Automated 3D-printing path generation for parts with holes using continuous fibre filament

The increasing popularity of continuous fibre 3D-printing brings new challenges to the composite design process. Usually, composite parts include physical obstacles: holes for bearings, inserts, bolts, external shape limitations, or exclusion zones. For such parts the well-known types of in-plane reinforcements – classical unidirectional infill, spiral reinforcement of holes, and generalised perimeters – do not provide satisfactory solutions. This article describes a completely new, specialised type of reinforcement based on the generalised belt-and-pulleys transmission principle, where the pulleys are generalised to any convex obstacles and the belt shows the fibre path connecting them. This type of fibre reinforcement provides an intuitive curvilinear connection between the obstacles and optimises the fibre direction in the most common case, when a load is applied to the obstacles. The developed algorithm has been implemented and is now an integral part of fibrify® Design Suite by 9T Labs.