JPH09226039A - Fiber-reinforced plastic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an FRP member which has a large resistance up to breakage and can absorb efficiently and stably energy after it reaches once breakage and exhibits a larger amt. of absorption energy than the absorption energy of a single body of a constitutional material. SOLUTION: A fiber-reinforced plastic member which has an inner layer [A] and an outer layer [B] each consisting of a fiber-reinforced plastic made of a reinforcing fiber and a resin and has an impact absorption energy being larger than the impact absorption energy of [A] alone and [B] alone, or a fiber-reinforced plastic member which has an inner layer [A] and an outer layer [B] each consisting of a fiber-reinforced plastic made of a reinforcing fiber and a resin and has a ratio of the elongation of [B] to the elongation of [A] is 0.7-0.95, is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber reinforced plastic (hereinafter abbreviated as FRP) composed of reinforcing fibers and resin.
The present invention relates to a manufactured member, and more particularly, to a structure of a high-impact FRP member having excellent absorbed energy performance at the time of impact.

[0002]

2. Description of the Related Art Since FRP is lightweight and highly rigid, it has rapidly spread as a member for sports, aircraft and other general industries.
It is one of the materials that make our lives more comfortable, but in order to further spread FRP, it is desired to improve not only the weight and rigidity, but also the energy absorption performance at the time of impact. .

For example, when the FRP member has an elongated shape such as a long pipe and is subjected to a bending impact, the reinforcing fiber near the neutral axis does not sufficiently bear the load (bending stress state). Physical properties such as the rigidity of the member, because the crack that started from the surface layer crosses the member cross section and totally breaks,
It is difficult to achieve a good balance with the impact characteristics (impact energy absorption performance), and the fact is that it has not been put to practical use sufficiently.

In order to improve the impact characteristics of the FRP member, a shock-absorbing material such as rubber or foam material is attached to the FRP member, or the FRP member is covered with a protective layer made of metal or plastic so that the FRP is not directly impacted. Try not to join. These buffer layers and protective layers are FR when viewed from the material alone.
It is a material with a higher impact energy absorption capacity than the P layer,
It does not increase the energy absorbed by the FRP layer itself.

The amount of energy to be absorbed can be adjusted by the thickness of the cushioning material and the protective layer. However, when it is desired to absorb more energy, the amount of the cushioning layer and the protective layer is increased and the rigidity and strength of the member are increased. It causes a decrease or an increase in weight that cannot be ignored (for example, Japanese Patent Laid-Open No. 5-321010).

Another method for improving the impact properties of FRP members is to use a matrix resin having high toughness / high elongation (for example, Japanese Patent Laid-Open No. 60-47104), but the impact improvement range is It is smaller than the above-mentioned buffer layer and protective layer, and the properties other than impact, such as high temperature physical properties, low temperature physical properties, and fatigue properties, are affected by changing the resin. For example, a typical resin of high toughness resin is a thermoplastic resin, but when changing the thermosetting resin to a thermoplastic resin, in addition to the above problems, molding equipment, molding conditions, fiber Adhesion etc. need to be changed drastically.

[0007]

DISCLOSURE OF THE INVENTION The object of the present invention is to provide a large resistance to destruction, to efficiently and stably absorb energy after destruction once, and to absorb the amount of energy of the constituent material. It is an object of the present invention to provide an FRP member having a structure with high practicality that is less than the absorbed energy of a single substance and has few restrictions on rigidity, weight, shape, and material.

[0008]

