# Design for Additive Manufacturing: Tool Review and a Case Study
## 4 Results and Discussion. Case Study: A Bicycle Stem  
Next, the case study design of a bicycle stem will be presented. This part is exposed to different loads and is optimized with two different strategies that will create a more efficient design. The part will undergo a topology optimization process and a lattice approach redesign. The goal of both processes is to reduce the part's weight while preserving the defined mechanical requirements. There are several publications that show the design process with advanced tools for additive manufacturing. The application of topological optimization in different aeronautical supports [30] or in classical mechanical elements such as beams or hooks is very common [31; 32]. Different studies show the possibilities of lattice structures regarding their behavior and mechanical properties. However, there are not many specific applications or study cases that illustrate the use of these tools for specific cases in terms of their procedure of use and execution with the combined use of these design tools [33]. The bicycle stem has maximum dimensions of 95 mm, and is loaded with to two main loads of 1500 N that simulate the weight of the user, increasing up to 3000 N to consider possible jumps or overloads, as shown in Figure 4. The bicycle stem also contains screws that are simulated with a load of 100 N in every hole due to the screw pressure and the pressure direction simulates the tightness of the screws. It also has a restriction of movement in all degrees of freedom due to the connection to the bicycle frame. The material selected for the manufacture and redesign of the part is polyamide 6 or nylon, due to its mechanical strength, hardness, rigidity and good toughness, in addition to a strong mechanical damping capacity and good resistance to fatigue and wear. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Scheme** & **Oriented to AM** & **Main Functions Related to AM** & **Ease of Use** & **Cost \({}^{*}\) \\ \hline Inspire & Yes & Optimization/Lattice/Simulation/ & & \\  & & Printing setup & & \\ \hline Abaqus, HyperWorks, & Not specifically but & & & \\ Ansys & useful & & & \\ \hline  & & Basic model- & & \\ \multirow{2}{*}{Ntop} & \multirow{2}{*}{Yes} & \multirow{2}{*}{\begin{tabular}{c} Modeling/Lattice/Mesh \\ editor/Topology optimization \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} Medium/Free \\ student version \\ \end{tabular} } \\ \hline Netfabb & Yes & Lattice/Mesh editor & Medium & High \\ \hline Pareto & Yes & TO & Low & Medium \\ \hline Tosca & Yes & TO and printing setup & Medium & High \\ \hline Paramatters & Yes & TO & Low & Low \\ \hline Digimat AM & Yes & Process simulation (polymers) & Low & Medium \\ \hline Simufact & Yes & Process simulation (metals) & High & High \\ \hline Alphastar & Yes & FEA/Process simulation & Medium & High \\ \hline  & & & & \\ \multirow{2}{*}{Cura/Prusa Slicer} & \multirow{2}{*}{Yes} & \multirow{2}{*}{\begin{tabular}{c} Process condition definition and \\ G-code generation \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} Low \\ Medium \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} Free \\ \end{tabular} } \\ \hline Simplify3D & Yes & \
\begin{tabular}{c} Process condition definition and \\ G-code generation \\ \end{tabular} & Medium & Low \\ \hline Meshmixer & Yes & Mesh edition & Low & Free \\ \hline Magics & Yes &
\begin{tabular}{c} Mesh edition, process conditions \\ definition and G-code generation \\ \end{tabular} & Low & High \\ \hline \hline \end{tabular} \({}^{*}\) Cost is an estimation from the academic environment based on a comparative analysis. Suppliers give specific quotations depending on final use. They can change depending on whether the client belongs to industry, academia or a research center. Note: TO (Topological Optimization).  
\end{table} 
Table 1: _Cont._The initial design was developed with SolidWorks, a parametric design tool, for the problem specifications. Through simple sketching and basic modeling operations, we can configure the geometry.