Design and Finite Element Modeling of 3D-Printed Porous Metamaterial Beam Cores for Hybrid Bone Plates

This study presents a metamaterial design framework for next-generation polymer-based bone plates that combine mechanical adaptability, tunable stiffness, and potential for enhanced biological integration. The proposed hybrid beam cores were designed using a gyroid triply periodic minimal surface (TPMS) geometry to create a uniform and interconnected porous architecture. To determine suitable materials for this design, thermoplastic polyurethane (TPU), polylactic acid (PLA), and photopolymer resin (RSN) were selected and experimentally evaluated for their mechanical performance and printability. For this purpose, beam-core specimens were fabricated using fused deposition modeling and digital light processing (DLP) 3D printing, and their structural behavior was assessed through three-point bending tests supported by analytical modeling. In addition, graph and pore network analyses in Dragonfly quantified the beam core's pore morphology and connectivity. Based on these evaluations, RSN demonstrated better print accuracy and mechanical stability, making it the optimal choice for practical fabrication. A bone plate incorporating the hybrid beam-core design was therefore produced from RSN using high-resolution DLP 3D printing, and its performance was validated through four-point bending tests supported by analytical and finite element modeling. This framework provides a pathway toward customizable bone fixation plates that support load sharing and biological healing.