The FRP member of the present invention comprises:
In order to solve the above-mentioned subject, it has either of the following composition. That is, a member having an inner layer [A] and an outer layer [B] made of a fiber-reinforced plastic made of a reinforcing fiber and a resin, the impact absorption energy of which is higher than the impact absorption energy of the [A] single substance and the [B] single substance. A member made of a fiber reinforced plastic characterized by the following: a member having an inner layer [A] and an outer layer [B] made of a fiber reinforced plastic consisting of a reinforcing fiber and a resin, the elongation of [B] and [A] A fiber-reinforced plastic member having a ratio of elongation of 0.7 or more and 0.95 or less, or
A member having an inner layer [A] and an outer layer [B] made of a fiber reinforced plastic including a reinforcing fiber and a resin,
The ratio of the elongation of [B] and the elongation of [A] is 0.7 or more, 0.9
A fiber reinforced plastic member having a shock absorption energy of 5 or less and higher than the shock absorption energy of [A] alone and [B] alone.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The FRP member of the present invention is a member having an inner layer [A] and an outer layer [B] made of a fiber reinforced plastic consisting of a reinforcing fiber and a resin, and shock absorbing energy of [A] alone. Further, since it is a member made of fiber reinforced plastic which is higher than the impact absorption energy of [B] alone, it is lightweight, has high strength, and has an extremely high impact resistance. Preferably, the shock absorption energy is 1.5 times or more higher than the shock absorption energy of either [A] alone or [B] alone.

The impact absorption energy in the present invention will be described with reference to FIG. FIG. 1 is a load-displacement diagram when an impact is applied to the FRP. It corresponds to the area under the curve. J
Although the absorbed energy is defined in ISK 7077, more specifically, the absorbed energy up to the maximum load value shown in FIG. The two may be distinguished from each other by taking the absorbed energy up to (the energy before the maximum load a plus the energy after the maximum load b (the area of the downward-sloping hatched portion)) as the total absorbed energy. In practical products, for parts that need to be replaced or repaired even if partial damage occurs, the absorbed energy before the maximum load is emphasized, and the part that is intended to absorb the impact by breaking the member The total absorbed energy is often important.

The reinforcing fibers used in [A] and [B] constituting the FRP are, for example, carbon fibers, glass fibers,
Inorganic fibers such as silicon carbide fibers, aromatic polyamide fibers, polyethylene fibers, polyphenylene benzbisoxazole (PBO) fibers, organic fibers such as polyimide fibers, and metal fibers such as boron fibers are examples of resins such as epoxy resin and vinyl. Thermosetting resin such as ester resin, unsaturated polyester resin, phenol resin, polyimide resin, polyurethane resin, or polyethylene resin,
Nylon resin, polypropylene resin, polyamide resin,
A thermoplastic resin such as ABS resin, polybutylene terephthalate resin, polyacetal resin, or resin such as polycarbonate can be used.

Examples of the form of the reinforcing fiber in each layer include filaments arranged in one direction, roving, woven fabric such as plain weave, and mats arranged randomly. The FRP member of the present invention also includes those containing a small amount of a filler, a plasticizer, a stabilizer, a flame retardant, a crystal nucleus material, and an additive in addition to the reinforcing fiber.

Such an FRP member is a member having an inner layer [A] and an outer layer [B] made of a fiber reinforced plastic consisting of a reinforcing fiber and a resin, and having an elongation of [B] and an elongation of [A]. It can be preferably obtained by setting the ratio to 0.6 or more and 0.95 or less. This makes it possible to provide a lightweight, high-strength, high-rigidity FRP member that can give high impact absorption energy as described above.

When a relatively low-velocity bending impact is applied to the FRP member having the above-mentioned structure, [B] in the outermost layer of the member is most deformed. At this time, if the elongation of [B] (precisely, the elongation at break or the fracture strain) is made smaller than that of [A] of the inner layer, the fracture surely starts from [B]. Although it progresses to A], the elongation of [A] at the point of contact with [B] is still smaller than the elongation of [A], so the fracture is between the [A] and [B] layers and the direction of impact. It also behaves in such a way that it propagates in a direction at right angles and absorbs energy. Once the fracture starts to exhibit such a mode, even in [A], the fiber parallel to the impact direction and the direction perpendicular to the impact (interlayer or layer) occur continuously, which is very Absorbs a lot of energy.

Therefore, when the ratio of the elongation of [B] and the elongation of [A] exceeds 0.95, the fracture at the time of impact often does not start from [B], and even if it starts, [B] The destruction started from [A] easily crosses [A] (there is almost no destruction in the direction perpendicular to the impact, only the destruction of the fiber), and the amount of energy absorbed is small, If the ratio of the elongation and the elongation of [A] is smaller than 0.6, [B]
Destruction does not progress to the above continuous destruction to [A], and the amount of energy absorbed is also small.
The ratio of the elongation of [B] to the elongation of [A] is preferably 0.7 to 0.9 in order to more reliably destroy the material from [B] and further increase the absorbed energy. .

