Theoretical analysis of micro-vibration between a high moisture content rape stalk and a non-smooth surface of a reciprocating metal cleaning screen matrix

• Physical contact model between rape stalk & non-smooth metal reciprocating surface.
• Mathematical model built according to theorem of impulse and the collision theory.
• Equivalent compact force deduced.
• Differential equations resolved according to Duhamel integral formula.
• Calculation example given to examine correctness of physical & dynamical models.

Because rape stalk has a high water content, rape materials easily adhere to the cleaning screens of combine harvesters leading to a high screen loss. Inspired by friction-reducing research on bionic non-smooth metal surfaces, a special rape cleaning screen with non-smooth surface was developed and compared with a standard screen in field experiment. It showed good anti-adhesion performance to rape components. To understand the mechanism, a reciprocating friction test between a rape stalk and non-smooth metal surface was carried out. The result was consistent with the findings of a field experiment. In the test, a vertical micro-vibration was discovered between rape stalk and the non-smooth metal surface. This did not exist in the case of a common smooth metal surface and was considered as an important factor in the mechanism. In this paper, a theoretical analysis was proposed to explain how the vertical micro-vibrations occurred during a horizontal reciprocating translation of non-smooth units. Firstly, according to the case of friction test, a geometry contact model and a dynamic equation were established. Then computing methods of vertical impact force and its action time were respectively deduced. Finally, a simulation was produced with a time-scale factor of two. The result from the simulation was consistent with basic trend of test data. Although the theoretical analysis requires improvement for further investigation, it could still provide the basis of a theoretical model and the foundation for further friction-reducing research for non-smooth surfaces.