This paper presents the identification of a multilinear isotropic hardening material model for PETG produced by fused filament fabrication (FFF) using a noncontact computer vision extensometer. A tensile test was performed on flat specimens with surface line markers, and the marker displacements were measured without contact by tracking them in recorded images. Strain was calculated from these displacements and combined with the measured force to obtain true stress and plastic strain, and ten points of the curve defined the model. The model was implemented in ANSYS Workbench and calibrated against the measured reaction forces of five specimens. The average absolute deviation of the calculated forces was 3.51 %. The results show the procedure provides an effective macroscopic description of the global tensile response of the tested PETG. The model assumes a homogeneous, isotropic material, and its applicability is limited to comparable printing parameters, specimen geometry and loading conditions.
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