The elongation (also referred to as breaking strain) in the present invention is [A] and [B] respectively ASTM D 3
The tensile test is performed according to 039, but it is [A] and [B].
If it cannot be separated, it can be obtained by cutting out the member and shaving [A] and [B] with a grinder or the like.
Alternatively, [B] may be obtained by a tensile test. Or,
The elongation may be measured by applying a load to the member by attaching a strain gauge or the like to the parts [A] and [B].

Further, since [B] in the present invention is a layer for playing a role of initiating destruction as described above, the thinner the thickness is, the more preferable it is for the purpose of reducing the weight of the member, but [B]. The thickness is 0.01 to the thickness of [A].
It is preferably in the range of 0.2. If it is less than 0.01, the destruction of [B] may not progress to [A], and if it is greater than 0.2, the absorbed energy in terms of thickness may not be sufficient. Because. The thickness of the member is preferably 0.5 mm or more. This is because if it is thinner than 0.5 mm, it is difficult to obtain a material having a thickness of [B] satisfying the above-mentioned ratio, and there is a possibility that a part of the breakage between the layers meanders and the whole breaks.

When the elongations and thicknesses of [B] and [A] are both within the above ranges, a high energy absorbing member having a balance of rigidity, strength and absorbed energy can be obtained.

Further, it is preferable to use continuous carbon fiber as the reinforcing fiber of [A] because a small amount of reinforcing fiber can make the member lighter and more rigid and the range of application can be expanded. Further, it is preferable that the amount of the reinforcing fiber is substantially constant in order to continuously progress the fracture as described above. Most preferred is a laminate of sheet materials (for example, UD prepreg) containing carbon fibers in a substantially constant amount, and having a fiber weight content of 35 to 80%. This is because if it is less than 35%, the rigidity of the member is insufficient, and if it exceeds 85%, voids are likely to remain in the case of thick molding and the fatigue strength of the member may decrease. Since carbon fiber is also high in strength, it has a characteristic that a large amount of energy is required to break the fiber, and a continuous fiber also has an effect of reliably breaking without the fiber coming off. Also,
Carbon fiber reinforced plastics have environmental resistance (acid resistance,
It also has the role of improving solvent resistance) and fatigue characteristics.

The carbon fiber is a so-called carbon fiber or graphite fiber produced by using polyacrylonitrile (PAN) fiber or pitch as a raw material, and the fiber diameter is usually 5 to 10 μm, but it is particularly high. PAN-based carbon fibers that are ductile carbon fibers are preferable, and those having an elastic modulus of 200 GPa to 400 GPa are more preferable in terms of balance with rigidity.

Further, in order to more effectively propagate the fracture in [A] to the layers, the interlaminar shear strength of [A] (this strength can be measured by ASTM D 3518) is 5
It is preferably 0 MPa to 140 MPa. If the interlaminar shear strength is lower than 50 MPa, the shear strength as a structural member member may not be sufficient,
This is because if it is larger than a, there is a possibility that the progress of fracture between layers may be difficult to proceed. In addition, since the interlaminar shear strength is affected by the amount of defects such as voids, the interlaminar shear strength of the member is easily controlled from 70 to 120 M from the viewpoint of productivity.
More preferably, it is Pa.

Specific methods for controlling the interlaminar strength include changing the surface treatment (functional group on the surface) of the fiber, changing the sizing agent coating the fiber, adhering between layers, or releasing. Means such as inserting a film or applying a coating can be used.

Next, [B] is a layer that plays a role of a trigger (trigger) site for the above-described impact-induced destruction, and is a layer that greatly affects the rigidity of the member,
Reinforcing fibers of [B] are continuous or long fibers (long fibers are 50 c
(a fiber longer than m) is preferably in the form of a roving or a cloth, and when [B] is an FRP having a mat structure of continuous or long fibers, the elongation is not only the type of fiber but also the arrangement and crossing. It is more preferable because the elongation can be designed depending on the state.

