Impact of FDM Process Conditions on the Thermal and Mechanical Behavior of TPU 90A

¹ University of Tunis, Higher National Engineering School of Tunis, LR99ES05, Mechanical, Material and Processes Laboratory, 1008, Tunis, Tunisia.
² University of Carthage, Preparatory Institute for Engineering Studies of Bizerte, 7021, Bizerte, Tunisia.
³ Department of Mechanical Engineering, University of Québec Trois-Rivières, Trois-Rivières, QC, Canada.

Abstract

This study presents a comprehensive investigation of the thermomechanical and shape memory behavior of TPU 90A in both raw filament and 3D printed forms after manufacturing via Fused Deposition Modeling (FDM). The influence of key printing parameters extrusion temperature, infill density, and infill orientation on material performance is systematically examined. A novel UMAT subroutine was implemented in Abaqus to simulate the thermomechanical and shape memory responses of TPU 90A under varying loads and temperatures. Validation against experimental data confirms a pronounced shape memory effect, with shape fixity (Rf) and recovery (Rr) ratios exceeding 98%. The numerical model shows excellent agreement with experiments, as the simulated Young’s modulus (53.97 MPa) closely matches the measured value (55.38 MPa) for printed samples. Optimal mechanical properties were achieved at 230°C extrusion temperature, 45° infill orientation, and 100% infill density. The approach’s practical relevance is demonstrated through the fabrication of a personalized finger orthosis, where stress analysis indicates peak values of 17.76 MPa, ensuring sufficient rigidity for medical stabilization.