Patent attributes
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.