[0024] The mat material is a mat-like material in which fibers are non-directionally or evenly stacked and evenly bonded with a binding material, and a continuous strand mat, a chopped strand mat, a surfacing mat. Examples thereof include a lami mat and a needle punch mat, but in the present invention, knit, non-woven fabric, paper form, felt, mesh and sheet forms are also included.

Since [B] plays a role of a start (trigger) site of destruction by impact,
Although the surface quality will be deteriorated, it may be possible to intentionally introduce defects such as cracks that start the destruction on the surface of [B]. In this case, the crack depth is 1/1 of the thickness of [B]
The range of about 0 to 1/4 is preferable from the viewpoint of reliably causing the breakage from [B] and the quality of the member.

When the reinforcing fiber of [B] has a higher elongation than the reinforcing fiber of [A], [B] is a random array mat of long fibers so that the reinforcing fibers are crossed with each other. The elongation of B] can be made smaller than that of the reinforcing fiber. Further, the elongation of [B] can be made lower than that of the reinforcing fiber by using a resin having a smaller elongation than that of the reinforcing fiber of [B] as the matrix of [B] (in this case, [B] ] The effect of lowering the elongation is increased when the amount of the reinforcing fiber is small). Further, the elongation can also be reduced by making the linear expansion coefficient of [B] larger than that of [A] so that the tensile thermal strain remains in the [B] layer. In this case, increase the linear expansion coefficient of the resin [B],
The elongation of [B] can be reduced as the layer thickness is reduced. Also, the elongation of [B] can be reduced by introducing defects or voids into [B] in advance as described above.

When the reinforcing fibers in the mat have a random arrangement, the elongations of [B] are equal in the plane,
Even if the supporting conditions of the members are different, it is preferable that the fracture starts with a substantially constant impact deformation.

Although carbon fiber, which is lightweight, is preferable as the reinforcing fiber used in [B], glass fiber is relatively inexpensive and can be obtained in various reinforcing forms. Various surface treatments can be applied to glass fiber, and the elongation can be easily controlled. The glass fibers are so-called E-glass, C-glass, S-glass, and other fibrous glass containing silicon oxide as a main component, and the fiber diameter is usually 5 to 20 μm.
m.

In particular, when [B] is a continuous glass fiber mat layer and [A] is a continuous carbon fiber, the member can have higher rigidity, lighter weight and higher strength. As shown in, the absorbed energy at the time of bending impact can be dramatically improved.

Next, the FRP member of the present invention preferably has a cylindrical shape, a columnar shape, or a flat plate shape. A cylindrical or flat plate member is relatively easy to form and has an advantage of being easy to form a layered structure. In addition, since it is often used in a long (slender) shape, it is easily subjected to bending impact in practical use, and the effect of the present invention can be utilized. Because it is easy. 2 to 4 show the basic shapes of these members as an example. INDUSTRIAL APPLICABILITY The present invention is applicable to a tapered cylinder, a cylinder in which the top of the cylinder is formed into a conical shape or a spherical shape, a cylinder with an elliptical cross section, a cylinder with a flange portion, a columnar member, and a corrugated member. Can also be applied. Further, [B] may be on both outsides or one outside of [A].

More specifically, the cylindrical member, which is a member of sports equipment, is a cylinder for a fishing rod, a cylinder for a golf shaft, a cylinder for ski poles, a racket frame for tennis, badminton or squash, a tent frame. For example, various types of poles, etc., such as outer shells of pressure vessels for general industry, and cylinders / pipes for structures such as truss materials are cited. As a flat plate member, a drawing material used as a building member, a shape member (referred to as a pipe, a square pipe, an angle, a channel, a C type, a T type, an I beam, a flat plate, a bar, a pillar, a girder material, etc.) Etc. are mentioned as an example. This is because these cylinders and flat plate members are members that require high impact absorption energy in addition to light weight, rigidity, and strength. Further, a helmet hat body for work is also an application in which the effect of the present invention can be utilized.

