Development and Validation of a Viscoelastic/Viscoplastic Mathematical Model for Predicting the Behaviour of PLA/GF in Additive Manufacturing

Proposal: This article proposes a mathematical behavioural model implemented in MCalibration™ to capture the mechanical response of specimens made of glass fibre-filled polylactic acid (PLA/GF). The aim was to validate the influence of different printing parameters on the resulting mechanical properties through simulations. Method: The specimens were manufactured according to the geometric specifications of the ASTM D638 tensile testing standard using various densities and packing patterns. The experiments were carried out at a quasi-static strain rate, obtaining experimental stress-strain curve data, which revealed behaviour typical of semi-crystalline polymers. A viscoelastic/viscoplastic mathematical model implemented in MCalibration™ was subsequently calibrated, achieving a prediction of 94.26%, compared to the experimental data, with a mean absolute difference (NMAD) of 8.18 and a coefficient of determination (R²) of 0.942. Finally, curves were fitted for the model constants for each packing pattern based on increasing density. Results: The curve fits achieved a prediction rate of over 90.39%. Using the resulting equations, simulations were performed and compared with experimental data, achieving a prediction rate of over 90%. This validates the proposed model for predicting the mechanical behaviour of elements printed with PLA/GF.