (Young's modulus), that is, a high rigidity is arranged in the center portion, and a glass fiber reinforced FRP material having a low Young's modulus is arranged above and below the FRP material. Is becoming As a result, a large elastic deformation is exhibited with respect to the bending stress in the vertical direction, and sufficient vibration absorption characteristics can be obtained as a leaf spring. On the other hand, since the leaf spring has high rigidity in the lateral direction, it is possible to obtain the rigidity against the lateral stress required for the leaf spring.

[0003]

In order to obtain a large elastic deformation in the FRP structure having a three-layer structure such as the leaf spring, the FRP constituting the upper and lower layers is formed.
It is necessary to make the Young's modulus of the material layer as small as possible.
However, the Young's modulus of the FRP material is almost specified by the Young's modulus of the reinforcing fibers that compose the reinforcing fiber base material. Aramid fiber, glass fiber, which is used as a reinforcing fiber
Since the Young's modulus of carbon fibers and the like is limited, the Young's modulus of FRP materials cannot be lowered so much. Therefore, in the FRP structure having the above three-layer structure, it was not possible to obtain a sufficient amount of elastic deformation. Therefore, it is an object of the present invention to provide an FRP structure capable of increasing the elastic deformation against the stress in the other direction while maintaining the rigidity against the stress in the specific direction.

[0004]

In order to solve the above-mentioned problems, the present invention provides a fiber-reinforced resin structure obtained by impregnating a reinforcing fiber base material with a synthetic resin and solidifying the resin. The material has a first base material in which high Young's modulus fibers extend in a substantially parallel direction, and a second base material laminated on both surface sides thereof, and the second base material is the same as the first base material. A fiber-reinforced resin structure, characterized in that a warp yarn extending in a direction perpendicular to the fiber orientation direction is knitted with a weft yarn having a low Young's modulus extending in the orthogonal direction (that is, the fiber orientation direction of the first base material). Created.

[0005]

The reinforcing fiber base material of the FRP structure of the present invention having the above-mentioned structure has a three-layer structure of the first base material of the central layer and the second base materials above and below the first base material. The upper and lower second base materials are formed by weaving warp yarns and weft yarns having a low Young's modulus. As a result, the second base material exhibits relatively high rigidity with respect to stress in the warp direction, while exhibiting extremely large elastic deformation with respect to stress in the weft direction. Therefore, the upper and lower layer portions of the FRP material reinforced with such a fiber substrate also show similar properties. For this reason, when bending stress acts from the vertical direction of the FRP structure of the present invention, the upper and lower layer portions to which a large strain is applied exhibit a large elastic deformation, and thus a large elastic deformation can be obtained as the entire FRP structure. here,
Since only a small amount of strain is generated in the center layer of the FRP structure, the F reinforced with the first base material composed of high Young's modulus fibers is used.
The presence of the RP layer does not hinder elastic deformation. On the other hand, when a bending stress is applied in the plane of the FRP structure, the FRP layer reinforced by the first base material made of the fiber having a high Young's modulus is present in the surface layer portion where a large strain is applied, and therefore bending in these directions is performed. Great rigidity is obtained with respect to stress. In this way, an FRP structure can be obtained in which the rigidity against stress in a specific direction can be maintained and the elastic deformation against stress in another direction can be increased.

[0006]

【Example】

First Embodiment Next, a first embodiment embodying the present invention will be described with reference to FIGS. 1 and 4. FIG. 1 is a perspective view showing Example 1 of the fiber-reinforced resin structure of the present invention. In the overall view (a) of FIG. 1, reference numeral 1 is a fiber-reinforced resin (FR).
P) is a structure, and the FRP structure 1 includes a synthetic fiber 4 (which is distributed over the entire reinforcing fiber base 2 in FIG. 1A) on the reinforcing fiber base 2. It is impregnated and solidified. The reinforcing fiber base material 2 is prepared as follows. First, a fiber base material formed by aligning continuous fiber bundles 22 of glass fibers in one direction is prepared and cut into a required size. Thereby, the 1st fiber base material 20 which comprises the center part of the fiber base material 2 for reinforcement is produced.

