Flow path assemblies for gas turbine engines and assembly methods therefore

1. A method for assembling an airfoil with a boundary structure, at least one of the airfoil and the boundary structure being formed from a composite material, the method comprising:

inserting the airfoil defining a first cutout into an opening defined by the boundary structure, the boundary structure defining a second cutout;

inserting a locking ring into the second cutout defined by the boundary structure or the first cutout defined by the airfoil prior to the airfoil being inserted into the opening defined by the boundary structure; and then

pressing the airfoil against the boundary structure such that the locking ring engages with the airfoil and the boundary structure,

wherein the airfoil is formed of the composite material, and

wherein when the airfoil is inserted into the opening and pressed against the boundary structure, the airfoil is in a green state.

2. The method of claim 1 , wherein prior to inserting the airfoil into the opening, the method further comprises:

machining the opening into the boundary structure;

machining the first cutout into the airfoil; and

machining the second cutout into the boundary structure.

3. The method of claim 1 , wherein prior to inserting the airfoil into the opening, the method further comprises:

forming the opening in the boundary structure by laying up one or more plies in such a way that the opening is formed in the boundary structure; and

forming the second cutout defined by the boundary structure by laying up one or more plies in such a way that the second cutout is defined by the boundary structure.

4. The method of claim 1 , wherein the method further comprises:

laying up one or more plies to form the boundary structure, wherein the one or more plies are laid up such that the boundary structure defines a first portion and a second portion, the first portion having a first thickness (T 1 ) and the second portion having a second thickness (T 2 ), the first thickness (T 1 ) of the first portion greater than the second thickness (T 2 ) of the second portion, wherein during machining the opening into the boundary structure, the opening is machined into the first portion of the boundary structure.

5. The method of claim 1 , wherein the opening defined by the boundary structure extends between an outer end and an inner end, and wherein when the locking ring is inserted into the second cutout defined by the boundary structure, the locking ring extends toward the outer end of the opening and projects outwardly into the opening so as to form a recess between the locking ring and the boundary structure, and wherein when the airfoil is inserted into the opening, a locking portion of the airfoil is inserted into the recess to interlock the airfoil with the boundary structure.

6. The method of claim 1 , wherein the second cutout machined into the boundary structure has a C-shaped cross section, and wherein the first cutout defined by the airfoil has a C-shaped cross section, and wherein the locking ring has an oval-shaped cross section.

7. The method of claim 1 , wherein the boundary structure defines an inner surface and an outer surface, and wherein the method further comprises:

positioning a tool about the opening along the inner surface of the boundary structure;

wherein, during pressing, the airfoil is pressed against the boundary structure and the boundary structure in turn presses against the tool such that the locking ring engages with the second cutout defined by the boundary structure and the first cutout defined by the airfoil.

8. The method of claim 1 , wherein after pressing the airfoil, the method further comprises:

bonding the airfoil, the locking ring, and the boundary structure to one another via a burnout process, a melt infiltration process, or a chemical vapor infiltration process.

9. A flow path assembly for a gas turbine engine, the flow path assembly comprising:

a boundary structure formed from a composite material and defining an opening, the boundary structure further defining a cutout proximate the opening;

an airfoil formed from a composite material and sized to fit within the opening of the boundary structure; and

a locking feature received within the cutout defined by the boundary structure to interlock the airfoil with the boundary structure and engage with the boundary structure and the airfoil,

wherein the locking feature is a locking ring having an oval-shaped axial cross section, the oval-shaped axial cross section defining a major axis that is defined by the longest diameter of the oval-shaped axial cross section, and

wherein the opening defined by the boundary structure extends between an outer end and an inner end, and wherein the major axis of the locking ring extends toward the outer end of the opening and projects into the opening so as to define a recess between the locking ring and the boundary structure, and wherein the airfoil comprises a locking portion that fills the recess to interlock the airfoil with the boundary structure.

10. A flow path assembly for a gas turbine engine, the flow path assembly comprising:

a boundary structure formed from a composite material and defining an opening, the boundary structure further defining a cutout proximate the opening;

an airfoil formed from a composite material and sized to fit within the opening of the boundary structure; and

a C-shaped locking feature received within the cutout defined by the boundary structure to interlock the airfoil with the boundary structure and engage with the boundary structure and the airfoil, wherein the C-shaped locking feature is integrally formed with the airfoil such that the C-shaped locking feature and the airfoil are formed as a monolithic component,

wherein the opening defined by the boundary structure extends between an outer end and an inner end, and wherein when the airfoil is inserted into the opening,

wherein a midline of the C-shaped locking feature formed integrally with the airfoil extends toward the inner end of the opening and projects into the cutout defined by the boundary structure so as to interlock the airfoil with the boundary structure.

11. The flow path assembly of claim 9 or 10 , wherein the opening is defined by one or more sidewalls of the boundary structure, wherein the opening defined by the boundary structure extends between an outer end and an inner end, wherein a midpoint is defined between the outer end and the inner end, and wherein the cutout is defined by the one or more sidewalls proximate the midpoint.

12. The flow path assembly of claim 9 or 10 , wherein the opening is defined by one or more sidewalls of the boundary structure, and wherein the opening defined by the boundary structure extends between an outer end and an inner end, and wherein the cutout is defined by the one or more sidewalls proximate at least one of the outer end and the inner end.