GB2032476A

GB2032476A - Fabric structure for composite material

Info

Publication number: GB2032476A
Application number: GB7929787A
Authority: GB
Original assignee: Toray Industries Inc
Current assignee: Toray Industries Inc
Priority date: 1978-08-29
Filing date: 1979-08-28
Publication date: 1980-05-08
Also published as: JPS5530974A; JPS5752221B2; NL7906446A; FR2434880A1; DE2934782A1

Abstract

A fabric structure for a composite reinforcing material comprises straight warp and weft yarns 2, 2' bound together binder yarns 3,3'. One of the binder yarns may also be straight or both may undulate. A leno weave embodiment is described wherein the straight warp and weft are bound together by undulating leno ends interlacing with the straight warps and an embodiment is described with undulating binders in one direction only. <IMAGE>

Description

SPECIFICATION Fabric structure for composite material This invention relates to a fabric structure for composite material which is particularly, but not exclusively, useful as a reinforcing material for FRP (fiber reinforced plastics) and FRM (fibre reinforced metals), especially for a resin to be used as a matrix in FRP.

FRP formed of a resin reinforced by a fibrous material composed of reinforcing fibers such as graphite fibers or glass fibers is well known. A woven fabric of reinforcing fibers is often used as the fibrous material.

In a fibrous material in the form of a woven fabric, however, since reinforcing fibers are bent at crossing points of warps and wefts, the stress is concentrated on those bent portions and therefore, characteristic properties of reinforcing fibers, such as high tenacity and high elasticity, cannot be sufficiently utilized.

Furthermore, when FRP having a cone-like or dome-like shell structure, such as an acoustic vibratory plate for a loud speaker, is formed by using one sheet of a woven fabric, since the reinforcing fibers come to have a shape resembling a bent corrugated sheet, the flexural stiffness is not sufficiently manifested.

Attempts have heretofore been made to form FRP by using a so-called unidirectional woven fabric composed of warps consisting of straight reinforcing fibers free of bends.

However, in the unidirectional woven fabric, since physical properties in the warp direction differ from those in the weft direction and the woven fabric is anisotropic in physical properties, warps should be arranged so that groups consisting of a plurality of warps are laminated to cross one another, and therefore, the operation of forming FRP becomes complicated and troublesome.

The present invention seeks to provide a fabric structure for a composite material in which the above-mentioned disadvantages involved in the conventional woven fabrics as reinforcing fibrous materials of composite materials may be eliminated, characteristic properties of reinforcing fibers, such as high strength and high modulus, can be manifested substantially completely and which can provide a composite material excellent in specific strength and specific modulus very simply and easiiy.

In accordance with the present invention, there is provided a fabric structure for a composite material, which comprises (a) a yarn group A composed of a plurality of straight reinforcing filamentary yarns gathered in one direction in parallel to one another in the form resembling a sheet, (b) a yarn group B composed of a plurality of straight reinforcing filamentary yarns gathered in one direction in parallel to one another in the form resembling a sheet, the sheet face of the yarn group B confronting the sheet face of the yarn group A and the reinforcing filamentary yarns of the group B intersecting the reinforcing filamentary yarns of the yarn group A, and (c) auxiliary filamentary yarns which hold integrally said yarn groups A and B, said auxililary filamentary yarns having a higher elongation at break than those of the reinforcing filamentary yarns of both the yarn groups A and B.

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 is an enlarged perspective view illustrating one embodiment of the fabric structure for a composite material according to the present invention; Figure 2 is an enlarged perspective view illustrating another embodiment of the fabric structure according to the present invention; Figure 3 is an enlarged perspective view illustrating a further embodiment of the fabric structure according to the present invention; Figure 4 is an enlarged perspective view illustrating a still further embodiment of the fabric structure according to the present invention; Figure 5 is an enlarged perspective view illustrating a yet still further embodiment of the fabric structure according to the present invention; and Figure 6 is an enlarged perspective view illustrating a yet still another embodiment of the fabric structure according to the present invention.

