## 3 Results  
### Mechanical Properties of the FDM 3D-Printed and Tensile-Tested ABS Specimens  
The tensile test data for all FDM 3D-printed ABS specimens are shown in Table 7.  
The graphical presentations of the tensile strength and strain for individual FDM 3D-printed ABS tensile-tested specimens are shown in Figures 4 and 5. Figure 4 illustrates the graphical representation of the tensile test outcomes for FDM 3D-printed ABS samples with a 30% fill density (referred to as Case 1), whereas Figure 5 shows the results of tensile tests for ABS samples with a 100% fill density (identified as Case 2). The examination of the graphs in Figure 4, combined with the mechanical parameters detailed in Table 7, clearly indicates that FDM 3D-printed ABS samples with a 100% infill density exhibit enhanced tensile strength and higher values for nominal strain at break. The average value of the tensile strength increased by 28.81% in FDM 3D-printed ABS specimens with 100% infill density (Table 7 and Figure 6a). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{3}{*}{**Case**} & \multirow{3}{*}{\begin{tabular}{c} **Specimen** \\ **Code** \\ \end{tabular} } & \begin{tabular}{c} **Tensile** \\ **Strength** \\ \(\sigma\) \\ \end{tabular} & \begin{tabular}{c} **Strain** \\ \(\varepsilon\) \\ **[\%]** \\ \end{tabular} & \begin{tabular}{c} **Nominal** \\ **Strain** \\ **at Break** \\ \(\varepsilon_{tB}\) \\ **[\%]** \\ \end{tabular} & \begin{tabular}{c} **Young’s** \\ **Modulus** \\ **E** \\ **[MPa]** \\ \end{tabular} \\ \hline \multirow{3}{*}{\begin{tabular}{c} Case 1 \\ \end{tabular} } & 1A\_30 & 19.423 & 2.11 & 2.51 & 1376.824 \\  & 2A\_30 & 19.756 & 2.15 & 3.13 & 1138.182 \\  & 3A\_30 & 19.545 & 2.14 & 2.42 & 1409.644 \\  & 4A\_30 & 18.911 & 2.22 & 2.76 & 1278.181 \\  & 5A\_30 & 19.912 & 2.17 & 2.54 & 1400.937 \\ \cline{2-6}  & \begin{tabular}{c} Average (St. \\ Dev.) \\ \end{tabular} & 19.509 (0.384) & 2.16 (0.04) & 2.67 (0.28) & \begin{tabular}{c} 1320.754 \\ (114.695) \\ \end{tabular} \\ \hline \multirow{3}{*}{\begin{tabular}{c} Case 2 \\ \end{tabular} } & 1A\_100 & 26.715 & 2.33 & 4.75 & 1730.422 \\  & 2A\_100 & 28.635 & 2.26 & 3.22 & 1831.286 \\  & 3A\_100 & 27.187 & 2.28 & 3.09 & 1751.838 \\  & 4A\_100 & 27.545 & 2.13 & 3.11 & 1920.691 \\  & 5A\_100 & 26.925 & 2.20 & 3.92 & 1788.691 \\ \cline{2-6}  & \
\begin{tabular}{c} Average (St. \\ Dev.) \\ \end{tabular} & 27.401 (0.756) & 2.24 (0.08) & 3.62 (0.72) &
\begin{tabular}{c} 1804.586 \\ (75.380) \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 7: FDM 3D-printed ABS tensile-tested specimens: test results. Figure 5: The tensile strength–strain curves for ABS specimens produced using FDM 3D printing with a 100% infill density (referred to as Case 2). Figure 6: The mechanical parameters of ABS 3D-printed specimens using FDM were tested under tensile loading conditions at two different infill densities: 30% (Case 1) and 100% (Case 2): (**a**) average tensile strength, (**b**) average strain, (**c**) average nominal strain at break, (**d**) average Young’s modulus. The average value of the strain increased by 3.57% in FDM 3D-printed ABS material specimens with 100% infill density compared to FDM 3D-printed ABS material specimens with 30% infill density (Table 7 and Figure 6b). The impact of infill density on the efficacy of ABS specimens produced via FDM 3D printing is distinctly evident in both the average nominal strain at break and the average Young's modulus, as demonstrated in Figure 6.  
The average nominal strain at break is 26.24% greater in FDM 3D-printed ABS specimens tested for tensile strength with 100% infill density when compared to specimens with 30% infill density (Figure 6c). The average Young's modulus exhibited a similar pattern, as shown in Figure 6d. The average Young's modulus was 26.81% lower in FDM 3D-printed ABS specimens tested for tensile strength with 30% infill density compared to those with 100% infill density.