Pultrusion-winding: A novel fabrication method for coreless wound fiber-reinforced thermoset composites with distinct cross-section

Bar frameworks integrally manufactured by coreless filament winding are often the superior design solution for voluminous component shapes with distinctive load cases. Numerical simulation results must be validated by full-scale tests due to uncertainties in the mesoscale fiber structure. Pultrusion-winding allows to reduce the geometrical uncertainty of the composite without the limiting use of molds. This is achieved by the combination of intermittent ultraviolet pultrusion, coreless filament winding, and a novel tool trajectory creating method. Straight fiber strand segments are directly cured during winding. This defines their cross-sectional shape and decreases surface irregularities. Around winding points, the curing is temporarily discontinued and the fiber strand remains flexible for hooking. The new fabrication method could be validated on a laboratory scale showing improved mechanical performance and reduced fluctuations in fiber volume ratio in comparison to coreless filament winding.