## 3 Results  
Representative waveforms depicting the relationship between cutting force and deformation for willow stems at a constant moisture content (25.43%) and varying cutting angles (0, 15, 30, 60\({}^{\circ}\)) are shown in Figure 3. Figure 4 presents the relationships observed when cutting willow stem samples with varying moisture content at a fixed cutting angle (45\({}^{\circ}\)). Figure 3: Waveforms showing cutting force versus deformation when cutting willow stems at a moisture content of 25.43% and cutting angles of 0, 15, 30, and 60\({}^{\circ}\). The relationships obtained were used to calculate shear stress and specific cutting energy, as summarised in Tables 3 and 4. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**MC, \%** & **Angle, \({}^{\circ}\)** & & \multicolumn{2}{c}{**Shear Stress \(\tau_{t}\), MPa**} & \multicolumn{2}{c}{**CV ***} \\ \hline  & & **Mean** & **Min \({}^{\star}\)** & **Max \({}^{\star}\)** & **SD \({}^{\star}\)** & \\ \hline  & 0 & 9.29 & 8.18 & 10.47 & 0.78 & 8.38 \\
46.30 & 15 & 9.79 & 8.29 & 11.37 & 1.05 & 10.74 \\  & 30 & 8.15 & 6.80 & 9.59 & 0.93 & 11.37 \\  & 45 & 8.81 & 7.73 & 9.72 & 0.62 & 7.07 \\ \hline  & 0 & 13.79 & 12.31 & 15.65 & 1.04 & 7.53 \\
37.05 & 15 & 13.54 & 12.35 & 15.51 & 0.94 & 6.94 \\  & 30 & 11.11 & 8.61 & 16.08 & 2.25 & 20.29 \\  & 45 & 6.84 & 6.42 & 7.32 & 0.31 & 4.55 \\ \hline  & 0 & 10.41 & 8.76 & 11.92 & 0.95 & 9.13 \\
25.43 & 15 & 16.52 & 14.87 & 18.09 & 1.02 & 6.18 \\  & 30 & 11.17 & 9.94 & 12.21 & 0.63 & 5.65 \\  & 45 & 7.37 & 5.81 & 8.45 & 0.93 & 12.61 \\ \hline  & 0 & 13.51 & 10.84 & 15.34 & 1.28 & 9.51 \\
15.21 & 15 & 13.93 & 11.39 & 16.89 & 1.77 & 12.70 \\  & 30 & 12.57 & 10.85 & 15.82 & 1.65 & 13.13 \\  & 45 & 9.58 & 8.20 & 11.88 & 1.11 & 11.62 \\ \hline  & 0 & 10.77 & 9.21 & 12.71 & 1.19 & 11.09 \\
1.35 & 15 & 10.21 & 9.45 & 11.69 & 0.70 & 6.88 \\  & 30 & 12.20 & 10.39 & 15.08 & 1.48 & 12.13 \\  & 45 & 6.96 & 5.54 & 7.84 & 0.71 & 10.22 \\ \hline \hline \end{tabular} \({}^{\star}\)CV—Coefficient of variation; SD—Standard definition; Min—Minimum value; Max—Maximum value.  
\end{table} 
Table 3: Shear stress values \(\tau_{t}\) obtained. Figure 4: Waveforms showing cutting force versus deformation when cutting willow stems with a fixed angle (45\({}^{\circ}\)) and with plant moisture content of 46.30, 37.05, 25.43, 15.21, and 1.35%. The results of multivariate analysis of variance revealed that both moisture content and sliding-cutting angle had highly statistically significant effects on shear stress and specific cutting energy values (Tables 5 and 6, Figures 5 and 6). The analysis included bivariate interactions between the studied parameters, which were also found to be significant. A comprehensive evaluation of the test results suggests that shear stress values vary more significantly with changes in the sliding-cutting angle than specific cutting energy values. For specific cutting energy, plant moisture content exerts a stronger influence on the observed values. The method of comparing the averages allowed us to clarify the differences detected by the analysis of variance [71; 72; 73]. It made it possible to group the obtained mean values and to isolate homogeneous groups, i.e., those for which there are no statistical differences [74; 75]. The confidence intervals do not overlap, and the difference between the means is significant. For greater readability of the results, presented in Table 6, they have been arranged in a continuous sequence. On this basis, it can be concluded that the change in the moisture content of willow shoots from 15.21% to 25.43% does not result in a significant change in the shear stress \(\tau_{t}\) and the specific cutting energy \(E_{j}\); they form one homogeneous group. In the case of a change in the sliding-cutting angle for the specific cutting energy \(E_{j}\), the analysis identified only two groups. Group I contains cutting angles \(0^{\circ}\), \(15^{\circ}\) and \(45^{\circ}\), while Group II has angles of \(30^{\circ}\).