Page 274 - IJB-10-1

International Journal of Bioprinting Permeability of NiTi gyroid scaffolds

Figure 6. Contour plots of gyroid sample 302: (a) cross-section of pressure contour, (b) velocity contour, (c) cross-sections of velocity contour.

Table 3. The regression equation coefficients for permeability wall thickness indicate the LPBF resolution limitation. In
20
calculation the previous study, a higher resolution was achieved by
implementing a single track-based scanning strategy for
Coefficient Estimate p-value manufacturing NiTi micro-objects. However, the reported
C 0 -9.9955e-10 0.69956 approach does not apply to the orthopedic scaffolding
C 6.0960e-9 0.02614 and implants. Thus, a single contour strategy results in a
1
C -2.7883e-8 0.00838 wall thickness of at least 150 µm, which is considered to
2
C -1.3047e-8 0.00214 be the limit for conventional lasers and powder fractions.
3
C 3.7383e-8 0.00867 Finally, the biomimetic limitation refers to the highest
4 permeability values for a cancellous human bone that have
C 5 -1.3047e-8 0.00062 been reported elsewhere. 15,16

porosity, which is more often used in the literature. In 3.3. Comparison of numerical and experimental
the considered window of design parameters, contours permeability
have close slopes that correspond to equivalent mass The in-plane permeability measurements with radial
transport behavior with an increase or decrease in overall unsaturated impregnation were conducted to validate the
porosity. Interestingly, the growth rate of the permeability CFD model. The in-plane radial experiment was chosen due
coefficient increases with unit cell size. Notably, a predicted to the following reasons. First, measurements were performed
zero permeability coefficient corresponds to the closure for two directions of porous media at once. Second, it
of channels in the gyroid structure. The lower values of was observed that the gyroid structures manufactured via

Volume 10 Issue 1 (2024) 266 https://doi.org/10.36922/ijb.0119