## 3 Design and Simulation of Bionic Tea Cutters
### Explicit Dynamic Analysis  
In order to study the changes in the tea stalks during the harvesting of tea leaves by the cutter, the contact between the cutting teeth of bionic cutters and the stems was taken as the starting point and the stem breakage was taken as the end point. In this study, ANSYS Explicit Dynamics was used to conduct the explicit dynamic simulation test for the above work process. The detailed operations are as follows. Figure 9: Static simulation test of cutting teeth. (**A**) Ordinary trapezoidal tooth. (**B**) Ordinary saw tooth. (**C**) Bionic cutting tooth 1. (**D**) Bionic cutting tooth 2. (**E**) Bionic cutting tooth 3. In this study, the bionic tea-harvesting cutter was set 70 mm away from the root of the tea stalk to cut the tea stalk. The 3D cutting tooth models of four bionic tea-harvesting cutter schemes are imported into the Explicit Dynamics of ANSYS workbench in STP format, and then the cutting teeth of the bionic tea-harvesting cutter and the cutting mechanical property parameters of tea stems are set in Engineering Data, as shown in Table 3. Secondly, material performance parameters and properties are specified for each model, with the stiffness of bionic cutting teeth as rigidity and the tea stalk as flexibility. We then use the Manual Contact Region in Connections and set the contact type as friction between the two bionic cutting teeth of each scheme and the tea stem, respectively, and the friction coefficient is 0.3. Finally, Mesh was selected to refine the surface of the cutting teeth edges and the whole tea stem module. The average diameter of the cross section of the tea stem was 2 mm. In order to simulate tea harvest conditions, fixed support constraints were added to the lower part of the tea stem structure model (that is, the root of the tea stem), and Displacements were added to the two bionic cutting teeth to make the bionic cutting teeth produce horizontal relative displacements, thus realizing the cutting simulation analysis of the tea stem, as shown in Figure 10. Click on Solve and once solved, the process of cutting the tea stalks is shown in Figure 11 to evaluate the maximum equivalent elastic strain of the model and the maximum force reaction of the two bionic cutting teeth. Figure 10: Explicit dynamics constraint load settings for bionic cutting teeth 3 and 4. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Test Materials**} & \multirow{2}{*}{
\begin{tabular}{c} **Density/** \\ **kg\(\cdot\)mm\({}^{-3}\)** \\ \end{tabular} } & \multicolumn{3}{c}{**Isotropic Elasticity**} \\ \cline{2-5}  & & **Young’s Modulus/MPa** & **Poisson’s Ratio** & **Bulk Modulus/MPa** & **Shear Modulus/MPa** \\ \hline Cutting tooth & \(7.85\times 10^{-6}\) & 200,000 & 0.3 & \(1.6667\times 10^{5}\) & \(7.6923\times 10^{4}\) \\ Tea stalk & \(6\times 10^{-7}\) & 54.28 & 0.344 & 57.991 & 20.193 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Parameters of cutting teeth and tea stalk. The state of tea stalks and bionic cutting teeth before cutting is shown in Figure 11A. When the bionic cutting teeth start cutting, extrusion deformation occurs between the tea stalk and the cutting teeth edge surface. Subsequently, the bionic cutting teeth edges continue to move to squeeze the surface of the tea stem, and the surface of the stem begins to break, as shown in Figure 11B. When the bionic cutting teeth edges cut into the tea stalk at a certain depth, the surface of the tea stalk fracture is extruded with the beveled surface of the teeth edges, as shown in Figure 11C. Finally, the state when the tea stalk breaks and completely separates is shown in Figure 11D. In this study, the relative cutting styles of ordinary trapezoidal teeth (Figure 12A), ordinary saw teeth (Figure 12F), and three bionic cutting teeth (as shown in Figure 12B-E,G) were compared one by one. Figure 12 shows the equivalent elastic strain cloud map of the explicit dynamic simulation test of ordinary trapezoidal teeth, ordinary saw tooth and three kinds of bionic cutting teeth.