TEST AND ANALYSIS OF MECHANICAL PROPERTIES OF BUCKWHEAT STEM DURING HARVEST

Abstract

Buckwheat crops are subjected to complex stress during harvest. And there are problems such as large deformation, severe brokenness, and high energy consumption of stems during the mechanical harvesting, such as cutting, transporting, threshing, separating and cleaning. In this study, the mechanical properties of buckwheat stem during mechanical harvesting were tested, including tensile, bending, shearing and dynamic cutting, and the effects of moisture content, stem position and working parameter on their mechanical properties were analyzed. The test results showed that the tensile strength, elastic modulus, cutting stress and unit area cutting energy of stem with higher moisture content were significantly greater than those of stem with lower moisture content (P<0.05). The flexural modulus and bending strength of stem with higher moisture content were significantly lower than those of stem with lower moisture content (P < 0.05). The flexural modulus, bending strength, shear strength, cutting stress and unit area cutting energy decreased gradually with the stem height increasing. The cutting parameters had significant effects on the mechanical properties of stem (P<0.05), and the cutting mechanical properties first decreased and then changed steadily with the average cutting speed increasing. The cutting stress gradually decreased with the blade oblique angle increasing, but the unit area cutting energy decreased first and then increased. The average cutting speed and blade oblique angle of buckwheat stem are recommended to be 0.75-1.0 m/s and 30o, respectively. This research can provide basic data for the design of the buckwheat harvesting machinery