The present invention will now be described in detail by reference to the embodiments illustrated in the accompanying drawings.

Referring to Fig. 1 which is an enlarged perspective view showing one embodiment of the fabric structure for a composite material (hereinafter referred to merely as "structure") according to the present invention, the structure 1 has reinforcing filamentary yarns 2 and 2' and auxiliary filamentary yarns 3 and 3'. In the structure 1, a yarn group A composed of a plurality of straight reinforcing filamentary yarns 2 gathered in one direction (the horizontal direction in Fig. 1) in parallel to one another in the form resembling a sheet is laminated on a yarn group B composed of a plurality of straight reinforcing filamentary yarns 2' gathered in one direction (the vertical direction in Fig. 1) in parallel to one another in the form resembling a sheet.In the embodiment illustrated in Fig. 1, each of the reinforcing filamentary yarns 2 and 2' is a multi-filament yarn composed of a plurality of single filaments. By the terms "form resembling a sheet" used herein is meant the state where reinforcing filaments are arranged on one plane, and by the term "straight" is meant the state in which the filaments are not conspicuously bent weavily as in ordinary woven fabrics but they may be wavy to some extent.

in the structure shown in Fig. 1, the face of the sheet composed of the yarn group A is made to confront the face of the sheet composed of the yarn group B. Namely, the sheets are laminated. The reinforcing filamentary yarns 2 and 2' cross one another. In this embodiment, these filamentary yarns cross one another at a right angle. Of auxiliary filamentary yarns 3 and 3', the auxiliary filamentary yarns 3' parallel to the reinforcing filamentary yarns 2' are located outside the yarn group A, that is, above the yarn groupA in the embodiment shown in Fig. 1, and they are arranged straightly among the reinforcing filamentary yarns 2' arranged in parallel to one another. In the embodiment shown in Fig. 1, since also the auxiliary filamentary yarns are straight, they are also laminated on the yarn group A.The other auxiliary filamentary yarns 3 are located among the reinforcing filamentary yarns 2 arranged in parallel to one another, and the auxiliary filamentary yarns 3 are arranged in parallel to the reinforcing filamentary yarns 2 but they are not straight. Namely, the auxiliary filamentary yarns 3 are bent while being entangled with the respective reinforcing filamentary yarns 2' and auxiliary filamentary yarns 3'.

The auxiliary filamentary yarns 3 are bent and arranged in the same manner as in ordinary woven fabrics. In the embodiment shown in Fig. 1, each of the auxiliary filamentary yarns 3 and 3' is composed of a multi-filament yarn as well as the reinforcing filamentary yarns 2 and 2'.

In the embodiment shown in Fig. 1, each of the reinforcing filamentary yarns 2 and 2' has a flat cross section. More specifically, in each of the reinforcing filamentary yarns, reinforcing filaments (single filaments) are arranged in the flat form so that each reinforcing filamentary yarn has a tape-like shape.

Therefore, the entire structure has no large thickness and it has a sheet-like shape.

The structure shown in Fig. 1 may be prepared in the following manner: Reinforcing filamentary yarns and auxiliary filamentary yarns are wound on different warp beams, and they are passed through different healds so that the reinforcing filamentary yarns and auxiliary filamentary yarns are arranged alternateiy one by one. Separately, reinforcing filamentary yarns and auxiliary filamentary yarns are beaten alternately one by one from the weft direction by a rapier loom or the like. At this point, the tension on the auxiliary yarn as the warps are made larger than the tension on the auxiliary filamentary yarns as the wefts.

Figure 2 is a view illustrating another embodiment of the structure of the present invention. The structure shown in Fig. 2 is similar to the structure shown in Fig. 1 but is different from the structure shown in Fig. 1 in the point that the number of reinforcing filaments constituting each of the reinforcing filamentary yarns 2 and 2' is two times the number of reinforcing filaments constituting each of the reinforcing filamentary yarns 2 and 2' in the structure shown in Fig. 1.

