Composite lobe joint and manufacturing method

1 . A method of making a composite drive shaft, the method comprising:

providing a removable mandrel having a cylindrical shape;

assembling a lobe joint member at an end of the removable mandrel, the lobe joint member comprising at least three lobes equally distributed about the lobe joint member;

assembling a removable end flange to the lobe joint member at an opposite end of the lobe joint member from the removable mandrel to form a manufacturing assembly;

applying a composite material to an exterior surface of the manufacturing assembly to form a composite tubular that includes the lobe joint member at an end thereof;

removing the removable end flange from the lobe joint member; and

removing the removable mandrel from within the composite tubular to form a composite drive shaft comprising the composite tubular and the lobe joint member integrally formed at an end of the composite tubular.

2 . The method of claim 1 , wherein the lobe joint member is a first lobe joint member arranged at a first end of the removable mandrel and the removable end flange is a first removable end flange, the method further comprising:

assembling a second lobe joint member at an end of the removable mandrel opposite the first lobe joint member; and

assembling a second removable end flange to the second lobe joint member at an opposite end of the second lobe joint member from the removable mandrel.

3 . The method of claim 1 , wherein the composite material comprises composite fibers and applying the composite fibers comprises automated fiber placement.

4 . The method of claim 1 , wherein the composite material comprises composite tape and applying the composite tape comprises automated tape laying.

5 . The method of claim 1 , wherein the removable mandrel comprises a metal material.

6 . The method of claim 1 , wherein the lobe joint member comprises an inwardly extending mounting flange.

7 . The method of claim 6 , wherein the removable end flange is attached to the lobe joint member by one or more fasteners to the mounting flange.

8 . The method of claim 1 , wherein the removable end flange is attached to the lobe joint member by one or more fasteners.

9 . The method of claim 1 , wherein the lobe joint member has an axis passing therethrough, the lobe joint member comprising a first sleeve at a first end of the lobe joint member in the axial direction, a first tapering portion of increasing material thickness extending from the first sleeve to the at least three lobes, a second tapering portion of decreasing material thickness extending from the at least three lobes toward a second sleeve at a second end of the lobe joint member, opposite the first sleeve.

10 . The method of claim 1 , further comprising trimming excess material of the composite material that was applied to the removable end flange during the application of the composite material to the manufacturing assembly.

11 . The method of claim 1 , wherein applying the composite material comprises applying at least one of composite fibers and composite tapes about the manufacturing assembly.

12 . The method of claim 11 , wherein multiple layers of the at least one of composite fibers and composite tapes are applied to the manufacturing assembly.

13 . The method of claim 12 , wherein each layer of the multiple layers is arranged at a different angle relative to an axis through the manufacturing assembly.

14 . The method of claim 1 , wherein assembling the lobe joint member at the end of the removable mandrel comprises securing the lobe joint member to the removable mandrel at a pilot feature of the removable mandrel.

15 . The method of claim 1 , wherein the composite material is applied to extend over at least an exterior surface of the removable mandrel and an exterior surface of the lobe joint member.

16 . The method of claim 15 , wherein the composite material is applied to extend over an exterior surface of the removable end flange.

17 . The method of claim 1 , wherein the removable mandrel is removed by at least one of melting, dissolving, and washing of the material of the removable mandrel from within the composite tubular.

18 . The method of claim 1 , wherein the removable mandrel is a multipiece removable mandrel and the removable mandrel is removed from with the composite tubular by disassembly of the removable mandrel.