## 3 Results and Discussion
### Results of the Optimisation of the CPM Mechanism Links
#### 3.3.1 Results of Optimising Link 3 of the CPM Main Positioner
The results of the strength analyses of the generated link 3 structures showed that the most favourable result was obtained when using AL 6061 material for optimisation at the 30% volume limit. The final object mass was 0.58 kg. Displacement was also improved by 2.48 mm compared to the original design's 5.43 mm, which in practice improved the value \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Parameter** & **Limit Volume 20\%** & **Limit Volume 30\%** & **Limit Volume 40\%** & **Limit Volume 50\%** \\ \hline Starting mass, [kg] & & 1.43 & \\ Valid value, [\%] & 15 & 27 & 37.6 & 50.0 \\ \hline \multicolumn{4}{c}{Parameters of link 3 after Generative Design optimisation} \\ \hline Displacement, [mm] & 7.3908 & 3.9095 & 2.336 & 1.662 \\ Von Mises Stress, [MPa] & 277.50 & 99.79 & 99.97 & 86.97 \\ Final mass, [kg] & 0.2140 & 0.3860 & 0.5380 & 0.7140 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Results of Generative Design optimisation of link 3—material MG-AL ALLOY. \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Parameter** & **Limit Volume 20\%** & **Limit Volume 30\%** & **Limit Volume 40\%** & **Limit Volume 50\%** \\ \hline Starting mass, [kg] & & 2.153 & & \\ Valid value, [\%] & 14.9 & 26.9 & 38.3 & 50.2 \\ \hline \multicolumn{4}{c}{Parameters of link 3 after Generative Design optimisation} \\ \hline Displacement, [mm] & 6.038 & 2.48 & 1.7284 & 1.0884 \\ Von Mises Stress, [MPa] & 279.76 & 112.74 & 101.01 & 87.06 \\ Final mass, [kg] & 0.3210 & 0.5800 & 0.8240 & 1.0800 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Results of Generative Design optimisation of link 3—material AL 6061. \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Parameter** & **Limit Volume 20\%** & **Limit Volume 30\%** & **Limit Volume 40\%** & **Limit Volume 50\%** \\ \hline Starting mass, [kg] & & 1.43 & & \\ Valid value, [\%] & Not generated & 26.4 & 38.1 & 50.0 \\ \hline \multicolumn{4}{c}{Parameters of link 3 after Generative Design optimisation} \\ \hline Displacement, [mm] & - & 4.27 & 2.63 & 1.66 \\ Von Misses Stress, [MPa] & - & 100.83 & 100.94 & 86.97 \\ Final mass, [kg] & - & 0.3770 & 0.5440 & 0.7150 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Results of Generative Design optimisation of link 3—material MG-AL-ZN ALLOY. of this parameter by 2.1 times. The von Mises stress for the tested design was 112.74 MPa, a slight change from the initial pre-optimisation value of 121.4 MPa, with no major effect on the optimised positioner link. The accumulation of von Mises stresses and the highest value of displacement in the case studied relate to the area of the link that forms the rotational connection to links 4 and 2 of the positioner. In the case of design tests assuming the MG-AL-ZN ALLOY material, the most favourable result was obtained for the Generative Design test at a limit volume of 50%. Although the final mass of the object was the highest of the structures generated (0.715 kg), the von Mises stress value was the lowest (86.97 MPa) and the displacement level was the lowest at only 1.66 mm. For this structure, the mass reduction was 0.10212 kg. In the case of design tests assuming the MG-AL ALLOY material, the most favourable result was obtained for the Generative Design test at a limit volume of 40%. The final object mass was 0.5380 kg. Strength tests showed that the von Mises stress value was 99.97 MPa and the displacement was 2.336 mm. In the case of the structure generated from the material in question, the weight reduction was as high as 0.27912 kg; hence, it represented the best of the results achieved.