Airfoil with fiber plies having interdigitated fingers in trailing end

1. An airfoil comprising:

an airfoil section defining suction and pressure sides and leading and trailing ends, the airfoil section being formed of a fiber-reinforced composite comprised of fiber plies, the fiber plies including at least one core fiber ply defining a tube that circumscribes an internal cavity and an overwrap fiber ply that wraps around the at least one core fiber ply, and aft of the internal cavity the overwrap fiber ply on the pressure side including first fingers and the overwrap ply on the suction side including second fingers, the first fingers being interdigitated with the second fingers to form an interlocked joint in the trailing end.

2. The airfoil as recited in claim 1 , wherein each of the first and second fingers has a forward finger section, an aft finger section that terminates at a fingertip, and a radial finger height, and the radial finger height of the aft finger section is less than the radial finger height of the forward finger section.

3. The airfoil as recited in claim 2 , wherein the aft finger sections define radial gaps there between.

4. The airfoil as recited in claim 3 , wherein the aft finger sections of the first fingers are arranged with an offset from the aft finger sections of the second fingers in a cross-radial direction.

5. The airfoil as recited in claim 4 , wherein the fiber plies further include a reinforcement ply interleaved with the aft finger sections through the gaps.

6. The airfoil as recited in claim 5 , further comprising at least one outer shell ply adjacent the overwrap ply, the at least one outer shell ply on the suction side and the at least one outer shell ply on the pressure side converging in the trailing end such that the interlocked joint is sandwiched there between.

7. The airfoil as recited in claim 1 , wherein the first and second fingers are straight.

8. The airfoil as recited in claim 1 , wherein the first and second fingers are hooked.

9. The airfoil as recited in claim 1 , wherein the first and second fingers are L-shaped.

10. The airfoil as recited in claim 1 , wherein each of the first and second fingers has a forward finger section and a finger hook section that projects radially from the forward finger section.

11. The airfoil as recited in claim 10 , wherein the first and second fingers are hooked in opposite radial directions such that the finger hook sections of the first fingers radially overlap the finger hook sections of the second fingers.

12. The airfoil as recited in claim 11 , further comprising at least one outer shell ply adjacent the overwrap ply, the at least one outer shell ply on the suction side and the at least one outer shell ply on the pressure side converging in the trailing end such that the interlocked joint is sandwiched there between.

13. The airfoil as recited in claim 1 , wherein the fiber-reinforced composite is a ceramic matrix composite.

14. A gas turbine engine comprising:

a compressor section;

a combustor in fluid communication with the compressor section; and

a turbine section in fluid communication with the combustor, the turbine section or the compressor section having airfoils disposed about a central axis of the gas turbine engine, each of the airfoils includes:

an airfoil section defining suction and pressure sides and leading and a trailing ends, the airfoil section being formed of a fiber-reinforced composite comprised of fiber plies, the fiber plies including at least one core fiber ply defining a tube that circumscribes an internal cavity and a plurality of overwrap fiber plies that wrap around the at least one core fiber ply, aft of the internal cavity the overwrap fiber plies on the pressure side including first fingers and the overwrap plies on the suction side including second fingers, and the first fingers being interdigitated with the second fingers to form an interlocked joint in the trailing end.

15. The gas turbine engine as recited in claim 14 , wherein each of the first and second fingers has a forward finger section, an aft finger section that terminates at a fingertip, and a radial finger height, the radial finger height of the aft finger section is less than the radial finger height of the forward finger section, and the aft finger sections define radial gaps there between.

16. The gas turbine engine as recited in claim 15 , wherein the aft finger sections of the first fingers are arranged with an offset from the aft finger sections of the second fingers in a cross-radial direction, and the fiber plies further include a reinforcement ply interleaved with the aft finger sections through the radial gaps.

17. The gas turbine engine as recited in claim 16 , further comprising at least one outer shell ply adjacent the overwrap ply, the at least one outer shell ply on the suction side and the at least one outer shell ply on the pressure side converging in the trailing end such that the interlocked joint is sandwiched there between.

18. The gas turbine engine as recited in claim 14 , wherein the first and second fingers are hooked.

19. The gas turbine engine as recited in claim 18 , wherein each of the first and second fingers has a forward finger section and a finger hook section that projects radially from the forward finger section.

20. The airfoil as recited in claim 19 , wherein the first and second fingers are hooked in opposite radial directions such that the finger hook sections of the first fingers radially overlap the finger hook sections of the second fingers.