JPH02169633A - Fiber-reinforced composite material - Google Patents

Abstract

PURPOSE:To obtain the title material which can realize the reduction of vibrations and noises when used in various structures by laminating at least two composite material layers each formed by impregnating a reinforcing fiber with a resin in such a manner that the angles of orientation vary among part or the whole of the layers, inserting viscoelastic material layers between the above layers and integrating the assemblage. CONSTITUTION:At least two prepreg sheets 1 each formed by impregnating an inorganic reinforcing fiber such as a carbon fiber or a glass fiber or an organic reinforcing fiber such as an aramid fiber with a resin such as an epoxy resin are laminated in such a manner that the angles of orientation of the fibers are different among at least part of the layers, and viscoelastic material layers 2 are inserted between at least part of the layers of different angles of orientation. The assemblage is integrated to obtain a fiber-reinforced composite material. This material can realize the reduction of vibration and noises when used in aerospace structures such as artificial satellites and structures such as OA machines, automobiles, commodities for leisure, etc.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a fiber-reinforced composite material that can be used in structures such as space structures such as artificial satellites, OA type equipment automobiles, and leisure goods to reduce vibration and noise. It's about materials.

[Conventional technology]

Fiber-reinforced composite materials such as CFRP are made by solidifying inorganic fibers such as carbon and glass fibers or organic fibers such as aramid fibers with resins such as epoxy resins, polyimide resins, and polyether ether ketone resins.

Compared to traditional metal structural materials, fiber-reinforced composite materials have
It is excellent in that it is light in strength, has high strength, and can achieve desired mechanical properties by controlling the fiber orientation angle. For this reason, it has come to be widely used as a structural material for space structures, aircraft, automobiles, leisure goods, etc., which particularly require weight reduction.

[Problem to be solved by the invention]

By the way, with the expansion of the uses of structures made of this type of composite material, vibration of the structures has become a problem.

The fiber-reinforced composite material is light and soft, and has small vibration damping properties (loss coefficient η = o,
oot~0.1), vibrations are likely to occur.

In addition, structures are often manufactured by integral molding, and unlike conventional metal structural materials, vibration damping (structural damping) due to friction at connections cannot be expected. For this reason, in space structures such as artificial satellites, problems such as failure of onboard equipment due to vibration of the structure and reduction in antenna positioning accuracy occur, and improving the vibration damping characteristics of fiber-reinforced composite materials is an important issue. It has become.

In order to solve these problems, methods are being considered to increase the vibration damping of composite materials by increasing the vibration damping of matrix resins. This is a method of producing a composite material using a resin that has increased vibration damping properties by adding a flexibility imparting agent such as polyethylene glycol, polypropylene glycol, or liquid rubber to a matrix resin. However, although the vibration damping properties of the resin can be improved several tens of times by adding a flexibility imparting agent, the vibration damping properties of the composite material can only be increased by several times, and this is accompanied by a large decrease in rigidity. Not effective.

The present invention is intended to solve the above problems, and its purpose is to provide a fiber-reinforced composite material that has high vibration damping properties.

[Means for Solving the Problems] In order to achieve the above objects, 1. In the fiber reinforced composite material of the present invention, inorganic reinforcing fibers such as carbon and glass fibers or organic reinforcing fibers such as aramid fibers are added to resin such as epoxy resin. Two or more impregnated composite material layers are laminated so that the orientation angle of the fibers is different in each layer or some layers, and a viscoelastic material layer is provided in part or all between the layers with different orientations to integrate the lamination. be.

[Effect]

When bending vibration is applied to a unidirectional fiber reinforced composite material, the vibration damping property ηC is the vibration damping property η of the matrix resin,
(loss coefficient) and elastic modulus E, vibration damping characteristics ηf of the fiber
, and elastic modulus E, respectively.

ζ; and νf is the volume content of fibers.

For example, consider the case where carbon fiber is filled at 50Vo1%. Since the elastic modulus of the resin is about 200 kg/an'', the 1 elastic modulus ratio E, /E is ~100. In this case, equation (1) can be rewritten as the following equation.

