Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Coated or impregnated woven – knit – or nonwoven fabric which... – Coated or impregnated inorganic fiber fabric
Patent
1996-09-09
1999-06-08
Bell, James J.
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Coated or impregnated woven, knit, or nonwoven fabric which...
Coated or impregnated inorganic fiber fabric
428408, 428902, 442334, 442394, B32B 502
Patent
active
059104562
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The present invention relates to prepregs and carbon fiber-reinforced composite materials, and particularly to prepregs and carbon fiber-reinforced composite materials excellent in compression strength under hot-wet conditions and suitable as a structural material, particularly as an aircraft primary structure material.
BACKGROUND ART OF THE INVENTION
Because a polymer-based composite material comprising carbon fibers and a matrix resin is light-weight and has excellent mechanical properties, it is broadly used for sporting goods uses, aerospace uses and general industrial uses. Although various methods are employed for production of carbon fiber-reinforced composite materials, a method for using a prepreg, which is an intermediate substrate prepared by impregnating a non-cured matrix resin into reinforcing fibers, is broadly applied. In this method, usually, a formed product of a composite material can be obtained by stacking prepregs and thereafter heating them.
As a matrix resin used for prepregs, thermoplastic resins and thermosetting resins are both used, and resins such as epoxy resins, maleimide resins, cyanate resins and polyimide resins are used.
With respect to mechanical properties of carbon fiber-reinforced composite materials, although the tensile strength thereof has been greatly increased as the tensile strength of carbon fibers increases, increase of the compression strength thereof is small even if high tensile-strength fibers are used instead of standard tensile-strength fibers. Accordingly, flexural strength important for practical uses, which is determined depending upon a smaller strength of either tensile strength or compression strength, is to be determined by the compression strength. Therefore, the compression strength is very important for uses of structural materials on which compression or flexural stress is applied. Particularly, the compression strength is an extremely important property for use as a primary structure material. Further, in a case of an aircraft, since there are many bolt holes, an open-hole compression strength becomes important.
Further, because mechanical property, particularly the compression strength, greatly decreases under a hot-wet condition, an open-hole compression strength under a hot-wet condition, which is a property under a severe condition, becomes a very important index. The open-hole compression strength (referred to as "Open Hole Compression": OHC) is a property determined as a compression strength of a connecting portion, that is, a compression strength at a position corresponding to a portion with a hole for connection, by small-scale measurement.
Further, when used as a primary structure material, a residual compression strength after impact damage due to hailstone or tools also becomes important. Therefore, a compression strength after impact (referred to as "Compression After Impact": CAI), which is determined by small-scale measurement as a residual compression strength after impact damage due to foreign materials such as collision of stones or fall of tools, is one of important properties inevitable for damage tolerance design.
Although a conventional polymer-based composite material has an advantage of light-weight, the above-described open-hole compression strength under a hot-wet condition and compression strength after impact thereof are not still sufficient, and these properties are desired to be further improved for enlarging the range of the applicable uses.
In order to increase the open-hole compression strength, it is known that it is effective to increase the amount of fibers taking charge of load or to increase the stiffness of a resin, but these methods are limited to a certain level. In order to increase the compression strength after impact, it is known that it is effective to increase the amount of a resin or to use a highly-tough resin such as a thermoplastic resin. However, the method for increasing the open-hole compression strength and the method for increasing the compression stre
REFERENCES:
patent: 5168004 (1992-12-01), Daumit et al.
patent: 5227237 (1993-07-01), Saruyama et al.
patent: 5462799 (1995-10-01), Kobayashi et al.
Kobayashi Masanobu
Matsuhisa Yoji
Okuda Akira
Shimizu Kazuharu
Bell James J.
Miller Austin R.
Toray Industries Inc.
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