Mechanical Testing of Polyethylene Terephthalate Glycol Processed with Fused Deposition Modelling

Polyethylene Terephthalate Glycol (PETG) is a thermoplastic material used in Fused Deposition Modelling for prosthetic applications, where mechanical properties are strongly dependent on process parameters. This study investigated the effects of carbon fibre (CF) content, print orientation (PO), and print temperature (PT) on the mechanical performance of PETG, fabricated using a Bambu Lab A1 printer. Tensile, three-point bending and impact testing were conducted to characterise the mechanical response of printed specimens. A Taguchi L9 array was employed to evaluate parameter effects while minimising experimental runs, and factor effects were quantified using per-response general linear models. Findings indicated that PO and PT significantly affected tensile behaviour, while CF content dominated flexural stiffness and impact response, with the strongest tensile response at 240 °C attributed to improved interlayer bonding. CF reinforcement increased stiffness and flexural strength but had limited effect on tensile strength and a reduced impact resistance at higher loadings, indicating increased brittleness. PO was identified as the most influential factor, with upright specimens exhibiting superior tensile performance, consistent with more favourable alignment of filament deposition with the loading direction. These findings demonstrate that the mechanical behaviour of CF-PETG is strongly process-dependent, informing its future application within prosthetic limb design.