Optimized internal structures for 3D-printed sandwich elements

The paper describes how internal structures for Fused Deposition Modeling (FDM) 3D Printing (3DP) can optimize the structural capacity of large-scale freeform sandwich elements for architecture. FDM enables the mold-less fabrication of plastics, allowing cost-effective production of geometrically complex artifacts. FDM can be used for the fabrication of large-scale freeform sandwich panels. To 3DP large elements, often a wide extrusion diameter is chosen. This leads to higher strength of parts and the reduction of fabrication-time, but also to heavier components. Thus, achieving structural integrity while maintaining lightness remains the challenge. Instead of increasing the material thickness, the research focuses on the 3DP of infill to reinforce the overall structure efficiently. While conventional infill strategies are limited to vertical extrusions, a more performative inner structure - namely 3D lattices oriented in multiple directions - can be adopted allowing the realization of functionally-graded, structurally-optimized sandwich structures. The research investigates a strategy of utilizing the 3D lattice infill structures for large-scale applications in order to optimize the weight-to-strength ratio of freeform FDM 3D-printed double-shell structures. The paper describes the investigation of the parametric design of infill structures, the fabrication strategy, the structural evaluation, and the full-scale 3DP demonstration of a chaise lounge as a sandwich, double-shell structure (Fig. 1).