Experimental methods for mechanical characterization of 3D-printed materials via filament tests
Çağlar Kahya, Kenan Tüfekci, Betül Gülçimen Çakan, Celal SoyarslanPurpose
This study aims to introduce and validate a robust experimental methodology for the tensile testing of compliant filaments such as thermoplastic polyurethane (TPU) to generate reliable material data for numerical modeling. Accurate strain measurement was a primary focus, particularly in the low-strain elastic regime (≤ 10%), where minimal elongation requires sensitive measurement techniques.
Design/methodology/approach
A custom desktop tensile testing setup with high-precision loading was developed to address the challenges of testing highly elastic filaments. Various clamping configurations and strain measurement methods were evaluated to minimize experimental errors. A modified printing strategy was introduced to solidify specimens before contacting the print bed, preserving their circular geometry and enabling easier removal. Tensile tests were conducted on both raw and printed TPU filaments to investigate the influence of the printing process on mechanical behavior. Two different filament diameters were also tested to evaluate potential nozzle diameter effects. Strain measurements obtained from clamp displacement tracking, an extensometer and optical strain measurement (OSM) were systematically compared. The resulting stress–strain data were used to calibrate an Ogden hyper-elastic model with isotropic, volume-preserving and rate-dependent parameters, while the Prony series was incorporated to capture rate effects.
Findings
Clamp displacement tracking overestimated strain due to slippage effects, while extensometer measurements presented alignment challenges for highly elastic TPU specimens. OSM provided more reliable strain data. The mechanical properties of printed filaments were found to be independent of filament diameter, whereas raw and printed filaments exhibited different tensile behaviors. The calibrated Ogden model accurately represented TPU behavior within the low-strain regime relevant to many engineering applications.
Originality/value
This study addresses the lack of reliable filament-level mechanical data for highly elastic materials such as TPU, which is essential for numerical modeling and constitutive material calibration. To the best of the authors’ knowledge, no prior study has systematically characterized raw and printed TPU filaments at this level for use in finite element modeling. The proposed experimental framework provides reliable material data for low-strain applications involving controlled elastic deformation, while more complex constitutive models for large deformations are left for future work.