Benchmarking PA12 and PA12CF35 for selective laser sintering of patient-specific implants: a thermo-mechanical analysis

The present research investigates the impact of carbon-filler reinforcement on the thermo-mechanical characteristics of polyamide 12 (PA12) during Selective Laser Sintering (SLS) for the production of specific cranial implants. A complete thermo-mechanical finite element analysis was developed using user subroutines (DFLUX, UMAT, and UEPActivationVol) from a commercial software Abaqus for modeling variations of temperature, warpage, crystallization kinetics, shrinkage, and residual stresses accumulation during the complete layer-wise sintering fabrication process. The model underwent quantitative validation against experimental benchmarks, demonstrating dimensional deviations of less than 5 % and warpage prediction errors below 15 %, thereby affirming its predictive reliability. The validated framework was subsequently utilized to compare neat PA12 with a 35 % carbon filler-reinforced composite (PA12CF35). The research results suggest that PA12CF35 displays a 26 % improvement in solidification speed, a 17.5 % decrease in shrinkage, and an estimated 5 % enhancement in warpage resistance compared to PA12. The use of carbon fillers improves thermal conductivity and reduces the peak temperature by 3.4 %, allowing more uniform melting and cooling across consecutive layers. Additionally, PA12CF35 exhibits a 7.7 % decrease in residual stress, resulting in improved structural stiffness and dimensional stability post-solidification. The assessed results reveal that the designed model approach efficiently guides process optimization and composite design in polymer-based SLS. The enhanced thermo-mechanical properties of PA12CF35 underscore its suitability for advanced cranial implants developed via additive manufacturing.