On the coupling effects of temperature and raster angle on the mechanical response and constitutive modelling of FDM-processed SCF-PA12 composites

This study investigates the fracture mechanisms and thermo-mechanical behaviour of SCF-PA12 composites at high temperatures through experiments and modelling. Uniaxial tensile tests were performed on samples with 0°, 45°, and 90° raster angles from 30 °C to 150 °C. Multiscale characterisation techniques, including SEM, GPC, and in situ XRD, were used to examine the synergistic effects of temperature and raster angle on mechanical performance and failure modes. Results showed that the material exhibits optimal interfacial properties at 110 °C, with a maximum fibre pull-out length of 115.9 μm. At 150 °C, brittle failure with a smooth fracture surface was observed, attributed to grain refinement and microdefect coupling, with GPC results ruling out molecular chain degradation. A constitutive model was developed to capture the coupled effects of temperature and raster angle, with parameters identified and validated using a particle swarm optimisation algorithm. The model demonstrated strong predictive capability across a wide temperature range and different raster angles, providing a cross-scale description from micro-mechanisms to macroscopic behaviour. This work provides valuable experimental and theoretical insights for the design and performance evaluation of high-performance composites in high-temperature environments.