# Comparison of CAD Software for Designing Cellular Structures for Additive Manufacturing
## Discussion
### Carbon(r) Design Studio Pro  
The program Design Studio Pro is proprietary software to help designers and engineers construct lattice structures with respect to the available AM machines as well as resins developed by Carbon(r) Inc. Unlike all the previously examined programs, this application runs directly in the browser, which is an advantage with respect to usability. All geometries, however, must be uploaded into the browser to produce the desired lattice structure design. Upon upload, the geometry can only be filled with a small number of different types of lattices such as icosahedral, Kagome, rhombic, tetrahedral, and Voronoi. The operation of the program is intuitive, and all necessary commands to form a lattice structure are clearly presented in an uncluttered workspace. The import of the geometry was performed in the form of STEP files. It is important to point out that the geometry of the helical gear was divided into the outer solid, the inner solid, and the design space in between (as described in Section 2). However, Design Studio Pro merged the three geometries into one single geometry upon import. Therefore, all three bodies had to be imported separately in order to fill only the design space with lattice structures (Figure 15a). As mentioned, before it was not possible to choose the lattice type in accordance with the previously defined BCC lattice type. Therefore, the tetrahedral and icosahedral lattice topologies with \(8\times 8\times 8\) mm cell size and \(1\) mm strut thickness were chosen (see Table 12). After the lattice generation, two additional operations, including solidify lattice and combine, had to be performed to generate unified meshes. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Criteria** & **Icosahedral** & **Tetrahedral** & **Relative Change** \\ \hline Lattice processing time & 17.4 s & 20.9 s & 20.1\% \\ Lattice solidifying time & 19.8 s & 21.35 s & 7.8\% \\ Lattice combine time & 21.4 s & 25 s & 16.8\% \\ Total & 58.6 s & 1 min 7.2 s & 14.7\% \\ \hline \hline \end{tabular}
\end{table} 
Table 12: Tetrahedral and icosahedral lattice generation calculation times of the helical gear in Design Engine Pro. Figure 15: Workflow for the helical gear in Design Studio Pro: (**a**) design space and (**b**) generated lattice structure. After the lattice generation, the model was exported as an STL-File, and the values are presented in Table 13.  
The same approach was used to generate a lattice within the design space of the bike seat, as seen in Figure 16. It is noticeable that in the narrow areas at the front of the seat, where the design space touches the inner and outer solids, the software was unable to generate a lattice. However, this is due to the fact that the cell dimensions were defined too large to fit these specific areas of the seat. The computed as well as the measured results can be seen in Tables 14 and 15. Additional capabilities  
* Basic shapes can be added to the uploaded geometry (cube, cylinder, sphere). * Lattices can be populated uniformly or with point clouds (*.csv-files). * Gradient lattices can be generated. * Structures can be trimmed, and individual struts can be removed. * Lattice performance can be analyzed (limited to Carbon's resin materials). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Criteria** & **Tetrahedral** & **Icosahedral** & **Relative Change** \\ \hline Resolution & no information & no information & \\ Export time & 10.7 s & 12.6 s & 17.8\% \\ File size & 8.2 MB & 15.7 MB & 91.5\% \\ \hline \hline \end{tabular}
\end{table} 
Table 13: Tetrahedral and icosahedral lattice generation values of the helical gear in Design Engine Pro. Figure 16: Workflow for the bike seat in Design Studio Pro: (**a**) design space and (**b**) generated lattice structure.