Design and evaluation of selective laser sintering of thermoset lattice structures

In the realm of additive manufacturing (AM), the construction of complex geometries, notably lattice configurations such as body-centered cubic (BCC), body-face-centered cubic (BFCC), and triply periodic minimal surface (TPMS) gyroid structures, represents a significant advancement that can fully utilize the design space AM offers. Though there have been many advancements in realizing these designs using thermoplastic AM, their mechanical and thermal properties are often suboptimal due to their thermoplastic nature. This study introduces the use of epoxy-based thermoset powder in selective laser sintering to fabricate BCC, BFCC, and TPMS gyroid lattice structures with a comprehensive thermomechanical properties analysis. The research investigated the physical and geometric attributes of 3D-printed parts before and after post-curing. Then we further assessed their compressive properties, deformation mechanism, and energy absorption capabilities at room temperature (RT) and an elevated temperature (ET) of 80 degrees C. The results demonstrate that TPMS (sheet-based) structures have superior mechanical properties compared to strut-based structures printed with thermoset material. Specifically, the gyroid structure demonstrated 941.5% higher specific strength than the BCC and 214.1% higher than the BFCC structure when tested at RT. At 80 degrees C, the structure displayed an even greater dominance, with a 1579.4% increase over the BCC and a 718.8% increase over the BFCC lattice. Finite element analysis was conducted to facilitate the understanding of their compressive behavior. Furthermore, it was found that the TPMS gyroid showed significant energy absorption capacity, especially at the ET (2040 kJ/g m3), and an extended plateau strain before densification, compared to BFCC (82.2 kJ/g m3) and BCC (58.2 kJ/g m3) structures. This study indicates that thermosets have great potential to deliver enhanced compressive and thermal resilience with considerable impact resistance capabilities, particularly for TPMS structures.