JPH0791401B2 - Composite material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to thermomechanical properties such as elastic modulus and coefficient of thermal expansion as a composite material having any property from isotropic to remarkable anisotropy. The present invention relates to a composite material using a reinforcing material capable of imparting.

[Conventional technology]

Composite materials represented by fiber reinforced plastics have been mainly used as thin wall materials. In this case, the reinforcing material is a unidirectional gathering material or a prefabricated flat cloth, and a thin material with a wall thickness of about 0.1 mm is used.The composite material is a resin impregnated after laminating these materials. It is composed by curing. Since the distribution of the orientation angle can be arbitrarily changed in the thin material laminated in this way, it is possible to design an anisotropic composite material having a large degree of freedom in terms of in-plane characteristics.

However, regarding the out-of-plane characteristics such as the strength in the out-of-plane direction and the interlaminar strength, the reinforcing effect cannot be expected, and it is impossible to control.
If the composite material is a thin surface material, these out-of-plane characteristics are practically negligible, but if it becomes a thick member or a complicated shape, the stress generated between layers and the stress in the out-of-plane direction cannot be ignored, Several interlayer or out-of-plane reinforcement methods have been considered. The most reliable method is to use a three-dimensional fabric.

Regarding the three-dimensional woven fabric, a triaxial three-dimensional woven fabric, including its manufacturing method and woven structure, has been disclosed in many documents including Japanese Patent Application Laid-Open No. 61-245335. For other fiber orientations, 4-axis woven fabrics have been published in which one axis out of the plane is added to one in which three axes of 0 ° ± 60 ° are arranged.

Also, in addition to this, at the planning stage, 4,5,6,7,9,
Three-dimensional fabrics having 10, 11, 13 axes have been proposed. The texture of each of these fabrics can be defined by the unit cell of the cube shown in Fig. 5. The three-dimensional three-dimensional fabric has X, Y, Z axes, and the four-axis three-dimensional fabric has T, U. , V, W axes, 6-axis 3D fabrics are K, L, M, N, R, S axes, 7-axis 3D fabrics are the above 3 and 4 axes combined, 9-axis 3D fabrics are the 3 Axial and 6-axis combined, 10-axis 3D woven above 4 and 6-axis combined, 11-axis 3D woven above 4 and 7-axis combined, 13-axis 3D woven above The fiber orientation angle is obtained by combining the 6-axis and the 7-axis.

[Problems to be Solved by the Invention]

As described above, the three-dimensional woven fabrics that have been realized so far are limited to the triaxial three-dimensional woven fabrics. However, the composite material using this is reinforced only by three axes, so that the anisotropy is It was only the one that was marked and left extremely weak. For example, if the reinforcement direction is three axes of x, y, and z, these axes are equally divided. It has been clarified that the elastic modulus and the strength are remarkably low in the direction of.

In addition, regarding the three-dimensional woven fabrics having three or more axes, which have already been announced, the characteristics of composite materials using these as reinforcement materials have not been clarified. No guidelines have been clarified as to whether material characteristics can be obtained and what kind of material design should be performed.

The present invention has been made to solve the above problems, and obtains a composite material having any of thermomechanical properties from isotropic to remarkable anisotropy of unidirectional reinforcement. Is intended.

[Means for Solving the Problems]

The composite material according to the present invention uses a three-dimensional seven-axis woven fabric having a fiber orientation angle of four axes formed by the farthest diagonals of a cube or a rectangular parallelepiped and three axes formed by the sides of the cube or a rectangular parallelepiped as a reinforcing material. Used.

[Action]

If the fiber contents of all seven axes of the woven fabric are made equal, the elastic modulus of the composite material in all directions becomes equal to a degree that can be regarded as isotropic in practical use. In addition, if any one of the seven axes is selected and only the fiber content of this fiber axis is increased or decreased, the elastic modulus is from isotropic to the extreme anisotropy of unidirectional reinforcement. A composite material having any properties is obtained. The design of a composite material having this arbitrary property is such that the fiber orientation angle of the four axes of the farthest diagonal of a cube or a rectangular parallelepiped among the seven axes is symmetrical with respect to one of the three axes of the other three sides. It can also be changed. Furthermore, by increasing or decreasing the fiber content of the four axes of the seven axes, it becomes possible to control the in-plane shear rigidity of the composite material determined by the two axes of the three axes.

