## 3 Results and Discussions
### Tensile Behavior  
Based on the UTS values, the means and standard deviations were determined for each color and specimen type (characterized by the printing scenario and by the position on the printing plate). The data presented in Table 5 were statistically analyzed using the Three Way ANOVA test. Figure 5: The variation of the cross-section area (mm\({}^{2}\)) for specimens printed in the central position (1.1, 3.2 and 5.3). As shown in Table 5, the maximal differences regarding the UTS values of three simultaneous printed PLA specimens in different positions on the build plate were, as follows: 0.87% for natural PLA; 1.25% for grey PLA; 2.98% for black PLA and respectively 4.97% for red PLA. Similar differences were found in case of five specimens printed simultaneous: 1.51% for red PLA; 2.97% for black PLA; 3.96% for grey PLA and respectively 5.31% for natural PLA. As one can observe, in case of the red and black PLA, increasing the number of simultaneous printed specimens from three to five led to smaller differences between the UTS values of different positioned specimens, while in case of the natural and grey PLA the differences grew up. This phenomenon may be explained as well by the different color-dependent properties of the different PLA types, that lead to different thermal printing conditions and subsequent over-extrusion, respectively under-extrusion, as described below in Section 3.4., when prolonging the time interval between two successive deposited filaments by simultaneous printing of three, respectively five specimens. Using the Three Way ANOVA test, it was examined whether the differences between the means of the measurements were statistically significant and implicitly whether the independent variables (filament color, number of specimens printed simultaneously, position of the specimens on the printing plate) and their interaction had an effect on the dependent variable (UTS). The confidence level was set to 95%. The results of simple main effects test showed that there was a statistically significant difference in:  
* the effect of the filament color on the UTS: F\({}_{01}\)(3,180) = 138.773, p\({}_{01}\) = 0.000;
* the effect of the specimen position on build plate and the UTS: F\({}_{03}\)(8,180) = 4.989, p\({}_{01}\) = 0.000. The strongest effect on UTS is exerted by filament color (\(\eta^{2}\) = 74.3%), followed by specimen position (\(\eta^{2}\) = 17.2%). After validation of the experimental results regarding their significance by the Three Way ANOVA test, the dependencies between independent variables (filament color, printing scenario) and dependent variable (UTS) were visualized by the graphical representations shown in Figure 6.  
As reflected by Figure 6a, the printing scenario with five specimens produced simultaneous led, for all filament colors, to smaller UTS values than those obtained in case of individual printing. The differences are color-dependent and situated between 2.23% for black PLA and 3.63% for grey PLA, the other two colors leading to intermediate reductions, respectively 3.03% for natural PLA and 3.30% for red PLA. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \multirow{2}{*}{**Code**} & \multirow{2}{*}{**Mean**} & \multirow{2}{*}{**Std. Dev. **} & \multicolumn{4}{c}{**UTS (MPa)**} & \multirow{2}{*}{**Mean**} & \multirow{2}{*}{**Std. Dev. **} & \multirow{2}{*}{**Mean**} & \multirow{2}{*}{**Std. Dev.