## 2 Finite Element Modeling of the Cutting Head Cutting Rock
### Simulation Results  
The cutting force of the cutting head during rock breaking is shown in Figure 4. It can be seen that the cutting force fluctuates macroscopically during the cutting process because the number of picks acting on the rock is different at different time periods. At 1 s or so, there were six picks cutting the rock at the same time, so the load was relatively large. Only four picks were simultaneously cutting the rock at about 2 s, so the load was relatively small. As the cutting head is subject to vibration because of microscopic fluctuations in the cutting force, a further analysis regarding the fatigue strength of the pick, pick holder, and drum is needed. As shown in Figure 5, during the rock cutting process, the load exerted by the rock on the cutting pick along the tangential direction of the pick is defined as the cutting resistance, while the load acting along the radial direction toward the center of the drum is defined as the traction resistance. The cutting resistance, traction resistance, and lateral force of a single pick on the cutting head change over time during the rock-breaking process. It can be seen that, during the cutting process, the cutting resistance and the traction resistance fluctuate up and down. This is a basic feature of the cutting force for brittle materials. The force of the cutting head increases noticeably and fluctuates significantly when it first touches the rock. This is because the tool has an existing loading speed during dynamic cutting, and when it touches the rock, it produces a large impact. This results in the pick having a plastic deformation compaction field, and there is a sudden increase in load. At the beginning of the cutting process, both the depth and the applied cutting force are small, so initially, only small pieces of rock are cut. As the cutting head continues to move forward, the cutting depth and the load continue to increase. Similar conclusions can also be found in other studies to support the data presented in this paper [27]. The \begin{table}
\begin{tabular}{c c c c} \hline
**Parameters** & **Value** & **Parameters** & **Value** \\ \hline N & 0.5 & \(k_{1}\) (Pa) & \(8.5\times 10^{10}\) \\ S\({}_{\text{max}}\) & 7 & \(k_{2}\) (Pa) & \(-1.7\times 10^{-11}\) \\ D\({}_{1}\) & 0.0031 & \(k_{3}\) (Pa) & \(2.08\times 10^{11}\) \\ D\({}_{2}\) & 1 & EPSO & 60 \\ \hline \end{tabular} In the above table: \(\rho\) is the density of the rock; G is the shear modulus of the rock; F\({}_{\text{c}}\) is the static yield strength of the rock (compressive strength); Smax is the maximum dimensionless strength; A is the dimensionless viscosity constant; B is the dimensionless pressure enhancement coefficient; C is the strain rate coefficient; N is the dimensionless pressure hardening exponent; D\({}_{1}\), D\({}_{2}\), and \(\epsilon_{\text{fmin}}\) are the material damage constants; \(k_{1}\), \(k_{2}\), and \(k_{3}\) are pressure coefficients; P\({}_{\text{crush}}\), and \(\mu_{\text{crush}}\) are the pressure and volume strain at the crushing point; P\({}_{\text{lock}}\) and \(\mu_{\text{lock}}\) are the pressure and volume strain at the compaction point of the material; T is the pressure constant (tensile strength).  
\end{table} 
Table 1: _Cont._  
Figure 4: Force curve for the drum. lateral force is basically balanced by the interaction with the rock on each side of the cutter. According to the fluctuation curve for the cutting resistance and traction resistance obtained by the simulation, the average values for the cutting resistance and traction resistance were 14.21 kN and 7.19 kN, respectively. The cutting force is one of the most important physical parameters in the cutting process. It determines the amount of power consumed during rock breaking and the fatigue life of the tool. The cutting force also directly affects the heat generated by friction with the rock and the abrasion, breakage, and durability of the tool.