As a molding method for manufacturing the FRP member of the present invention, any known molding method can be used. For example, filament winding method (FW), sheet winding method, sheet layup method, sheet wrap method, tape winding method, tape wrapping method, hand layup method,
Sheet molding method (SMC), stamping molding method, resin injection molding (RIM)
The law and so on. In forming the member, the [A] part and the [B] part may be integrally formed at the same time, or the [A] part and the
There is no problem even if the [B] parts are separately molded and then adhesively joined.

[0033]

【Example】

(Example 1) Carbon fiber T700S manufactured by Toray Industries, Inc.
(Elongation 2.0%, elastic modulus 230 GPa, thread diameter 7 μm) arranged in one direction epoxy resin prepreg (thickness 145
μm, fiber basis weight = 150 g / m ² , fiber weight content = 6
7%), 12 layers of continuous glass fiber mat (Continuous Strand Mat SM3600E, fiber weight = 30 g / m ² ) made by Asahi Fiber Glass Co., Ltd., and epoxy resin on both sides. A laminate of two films (resin weight = 50 g / m ² ) was molded in an autoclave at 130 ° C to obtain a 1.89 mm thick FRP flat plate having a layer structure.

The thickness of the carbon fiber layer (corresponding to [A]) is 1.75 mm, and the thickness of the mat layer (corresponding to [B]).
Was 0.07 mm on both upper and lower surfaces.

From this FRP flat plate, width 10 mm, length 60
mm test pieces for Charpy test were cut out and subjected to a three-point bending test and a Charpy impact test.

The conditions of the three-point bending test were as follows.

Tester: Instron 4201 tester Sample width: 12.7 mm Span distance: 60 mm Addition speed: 2.0 mm / min Test temperature: 25 ° C. Charpy impact test conditions are as follows:

Tester: Instrumentation Charpy tester manufactured by Yonekura Seisakusho-300CS Distance between fulcrums: 60 mm Weight of hammer blade: 5.275 kgf · cm Hammer blade radius: 2 mm Hammer blade angle: 30 ° Hammer lifting angle: 143 0.5 ° Hammer swing angle: 134.0 ° Hammer speed at striking point: 3.65 m / sec Specimen: flatwise test specimen without notch Specimen width: 10.0 ± 1.0 mm Test temperature: 25 ° C Bending The strength, flexural modulus, absorbed energy before maximum load, and total absorbed energy are shown in Table 1, and the absorbed energy is compared in absolute value or in converted value per thickness,
It was about twice that of the comparative example described later.

Separately from the above, an inner layer ([A]),
In order to obtain the elongation of the outer layer ([B]), eight sheets of the same carbon fiber / epoxy prepreg as described above were laminated, and the same continuous fiberglass mat and epoxy resin film as the above were 11 sheets and 22 sheets, respectively. FR obtained by stacking sheets
A test piece was cut out from the P plate and subjected to a tensile test according to ASTM D3039. The result is that [A] is 2.0%,
[B] was 1.5% (thus, the elongation ratio of [B] and [A] was 0.75).

Example 2 A test piece was cut out and subjected to a bending and Charpy impact test in the same manner as in Example 1 except that two mats were laminated on the upper side and four resin films were laminated on the upper side. The results are shown in Table 1. Similar to Example 1, the absorbed energy was about 2.5 times that of the Comparative Example described later, both in terms of absolute value and in terms of converted value per thickness.

Example 3 Instead of laminating 12 carbon fiber / epoxy resin prepregs in Example 1,
After stacking 6 carbon fiber / epoxy resin prepregs,
1 resin film, then 1 mat, then 1 resin film, then 1 carbon fiber /
A molded plate was prepared in the same manner as in Example 1 except that six epoxy resin prepregs were laminated, and test pieces were cut out and subjected to bending and Charpy impact tests. The results are shown in Table 1. The absorbed energy was about 1.3 times that of the Comparative Example described later, both in terms of absolute value and in terms of converted value per thickness.