Accordingly, in the structure shown in Fig. 2, the width of the reinforcing filamentary yarns 2 and 2' is larger than in the structure shown in Fig. 1. In the structure shown in Fig. 2, the quantity of the reinforcing filaments per unit volume is larger than in the structure shown in Fig. 1, and therefore, the strength is increased.

The structure shown in Fig. 2 may be prepared by using reinforcing filamentary yarns comprising a large number of filaments according to the method described hereinbefore with respect to the structure shown in Fig. 1. Moreover, the structure shown in Fig. 2 may be prepared by using the same reinforcing filamentary yarns as used for formation of the structure shown in Fig. 1, passing the reinforcing filamentary yarns and auxiliary filamentary yarns through different healds so that two reinforcing filamentary yarns alternate with one auxiliary filamentary yarn, and beating reinforcing filamentary yarns and auxiliary filamentary yarns from the weft direction so that two reinforcing filamentary yarns alternate with one auxiliary filamentary yarn.

Figure 3 is a view showing a further embodiment of the structure of the present invention. The structure shown in Fig. 3 is similar to the structure shown in Fig. 1 but is different from the structure shown in Fig. 1 in the point that the number of the reinforcing filaments constituting each of the reinforcing filamentary yarns 2' is two times the number of the reinforcing filaments constituting each of the reinforcing filamentary yarns 2' in the structure shown in Fig. 1, and therefore, in the structure shown in Fig. 3, the width of the reinforcing filamentary yarns 2' is increased. In the structure shown in Fig. 3, the strength in the axial direction of the reinforcing filamentary yarns 2' is increased and the directional characteristic of the strength is given the structure.

The structure shown in Fig. 3 may be prepared by winding reinforcing filamentan/varns and auxiliary filamentary yarns on different warp beams, passing them through different healds so that two reinforcing filamentary yarns alternate with one auxiliary filamentary yarn and beating reinforcing filamentary yarns and auxiliary filamentary yarns alternately one by one from the weft direction by using a rapier loom or the like.

Figure 4 is a view illustrating a still further embodiment of the structure in accordance with the present invention. The structure of Fig. 4 resembles the one shown in Fig. 1 but is different from the structure shown in Fig. 1 in the point that both the auxiliary filaments 3 and 3' are arranged in the bent state. In this structure, the tension of the auxiliary filamentary yarns as warps is equal to the tension of the auxiliary filamentary yarns as wefts. The structure shown in Fig. 4 may be prepared according to the method described hereinbefore with respect to the structure shown in Fig. 1.

Fig. 5 is a view illustrating still another embodiment of the structure of the present invention. The structure shown in Fig. 5 is the same as the structure shown in Fig. 1 with respect to the arrangement of the reinforcing filamentary yarns 2 and 2' but is different from the structure shown in Fig. 1 with respect to the arrangement of the auxiliary filamentary yarns. More specifically, in the structure shown in Fig. 5, the auxiliary filamentary yarns 31t are not in parallel to the reinforcing filamentary yarns 2 and 2' and the auxiliary filamentary yarns 3" are bent an S-shaped manner to alternate with the yarns 2 and 2'. Although the method for.production of such structure is relatively complicated, there is attained an advantage that the reinforcing filamentary yarns can be fixed only by auxiliary filamentary yarns in one direction.

The structure shown in Fig. 5 may be prepared according to the following method.

Reinforcing filamentary yarns and auxiliary filamentary yarns are wound on different warp beams, and one auxiliary filamentary yarn and one auxiliary filamentary yarn are passed through one doup heald so that they alternate with each other. The reinforcing filamentary yarn and auxiliary filamentary yarn passed through the same doup heald are introduced into one reed. Every time one weft, that is, one reinforcing filamentary yarn, is beaten, the relative position of the reinforcing filamentary yarn and auxiliary filamentary yarn as the warps are changed by a leno weaving apparatus.

