Dynamic analysis for the thresher of a combined harvester subjected to stalk winding

Abstract

In this paper, the whirl characteristics and instability of the thresher in a combined harvester subjected to stalk winding are investigated. Using the spinning Timoshenko beam assumptions, the governing equations of motion for the thresher-stalk system are obtained via Hamilton’s principle. Considering the elastic end supports, the exact and approximated dimensionless whirl frequency equations are derived. On the basis of the obtained formulas, both whirl characteristics and stability of the thresher-stalk system are investigated numerically, and the validation of the present analysis is conducted by comparing with the results available in the literature. In addition, the effects of mode number, mass ratio, eccentric distance, shear deformation, and slenderness ratio on the critical spinning speed, stability, and instability boundary are deeply discussed. The results show that the whirl characteristics and stability of the thresher-stalk system are strongly dependent on the stalks wound around the thresher.