Next, as shown in a partially enlarged view (b) of FIG. 1, a weft yarn 14 made of foamed rubber fiber having a low Young's modulus is three-dimensionally oriented with respect to a warp yarn 12 made of glass fiber. Knit As a result, the tensile and compressive stresses in the X and Z directions and the bending moment in the Z-X plane of FIG. 1 (b) are soft, and the tensile and compressive stress in the Y direction and the XY plane. The fiber base material exhibits high rigidity with respect to bending moment in the YZ plane and has large shear strength. By cutting this fiber base material into a required size so that the weft threads 14 extend in the longitudinal direction, the second fiber base material 10 constituting the upper and lower layers of the reinforcing fiber base material 2 is created. And FIG.
As shown in (a), the upper and lower sides of the first fiber base material 20 are sandwiched between two second fiber base materials 10, and the entire three fiber base materials are vertically penetrated by continuous fibers 30. To stitch. Thereby, the upper and lower second fiber base materials 10
And the first fiber base material 20 in the center are integrally connected. In this way, the reinforcing fiber base material 2 is created.

The reinforcing fiber base material 2 is impregnated with a rubber-modified epoxy resin 4. The impregnation with the resin is performed by the same method as the resin impregnation during the production of the conventional FRP material. Thereafter, the entire reinforcing fiber base material 2 impregnated with the resin 4 is heat-treated, whereby the rubber-modified epoxy resin 4
Is thermally cured, and the preparation of the FRP structure 1 is completed. Here, the continuous fiber bundle 22 that constitutes the first fiber base material 20 may be any fiber as long as it has a high Young's modulus, and in addition to the glass fiber of the present embodiment, a fiber material such as aramid fiber or carbon fiber. Can be used. Further, as the weft yarn 14 among the fibers constituting the second fiber base material 10, any kind of fiber having a low Young's modulus may be used other than the foamed rubber fiber of the present embodiment. Although glass fibers are used as the warp threads 12 of the second fiber base material 10 in this embodiment,
The warp yarn 12 may use fibers having any characteristics. Further, the synthetic resin 4 to be impregnated may be any synthetic resin that can be expected to be stretched. In addition to the rubber-modified epoxy resin of this embodiment, a rubber-modified epoxy resin which is also a thermosetting resin, etc. Alternatively, a thermoplastic elastomer may be used.

Therefore, the first fiber base material 20 constitutes a first base material in which the fibers 22 having a high Young's modulus extend in a substantially parallel direction. The second fiber base material 10 constitutes a second base material in which a warp yarn 12 extending in a direction perpendicular to the fiber orientation direction of the first base material 20 and a weft yarn 14 having a low Young's modulus extending in the orthogonal direction are knitted. is doing. And the fiber reinforced resin structure 1
The reinforcing fiber base material 2 is composed of the first base material 20 and the second base material 10 laminated on both surface sides thereof.

With respect to the characteristics of the FRP structure 1 of the present embodiment constructed as described above with respect to stress in each direction,
This will be described with reference to FIGS. 1 and 4. Reinforcing fiber substrate 2
Has a three-layer structure as described above, and the upper and lower second fiber base materials 10 are warp yarns 1 extending in the lateral direction of the FRP structure 1.
2 and a weft thread 14 having a low Young's modulus and extending in the longitudinal direction are knitted. As a result, the second fiber base material 10 exhibits relatively high rigidity with respect to the tensile stress and the compressive stress in the Y direction of the FRP structure 1, while X
It exhibits very large elastic deformation with respect to tensile stress and compressive stress in the Z direction and the Z direction. Therefore, the FRP structure 1 reinforced with the second fiber base material 10 having such stress characteristics
The upper and lower layer portions of have similar characteristics.