Fig. 6 is a view illustrating still another embodiment of the structure of the present invention. The structure 1 is composed of straight reinforcing filamentary yarns and auxiliary filamentary yarns as in the structure shown in Fig. 1, but in other points, the structure shown in Fig. 6 is considerably different from the structure shown in Fig. 1. In the structure 1 shown in Fig. 6, a sheet-like yarn group A composed of reinforcing filamentary yarns 2, a sheet-like yarn group B composed of reinforcing filamentary yarns 2' and a sheet-like yarn group C composed of reinforcing filamentary yarns 2" are laminated to form a 3-plies structure in which the three yarn groups cross one another alternately.

Auxiliary filamentary yarns 3' are arranged in parallel to the reinforcing filamentary yarns 2' and they are bent so that they intersect the reinforcing filamentary yarns 2 and 2" alternately one after another.

In this structure, there is attained an advantage that the quantity of the reinforcing fibers per unit volume is increased in FRP and therefore, the strength can be improved. The structure shown in Fig. 6 may be prepared by winding reinforcing filamentary yarns and auxiliary filamentary yarns on different warp beams, passing them through different healds so that the reinforcing filamentary yarns and auxiliary filamentary yarns are arranged alternately one by one, and beating reinforcing filamentary yarns from the weft direction.

Preferred applications of the structure of the present invention will now be described.

By the term "composite material" used herein is meant not only FRP but also FRM. In each case, the arrangement of the reinforcing filamentary yarns and auxiliary filamentary yarns is not changed in the fabric structure of the present invention as the reinforcing fibrous material.

As the fibers constituting the reinforcing filamentary yarns, there can be used, for example, carbon fibers, graphite fibers, glass fibers, polyalamide fibers, silicon carbide fibers, boron fibers and metal fibers. Multi-filament yarns composed of fibers selected from the foregoing fibers are used as the reinforcing filamentary yarns.

As the fibers constituting the auxiliary filamentary yarns, there can be used, for example, glass fibers, acrylic fibers, rayon fibers, polypropylene fibers, polyamide fibers, polyalamide fibers and polyester fibers. Mono-filament or multi-filament yarns composed of fibers selected from these fibers are used as the auxiliary filamentary filaments.

In the present invention, it is indispensable that the elongation at beak of the auxiliary filamentary yarns should exceed that of the reinforcing filamentary yarns, and it is preferred that the elongation at break of the auxiliary filamentary yarns be at least 2 times the elongation at break of the reinforcing filamentary yarns. Accordingly, the materials of the reinforcing filamentary yarns and auxiliary filamentary yarns should be selected and combined after due consideration of the above-mentioned condition of the elongation at break. Preferred combinations are described below.

For example, when carbon fibers, graphite fibers, silicon carbide fibers or boron fibers are chosen as the reinforcing fibers, acrylic fibers, rayon fibers, polypropylene fibers, glass fibers, polyamide fibers, polyalamide fibers or polyester fibers are chosen as the auxiliary fibers. When glass fibers or polyalamide fibers are chosen as the reinforcing fibers, acrylic fibers, rayon fibers, polypropylene fibers, polyamide fibers or polyester fibers are chosen as the auxiliary fibers. When fibers of metals such as steel, beryllium and tungsten are chosen as the reinforcing fibers, acrylic fibers, rayon fibers, polypropylene fibers, polyamide fibers or polyester fibers are chosen as the auxiliary fibers. A most preferred combination is a combination graphite fibers as the reinforcing fibers with glass fibers as the auxiliary fibers.

The most characteristic feature of the fabric structure of the present invention is that the reinforcing filamentary yarns are not bent but straightly gathered and sheet-like yarn group composed of the reinforcing filamentary yarns are not entangled with each other but laminated. Accordingly, the texture of the fabric structure of the present invention is different from the textures of known woven fabrics of reinforcing fibers. In the conventional woven fabrics, warps and wefts cross one another and reinforcing fibers are bent at these crossing points. Accordingly, the stress is concentrated on these bent portions and high strength and high modulus inherent of the reinforcing fibers cannot be sufficiently utilized. In the fabric structure of the present invention, the reinforcing fibers are straightly gathered and the foregoing characteristic properties of the reinforcing fibers can be exerted completely.

