PSO-based multi-objective optimization of chemical vapor smoothing parameters in SLS-fabricated PA1101 tetrakaidecahedron lattice structures

Polyamide 11 (PA1101) tetrakaidecahedron (TKD) lattice structures fabricated using selective laser sintering (SLS) were examined to understand the combined influence of structural density and chemical vapor smoothing (CVS) on compressive mechanical performance. Lattices with relative densities of 10-30% were fabricated and treated in a solvent system consisting of hexafluoroisopropanol (HFIP) diluted in dichloromethane (DCM). The treatment was conducted under controlled exposure time (5-15min) and temperature conditions (40-50°C). The results indicate that vapor treatment alters the compressive performance of the lattice structures depending on both density and processing severity. At 10% relative density, ultimate compressive strength increased from 0.29 ± 0.01 MPa in the as-built condition to 0.59 ± 0.16 MPa after vapor smoothing treatment. Correspondingly, Young’s modulus increased from 2.69 ± 0.12 MPa to 4.94 ± 1.35 MPa, while energy absorption increased from 0.16 ± 0.01 J to 0.32 ± 0.06 J. At 20% relative density, it exhibited moderate improvement, with compressive strength increasing from 1.29 ± 0.03 MPa to 1.45 ± 0.11 MPa, and Young’s modulus values increasing from 11.88 ± 0.30 MPa to 12.26 ± 0.86 MPa. Energy absorption varied between 0.69 ± 0.04 J and 0.79 ± 0.15 J after vapor smoothing. For 30% relative density, compressive strength increased from 2.81 ± 0.20 MPa to 3.40 ± 0.38 MPa, while Young’s modulus increased from 23.52 ± 0.36 MPa to 24.97 ± 3.54 MPa, accompanied by energy absorption values increasing from 1.64 ± 0.21 J to 1.93 ± 0.41 J. A particle swarm optimization (PSO) based multi-objective framework was used to determine balanced processing parameters, indicating that higher relative density, combined with moderate exposure time and controlled temperature, provides improved room-temperature compressive strength without a significant reduction in stiffness.