Abstract
Dynamic analysis of grain motion in an experimental rubber roll husker was carried out using short and long grain rice. The short grain rice variety used was Akitakomachi and the long grain rice varieties were Delta and L201. Single grains used in the analysis were fed vertically and horizontally in between the rollers. Considering the direction of grain feed and the shape of the grain, a new equation for contact distance was derived based on the radius of curvature of the grain. The new equation gave a better estimation of contact distance compared to the traditional equation. Contact distance was used in the computation of grain speed, projected area and contact area. Grain motion was observed using a high-speed camera. Computed grain speed was found to be closer to the auxiliary roll speed than the main roll speed and at low roll deflection, projected area was close to contact area. Maximum shear stress determined from shear force caused by friction force and projected area occurred close to the maximum husking energy efficiency.