In the fabric structure of the present invention, there are present auxiliary filamentary fibers for integrally fixing yarn groups of the reinforcing filamentary yarns. The fabric structure of the present invention is characterized in that the elongation at break of the auxiliary filamentary yarns is higher than the elongation at break of the reinforcing filamentary yarns, and it is preferred that the elongation at break of the auxiliary filamentary yarns be at least 2 times the elongation at break of the reinforcing filamentary yarns. In the fabric structure of the present invention, since the reinforcing filamentary yarns are straightly gathered, the auxiliary filamentary yarns arranged in an extremely bent manner.

Accordingly, in a composite material including the fabric structure of the present invention, if a stress is imposed, the stress is concentrated on the bent portions of the auxiliary filamentary yarns. Therefore, the auxiliary filamentary yarns should have a high elongation at break, preferably at least 2 times the elongation at break of the reinforcing filamentary yarns.

The auxiliary filamentary yarns may be either multi-filament yarns or mono-filament yarns. It is preferred that the cross sectional area of the auxiliary filamentary yarns be small, especially less than 1/3 of the cross sectional area of the reinforcing filamentary yarns. If the cross sectional area of the auxiliary filamentary yarns is larger than the cross sectional area of the reinforcing filamentary yarns, the following disadvantages are caused.

(1 ) The proportion of the reinforcing filamentary yarns occupying a certain volume of the structure becomes small, and the characteristic properties of the reinforcing filamentary yarns cannot be sufficiently exerted.

(2) When FRP is formed by using this fibrous structure, a resin is intruded into spaces defined by convexities and concavities of the auxiliary filamentary yarns and a composite material having a high fiber volume ratio cannot be obtained.

(3) The rigidity of the auxiliary filamentary fibers is increased and the reinforcing filamentary yarns are bent by such high rigidity of the auxiliary filamentary yarns.

In accordance with a preferred embodiment of the present invention, the rigidity of the auxiliary filamentary yarns is less than 1/5 of the rigidity of the reinforcing filamentary yarns. If the rigidity of the auxiliary filamentary yarns is too high, the reinforcing filamentary yarns are readily bent by the auxiliary filamentary yarns.

Two sheet-like yarn groups of the reinforcing fiiamentary yarns are laminated according to a most preferred embodiment, but three sheet-like yarn groups as shown in Fig. 6 or more sheet-like yarn groups may be used in the present invention.

It is preferred that the cross sectional shape of the reinforcing filamentary yarns be flat. Namely, it is preferred for the reinforcing filamentary yarns to have a tape-like configuration. As means for expanding the width of the reinforcing filamentary yarns, there may be adopted a method in which respective filaments are arranged flatly or a method in which the number of the filaments is increased and the filaments are arranged flatly to increase the width of each filamentary yarn.

Yarn groups of the reinforcing filamentary yarns should be laminated so that the yarn directions of the yarn groups cross each other. It is most preferred the crossing angle be a right angle.

The so prepared structure of the present invention is impregnated with an uncured thermosetting resin to form a so-called prepreg. - As the thermosetting resin, there may be employed an unsaturated polyester resin, an epoxy resin, a polyimide resin and a phenolic resin.

The prepreg of the present invention may be formed into a fiber-reinforced plastic articie by thermally setting the impregnated thermosetting resin, and the resulting fiber-reinforced plastic article can be used for aerial or spatial structural members such as an air plane wing, a helicopter rotor, an air plane body, a wing girder and a door flap of an air plane, sporting goods such as a boat, a canoe, a yacht, a fishing rod, a racket, skis, a bow, an arrow, a club, a hockey stick and a bicycle frame, and ordinary industrial articles such as an automobile body, an automobile part, a bumper, a dash board, a medicinal instrument, an X-ray cassette, a tanker stand, a tank, a loud speaker, a musical instrument, a ship, a centrifugal separation equipment and a fly wheel.

