Overcoming fabrication constraints in concrete 3D printing using interlacing Bezier curves: a numerical and experimental analysis

Fabrication constraints are one of the main challenges in implementing optimized solutions within the additive manufacturing of concrete structures. Indeed, optimization algorithms often only address material and design restrictions, disregarding the issues related to specific requirements of layered-extrusion techniques. Therefore, the solutions frequently require post-processing operations to adjust the design to the printing technology available, disrupting the structural performance. This work shows how a curve-based approach yields optimized designs that do not require post-processing operations that can be faithfully printed. Using a set of interlacing Bézier curves, our solution algorithm optimizes the design of concrete structures accounting for layer interfaces, path continuity, and extrusion width. The numerical simulations evidence that this solution algorithm can faithfully reproduce feasible trajectories of a printing apparatus in a diverse set of numerical case studies, achieving reduced weights while respecting the strength limits. The developed algorithm was employed to design a topology optimized beam. The beam was successfully 3D printed and tested through a 3-point bending test, enabling the validation of the optimized beam shape in printability requirements, and bearing designed capacity.