Influencing the draping behaviour of solid epoxy prepregs by applying 3D-printed resin patterns

This study presents a novel strategy to overcome the limitations of solid resin prepregs (SRPs) - namely the inability to drape at room temperature and hindered gas evacuation during vacuum-bag-only (VBO) processing - by 3D-printing a regular, uncured solid epoxy resin (SR) pattern on a dry woven textile. The locally patterned resin distribution preserves dry textile regions, enabling room temperature drapeability and more robust VBO-processing due to improved gas evacuation. By adjusting pattern parameters such as element geometry and coverage, the draping behaviour can be controlled to adapt to a desired draping condition. In order to be able to design the right pattern for given draping conditions, the influence of these parameters on bending and shearing was studied. Manual draping showed that bending radii down to 4 mm were achievable, governed only by the element length in bending direction, while coverage had no significant effect. In contrast, picture-frame-tests showed that the shearing is mainly influenced by the coverage and that a maximal shearing angle of 30° can be achieved. These results show that the SRPs bending and shearing can be independently influenced through pattern design. The derived structure–drapeability relationships enable targeted design of SRPs for robust, autoclave-free composite manufacturing.