JPH01204733A - Fiber-reinforced composite - Google Patents

Abstract

PURPOSE:To contrive improvement in vibration attenuation characteristics, by a method wherein a composite layer obtained by filling resin with inorganic fiber such as carbon fiber or glass fiber or organic fiber such as aramid fiber and an unrestricted vibration-damping material layer are laminated and integrated. CONSTITUTION:A composite layer 1 obtained by filling epoxy resin with a carbon fiber (unidirection) and an unrestricted vibration-damping material layer 2 are integrated by laminating them alternately in multiple layers. A matter obtained by filling a cured matter obtained by curing the epoxy resin with polyamide amin by adding aromatic polymeric oil to the epoxy resin with about 20vol.% calcium carbonate powder is used for the unrestricted vibration-damping material layer 2. Thickness of the composite material layer 1 and vibration damping material layer 2 are 100mum and about 10mum respectively on the average. Then not only epoxy vibration damping material but also a vinyl chloride or other resin vibration-damping material can be applied to the composite material layer 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to space structures such as artificial satellites, OA equipment, automobiles,
This invention relates to fiber-reinforced composite materials used as structural materials for leisure goods such as golf clubs.

[Conventional technology]

Fiber-reinforced composite materials such as CFRF' 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.

Fiber-reinforced composite materials are superior in that they are lighter and stronger than conventional metal structural materials, and desired mechanical properties can be achieved by controlling the fiber orientation angle. For this reason,
Space structures, aircraft, automobiles, etc. that require strong weight reduction
It has come to be widely used as a structural material for leisure goods and other items.

[Problem to be solved by the invention]

With the expansion of applications for structures made from this type of composite material,
Vibration of the structure is a problem.

Fiber-reinforced composite materials are lightweight and have low vibration damping properties (loss coefficient η = O, OO1) comparable to conventional metal structural materials.
~0.01), it is easy to cause vibration. Furthermore, structures are often manufactured by integral molding, and unlike conventional metal structural materials, vibration damping (structural damping) due to friction at joints cannot be expected. For this reason, in space structures such as artificial satellites, vibrations of the structure cause damage to onboard equipment and a decrease in antenna position accuracy. Therefore, increasing the vibration damping properties of fiber-reinforced composite materials has become an important issue.

In order to solve these problems, methods are being considered to increase the vibration damping of a composite material by increasing the vibration damping of a matrix resin. This is a method of producing a composite material using a resin that has increased vibration damping by adding a flexibility imparting agent such as polyethylene glycol, polypropylene glycol, or liquid rubber to a matrix resin. The vibration damping properties of the resin can be increased up to 10 by adding the flexibility imparting agent.
Although the vibration damping properties of the composite material are greatly increased by a factor of about 0, the vibration damping properties of the composite material are only increased by a factor of several times and are not effective.

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

[Means to solve the problem]

The present invention is a fiber-reinforced composite material characterized by laminating and reinforcing a composite material layer in which a resin is filled with inorganic fibers such as carbon fibers and glass fibers, or organic fibers such as aramid fibers, and a non-restrictive damping material layer. It is.

[Effect]

When bending vibration is applied to a unidirectional fiber reinforced composite material, the vibration damping characteristic ηC is the vibration damping characteristic ηm of the matrix resin.
(loss coefficient) and elastic modulus EII1. It is expressed by the following equation using the vibration damping characteristic ηf and the elastic modulus Ef of the fiber, respectively.

Here, vf is the volume content of fiber.

For example, consider a case where carbon fiber is filled at 50Vo1%. Since the elastic modulus of the resin is about 200 kg/in'', the elastic modulus ratio E t /E m is ~100. In this case, equation (1) can be rewritten as the following equation.

ηc=h翳子上树栃+ηf(2) Usually, the vibration damping characteristic η1 of the resin is 0.01 or less,
Also, since η of carbon fiber is about 0.002,
From equation (2), η. is approximately 0.002. Furthermore, even if flexibility is imparted and η of the resin is increased, a large increase in ηC cannot be expected, as is clear from equation (2).

In the composite material of the present invention, since a non-restrictive damping material layer is provided, vibration damping occurs due to expansion and contraction deformation of the damping material. In this case, the composite material layer made of fibers and resin corresponds to a substrate, and can be considered as a combination of a substrate and a damping material stacked together in several layers.

The damping characteristic η of one unit (composite material layer/unconstrained damping material layer) can be expressed by the following equation.

where E: Young's modulus, H: thickness ratio of damping material and substrate, E
"; loss modulus. Subscripts 1 and 2 represent a composite material layer and an unconstrained damping material layer, respectively.

The damping characteristics in the case of multi-layering can be considered to be approximately the same as that obtained by equation (3). Therefore, as is clear from equation (3), the vibration damping characteristics of the composite material increase as the thickness and loss modulus E' of each damping layer increases.

〔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 figure, the example shows an example in which a composite material layer 1 in which an epoxy resin is filled with carbon fibers (one direction) and a non-restrictive damping material layer 2 are alternately laminated and reinforced in multiple layers. For the non-restrictive damping material layer 2, a cured product obtained by adding an aromatic polymerized oil to an epoxy resin and curing it with polyamide amine was used, which was filled with 20Vo1% of calcium carbonate powder. room temperature,
Loss modulus (bi) 10”dy under 100Hz vibration environment
It has n#j.

In the example, a carbon fiber prepreg coated with the damping material layer 2 was laminated and cured by heating under pressure.

The average thickness of the composite material layer 1 is 100 μm, and the thickness of the damping material layer 2
The average thickness is 10-.

In the embodiment, an epoxy-based damping material has been described, but this is not limited, and it is possible to apply a vinyl chloride-based or other resin-based damping material. Further, as for the manufacturing method, although prepreg was used in the example, other manufacturing methods (for example, hand lay-up method) can be applied.

FIG. 2 shows a comparison of the loss coefficient and frequency between the fiber-reinforced composite material of the embodiment of the laminate shown in FIG. 1 and a conventional epoxy resin-carbon fiber composite material (CFRP). In the figure, solid line 3 indicates the characteristics of the composite material of the present invention, and broken line 4 indicates the conventional CFR.
This is a characteristic of P. In each case, a material with a width of 30 I and a thickness of 5 I was used, and the length was varied from 30 cm to 180 cm in order to obtain different natural frequencies. The loss coefficient was determined from the half-width of the vibration transfer function at the natural vibration.

As is clear from FIG. 2, the composite material of the present invention has a loss coefficient that is 10 times or more greater than that of the conventional composite material at each frequency.

〔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, which can cause damage to onboard equipment in space structures such as artificial satellites, decrease in antenna position accuracy, and reduce noise caused by automobiles. This has the effect of solving the problem.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
It is a figure comparing the loss coefficient of the composite material of the example of a figure, and a conventional composite material (CFRP).

Claims (1)

[Claims] 1. A fiber-reinforced composite material characterized by laminating and integrating a composite material layer in which a resin is filled with inorganic fibers such as carbon fibers and glass fibers, or organic fibers such as aramid fibers, and a non-restrictive damping material layer.