Autonomous Continuous Fiber Infill Generation for Composites 3D Printing

Abstract

Additive Manufacturing (AM) techniques are advantageous in manufacturing polymeric composites over traditional procedures that require molding, mounting, etching, and post-cleaning. AM is conducive to material allocation reinforcing in critical regions or directions by increasing the fiber volume fraction or by the selective orientation of the fibers. However, state-of-the-art entails fiber orientations be specified manually during the slicing and infill planning steps without any awareness of the desired material properties. In this paper, we formulate and solve the continuous fiber infilling with additively manufactured parts as a fiber path planning problem with constraints on the desired minimum fiber-volume fraction and optimal fiber orientations. The autonomous path planner maximizes the fiber-volume fraction in areas requiring high stiffness while minimizing the continuous-carbon filament in the rest of the part. The fiber orientation is also optimized to maximize the use of continuous carbon filaments. The software tools for generating continuous carbon fiber infills packaged with commercial composite 3D printers cannot automatically satisfy machine-imposed constraints, and the user is often asked to provide the infill geometries manually. The algorithms presented in this paper consider the geometry, stiffness requirements, and printing device constraints while formulating the infill structure. The algorithm was implemented into an open-source parametric 3D modeler. The implementation imports the mesh file representing the solid geometry, cleans and repairs the mesh, calculates the space between faces, and slices the part. Before creating the infill path, the algorithm obtains the face and hole contours and establishes the continuous carbon infill regions. The continuous carbon fiber placement paths are then determined within the infill region to maximize the fiber volume fraction while satisfying the machine constraints. The paper describes solutions with continuous fiber infilling using several example part geometries.