## 3 Results and Discussion
### Additive Manufacturing Results  
To visualize printing defects in the cellular structures incorporated in the internal part of the insole and calculate their printing time, the insole was manufactured with BCC and TPMS cellular structure with 14.57% relative density (see Figures 13 and 14, respectively). The printing time for the BCC cell structure was 36 h, while, for the TPMS cell structure, it was 50 h. The difference could be attributed to the fact that the insole with surface structure was fabricated with a layer height of 0.1 mm because the geometry of the unit cell is more complex. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Author** & **Insole Material** & \
\begin{tabular}{c} **Internal Structures of** \\ **the Insole** \\ \end{tabular} & **Max. Deformation (mm)** &
\begin{tabular}{c} **Max. Von Mises Stress** \\ **(MPa)** \\ \end{tabular} \\ \hline \multirow{3}{*}{This work} & TPU & Unit cell & 1.29 & 11.99 \\  & BCC & 0.04 & 0.59 \\ \cline{1-1}  & TPU & Solid & 0.47 & 0.07 \\ \cline{1-1}  & DuraForm PA & Solid & 0.98 & 0.121 \\ \cline{1-1}  & EVA & Solid & - & 0.25 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Comparison of simulation results with other works. A sectioned insole model was printed, as presented in Figures 13 and 14, to observe the printing quality corresponding to the insoles with BCC and TPMS cellular structure, respectively. Selected areas were used for analysis. In Figure 13a, it can be observed that the joining between the BCC cells presented threads and that the size of the struts varies between unit cells. In contrast, in Figure 14a, a difference between the internal circumferences of the surface structure can be appreciated, presenting the \"stair-stepping\" effect, causing the curvatures not to be smooth. This effect is common in cellular structures  
Figure 14: Insole resulting from additive manufacturing by the FFF method. (**Left**) Insole with TPMS cellular structure. (**Right**) Cross-section of the TPMS cellular structure inside: (**a**) TPMS cellular structure; (**b**) narrow zone; (**c**) arc periphery; (**d**) sloping periphery. Figure 13: Insole resulting from additive manufacturing by the FFF method. (**Left**) Insole with BCC cellular structure. (**Right**): Cross-section of the BCC cellular structure inside: (**a**) BCC cellular structure; (**b**) narrow zone; (**c**) arc periphery; (**d**) sloping periphery. manufactured via FFF. The authors of [38; 39] analyzed the manufacture of various cellular structures and reported that all of them presented this effect regardless of the printing parameters, although the effect is more notable when the layer height is greater. Comparing Figures 13a and 14a, note that the layer height used in the printing process has a direct impact on the building of the unit cell. For instance, for the BCC topology with a layer height of 0.28 mm was used and the constituent strut resulted in various diameter variations along their length. On the other hand, in the TPMS structure, a layer height of 0.1 mm was implemented and the geometry of the cellular structure was formed with higher accuracy, except for a slight accumulation of excess material near the edges of the insole outer surface. The resulting variation in layer height between the models (and other defects) could affect both the accuracy of the building of the cellular topology and the stress concentration and distribution. Figures 13 and 14 were obtained from intentionally designed sectioned insole models. These were designed and used for demonstration purposes, allowing visual inspection of the printing results at the inner zones of the insole. Figures 13b and 14b show where the unit cells were partially located. As the hollow of the insole area narrowed, the geometry presented more deformations while a quasi-solid area was generated. The areas shown in Figure 13c,d and Figure 14c,d show the contact between the unit cells and the periphery of the insole.