The thickness of the [A] layer was 1.95 mm, and the thickness of the [B] layer was 0.07 mm. Further, as a result of conducting a tensile test on only [A], the elongation was 2.0% (hence,
The elongation ratio of [B] and [A] is 0.75).

(Comparative Examples 1 and 2) From the CFRP molded plate in which only 13 carbon fiber prepregs identical to those in Examples were laminated and the GFRP molded plate in which only 28 matte materials and resin films identical to those in Examples were laminated, Test pieces were cut out in exactly the same manner as in Example 1 and subjected to bending and Charpy impact tests of CFRP alone and GFRP alone. The results are shown in Table 1.

In any of Examples 1, 2, and 3, the absorbed energy is remarkably increased as compared with either of [A] alone or [B] alone. In particular, the FRP of Example 1
Is slightly lighter than CFRP alone,
Moreover, the absorbed energy of impact is more than twice that of CFRP alone, and both bending strength and bending rigidity are CFRP.
It is as good as a simple substance and has extremely excellent performance that has never been seen before.

[0045]

[Table 1]

[0046]

As described above, the FRP member of the present invention can dramatically increase the absorbed energy at the time of impact as compared with the absorbed energy of [A] simple substance and [B] simple substance. Can be made even lighter and have higher performance.

[Brief description of drawings]

FIG. 1 is a displacement-load diagram when an impact is applied to an FRP.

FIG. 2 is a schematic view of a cylindrical FRP member according to an embodiment of the present invention.

FIG. 3 is a schematic view of a flat FRP member according to an embodiment of the present invention.

FIG. 4 is a schematic view of a cylindrical FRP member having a taper according to an embodiment of the present invention.

[Explanation of symbols]

 1: [A] layer 2: [B] layer 3: hemispherical defect introduced on the surface of [B] 4: linear crack introduced on the surface of [B]

Claims (12)

[Claims] 1. A member having an inner layer [A] and an outer layer [B] made of a fiber reinforced plastic consisting of a reinforcing fiber and a resin, the impact absorption energy of which is [A] simple substance and [B].
A fiber reinforced plastic member characterized by having a higher impact absorption energy than a single unit. 2. A member having an inner layer [A] and an outer layer [B] made of a fiber reinforced plastic composed of a reinforcing fiber and a resin, wherein the ratio of the elongation of [B] to the elongation of [A] is 0. A member made of fiber reinforced plastic, which is not less than 0.6 and not more than 0.95. 3. A member having an inner layer [A] and an outer layer [B] made of a fiber reinforced plastic composed of a reinforcing fiber and a resin, wherein the ratio of the elongation of [B] to the elongation of [A] is 0. A fiber-reinforced plastic member having a shock absorption energy of 0.6 or more and 0.95 or less and higher than the shock absorption energy of [A] alone and [B] alone. 4. Impact absorption energy is [A] simple substance, [B]
The fiber-reinforced plastic member according to claim 1 or 3, which is 1.5 times or more higher than the impact absorption energy of any of the single substances. 5. The ratio of the thickness of [B] to the thickness of [A] is 0.01.
It is-0.2, The fiber-reinforced plastic member in any one of Claims 1-4 characterized by the above-mentioned. 6. The fiber-reinforced plastic member according to claim 1, wherein the [A] portion absorbs impact energy by breaking the fiber and the interlayer. 7. The fiber-reinforced plastic member according to claim 1, wherein the reinforcing fiber constituting [A] is a continuous carbon fiber. 8. The interlaminar shear strength of [A] is 50 MPa or more,
It is 140 MPa or less, It is characterized by the above-mentioned.
A member made of a fiber-reinforced plastic according to any one of 1. 9. The fiber-reinforced plastic member according to claim 1, wherein the reinforcing fibers in [B] are continuous or long fibers. 10. The fiber-reinforced plastic member according to claim 1, wherein the reinforcing fibers in [B] are mat-shaped. 11. The fiber-reinforced plastic member according to claim 1, wherein the reinforcing fibers constituting [B] are carbon fibers or glass fibers which are continuous fibers. 12. The member is one of a cylindrical member, a column member, and a plate member.
10. A member made of fiber reinforced plastic according to any one of 10 to 10.