In the structure of the present invention, the reinforcing fibers and auxiliary fibers may be coated with thin metal films.

As the coating metal, there can be used copper, nickel, aluminum and alloys containing at least one member selected from these metals as the main component.

FRM including the structure of the present invention may be prepared by laminating a plurality of the metal-coated structures and then heating and pressing the laminates, for example.

FRM including the structure of the present invention may be used for a bearing, a bearing member a vane material and a collecting slide plate. As the preferred material for coating metals, there can be mentioned carbon fibers, graphite fibers, silicon carbide fibers, boron fibers and metal fibers.

The present invention will now be described in detail by reference to the following Examples that by no means limit the scope of the invention.

EXAMPLE 1 High strength graphite filamentary yarns composed of 3000 filaments having an average monofilament diameter of 7 y and having a strand strength of 300 Kg/mm2 and a strand modulus of 23.5 x 103 Kg/mm2 (hereinafter referred to as "TORAYCA" T3000 fil) were used as the reinforcing filamentary yarns and 22.5 texture count glass filamentary yarns formed by twisting glass fiber yarns composed of 200 filaments having an average monofilament diameter of 5 zt at a twist number of 4.4 twists per inch (hereinafter referred to as ECD 450 1/2) were used as the auxiliary filamentary yarns. By using these filamentary yarns, there was prepared a structure A as shown in Fig. 1, in which the yarn density was 1 2 yarns per cm in either the longitudinal direction or the lateral direction.Both of the density of the graphite filamentary yarns and glass filamentary yarns were 6 yarns per cm.

Each of conventional graphite fiber woven fabrics B and C including bent reinforcing yarns, shown in Table 1, and the so-prepared structure A of the present invention was coated with a solution formed by diluting a hardener-incorporated, preliminarily polymerized epoxy resin with methylethyl ketone, and a prepreg was prepared by stripping off methylethyl ketone. The prepreg was inserted between iron plates coated with a mold release prepared from a wax, a silicone and a polyvinyl alcohol solution. In case of the conventional graphite fiber woven fabric both 1-ply and 2-plies (lamination angle: 00--00) structures were formed, and in case of the conventional graphite fiber woven fabric C and the structure A of the present invention, a 1-ply structure was formed.For the formation of the graphite fiberreinforced resin plate, curing was conducted at 1 200C. for 1 hour under a pressure of 10 Kg/cm2 in a hot press and after-curing was conducted at 1 300 C. for 2 hours.

The characteristic frequency of each graphite fiber-reinforced resin plate was measured and the flexural modulus was calculated from the measured value. Also the specific gravity and surface density were measured. Obtained results are shown in Table 1.

In the 2-plies product including the conventional graphite fiber woven fabric B, the elasticity modulus of 5.6 x 103 Kg/mm2 was obtained, but in the 1-ply product including the conventional graphite fiber woven fabric B or C, the flexural modulus was as low as 3.2 - 3.5 Kg/mm2. On the other hand, when the structure A of the present invention was employed, a graphite fiber-reinforced resin plate having such a high flexural modulus as 5.5 x 103 Kg/mm2 was obtained.

A speaker cone was formed by using the so-prepared graphite fiber-reinforced resin plate inc!uding the structure A of the present invention. Since this resin plate had a thin 1-ply structure having a small surface density and a high flexural modulus, the molding operation could be performed very easily and a light speaker cone was obtained.

EXAMPLE 2 Epoxy resin prepregs were prepared by using the conventional graphite fiber woven fabric C shown in Example 1, a conventional unidirectional graphite fiber assembly D and the structure A of the present invention shown in Example 1. In case of the woven fabric C and the structure A of the present invention, 7 epoxy resin prepregs were laminated in the same direction (the warp axial direction), and in case of the conventional unidirectional graphite fiber assembly D, 8 epoxy resin prepregs were laminated at a crossing angle of 00/900.

