Influence of Fused Deposition Modeling Process Parameters on Constitutive Model of Hyperelastic Thermoplastic Polyurethane

Thermoplastic polyurethanes (TPUs) are suited for fused deposition modeling (FDM) of parts that require high levels of flexibility and strength. Predicting the deformation of TPU parts produced using FDM may be difficult, especially under large deformations, as their constitutive models depend on the printing process parameters. The lack of understanding led to the absence of constitutive models for TPU parts produced using FDM. This work aims to identify accurate hyperelastic constitutive models. Six groups of uniaxial tensile specimens were produced using FDM. These groups were made with variations in two process parameters, which were infill geometry and extrusion nozzle temperature. Infill geometries either corresponded to a zero-deposition angle (wall-only) or an infill deposition of ±45° raster angle (infill-only). It was determined that a third-order Mooney-Rivlin constitutive model can accurately describe these six groups. A finite element analysis (FEA) of the experiments using the proposed constitutive models resulted in limited errors for all groups. The proposed approach was verified through a combination of experiments and FEA of FDM TPU components undergoing large deformation.