Here, as shown in FIG.
Consider a case where one end of the RP structure 1 is fixed to the fixing surface 6 with an adhesive or the like, and stress is applied to the other end of the FRP structure 1. First, as shown in FIG. 4A, when a bending moment M in the Z-X plane of the FRP structure 1 acts, a large strain σ _a occurs near the upper and lower surfaces of the FRP structure 1. Almost no distortion occurs in the center (near the center plane N). Therefore, with respect to the bending stress M in the vertical direction, the upper and lower layer portions that are largely strained in the X direction exhibit large elastic deformation with respect to the tensile stress and the compressive stress in the X direction. Can also obtain a large elastic deformation. Since only a small strain is generated in the central layer of the FRP structure 1, the first fiber substrate is composed of the fibers 22 having a high Young's modulus oriented in the X direction and exhibiting high rigidity against tensile stress and compressive stress in the X direction. Even if there is the FRP layer reinforced with the material 20, elastic deformation is not hindered.

On the other hand, when a bending moment in the XY plane of the FRP structure 1 is applied, as shown in FIG. 1 (a), not only the central portion that produces a small strain in the X direction, Since the FRP layer reinforced by the first fiber base material 20 having high rigidity in the X direction is also present in the surface layer portion that is greatly distorted in the X direction, large rigidity can be obtained as a whole of the FRP structure 1. Similarly, Y- of FRP structure 1
Even when a bending moment in the Z plane is applied, the FRP layer reinforced by the first fiber base material 20 is present in the surface layer portion to which a large strain is applied, so that a large rigidity can be obtained. For bending moments in these directions, the second fiber base material 10
The warp yarns 12 constituting the part also play a role of increasing rigidity. Further, as shown in FIG. 4B, when the tensile stress P acts in the X direction, the strain σ _{b of the} same degree is generated in the upper and lower layers and the central portion of the FRP structure 1. Therefore, high rigidity is obtained by the FRP layer reinforced by the first fiber base material 20 composed of the fibers 22 having a high Young's modulus in the central portion of the FRP structure 1 shown in FIG. In this way, in the FRP structure 1 of the present embodiment, the rigidity with respect to the stress in a specific direction (bending moment in the XY plane and the YZ plane) is maintained, while the stress in the other direction (Z-
The elastic deformation with respect to the bending moment in the X plane) is increased.

As an effect peculiar to this embodiment, a warp yarn 12 made of glass fiber and a weft yarn 14 made of foamed rubber fiber are three-dimensionally oriented and knitted in the second fiber base material 10. Therefore, there is an advantage that the FRP structure is extremely soft with respect to the bending moment in the Z-X plane and has a large shear strength.

Second Embodiment Next, a second embodiment embodying the present invention will be described with reference to FIG. The same members as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. FIG. 2 is a perspective view showing Example 2 of the fiber-reinforced resin structure of the present invention. In the overall view (a) of FIG. 2, reference numeral 201 is an FRP structure, and this FRP structure 201 is a reinforcing fiber base material 20.
2 is impregnated with a synthetic resin 4 (in FIG. 2A, it is assumed to be distributed throughout the reinforcing fiber base material 202) and solidified. The reinforcing fiber substrate 202 is
It is created as follows. First, as shown in FIG. 2C, a first fiber base material 20 made of glass fibers 22 is prepared in the same manner as in Example 1. Next, as shown in a partially enlarged view (b) of FIG. 2, a warp yarn 12 made of glass fiber and a weft yarn 1 made of foamed rubber fiber having a low Young's modulus are provided.
Knit 4 and 2 in a plane. After stacking this in the vertical direction,
The second fiber base material 210 that constitutes the upper and lower layers of the reinforcing fiber base material 202 is created by cutting the weft thread 14 so as to extend in the longitudinal direction and cutting it into a required size.

Then, the upper and lower sides of the first fiber base material 20 are sandwiched between two second fiber base materials 210, and the entire three fiber base materials are connected to each other as shown in FIG. 2 (a). By using the vertical direction to stitch through. As a result, the upper and lower second fiber base materials 210 and the central first fiber base material 2
0 is connected integrally. In this way, the reinforcing fiber base material 202 is created. The reinforcing fiber base material 202 is impregnated with the rubber-modified epoxy resin 4 and then heat-treated,
As a result, the rubber-modified epoxy resin 4 is thermally cured, and F
Creation of the RP structure 201 is completed.