Test pieces for the tensile test having a width of 1 2.7 mm, a length of 230 mm, a measurement length of 100 mm and a thickness of about 1.5 mm were cut out from the resulting cured plates so that the measurement axis was in agreement with the warp direction in case the woven fabric C and structure A and the measurement taxis was in agreement with the 0 direction in case of the unidirectional graphite fiber assembly D.

Results of the measurement of physical properties of these graphite fiber-reinforced resin plates are shown in Table 2.

At the fiber volume fraction of 60%, the tensile strength of the resin plate including the conventional composite C was as low as 48 Kg/mm2 because of concentration of the stress on the climp portion but the tensile strength of the resin plate including the composite A of the present invention was 82 Kg/mm2 close to the theoretical value calculated according to the law of mixture, which was higher than the value of 62 Kg/mm2 obtained in the resin plate composed of 00/900 laminated epoxy resin prepegs including the conventional unidirectional graphite fiber assembly D.

The terms "graphite fibers" and "carbon fibers" used herein conform with the definitions and usage in the United States of America.

TABLE 1

Materi al s A B C - 3000 1000f 3000 GF Warp CF EC0450 1/2 Yarn GF 3000 1 1000f 3000 I o' CF ECG450 1/2 o GF(/cm) 6 10 5 o o Count GF( /cm) 6 10 5 Weft CF( cm) 6 Weight (g/m2) 267 133 200 Weight(g/m Weave Plain 2/2 Twill 2/2 Twill ~ Number of ply 1 1 2(0"-0") 1 ~ Thickness after cure (mm) 0.25 0.11 0.21 0.18 co, 1 o Weight (glum') 342 169 330 254 I uf 1 E Fiber content (vol. O/o) 70 72 74 72 2 L Specific gravity 1.63 1.60 1.60 1.59 Flexural modulus (103 Kg/mm2) 5.5 3.2 5.6 3.5 Note: GF: graphite fiber CF: carbon fiber TABLE 2

4 C D Materi al s Tensile modulus 6.: 5.7 6.3 (103 Kg/mm2) P roperti es 48 62 of Tensile strength Fiber content (vol. %) 60 1 60 60

Claims

1. A fabric structure for a composite material, which comprises (a) a- yarn group A composed of a plurality of straight reinforcing filamentary yarns gathered in one direction in parallel to one another in the form resembling a sheet, (b) a yarn group B composed of a plurality of straight reinforcing filamentary yarns gathered in one direction in parallel to one another in the form resembling a sheet, the sheet face of the yarn group B confronting the sheet face of the yarn group A and the reinforcing filamentary yarns of the group B intersecting the reinforcing filamentary yarns of the yarn group A, and (c) auxiliary filamentary yarns which hold integrally said yarn groups A and B, said auxiliaryfilamentary yarns having a higher elongation at break than those of the reinforcing filamentary yarns of both the yarn groups A and B.

2. A fabric structure, as set forth in claim 1 wherein (a) said auxiliary filamentary yarns include wefts and warps and one group of the auxiliary filamentary yarns are straightly arranged outside the yarn group A and intermediately between every two adjacent reinforcing filamentary yarns of the yarn group B in parallel to the reinforcing filamentary yarns of the yarn group B and (b) the other group of the auxiliary filamentary yarns are arranged outside the yarn group B and intermediately between every two adjacent reinforcing filamentary yarns of the yarn group A in parallel to the reinforcing filamentary yarns of the yarn group A while the other group of the auxiliary filamentary yarns are bent in such a manner that they cross the reinforcing filamentary yarns of the yarn group B and the auxiliary filamentary yarns of said one group alternately.

