Additive manufacturing of continuous gradients to prevent nodal failure and improve energy absorption in lattice structures

Cellular solids are widely observed in many natural systems such as bones, honeycombs, and shells due to their strength-to-weight ratio and energy absorption benefits. Taking inspiration from these natural systems, additive manufacturing (AM) has opened the design space for architected lattices that can be functionally graded geometrically and/or compositionally for desired properties, e.g., stiffness, strength, energy absorption, etc. To fabricate functionally graded structures using traditional extrusion-based AM, print paths are discretized into short segments which leads to defects, puts mechanical burdens on the 3D printer, and requires large part files. In this study, we develop a low-cost, generalizable method to fabricate graded structures using an anti-stutter, continuous print path. This method is employed to design lattices with diameter varying struts to prevent nodal failure and improve energy absorption as compared to their non-graded alternative. These geometric gradients, as well as compositional gradients, have implications for the next generation of architected lattices in sports equipment, packaging, biomedical implants/scaffolds, and automotive/aerospace protective structures.