Abstract: A fiber-reinforced polymer composite shaft for transmitting loads along a central axis. The composite shaft comprises a first interface surface extending along the central axis and comprising at least one helical groove and/or a plurality of circumferential grooves for engaging with at least one corresponding helical ridge and/or a plurality of corresponding circumferential ridges of a second interface surface of an end fitting. The at least one helical groove and/or the plurality of circumferential grooves comprises at least one flank with a flank angle of between 32° and 51°. In such an assembly, a preload structure is arranged to provide a radial biasing force to bias the first interference surface against the second interference surface.

Abstract: A method of manufacturing a composite structure includes providing a mandrel comprising a base part and at least one conical part. The base part comprises an elongate shaft. The base part of the mandrel comprises a cylindrical surface around a longitudinal axis of the base part. The at least one conical part extends from the cylindrical surface of the base part. The mandrel and a braiding machine are moved relative to one another such that fibre tows are braided over at least the base part of the mandrel. The mandrel and the braiding machine are arranged such that during the braiding process, none of the fibre tows intersect with a vertex of the at least one conical part of the mandrel.

Abstract: A pipe is provided which extends from a first portion to a second portion. The pipe is arranged to transfer fluid at an operational pressure from the first portion to the second portion. The pipe comprises a bend portion between the first and second portions in which the pipe transitions from extending in a first direction A to extending in a second direction B. The bend portion of the pipe comprises a non-circular cross section, the non-circular cross section having a shape selected to resist relative movement of the first and second portions when the pipe is subject to the operational pressure.

Abstract: A fibre-reinforced polymer composite shaft for transmitting loads along a central axis is provided. The composite shaft comprises a first interface surface extending along the central axis and comprising at least one helical groove and/or a plurality of circumferential grooves for engaging with at least one corresponding helical ridge and/or a plurality of corresponding circumferential ridges of a second interface surface of an end fitting. The at least one helical groove and/or the plurality of circumferential grooves comprises at least one flank with a flank angle of between 32° and 51°. In such an assembly, a preload structure is arranged to provide a radial biasing force to bias the first interference surface against the second interference surface.

Abstract: A fibre-reinforced polymer composite shaft for transmitting loads along a central axis is provided. The composite shaft comprises a first interface surface extending along the central axis and comprising at least one helical groove and/or a plurality of circumferential grooves for engaging with at least one corresponding helical ridge and/or a plurality of corresponding circumferential ridges of a second interface surface of an end fitting. The at least one helical groove and/or the plurality of circumferential grooves comprises at least one flank with a flank angle of between 32° and 51°. In such an assembly, a preload structure is arranged to provide a radial biasing force to bias the first interference surface against the second interference surface.

Abstract: A composite shaft with an end fitting mounted on one end of said shaft and a preload structure arranged to provide a biasing force to bias the composite shaft against the end fitting. The end fitting has a first interface surface, the first interface surface being tapered at an angle to the shaft axis and the shaft has a second interface surface for engagement with the first interface surface and is tapered at an angle to the shaft axis, the second interface surface extending axially from a first end to a second end, the shaft being thicker at the second end than at the first end. The shaft has a third interface surface and the preload structure has a fourth interface surface and the contact pressure of the third interface against the fourth interface increases from the first end of the shaft to the second end of the shaft.

Abstract: A fibre-reinforced polymer composite shaft for transmitting loads along a central axis is provided. The composite shaft comprises a first interface surface extending along the central axis and comprising at least one helical groove and/or a plurality of circumferential grooves for engaging with at least one corresponding helical ridge and/or a plurality of corresponding circumferential ridges of a second interface surface of an end fitting. The at least one helical groove and/or the plurality of circumferential grooves comprises at least one flank with a flank angle of between 32° and 51°. In such an assembly, a preload structure is arranged to provide a radial biasing force to bias the first interference surface against the second interference surface.

Abstract: A composite shaft with an end fitting mounted on one end of said shaft and a preload structure arranged to provide a biasing force to bias the composite shaft against the end fitting. The end fitting has a first interface surface, the first interface surface being tapered at an angle to the shaft axis and the shaft has a second interface surface for engagement with the first interface surface and is tapered at an angle to the shaft axis, the second interface surface extending axially from a first end to a second end, the shaft being thicker at the second end than at the first end. The shaft has a third interface surface and the preload structure has a fourth interface surface and the contact pressure of the third interface against the fourth interface increases from the first end of the shaft to the second end of the shaft.