The FRP of this embodiment constructed as described above
The characteristics of the structure 201 with respect to stress in each direction are shown in Example 1.
This is almost the same as the case of the FRP structure 1 of. That is,
When a bending moment in the Z-X plane of FIG. 2A is applied, the upper and lower layer portions, which are greatly strained, are greatly elastically deformed by the second fiber base material 210, so that the FRP structure 201 as a whole is Can also obtain a large elastic deformation. Since only a small strain is generated in the central layer of the FRP structure 201, the first layer composed of the fibers 22 having a high Young's modulus is used.
Even if there is the FRP layer reinforced with the fiber base material 20, elastic deformation is not hindered. On the other hand, the FRP structure 201
When a bending moment in the XY plane or in the YZ plane is applied, the fiber 22 having a high Young's modulus is formed not only in the central portion where only a small strain is generated but also in the surface layer portion where a large strain is applied. Since there is the FRP layer reinforced with the first fiber base material 20, a large rigidity can be obtained as a whole of the FRP structure 201.

As an effect peculiar to this embodiment, the warp yarn 12 made of glass fiber and the weft yarn 14 made of foamed rubber fiber are planarly knitted and then laminated on the second fiber base material 210. The advantages that the second fiber base material 210 can be easily prepared and the thickness of the second fiber base material 210 can be freely adjusted are obtained.

Third Embodiment Next, a third embodiment embodying the present invention will be described with reference to FIGS. 3 and 2. In addition, Example 1 and Example 2
The same members as those described above are designated by the same reference numerals and description thereof will be omitted.
FIG. 3 is a perspective view showing Example 3 of the fiber-reinforced resin structure of the present invention. In FIG. 3, reference numeral 301 is FRP.
This FRP structure 301 is obtained by impregnating the reinforcing fiber base material 302 with the synthetic resin 4 (in FIG. 3, it is assumed to be distributed throughout the reinforcing fiber base material 302) and solidifying it. It is a thing. This reinforcing fiber substrate 302
Is created as follows. First, as shown in FIG. 2, the first fiber base material 20 made of the glass fiber 22 is prepared in the same manner as in Example 1. Next, as shown in the partially enlarged view (b) of FIG. 2, the warp yarn 12 made of glass fiber and the weft yarn 14 made of foamed rubber fiber having a low Young's modulus are knitted in the same manner as in Example 2. .. After the layers are laminated in the vertical direction, the weft yarns 214 are cut into a required size so as to extend in the longitudinal direction, so that the second fiber base material 2 constituting the outer peripheral layer of the reinforcing fiber base material 202 is formed.
10 is created.

Then, as shown in FIG. 3, the first
The upper and lower sides and front and back of the fiber base material 20 are wrapped with the second fiber base material 210, and the entire fiber base material is pierced by the continuous fibers 30 in the up and down direction and the front and back direction and stitched. As a result, the second fiber base material 210 at the outer peripheral portion and the first fiber base material 20 at the center are integrally connected. In this way, the reinforcing fiber base material 302 is created. This reinforcing fiber substrate 3
02 is heat-treated after being impregnated with the rubber-modified epoxy resin 4, whereby the rubber-modified epoxy resin 4 is thermoset, and the preparation of the FRP structure 301 is completed.

The FRP of this embodiment constructed as described above
The characteristics of the structure 301 with respect to stress in each direction are shown in Example 1.
And, it is different from the case of the second embodiment. That is, when a bending moment in the XY plane of FIG. 3 is applied, a portion of the surface layer (the front and rear layers in FIG. 3) that is greatly distorted shows a large elastic deformation by the second fiber base material 210. , A large elastic deformation is obtained as a whole of the FRP structure 301. Since only a small strain is generated in the central layer of the FRP structure 301, even if there is the FRP layer reinforced with the first fiber base material 20 composed of the fibers 22 having a high Young's modulus, the elastic deformation is not hindered. .. In addition, F of FIG.
A large elastic deformation is obtained when a bending moment in the Z-X plane of the RP structure 301 acts, and the FRP structure 3
A large rigidity is obtained when a bending moment of 01 in the YZ plane acts, as in the first and second embodiments. Thus, the FRP structure 30 of this embodiment is
In No. 1, large elastic deformation is obtained for bending moments in two directions.

