# Influencing Factors Analysis and Simulation Calibration of Restitution Coefficient of Rice Grain
## 3 Results and Discussion  
### Results Analysis of Single Factor  
The orthogonal test showed that the contact materials had an extremely significant effect on the coefficient of restitution of rice grain. The single factor test further showed that the restitution coefficient between rice grain and all kinds of contact materials was the Q235 steel plate, plexiglass plate, seed plate, and rubber plate in descending order. The values of Longjing 29 were 0.567, 0.513, 0.508, 0.485; of Wuyoudao 4 were 0.497, 0.477, 0.465, 0.430; of Jijing 88 were 0.541, 0.534, 0.529, 0.461; and of Shennong 9903 were 0.535, 0.518, 0.502, 0.477, respectively, as shown in Figure 6.  
The contact and collision between rice grain and various materials were a very complex process of energy change. During the process of point line plane collision, the rice grain experienced two stages of deformation and recovery, including not only the deformation and recovery of the rice grain surface, but also the relative motion within each material layer [31]. The whole collision process satisfied the law of conservation of energy. When the rice grain fell freely from a certain height, the influence of air resistance on the grain was ignored, and the gravitational potential energy was converted into kinetic energy. The potential energy was the minimum, and kinetic energy reached the maximum immediately before the collision. During the collision, both the rice grain and the collision material produced a certain amount of deformation, and the surface friction of the collision material did work on the rice grain. The collision deformation mainly included elastic deformation and plastic deformation. In the compression stage, part of the kinetic energy was transformed into elastic potential energy produced by elastic deformation, and the other part was transformed into internal energy produced by friction and plastic deformation. In the recovery stage, one part of the elastic potential energy was converted into kinetic energy; the other part was converted into internal energy by friction and potential energy by overcoming gravity. When the rice grain leaves the surface of the contact material, the kinetic energy was transformed into the rebound speed of the rice grains, which made the rice grains rise to a certain height. Because the hardness of the Q235 steel plate was the largest, the contact area of rice grain and its impact was small, and the deformation of steel plate was small, which led  
Figure 6: Effect of contact materials on restitution coefficient of rice grain. Note: The compression of spring was 150 mm, and the moisture content was 18.91%. to the large restitution coefficient of rice grain. However, the hardness of the rubber plate was small, and the contact area of rice grain and its impact was large, and the deformation was large. Most of the energy generated by the collision of rice grains was absorbed by the rubber plate, which played a certain buffer role and made the restitution coefficient of rice grains small. The effect of spring compression on the restitution coefficient of rice grain is second only to the contact materials. The amount of spring compression defined the initial velocity of rice grain in the test of the restitution coefficient. The single factor test showed that the restitution coefficient decreased with the increased spring compression. The quadratic regression equations between the spring compression and the restitution coefficient of [PERSON] 29, [PERSON] 4, [PERSON] 88, and [PERSON] 9903 were obtained. The quadratic regression equations can be used to analyze and predict the relationship between the restitution coefficient of different rice varieties and spring compression, as shown in Figure 7. \(R^{2}\) was used to measure the overall fitting degree of the regression equation. From Figure 7, the minimum value of \(R^{2}\) was 0.985, indicating that the quadratic regression equation had a high fitting degree and good predictability.