Structural damage modes for rice stalks undergoing threshing

Abstract

When rice stalk is impacted by the threshing bars during threshing process, the grain is separated but the rice stalk is also damaged. Damage of the rice stalk not only increases the energy consumption of process, but also results in small parts of the rice stalk being mixed with the grain increasing the difficulty of grain cleaning. The states of rice stalk before and after threshing were investigated by analysing the state response of rice stalks under the reaction of the threshing bars. The structural damage of rice stalks was analysed by comparing the relationship between the threshing force and the reaction tensile force, the bending force, and the pressing force during threshing. Damage modes were observed from the microstructure of rice stalks and rice leaves. The results showed that during rice stalk threshing, the force of the threshing bar was between 36.4 N and 121.0 N. Single rice grain and multiple grains are threshed, hollow stalks, stalk node and leaves are pressed damage and stalk root and stalk nodes maybe tensile damaged in threshing process. The microstructure of rice stalk following threshing was destroyed. The thin-walled tissues were completely deformed and the original structure was not visible. The main connections between the rice leaves were interrupted and flat, completely losing the normal shape of the original leaves. The research results revealed the level of the reaction force and microstructure damage of rice stalks. • Threshing force and reaction force reveals damaged distribution of rice stalk. • Rice stalk damage modes were obtained from microstructure after threshing. • Rice stalk is damaged during the process of grain threshing and separated.