Normally, the vibration damping characteristic η of #j fat is 0.01 or less, and η1 of carbon fiber is about 0.002, so η is determined from equation (2). is approximately 0.002. Furthermore, even if flexibility is imparted and η1 of the resin is increased, a large increase in ηC cannot be expected, as is clear from equation (Z).

In the composite material of the present invention, a viscoelastic material is provided between layers having different orientation angles. Therefore, when the composite material undergoes expansion/contraction deformation, shear deformation occurs in the viscoelastic material between the layers since the deformation state of each layer differs due to the anisotropy of each layer.

Since viscoelastic materials generally have high viscosity, part of the vibrational energy is converted into thermal energy by the shearing deformation,
Absorb vibrations. Therefore, the vibration damping characteristics are increased.

The vibration damping characteristics depend on the efficiency (mechanical loss tan δ) of the viscoelastic material in converting vibration energy into thermal energy. Therefore, by using a viscoelastic material with a large low frequency tan δ, large vibration damping characteristics can be achieved even at low frequencies.

Further, when the composite material undergoes bending deformation, a restraining type vibration damping mechanism similar to that of a vibration damping steel plate is generated, and large vibration damping characteristics can be realized at high frequencies.

If a viscoelastic material is provided between layers having the same orientation angle, only the latter constraint type vibration damping mechanism will occur, and large vibration damping characteristics under expansion and contraction deformation cannot be expected.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional view of the fiber-reinforced composite material of the present invention. In the example, a prepreg sheet (AS/J1201; Sumitomo Chemical ■) 1 made of carbon fiber and epoxy resin was ) S is laminated, and a viscoelastic material 2 is provided between each layer to integrate the lamination. As the viscoelastic material 2, a polyurethane resin material prepared by reacting a polyol resin with a polyisocyanate compound was used. The said material is.

It has a value of tan δ = 1.5 at room temperature.

In the examples, prepreg sheets were coated with an uncured viscoelastic material, stacked on top of each other in the above-mentioned stacking order, and heated and cured under pressure.

Figure 2 shows the deformation when tensile stress F is applied to the single layer plate 10 at +45° and -45°.The viscoelastic material provided between the layers is designed to restrain these deformations. act, causing shear deformation.

FIG. 3 shows the relationship between the loss coefficient and frequency of the fiber-reinforced composite material of the example of the laminate shown in FIG.

In the figure, the solid line 3 is the characteristic for bending vibration, and the broken line 4 is the characteristic for longitudinal vibration. In both cases, the loss factor is 0
．． It is a large value of 02 or more.

FIG. 4 shows the characteristics when the viscoelastic material is provided only between layers having the same orientation angle (that is, between 90° layers) in the laminate shown in FIG. 1. In longitudinal vibration and bending vibration, the loss coefficient is smaller than in the case of FIG. 3 at frequencies of 100 Hz or less.

In the above example, an example using carbon fiber was shown, but
Other inorganic reinforcing fibers such as glass fiber.

The same effect can be obtained by using organic reinforcing fibers such as aramid fibers.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to realize a fiber-reinforced composite material with high vibration damping characteristics, which can prevent equipment failures in space structures such as artificial satellites, decrease in antenna position accuracy, etc. This has the effect of solving noise problems.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is a +45
Figure 3 shows the frequency characteristics of the loss coefficient of the composite material of the example shown in Figure 1. Figure 4 shows the deformation of the layer.
It is a figure which shows the frequency characteristic of a loss coefficient when a viscoelastic material is provided between layers.

Claims (1)

[Claims] (1) Two or more composite material layers made by impregnating inorganic reinforcing fibers such as carbon or glass fibers or organic reinforcing fibers such as aramid fibers with resin such as epoxy resin, so that the orientation angle of the fibers is different in each layer or some layers. A fiber-reinforced composite material characterized in that the layers are laminated together, and a viscoelastic material layer is provided between some or all of the layers having different orientations to form an integrated lamination.