Turbine engine rotor including blade made of composite material and having an added root

1. A turbine rotor comprising a plurality of blades of composite material comprising fiber reinforcement densified by a matrix, each blade comprising a blade body extending between an inner end having a blade root and an outer end forming the tip of the blade, wherein the rotor includes a plurality of outer platform elements of composite material comprising fiber reinforcement densified by a matrix, each outer platform element including at least one opening in which the outer end of at least one of the plurality of blades is engaged, a portion of the outer end of each blade that extends beyond the outer platform element including at least one slot or notch for receiving a locking element,

wherein each outer platform element has an outer platform overhang plate and an outer platform wiper plate, and

wherein the outer platform wiper plate and the outer platform overhang plate present equivalent lengths in a longitudinal direction of the platform element while being offset relative to each other in said longitudinal direction in order to enable two adjacent outer platform elements to overlap in part and to seal a passage between the two adjacent outer platforms.

2. A rotor according to claim 1 , wherein the outer end of each blade presents dimensions that are smaller than the dimensions of the underlying portion of the blade body so as to define a shoulder forming a bearing surface for the outer platform element.

3. A rotor according to claim 1 , wherein each outer platform element has a plurality of openings so as to engage each outer platform element with the outer ends of a plurality of adjacent blades.

4. A rotor according to claim 1 , wherein the outer end of each blade extending beyond the outer platform element includes two slots or notches, and in that each locking element has two arms respectively engaged in said slots or notches.

5. A rotor according to claim 1 , wherein each locking element includes, at one end, a rim that co-operates with a housing formed in each outer platform element so as to hold each locking element in position.

6. A rotor according to claim 1 , wherein the fiber reinforcement of each blade is obtained by multilayer weaving of yarns.

7. A rotor according to claim 1 , wherein each blade and each outer platform element is made of ceramic matrix composite (CMC) material.

8. A rotor according to claim 1 , wherein each blade and each outer platform element is made of organic matrix composite (OMC) material.

9. A compressor fitted with a rotor according to claim 1 .

10. A turbine engine fitted with a compressor according to claim 9 .

11. A method of fabricating a turbine engine rotor, the method comprising making a plurality of blades, the method comprising for each blade:

making a blade fiber blank as a single piece;

shaping the fiber blank so as to obtain a single-piece blade fiber preform having a first portion forming a preform for a blade airfoil and a blade root;

densifying the blade preform with a matrix in order to obtain a composite material blade having fiber reinforcement constituted by the preform and densified by the matrix, and comprising a blade body extending between an inner end comprising a blade root and an outer end forming a blade tip;

wherein the method further comprises:

making at least one slot or notch in the outer end of each blade;

making at least one single-piece fiber blank for each of a plurality of outer platform elements;

shaping the fiber blank to obtain an outer platform element fiber preform;

densifying the outer platform element preform with a matrix to obtain the plurality of outer platform elements of composite material having fiber reinforcement constituted by the preform and densified by the matrix;

making at least one opening in each outer platform element;

mounting each blade on a hub by engaging the root of each blade in a housing of complementary shape formed in the periphery of said hub;

mounting each outer platform element on at least one blade by engaging the outer end of the blade in the opening or notch in the outer platform element, each outer platform element being provided with an outer platform overhang plate and an outer platform wiper plate, the outer platform wiper plate and the outer platform overhang plate presenting equivalent lengths in a longitudinal direction of the platform element while being offset relative to each other in said longitudinal direction in order to enable two adjacent outer platform elements to overlap in part and to seal a passage between the two adjacent outer platforms; and

arranging a locking element in at least the slot in the outer end of each blade.

12. A method according to claim 11 , wherein the outer end of each blade is machined so as to define a shoulder forming a bearing surface for the outer platform element.

13. A method according to claim 11 , wherein the fiber blank of each outer platform element is made by multilayer weaving between a plurality of yarn layers, and in that it includes partial zones of non-interlinking between two series of adjacent yarn layers, one of the two series of layers being folded out during shaping of the blank so as to form the outer platform wiper plate.