3. A fabric structure as set forth in claim 1 wherein (a) said auxiliary filamentary yarns include two groups and one group of the auxiliary filamentary yarns are arranged in a bent state outside the yarn group A and intermediately between every two adjacent reinforcing filamentary yarns of the yarn group B in parallel to the reinforcing filamentary yarns of the yarn group B, and (b) the other group of the auxiliary filamentary yarns are arranged outside the yarn group B and intermediately between every two adjacent reinforcing filamentary yarns of the yarn group A in parallel to the reinforcing filamentary yarns of the yarn group A while the other group of the auxiliary filamentary yarns are bent so that they cross the auxiliary filamentary yarns of said one group alternately.

4. A fabric structure as set forth in claim 1, wherein another yarn group is laminated on the yarn group A so that the sheet faces of the three yarn groups confront one another, and the reinforcing filamentary yarns of one yarn group cross the reinforcing filamentary yarns of at least one of the remaining two yarn groups alternately.

5. 'A fabric structure as set forth in any one of the preceding claims, wherein the reinforcing filamentary yarns are composed of at least one member selected from the group consisting of carbon fibers, graphite fibers, glass fibers, polyalamide fibers, silicon carbide fibers, boron fibers and metal fibers.

6. A fabric structure as set forth in any one of the preceding claims, wherein the reinforcing filamentary yarns have a flat cross sectional shape.

7. A fabric structure as set forth in any one of the preceding claims, wherein the filament number is equal in all the reinforcing filamentary yarns but the yarn width differs in the yarn groups.

8. A fabric structure as set forth in any one of claims 1 to 6, wherein both the filament number in the reinforcing filamentary yarns and the yarn width differ in the yarn groups.

9. A fabric structure as set forth in any one of the preceding claims, wherein the auxiliary filamentary yarns are composed of at least one member selected from the group consisting of glass fibers, acrylic fibers, rayon fibers, polypropylene fibers, polyalamide fibers, polyamide fibers and polyester fibers.

10. A fabric structure as set forth in any one of the preceding claims, wherein the elongation at break of the auxiliary filamentary yarns is at least 2 times the elongation at break of the reinforcing filamentary yarns.

11. A fabric structure as set forth in any one of the preceding claims, wherein the cross sectional area of the reinforcing filamentary yarns is at least 3 times the cross sectional area of the auxiliary filamentary yarns.

12. A fabric structure as set forth in any one of the preceding claims, wherein the rigidity of the reinforcing filamentary yarns is at least 5 times the rigidity of the auxiliary filamentary yarns.

13. A fabric structure as set forth in any one of the preceding claims, wherein both the reinforcing filamentary yarns and the auxiliary filamentary yarns are multifilament yarns.

14. A fabric structure as set forth in any one of claims 1 to 1 2, wherein the auxiliary filamentary yarns are mono-filament yarns.

1 5. A fabric structure as set forth in any one of the preceding claims, wherein the reinforcing filamentary yarns of the respective yarn groups cross one another at a right angle.

1 6. A fabric structure as set forth in any one of the preceding claims, wherein the reinforcing filamentary yarns and the auxiliary filamentary yarns are impregnated with an uncured thermo-setting resin.

1 7. A fabric structure as set forth in any one of claims 1 to 1 5, wherein the reinforcing filamentary yarns and the auxiliary filamentary yarns are impregnated with at least one uncured thermosetting resin selected from the group consisting of unsaturated polyester resins, epoxy resins, polyimide resins and phenolic resins.

18. A fabric structure as set forth in any one of claims 1 to 1 5, wherein the reinforcing filamentary yarns are coated with a thin film of a metal selected from copper, nickel, aluminium and alloys containing at least one member selected from said metals as the main component.

1 9. A fabric structure as set forth in claim 1 and substantially as hereinbefore described in the Examples or with reference to and as shown in the accompanying drawings.

20. A fiber-reinforced resin including a fabric structure as set forth in any of claims 1 to 1 9.

21. A fiber-reinforced metal including a fabric structure as set forth in any of claims 1 to 19.