In the second and third embodiments described above, the continuous fiber bundle 22 constituting the first fiber base material 20 is
Any fiber having a high Young's modulus may be used, and fiber materials such as aramid fiber and carbon fiber other than the glass fiber of this embodiment can be used. Further, as the weft yarn 14 among the fibers constituting the second fiber base material 210, any kind of fiber having a low Young's modulus may be used other than the foamed rubber fiber of each of the above-mentioned embodiments. .. Although glass fibers are used as the warp yarns 12 of the second fiber base material 210 in this embodiment, fibers having any characteristics may be used as the warp yarns 12. Further, the synthetic resin 4 to be impregnated may be any synthetic resin that can be expected to be stretched. In addition to the rubber-modified epoxy resin of this embodiment, a rubber-modified epoxy resin which is also a thermosetting resin, etc. Alternatively, a thermoplastic elastomer may be used.

In this embodiment, the FRP structure having a substantially rectangular parallelepiped shape is used as a whole, but FRs having other shapes are used.
The same effect can be obtained with the P structure. Further, although the high Young's modulus fibers of the first base material and the low Young's modulus weft threads of the second base material are oriented in the longitudinal direction, they may be oriented in other directions depending on the application. Further, although the continuous fibers 30 are stitched to reinforce the reinforcing fiber base material, the stitching is not always necessary. The shape, size, material, arrangement, etc. of other portions of the FRP structure are not limited to those in this embodiment.

[0023]

INDUSTRIAL APPLICABILITY In the present invention, a warp yarn extending in a direction perpendicular to the orientation direction of the fiber is formed on both surfaces of a first substrate made of a fiber having a high Young's modulus and a low Young's modulus extending in a direction orthogonal to the warp yarn. Since a fiber-reinforced resin structure was created by impregnating a synthetic resin into a reinforcing fiber substrate having a second substrate formed by weaving a weft and solidifying it, the other direction while maintaining rigidity against stress in a specific direction The elastic deformation with respect to the stress can be increased. This realizes a member that supports other components in one direction while obtaining a large deformation stroke in the other direction. Further, as a spillover effect of the present invention, since the FRP structure is reinforced with continuous fibers, the effect that the strength as a whole becomes extremely high is obtained, and a fiber-reinforced resin structure excellent in practicability is obtained. Become.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of a fiber-reinforced resin structure of the present invention.

FIG. 2 is a perspective view showing Example 2 of the fiber-reinforced resin structure.

FIG. 3 is a perspective view showing Example 3 of the fiber-reinforced resin structure.

FIG. 4 is an explanatory diagram showing a strain generated in the fiber-reinforced resin structure when a stress acts on the fiber-reinforced resin structure.

[Explanation of symbols]

 1 Fiber Reinforced Resin Structure 2 Reinforcing Fiber Substrate 4 Synthetic Resin 10 Second Substrate 12 Warp 14 Low Young's Modulus Weft 20 First Substrate 22 High Young's Modulus Fiber

Claims (1)

[Claims] 1. A fiber-reinforced resin structure in which a reinforcing fiber base material is impregnated with a synthetic resin and solidified, wherein the reinforcing fiber base material is formed by extending fibers having a high Young's modulus in substantially parallel directions. It has a first base material and a second base material laminated on both surface sides thereof, and the second base material is a warp yarn extending in a direction orthogonal to the fiber orientation direction of the first base material and a low yarn extending in the orthogonal direction. A fiber-reinforced resin structure, characterized in that a weft yarn having a Young's modulus is knitted.