# Experiment and Analysis on Friction Damage and Energy Loss Characteristics of Potatoes
## 3 Results and Discussion  
### Factorial Test Results and Discussion  
The factors and their levels in the factorial test are shown in Table 1. After determining the factor level, Minitab software was used to design the trial in the form of \(-1\) and \(+1\) codes. The 2V5-1 trial design was used and a total of 16 groups of trials were required. At the same time, the proportion of epidermal damage was taken as the test index. Each group of trials was repeated 10 times, and the average value was taken as the test result. The design scheme and results are shown in Table 2. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Factors**} & \multirow{2}{*}{**Coding**} & \multicolumn{2}{c}{**Coding Level**} \\ \cline{3-4}  & & **Low Level (\(-\)1)** & **High Level (+1)** \\ \hline Initial height (mm) & \(X_{1}\) & 300 & 700 \\ Potato mass (g) & \(X_{2}\) & 150 \(\pm\) 5 & 550 \(\pm\) 5 \\ Potato varieties & \(X_{3}\) & Xuechuanhong & Xisen 1 \\ Friction materials & \(X_{4}\) & Potato & 65 Mn steel \\ Temperature (\({}^{\circ}\)C) & \(X_{5}\) & 4 \(\pm\) 1 & 22 \(\pm\) 1 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Table of factorial test factors and levels. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Test**} & \multicolumn{4}{c}{**Factors**} & \multicolumn{2}{c}{**Epidermal Damage**} \\ \cline{2-7}  & **Initial Height** & **Potato Mass** & **Potato** & **Friction** & **Temperature** & **Proportion** \\  & **(mm)** & **(g)** & **Varieties** & **Materials** & **(\({}^{\circ}\)C)** & **(\%)** \\  & \(X_{1}\)** & \(X_{2}\)** & \(X_{3}\)** & \(X_{4}\)** & \(X_{5}\)** & \\ \hline
1 & 1 & \(-1\) & 1 & \(-1\) & 1 & \(13.03\pm 2.64\) \\
2 & 1 & 1 & 1 & \(-1\) & \(-1\) & \(24.80\pm 2.83\) \\
3 & 1 & 1 & 1 & 1 & \(22.69\pm 2.17\) \\
4 & 1 & 1 & \(-1\) & 1 & \(-1\) & \(15.97\pm 1.68\) \\
5 & \(-1\) & \(-1\) & 1 & \(-1\) & \(-1\) & \(4.49\pm 1.58\) \\
6 & 1 & \(-1\) & \(-1\) & \(-1\) & \(-1\) & \(5.51\pm 1.05\) \\
7 & 1 & 1 & \(-1\) & \(-1\) & \(1\) & \(14.06\pm 3.34\) \\
8 & \(-1\) & 1 & \(-1\) & \(-1\) & \(-1\) & \(6.10\pm 1.42\) \\
9 & 1 & \(-1\) & \(-1\) & 1 & \(1\) & \(8.47\pm 1.03\) \\
10 & \(-1\) & \(-1\) & \(-1\) & 1 & \(-1\) & \(6.49\pm 1.27\) \\
11 & \(-1\) & 1 & \(-1\) & 1 & \(1\) & \(5.58\pm 1.80\) \\
12 & 1 & \(-1\) & 1 & 1 & \(-1\) & \(12.19\pm 1.65\) \\
13 & \(-1\) & 1 & 1 & \(-1\) & \(1\) & \(7.85\pm 1.52\) \\
14 & \(-1\) & 1 & 1 & 1 & \(-1\) & \(13.48\pm 2.83\) \\
15 & \(-1\) & \(-1\) & \(-1\) & \(-1\) & \(1\) & \(6.32\pm 1.99\) \\
16 & \(-1\) & \(-1\) & 1 & 1 & \(1\) & \(4.34\pm 1.53\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Factorial testing design scheme and results table. The analysis of variance was carried out under the condition that the data conformed to a normal distribution. The data were first subjected to the Shapiro-Wilk test using SPSS software, and the sample data were all found to conform to a normal distribution. Then the variance of the test results was analyzed by Minitab software, and the results are shown in Table 3.  
According to Table 3, the significant factors affecting friction damage to potatoes are initial height, potato mass and potato varieties. Among them, the effect of initial height is extremely significant, and the effects of potato mass and varieties are significant. There are many studies on the significant factors affecting the damage characteristics of potatoes, most of which were obtained through the potato drop impact test. Among them, some studies showed that the significant factors affecting the impact recovery coefficient of potatoes were the impact material, falling height, potato mass and moisture content [26]. Another study concluded that the order of factors affecting the depth of potato collision damage was: falling height, impact material, impact times and potato mass [13]. Similarly, the initial height, potato mass, potato temperature and collision materials were identified as significant factors affecting the collision damage volume of potatoes [27].