Method of producing a fibrous layer for the manufacture of a preform of a composite part

1. A method of making a fiber ply for forming a preform of a composite part in the form of a body of revolution having a non-developable surface, the method comprising the steps of:

defining an annular space with first and second canvases respectively defining an inner periphery and an outer periphery thereof;

placing fibers between the canvases by placing the fibers in the annular space in at least one direction and by holding said fibers on the canvases by stitching;

implementing circular connection stitching in the vicinity of the inner periphery of the annular space; and

cutting out the fiber ply as made in this way in the annular space in order to extract it from the canvases.

2. A method according to claim 1 , characterized in that additional fibers are added to fill in the empty gaps present between the fibers placed between the two canvases, the additional fibers being secured to the adjacent fibers by stitching.

3. A method according to claim 2 , characterized in that:

the fibers are carbon fibers or glass fibers; and

the fibers are put into place and stitched by an automatic embroidery machine.

4. A method of fabricating fiber reinforcement for a composite strength member of a flexible abutment, the method comprising forming a preform by alternating at least two fiber plies and being characterized in that the first ply is made in accordance with the method according to claim 3 , and in that:

the second ply is made by placing on the first ply, while held in shape on a spherical tool, a ply of fibers that are oriented perpendicularly to the fibers of the first ply;

the second ply is made by filamentary winding on the first ply; and

the plies of fiber reinforcement are bonded together by threads.

5. A method of fabricating a strength member for a flexible abutment, the method being characterized in that it comprises fabricating fiber reinforcement in accordance with the method according to claim 4 , and in that:

the fiber reinforcement is placed in a mold into which a thermosetting resin is injected under pressure, the resin subsequently be polymerized by heat treatment and

the resin is an epoxy resin.

6. A method of fabricating a flexible abutment made up of a laminated structure comprising a plurality of rigid strength members interleaved with layers of elastically deformable material, the method being characterized in that:

each strength member is made in accordance with the method according to claim 5 ;

the layers of elastic material are made up of elastomer or of rubber; and

the laminated structure is subjected to heat treatment to vulcanize the elastomer or the rubber.

7. A method according to claim 6 , characterized in that the layers of elastic material are made of elastomer and in that the laminated structure is subjected to heat treatment to vulcanize the elastomer.

8. A method of fabricating a flexible abutment made up of a laminated structure comprising a plurality of rigid strength members interleaved with layers of elastically deformable material, the method comprising the steps of:

making a plurality of fiber reinforcements of increasing size in application of the method according to any one of claim 4 ;

maintaining the reinforcements one within another by means of spacers between adjacent strength members, said spacers defining the thicknesses of the layers of elastically deformable material;

injecting a thermosetting resin under pressure into the reinforcements;

applying heat treatment to polymerize the resin in each reinforcement so as to form a plurality of rigid composite strength members;

removing the spacers; and

injecting or casting an elastic material into the spaces present between the rigid composite strength members in order to form layers of elastic material between them.

9. A method of fabricating a composite part of the casing type, the method comprising making at least one fiber ply according to claim 8 , and forming a fiber reinforcement by adding fibers to the at least one fiber ply such that the added fibers are oriented in a different direction than the fibers in the at least one fiber ply, wherein

one or more thickener portions are formed at determined locations on each fiber ply, said portions being made by repeatedly placing fibers at determined locations on the at least one fiber ply;

the reinforcement is placed in a mold into which a thermosetting resin is injected, the resin subsequently being polymerized by heat treatment; and

the resin is a cyanate-ester resin.

10. A method according to claim 1 , characterized in that the fibers are carbon fibers or glass fibers.

11. A method according to claim 1 , characterized in that the fibers are put into place and stitched by an automatic embroidery machine.

12. A method of fabricating fiber reinforcement for a composite strength member of a flexible abutment, the method comprising forming a preform by

defining an annular space with first and second canvases respectively defining an inner periphery and an outer periphery thereof;

placing fibers between the canvases by placing the fibers in the annular space in at least one direction and by holding said fibers on the canvases by stitching;

implementing circular connection stitching in the vicinity of the inner periphery of the annular space;

cutting out the fiber ply as made in this way in the annular space in order to extract it from the canvases to create a first fiber ply; and

forming a second fiber ply by placing on the first fiber ply, while held in shape on a spherical tool, a ply of fibers that are oriented perpendicularly to the fibers of the first ply.

13. A method according to claim 12 , characterized in that the second ply is made by filamentary winding on the first ply.

14. A method according to claim 12 , characterized in that the plies of fiber reinforcement are bonded together by threads.

15. A method of fabricating a strength member for a flexible abutment, the method being characterized in that it comprises fabricating fiber reinforcement in accordance with the method according to claim 12 , and in that the fiber reinforcement is placed in a mold into which a thermosetting resin is injected under pressure, the resin subsequently be polymerized by heat treatment.

16. A method according to claim 15 , characterized in that the resin is an epoxy resin.

17. The method according to claim 15 wherein a plurality of said strength members are interleaved with layers of elastically deformable material to form a laminated structure for a flexible abutment.

18. A method according to claim 17 , characterized in that the layers of elastic material are made up of elastomer or of rubber, and in that the laminated structure is subjected to heat treatment to vulcanize the elastomer or the rubber.

19. A method according to claim 17 , characterized in that the layers of elastic material are made of elastomer and in that the laminated structure is subjected to heat treatment to vulcanize the elastomer.

20. A method of fabricating a flexible abutment made up of a laminated structure comprising a plurality of rigid strength members interleaved with layers of elastically deformable material, the method comprising the steps of:

making a plurality of fiber reinforcements of increasing size in application of the method according to claim 12 ;

maintaining the reinforcements one within another by means of spacers between adjacent strength members, said spacers defining the thicknesses of the layers of elastically deformable material;

injecting a thermosetting resin under pressure into the reinforcements;

applying heat treatment to polymerize the resin in each reinforcement so as to form a plurality of rigid composite strength members;

removing the spacers; and

injecting or casting an elastic material into the spaces present between the rigid composite strength members in order to form layers of elastic material between them.

21. A method of fabricating a composite part of the casing type, the method comprising making at least one fiber ply according to claim 20 , and forming a fiber reinforcement by adding fibers to the at least one fiber ply such that the added fibers are oriented in a different direction than the fibers in the at least one fiber ply.

22. A method according to claim 21 , characterized in that one or more thickener portions are formed at determined locations on each fiber ply, said portions being made by repeatedly placing fibers at determined locations on the ply.

23. A method according to claim 21 , characterized in that the reinforcement is placed in a mold into which a thermosetting resin is injected, the resin subsequently being polymerized by heat treatment.

24. A method according to claim 23 , characterized in that the resin is a cyanate-ester resin.