Method for manufacturing a complexly shaped composite material part

1. A method of fabricating a complex part out of composite material comprising three-dimensional woven fiber reinforcement densified by a matrix, the method comprising:

three-dimensionally weaving a continuous fiber strip comprising a succession of fiber blanks for preforms of a plurality of parts that are to be fabricated;

subsequently cutting individual fiber blanks out from the strip, each blank being a one-piece blank;

shaping a cut-out blank to obtain a one-piece fiber preform having a shape that is close to the shape of a part that is to be fabricated; the cut-out blank to be shaped comprising portions that are adjacent to a zone of de-bonding, the zone of de-bonding having been formed during the weaving, the shaping comprising folding or folding back said portions, wherein in the zone of de-bonding, fibers of a first portion do not extend to a second portion and fibers of the second portion do not extend to the first portion;

consolidating the preform in the desired shape; and

densifying the consolidated preform by forming a matrix by chemical vapor infiltration.

2. A method according to claim 1 , wherein prior to cutting out the individual fiber blanks, the woven fiber strip is impregnated by a consolidation liquid composition comprising a resin, and consolidation is performed by curing and pyrolyzing the resin.

3. A method according to claim 2 , wherein prior to impregnating with the consolidation composition, a fiber-matrix interphase layer is formed on the fibers of the woven fiber strip, the interphase layer being made of a material selected from pyrolytic carbon (PyC), boron nitride (BN), and boron-doped carbon (BC).

4. A method according to claim 3 , wherein the interphase layer has a thickness of no more than 100 nm.

5. A method according to claim 3 , wherein after obtaining the consolidated preform and prior to densifying it with the matrix, an additional fiber-matrix interphase layer is formed.

6. A method according to claim 5 , wherein the additional interphase layer is made by chemical vapor infiltration, and wherein the forming of the additional interphase layer and the densification are performed one after the other in an oven.

7. A method according to claim 1 , wherein the fiber strip is impregnated with a consolidation composition before cutting out the blanks, said consolidation composition comprising a consolidation resin, and wherein after impregnation with the consolidation composition and before cutting out the blanks, the consolidation resin is subjected to pre-curing.

8. A method according to claim 1 , wherein the consolidation comprises curing and pyrolysis of a consolidation resin, and wherein the fiber blank is shaped in a mold in which curing and pyrolysis of the consolidation resin are performed one after the other.

9. A method according to claim 1 , wherein a resin is pyrolyzed during a temperature rise that is performed in preparation for an operation of chemical vapor infiltration.

10. A method according to claim 1 , wherein the consolidation is performed by partial densification of the preform by chemical vapor infiltration while the preform is held in the desired shape.

11. A method according to claim 10 , wherein after shaping and before curing a fiber-matrix interphase coating is formed on the fibers of the preform, the interphase coating being made of a material selected from pyrolytic carbon (PyC), boron nitride (BN), and boron-doped carbon (BC).

12. A method according to claim 1 , wherein the densification comprises two steps separated by an operation of machining the partially densified preform.

13. A method according to claim 1 , wherein the woven strip comprises a plurality of rows of fiber blank that extend in the longitudinal direction of the strip.

14. A method according to claim 1 , wherein the strip is woven with zones of extra length in the warp and weft directions all around the fiber blanks.

15. A method according to claim 1 , for fabricating a turbomachine blade, wherein the continuous strip is woven with a succession of fiber blanks that are suitable, after being shaped, for constituting fiber preforms, each constituting a one-piece preform for at least an airfoil and a root of a blade, the fiber blanks being woven with their longitudinal direction, which corresponds to the longitudinal direction of the blades that are to be fabricated, extending in the weft direction or in the warp direction.

16. A method according to claim 1 , wherein surface treatment is performed on the fibers of the woven fiber strip, which treatment comprises at least one of the following operations: removing sizing from the fibers and acid treatment of the fibers.

17. A method according to claim 1 , wherein the fibers of the first portion and the fibers of the second portion are not interlocked.

18. A method of fabricating a complex part out of composite material comprising three-dimensional woven fiber reinforcement densified by a matrix, the method comprising:

three-dimensionally weaving a continuous fiber strip comprising a succession of fiber blanks for preforms of a plurality of parts that are to be fabricated;

subsequently cutting individual fiber blanks out from the strip, each blank being a one-piece blank;

after cutting, shaping a cut-out blank to obtain a one-piece fiber preform having a shape that is close to the shape of a part that is to be fabricated; the cut-out blank to be shaped comprising portions that are adjacent to a zone of de-bonding, the zone of de-bonding having been formed during the weaving, the shaping comprising folding or folding back said portions wherein in the zone of de-bonding, fibers of a first portion do not extend to a second portion and fibers of the second portion do not extend to the first portion; the shaping comprising deforming the cut-out blank so as to increase a curvature of the cut-out blank where the cut-out blank is observed in cross-section relative to a longitudinal direction of the cut-out blank;

consolidating the preform in the desired shape; and

densifying the consolidated preform by forming a matrix by chemical vapor infiltration.

19. A method of fabricating a complex part out of composite material comprising three-dimensional woven fiber reinforcement densified by a matrix, the method comprising:

three-dimensionally weaving a continuous fiber strip comprising a succession of fiber blanks for preforms of a plurality of parts that are to be fabricated; the strip comprising:

a plurality of rows of successive fiber blanks, each of said rows comprising a plurality of fiber blanks, or

a row of fiber blanks woven perpendicularly to a longitudinal direction of the strip, subsequently cutting individual fiber blanks out from the strip, each blank being a one-piece blank;

shaping a cut-out blank to obtain a one-piece fiber preform having a shape that is close to the shape of a part that is to be fabricated; the cut-out blank to be shaped comprising portions that are adjacent to a zone of de-bonding, the zone of de-bonding having been formed during the weaving, the shaping comprising folding or folding back said portions wherein in the zone of de-bonding, fibers of a first portion do not extend to a second portion and fibers of the second portion do not extend to the first portion

consolidating the preform in the desired shape; and

densifying the consolidated preform by forming a matrix by chemical vapor infiltration.