Effects of FDM process parameters on dimensional errors of star-shaped negative Poisson’s ratio structures

This work investigates lightweight carbon fiber-reinforced PETG star-shaped stacked structures with a negative Poisson’s ratio (NPR) effect. We systematically evaluated the effect of fused deposition modeling parameters on their dimensional deviations. A 30-group Central Composite Design matrix was used to analyze printing speed, printing temperature, bed temperature, and layer height. Sample dimensions were accurately measured via a coordinate measuring machine. The analysis of variance reveals that outer diameter error is highly sensitive to process parameters. The interaction of printing temperature and layer height is significant for both outer diameter (P < 0.01) and width errors (P < 0.05). The global optimization of the overall dimensional deviation was performed using response surface methodology with an ant colony optimization algorithm. The optimal parameters were a printing speed of275 mm/sec, printing temperature of 240 °C, bed temperature of 47.5 °C, and layer height of 175 μm. Optimized samples underwent quasi-static compression testing and LS-DYNA explicit dynamic finite element simulations. During compression, the structure displayed three distinct stages: a linear elastic stage (0–2 mm), a stable plastic deformation energy absorption plateau (2–10 mm, loads of 200–400 N), and a densification stage peaking at 709.8 N. Simulations accurately reproduced strut bending and deep folding behaviors across strain levels, visually verifying the uniform transverse contraction characteristic of the NPR effect. In this study, we have successfully optimized the process parameters and compensated for the dimensional errors. These results are beneficial guidelines for the manufacture of high-precision lightweight NPR units with better energy absorption performance.