Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Woven fabric – Woven fabric is characterized by a particular or...
Patent
1996-07-03
1997-12-30
Bell, James J.
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Woven fabric
Woven fabric is characterized by a particular or...
428408, 428902, 139426R, B32B 700
Patent
active
057029938
DESCRIPTION:
BRIEF SUMMARY
This application claims benefit of international application PCT/JP95/02248, filed Nov. 2, 1995, published as WO96/14455 May 15, 1996.
1. Technical Field
The present invention relates to a triaxial fabric composed of carbon fiber strands suitable for various members used in the space industry, such as those of an artificial satellite, which requires reduced weight and a high specific modulus.
2. Background Art
Carbon fiber-reinforced plastics have been widely used in various fields including the sport/leisure industry, the general industry and the aerospace industry, because they are light in weight and excellent in specific strength and specific modulus. Recently, the application of such materials to the aerospace industry, particularly to various members of artificial satellites, has been highlighted due to their characteristics.
Carbon fibers used as reinforcement are classified as PAN-based or pitch-based carbon fibers in accordance with the starting materials thereof. The pitch-based carbon fibers are more suitable for the space industry than the PAN-based carbon fibers because a graphite crystal structure easily grows in the fiber, to result in a high elastic modulus, high thermal conductivity and low thermal expansion coefficient, which are favorable in the space industry. A reinforcement substrate used for a composite may have various configurations such as unidirectional fibers, two dimensional fabrics or three dimensional fabrics in accordance with the use of the resultant composites. An ordinary fabric wherein two sets of fiber strands are interwoven with each other at a right angle (generally referred to as a "biaxial fabric") is usually used for a carbon fiber reinforced plastic material. Because this fabric exhibits a strong anisotropic property, it is necessary, when used in a portion wherein an isotropic property is required, to ply a plurality of such fabrics while varying orientation angles so that a so-called cross ply structure is obtained. Accordingly, there is a tendency for increased weight and for generating delamination between plies.
On the other hand, a triaxial fabric shown in FIGS. 1 and 2 has a structure wherein two sets of warp yarns (bias yarns) 2 are interwoven with one set of weft yarns (0.degree. directional yarns) 1 at .+-.60.degree. relative to a widthwise direction of the fabric. This fabric is inherently quasi-isotropic even as a single ply and thus needs no laying up, which results in the weight reduction and the prevention of delamination. It is also easy to further reduce the thickness of the single fabric. In addition, this fabric has advantages in that the shape-retaining ability is excellent due to its high shearing rigidity, and the strength per unit weight and the compression strength after damage by impact are high, and further it has a good aesthetic appearance.
The triaxial fabric, however, has a larger crimp (wave configuration of fiber strand) then the ordinary fabric, which means that fiber strands in the triaxial fabric are forcibly bent. Accordingly, in the triaxial fabric of carbon fiber strands, the fiber strands are abrasive in the intersection thereof and liable to be damaged to cause fiber breakages as shown in FIG. 3. The fabric having fiber breakages is not only unfavorable from the viewpoint of surface quality, but also has a risk of fabric breakage when the fabric is stretched even under a relatively low load. It is surmised that such fiber breakages are caused by the following mechanisms; one is that a large recovery force generates in the carbon fiber strand when the same is bent because of its high elastic modulus, which causes a large abrasive force between the intersecting portion of the fiber strands; and other is that, since the elongation at break of carbon fiber is small, the fiber is easily broken under the abrasion. Therefore, when carbon fibers having a high elastic modulus and a smaller elongation at break are used, the generation of fiber breakage will be further accelerated.
Accordingly, a triaxial fabric having less fiber break
Kimura Hiromi
Kubomura Kenji
Shibata Hirotaka
Bell James J.
Nippon Steel Corporation
Sakase Adteck Co.
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