Wet fiber placement (WFP) is a novel additive manufacturing process for complex shaped parts made of fiber-reinforced polymers (FRP) with continuous reinforcement. Combined with a methodology for a topology-optimized design, WFP provides enormous lightweight potential. The material can be placed only where really needed and fiber orientation can be adapted to the local load directions, exploiting the anisotropic material properties. However, for an efficient workflow, the anisotropy and the manufacturing restrictions introduced by WFP must be considered during topology optimization and subsequent design steps. In addition, the topology optimization result has to be transferred to fiber placement paths. In this context, the target of the presented work is to establish a corresponding methodology for a topology-optimized design.

Regarding the anisotropic material properties, a combination of bi-directional evolutionary structural optimization (BESO) and fiber-angle optimization is used. A dilate filter is integrated into BESO for considering the width of fiber bundles. For 3D-BESO, the dilate filter is combined with a projection scheme in order to prevent non-manufacturable undercuts transverse to the placement plane. Furthermore, Puck’s failure criteria is integrated into topology optimization as a control variable in order to minimize the parts weight as far as possible, while maintaining its ability to withstand the specified loads. Based on the optimization result, 2D- and 2.5D-paths for WFP are derived, using a methodology consisting of vector clustering and a streamline algorithm to which a new stress based seeding strategy is applied. The resulting placement paths follow the main load paths and are parallel to neighboring pathways due to clustering. In addition, the paths consider the shortest necessary placement length for WFP and overlaps are completely avoided. Due to the high degree of automation, the proposed workflow significantly reduces manual design steps.