초록 ▼

The invention relates to an intermediate product intended for the production of a composite part in combination with a resin matrix, formed by at least two unidirectional sets of reinforcing yarns, the yams of each set extending in a different direction, whereby the sets are interlinked by means of

The invention relates to an intermediate product intended for the production of a composite part in combination with a resin matrix, formed by at least two unidirectional sets of reinforcing yarns, the yams of each set extending in a different direction, whereby the sets are interlinked by means of stitching or knitting using at least one stitching or knitting yarn. The invention is characterized in that the stitching or knitting yarn has a yarn count of less than or equal to 30 dTex, preferably less than or equal to 25 dTex, in accordance with standard EN ISO 2060.

대표청구항 ▼

1. A composite part comprising two layers that each comprises unidirectional fibers selected from the group consisting of carbon fibers, glass fibers, basalt fibers, aramid fibers, silica fibers, ceramic fibers and mixtures thereof, said layers being located next to each other such that the unidirec

1. A composite part comprising two layers that each comprises unidirectional fibers selected from the group consisting of carbon fibers, glass fibers, basalt fibers, aramid fibers, silica fibers, ceramic fibers and mixtures thereof, said layers being located next to each other such that the unidirectional fibers of one layer extend in a direction that is different from the other layer, said layers being bonded together by a polyester stitching yarn that has a count of less than or equal to 30 dTex, as determined according to the EN ISO 2060 standard and a cured resin matrix wherein an elliptical cured resin-rich zone is located at said stitching yarn, said elliptical cured resin-rich zone having a major axis that extends through the two ends of the elliptical cured resin-rich zone and a minor axis or height that extends perpendicular to said major axis, said height being 0.09 mm to 0.11 mm and wherein said composite part exhibits a crack density of 0 after being subjected to 1600 hygrothermal cycles. 2. A composite part according to claim 1 wherein said polyester stitching yarn has a moisture absorption factor of less than or equal to 0.4%, as determined by the ASTM D629-99 (paragraph 9) standard. 3. A composite part according to claim 1 wherein said cured resin matrix is selected from among epoxies, unsaturated polyesters, vinyl esters, polyurethanes, phenolics, polyimides, bismaleimides, and mixtures thereof. 4. A composite part according to claim 1 wherein said polyester stitching yarn has a fracture toughness between 20 cN/Tex and 100 cN/Tex, as measured according to the 1995 version of EN ISO 2062. 5. A composite part according to claim 1 wherein said polyester stitching yarn has a rupture elongation between 10% and 60%, as measured according to the 1995 version ISO EN 2062. 6. A composite part according to claim 1 wherein said, polyesters stitching yarn has a count that is equal to 23 dTex. 7. A composite part according claim 1 wherein the surface density of each of said layers is in the range of 50 g/m2 to 600 g/m2, as determined according to the March 1998 version of standard NF EN 12127. 8. A composite part according to claim 1 wherein said layers are bonded together by stitches or knitting of said polyester stitching yarn that extend along parallel lines. 9. A composite part according to claim 8 wherein said layers are bonded together with said polyester stitching yarn such that stitching or knitting points are formed that are spaced linearly apart by 1 to 20 mm and wherein said parallel lines are 2 to 50 mm apart. 10. A composite part according to claim 1 wherein said unidirectional fibers extend in directions selected from among the angles 0°, 30°, 45°, 60°, 90°, 120°, 135°. 11. A composite part according to claim 1 wherein said composite part is an aircraft part selected from the group consisting of fuselage frames, wing skins, fuselage skins, fin skins, horizontal tail skins, bulkheads, wing spar boxes, reactor blades. 12. A composite part according to claim 1 wherein the length of the major axis that extends through the two ends of the elliptical cured resin-rich zone is from 2.0 mm to 2.8 mm. 13. A composite part according to claim 1 wherein the stitching yarn size along said major axis is from 0.17 mm to 0.19 mm. 14. A composite part according to claim 1 wherein said polyester stitching yarn has a count of less than or equal to 25 dTex. 15. A process for making a composite part comprising the steps of: providing an intermediate product that comprises at least two layers of unidirectional reinforcement fibers selected from the group consisting of carbon fibers, glass fibers, basalt fibers, aramid fibers, silica fibers, ceramic fibers and mixtures thereof, said layers being stitched together using at least one polyester stitching yarn wherein said polyester stitching yarn has a count of less than or equal to 30 dTex, as determined according to the EN ISO 2060 standard and a thermosetting resin; andcuring said thermosetting resin to form a cured resin matrix wherein an elliptical cured resin-rich zone is located at said stitching yarn, said elliptical cured resin-rich zone having a major axis that extends through the two ends of the elliptical cured resin-rich zone and a minor axis or height that extends perpendicular to said major axis, said height being from 0.09 mm to 0.11 mm and wherein said composite part exhibits a crack density of 0 after being subjected to 1600 hygrothermal cycles. 16. A process according to claim 15 wherein said thermosetting resin is selected from the group consisting of epoxies, unsaturated polyesters, vinyl esters, polyurethanes, phenolics, polyimides, bismaleimides, and mixtures thereof. 17. A composite part that is made according to the process of claim 15. 18. A composite part according to claim 17 that comprises more than two layers of unidirectional fibers. 19. A composite part according to claim 17 wherein said composite part is an aircraft part selected from the group consisting of fuselage frames, wing skins, fuselage skins, fin skins, horizontal tail skins, bulkheads, wing spar boxes, reactor blades.