*3.3. Effect of Material Thickness on Wheat Recovery Coefficient*

Table 5 presents experimental data for different material thicknesses. A distribution map of the factors influencing single-factor material thickness on the recovery coefficient can be created (Figure 5). Analysis demonstrates that under the test premise of utilizing Q235 steel for the collision material and maintaining the drop height at 180 mm, the recovery coefficient of wheat exhibits an increasing trend as material thickness grows. When the thickness reaches approximately 7 mm, the increase in recovery coefficient levels off and stabilizes. Material thickness directly reflects the stiffness properties of the material. As material thickness increases, stiffness follows suit. Consequently, when wheat deformation is reduced during collision events, energy loss also decreases, resulting in a larger elastic recovery coefficient.


**Table 5.** Material thickness unifactor experimental data.

**Figure 5.** Single factor of material thickness affects the recovery factor.

#### *3.4. Effect of Drop Height on Wheat Recovery Coefficient*

The data from experiments with varying fall heights are presented in Table 6, from which a univariate fall height influence factor recovery coefficient distribution map can be derived, as depicted in Figure 6. Upon analysis, it becomes evident that, when utilizing Q235 steel as the collision material and maintaining a constant material thickness of 4 mm, the falling height of wheat grains exerts an influence on the recovery coefficient. For wheat with different moisture content, the impact of falling height on the recovery coefficient remains relatively consistent. As the fall height of wheat grains increases, the recovery coefficient between them and the collision material diminishes. This phenomenon can be attributed to the rising falling height of wheat particles, which leads to increased deformation during collisions with the test plate and heightened frictional resistance between the air and the collision plate. Consequently, the energy loss of wheat particles escalates during the collision process, causing the rebound velocity of grains to decrease after the collision and subsequently leading to a reduced recovery coefficient, as calculated based on the principle of elastic recovery coefficient.


**Table 6.** Single-factor experimental data of drop height.

**Figure 6.** Single factor of fall height affects the recovery coefficient.