It should be noted that the reason why the three-dimensional seven-axis woven fabric is focused on in the present invention is that the elastic modulus is isotropic, but that is not the only reason. One of the reasons is that this woven fabric has a high fiber content ratio (determined assuming that the fiber bundle is a cylinder) determined by the geometrical arrangement of the abandoned mine fibers, which is as high as 56.4% by volume, and that high-level composite material properties can be expected. . The fiber content at this time is 7.56% per axis for the four axes consisting of the farthest diagonals and 1 for the axis consisting of three sides.
It is 8.73% per axis.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. The composite material of this embodiment uses epoxy resin and a three-dimensional seven-axis woven fabric made of carbon fiber T300 as a reinforcing material.

Fig. 1 shows the fiber orientation axis of this three-dimensional 7-axis woven fabric. Fig. 3 focuses on the Z axis in Fig. 1 and sets the total fiber content V _f to 0.4 (40%). It shows the evaluation result of Young's modulus E of the composite material when the relative filling rate N _z for the same content rate V _f of Z axis is fixed and increased to 2/8, 3/9, 4/10. . The horizontal axis θ in FIG. 3 represents the observation angle, and this definition is shown in FIG. That is, θ is an angle measured from the Z axis in the plane including the Z axis and including the lowest Young's modulus.

As shown in FIG. 3, the characteristics of the Z axis (θ = 0 °) are greatly improved, but the characteristics of both the X axis and the Y axis (θ = 90 °) are slightly reduced. Moreover, although not shown in this figure, the isotropic properties in the X and Y planes are almost maintained. It is difficult to fabricate those having such characteristics from conventional composite materials.

Next, when controlling the characteristic of the composite material in one uniaxial direction, the uniaxial axis of the cube forming the unit cell is expanded and contracted into a rectangular parallelepiped, and the four-axis fiber orientation angles of T, U, V, W are changed. It can also be obtained. However, in this case, it should be noted that when the cubic expansion and contraction is performed violently, the fiber orientation angle is biased and the characteristics may be deteriorated.

It is also possible to design to improve the rigidity of two of the three X, Y and Z axes. For example, by changing the fiber content of each axis of T, U, V, W, it is possible to control the shear elastic modulus in the plane composed of two of the three axes of X, Y, Z. .

Table 1 shows the maximum fiber content of the three-dimensional fabric obtained from FIG. Fig. 3 shows that the fiber orientation axis number N is 3, 4, 6,
Using the Young's modulus E of the composite materials of 7, 9 and the maximum fiber content V _f-max in Table 1 Θ is an angle measured from the Z axis in the plane including the Z axis and including the minimum value of Young's modulus. 3 from this figure
It can be seen that the composite material using the dimensional 7-axis woven fabric exhibits superior properties as compared with the composite material using other woven fabrics.

In the above-described embodiment, the material design is performed so that the fiber content of each axis is as uniform as possible, but if the fiber content of each axis is varied, a wider range of material design is possible.

[Effects of the Invention] As described above, according to the present invention, since the three-dimensional seven-axis woven fabric is used as the reinforcing material, the optimally designed seven-axis can be used as the fiber orientation angle. It is possible to obtain a composite material having thermomechanical properties such as strength having any property ranging from isotropic to remarkable anisotropy.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing the fiber orientation of a 7-axis three-dimensional fabric used as a reinforcing material in the embodiment of the present invention,
FIG. 2 is an explanatory view of the definition of the observation angle θ in FIG. 3 described later, FIG. 3 is a graph showing Young's modulus in various design examples of composite materials using a 7-axis three-dimensional fabric, and FIG. Axis 3
A graph comparing Young's moduli of various composite materials using a three-dimensional woven fabric as a reinforcing material with the number of axes as a parameter, and FIG. 5 is an explanatory view schematically showing the fiber orientation of a multiaxial three-dimensional woven fabric. In the figure, X, Y, Z are axes formed by the farthest diagonals of a cube or a rectangular parallelepiped, and U, V, W, T are axes formed by the sides of the cube or a rectangular parallelepiped. In the drawings, the same reference numerals indicate the same or corresponding parts.

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Claims (1)

[Claims] 1. A four-axis formed by the farthest diagonal of a cube or a rectangular parallelepiped and a side formed by a cube or a rectangular parallelepiped.
A composite material using as a reinforcing material a three-dimensional 7-axis woven fabric whose axis is the fiber orientation angle.