Understanding compressive viscoelastic properties of additively manufactured PLA for bone-mimetic scaffold design.

Bone tissue engineering has been recognized as a promising strategy to repair or replace damaged bone tissues. The mechanical properties of bone scaffolds play a critical role in successful bone regeneration, as it is essential to match the mechanical properties of the scaffold with the surrounding bone tissue. In this study, we investigated the effects of fused deposition modeling (FDM) process parameters, including printing speed, printing temperature, and layer thickness, on the compressive viscoelastic properties of polylactic acid (PLA) scaffolds. The compressive viscoelastic properties of bulk PLA specimens were characterized using a Zhu-Wang-Tang (ZWT) constitutive model under different compressive strain rates. A comprehensive statistical analysis comprising multivariate and univariate analysis of variance (MANOVA and ANOVA) and Tukey's post hoc analysis was utilized to quantify the effect of each FDM parameter on the viscoelastic mechanical properties of the PLA specimens. Subsequently, we fabricated modified face-centered cubic (MFCC) scaffolds using FDM and varied the FDM process parameters to achieve a compressive viscoelastic response that matched the natural trabecular bone tissue. The viscoelastic performance of the MFCC scaffolds was compared with traditional orthogonal cylindrical struts (OCS) scaffolds. Our methodology contributes to the design of bone-mimetic scaffolds with optimized mechanical properties by controlling FDM process parameters.