## 2 Materials and Methods
### Mechanical Engineering Analysis
#### 2.2.3 Application of Contacts  
To perform a reliable simulation using FEM, it is necessary to determine the existing contacts between the elements that comprise the ensemble. Autodesk Inventor Professional 2024 allows for the automatic creation of contacts, applying the 'Bonded' contact to all elements, which does not accurately reflect reality. This poses a drawback, necessitating the manual modification of certain components to avoid a time-consuming process due to the large number of contacts. Among the contacts to be selected manually, the most appropriate type can be applied, with the following being particularly noteworthy:  
* Bonded contact: Assumes the rigid fixation of contact faces to each other, preventing them from moving or deforming relatively between other components. It is primarily used for threaded connections, welds, or bonded parts. * Separation contact: Assumes the total or partial separation of contact faces when they slide during the analysis, allowing space between components. This allows components to move when applied forces exceed a certain limit. It is used in modeling where parts are expected to separate, such as in crack opening or component separation itself. * Sliding contact: Assumes the fixation of contact faces in the perpendicular direction of the face while sliding in a specific direction. It is used in situations where sliding is expected, such as in guides. * Separation/no-slide contact: Assumes total or partial contact separation without sliding them against each other. It is used when there is high friction or locking under certain conditions, such as in the case of a rubber part on rough surfaces. * Sliding/shrink fit contact: Provides conditions such as'separation' with components initially overlapped, and therefore, the initial distance between contact faces is negative. It is used for joints where there is a clearance tolerance. * Non-sliding/shrink fit contact: Provides separation conditions without sliding with initially overlapped parts. Used in joints where there is an interference fit tolerance. * Spring contact: Creates equivalent springs between two faces, allowing the definition of total tangential and normal stiffness. It is used to simulate contacts that require controlled compression or expansion forces, such as in elastic elements or suspensions. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Material**} & **Young’s Modulus** & **Poisson** & **Density** & **Yield Strength** \\  & **(MPa)** & **Coefficient** & **(kg/m\({}^{3}\))** & **(MPa)** \\ \hline AISI 1080 Steel & 195,000 & 0.300 & 7850 & 206.84 \\ Brick & 7000 & 0.210 & 2150 & 5.00 \\ Brass & 109,600 & 0.330 & 8470 & 103.40 \\ Cast Bronze & 109,600 & 0.340 & 8870 & 128.00 \\ Copper & 117,500 & 0.340 & 8940 & 46.00 \\ Mild Steel & 220,000 & 0.280 & 7850 & 250.00 \\ Rubber & 3000 & 0.490 & 1250 & 10.34 \\ Stainless Steel & 193,000 & 0.300 & 8000 & 250.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Properties of each material used in the analysis. Subsequently, several examples of the contact types utilized in the assembly are illustrated. Figure 10 depicts the application of a bonded contact between the bedplate and the crankshaft support, employed to simplify the model by eliminating the representation of screws. Figure 11 shows the implementation of a sliding contact between the piston rod and the cylinder front cover. Finally, Figure 12 illustrates the application of a spring contact to the spring located within the control unit and the wall of the dashpot housing, with an identical independent application at the opposing end. Figure 11: Example of application of sliding contact. Figure 10: Example of application of bonded contact. The majority of applied contacts are of the 'bonded' and'sliding contact' types, specifically for the contacts of the valves and piston within the cylinder block, as well as for the crosshead.