Field-driven design of functionally graded TPMS-based 3D printed sandwich structures: Modeling, printing and testing

Sandwich structures with Triply Periodic Minimal Surface (TPMS) cores represent an innovative solution for lightweight applications requiring optimized mechanical properties and high strength-to-weight ratios. In this work, functionally graded TPMS-based sandwich structures were designed using a Field-Driven Design approach, allowing precise spatial variation of core thickness. Samples were fabricated via Material Extrusion (MEX), ensuring accurate reproduction of the designed gradient. Mechanical characterization through ASTM D790 three-point bending tests revealed that functional gradients significantly improve mechanical efficiency, particularly at higher fill percentages (≥30%), with strength increases up to 55% compared to uniform-thickness structures. However, at lower fill percentages (~20%), this advantage diminishes, highlighting a critical threshold for effective gradient application. The clear identification of this threshold constitutes a novel contribution, providing practical guidelines for the design and optimization of advanced TPMS-based sandwich structures.