## 4 Wear Evaluation Results  
### Wear Shape Comparison  
A cross-section was selected from the height direction of the wear plate, and the calculated wear shape and cross-sectional area loss ratio were compared with the experimental results. Seven sections were selected 25, 75, 125, 180, 200, 202, and 204 mm apart from the uppermost surface of the specimen, and the worn cross-sectional shape and cross-sectional area loss ratio were compared. In Figure 9, the wear cross-sectional shape measured after the experiment was performed and predicted by the analysis were compared. The area loss ratio for each section is shown in Table 3. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Soil Particles** & **Wear Plate** \\ \hline Density [kg/m\({}^{3}\)] & 1560 & 7850 \\ Bulk Young’s modulus [MPa] (Equation (7)) & 40 & \(2\times 10^{5}\) \\ Poisson’s ratio & 0.3 & 0.3 \\ Shear work ratio [m\({}^{3}\)/J] (Equation (13)) & – & 500 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Material properties. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Soil Particle–Soil Particle** & **Soil Particle–Wear Plate** \\ \hline Static friction coefficient (Equation (3)) & 0.6 & 0.5 \\ Dynamic friction coefficient (Equation (3)) & 0.3 & 0.5 \\ Tangential stiffness ratio (Equation (8)) & 1 & 1 \\ Restitution coefficient (Equation (6)) & 0.2 & 0.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Material interaction properties. Figure 9: Comparison of wear shape: (**a**) reference study [22]; (**b**) present study. The reference study ([PERSON] et al. [22]) showed that the experimental and analysis results were consistent with the lower section, but there was a significant difference at the upper section. The simulation model presented in this study was more consistent with the experimental results in all sections. It also performed relatively accurate evaluations of the wear shape. For the cross-section at 25, 75, and 125 mm evaluated in this study, the protruding area was worn in a curved shape, which is similar to the shape of the experiment. The cross-sectional wear shape at 200, 202, and 204 mm was predicted to be rounded at angular corners, which is similar to the experimental measurement results. Figure 10 shows the shape and amount of wear on the surface of the specimen, and regions 1 and 2 are worn in a rounded shape. It shows that the angular part is worn in a circular shape in region 3, and the amount of wear on the bottom part of the specimen is relatively large due to the compacted particles. The wear evaluation results of each section are shown in Figures 11-14. The wear shape predicted in this study was similar to the wear shape measured by the reference study. Figure 10: Distribution of worn surface on the surface of specimen predicted by simulation. Figure 11: Worn displacement on Section 1. Figure 12: Worn displacement on Section 2. Figure 13: Worn displacement on Section 3. The reference study analyzed the reasons for the difference between the experimental results and the simulation results in two ways. The first reason is that it is difficult to accurately define the nonlinear properties of various types of soil particles in a numerical model. The second reason is that soils that are not uniform in size and type are defined as one type of particle. However, in this study, the same particle properties were used and the particle was modeled as one type, but the wear shape and wear rate could be accurately predicted. These results are related to the size of the particle. Due to the numerical characteristics of the DEM, when the particle size decreases, the time step becomes smaller, and the calculation time increases. Therefore, for the efficiency of the analysis, the particle size applied is larger than the actual size. However, if the ratio between the specimen and the particle in the analysis differs greatly from the actual environment, the relative behavior between the particle and the specimen cannot be accurately simulated.