Composite turbomachine blade with in-built root

1. A method of fabricating a turbine engine blade out of composite material comprising fiber reinforcement densified by a matrix, the method comprising:

making a fiber blank by multilayer weaving a single piece comprising, in the longitudinal direction of said fiber blank corresponding to the longitudinal direction of the blade to be fabricated: a first set of a plurality of yarn layers that are interlinked to form a first portion of the blank corresponding to an airfoil preform; and a second set of one or more yarn layers that are interlinked at least locally to form at least a second portion of the blank corresponding to a blade root preform; the yarns of the first set of yarn layers not being interlinked with the yarns of the second set of yarn layers, the first set of yarn layers having the yarns of the second set of yarn layers crossing therethrough in the second portion of the blank;

shaping the fiber blank to obtain a one-piece fiber preform having said first portion forming an airfoil preform and at least said second portion forming a blade root preform; and

densifying the preform with a matrix in order to obtain a composite material blade having fiber reinforcement constituted by the preform and densified by the matrix, forming a single piece incorporating a blade root.

2. The method according to claim 1 , wherein the fiber blank is woven with a second continuous set of yarn layers, and the shaping of the fiber blank comprises eliminating portions of the second set of yarn layers outside the second portion of the fiber blank by cutting them off.

3. The method according to claim 2 , wherein it includes machining said second portion to the shape of the blade root that is to be made.

4. The method according to claim 1 , wherein the fiber blank also includes at least one third portion forming some or all of the following elements:

an inner platform with or without overhangs and with or without an anti-tilting rim; and

an outer platform with or without outer platform overhangs and with or without outer platform wipers; and

in that shaping the fiber blank comprises shaping the third portion of the fiber blank to obtain a single piece fiber preform also having said third portion, the blade obtained after densification of the preform with a matrix forming a single piece that incorporates a blade root and that incorporates some or all of an element selected from the following elements:

an inner platform with or without overhangs and with or without an anti-tilting rim; and

an outer platform with or without outer platform overhangs and with or without outer platform wipers.

5. The method according to claim 4 , wherein the third portion is formed by said second set of a plurality of yarn layers, the first set of yarn layers having yarns of the second set of yarn layers crossing therethrough in the third portion of the blank.

6. The method according to claim 4 , wherein the fiber blank is woven with the continuous second set of yarn layers, and the shaping of the fiber blade comprises eliminating portions of the second set of yarn layers outside the third portion of the fiber blank, by cutting them off.

7. The method according to claim 4 , wherein the number of yarn layers in the second set of yarn layers is greater in the second portion of the fiber blank than in the third portion.

8. The method according to claim 4 , wherein the weight of the yarns in the second set of yarn layers is greater in the second portion of the fiber blank than in the third portion.

9. The method according to claim 4 , wherein the third portion corresponds to a fiber texture fitted onto the first portion of the fiber blank.

10. A turbine engine blade made of composite material comprising fiber reinforcement obtained by multilayer weaving of yarns and densified by a matrix; wherein it comprises a first portion constituting an airfoil formed as a single piece with at least one second portion constituting a blade root, the first portion constituting an airfoil comprising a first set of a plurality of yarn layers that are interlinked to form a first portion of the fiber reinforcement of the blade, the second portion constituting a blade root comprising a second set of one or more yarn layers that are interlinked at least locally to form a second portion of the fiber reinforcement of the blade, the yarns of the first set of yarn layers not being interlinked with the yarns of the second set of the yarn layers, the first set of yarn layers having the yarns of the second set of yarn layers crossing therethrough in the second portion of the fiber reinforcement of the blade.

11. The blade according to claim 10 , wherein it further comprises at least one third portion forming some or all of the following elements:

an inner platform with or without overhangs and with or without an anti-tilting rim; and

an outer platform with or without outer platform overhangs and with or without outer platform wipers.

12. The blade according to claim 11 , wherein the fiber reinforcement portions corresponding to the first and third portions of the blade are mutually interleaved, at least in part, with yarns of the first fiber reinforcement portion penetrating into the second fiber reinforcement portion.

13. A rotor having one or more blades according to claim 10 .

14. A compressor fitted with a rotor according to claim 13 .

15. A turbine engine fitted with a compressor according to claim 14 .