The Mechanical Behavior of Dual TPU/Nylon 3D Printed Parts

This study examines how material arrangement and infill geometry affect the mechanical performance of dual‐material fused‐filament fabrication (FFF) parts made from thermoplastic polyurethane (TPU) and polyamide (Nylon). The goal was to identify printing strategies that balance strength, stiffness, and ductility for engineering applications. Specimens were printed in three configurations—Nylon‐outer with TPU core, alternating TPU–Nylon layers, and TPU‐outer with Nylon core—each using line, grid, and triangular infills. Tensile and flexural tests were conducted. Material arrangement was the dominant factor influencing performance. The Nylon‐outer structure achieved the highest tensile (~13.4 MPa) and flexural (~74 MPa) strengths but showed low elongation (~12%–27%). The TPU‐outer design improved ductility (up to ~34%) but reduced strength, while alternating TPU–Nylon layers provided a balanced response, combining high strength with ~30% elongation. Infill geometry further affected properties: line infill aligned with the load path enhanced both strength and ductility, whereas grid and triangular infills reduced performance. Nylon outer structures suit stiffness‐critical components, TPU outer designs are ideal for flexible or damping parts, and alternating layers offer the best strength–ductility compromise. These insights clarify how dual‐material FFF parameters can be tuned to meet specific mechanical requirements in engineered components.