Dynamic simulation and high-speed photography experiment on corn-ear husking

Abstract: The moisture content of corn kernel is generally 25%-40% when corn ear is harvested in China, which makes it not suitable for using direct way of threshing and harvesting. As an important part of harvesting, corn ear husking plays a great role in the harvest performance. At present, research on the performance of corn ear husker is commonly implemented by field experiments and bench tests. However, these approaches are restricted by the various kinds of corn and the shortage of harvesting time. Therefore, there are limitations on the test results. To deal with the problems mentioned above, a method combining theory analysis, virtual prototyping technology with high-speed photography was proposed in this paper to study the motion pattern of the corn ear on the husking device. First of all, to obtain the main influence factors of husking rate, efficiency and damage rate, the force and movement of corn ear in husking mechanism was analyzed in theory. Secondly, the three-dimensional (3D) model of husking mechanism was established using 3D design software, and then the 3D model was imported to ANSYS/LS-DYNA. After that the finite element model of corn ear and corn husker was set up by setting the material model and adding constraint and load. The velocity of corn ear in the direction of husking roller, the angular speed of corn ear around its own axis and the force of corn ear corresponding to the performance of the corn husker, were obtained by simulation analysis. The simulation results showed that the movement speed of corn ear along husking roller rose from 0.2 to 0.4 m/s with the increase of husking roller rotating speed; the angular velocity of corn ear ranged from 0 to 15 rad/s when the rotating speed of husking roller increased from 350 to 550 r/min; meanwhile, the force which was applied to corn ear increased and showed strong fluctuations, and the maximum stresses under three kinds of working conditions were about 11.9, 14.5 and 16.3 N, respectively. Finally, the husking test bench was built in the basis of the 3D model. The husking experiment was carried out with different rotating speeds of husking roller using high-speed photography. The test bench was made up of base frame, husking device, transmission mechanism, variable frequency motor (rated power of 3 kw), frequency converter, NI National Instruments data acquisition card, computer and high-speed photography (Phantom v9.1). The test condition was mainly consistent with the simulation condition. In order to avoid the influence of different sizes of corn ear, corn ear in the experiment was similar to that in the simulation in length and diameter size. At the same time, for reducing the influence of accidental factors on test results, the experiment was carried out three times. Taking the actual velocity and acceleration of corn ear in the direction of husking roller as validation arguments, the simulation data were compared with the high-speed photography test data. It was found that the simulation results agreed well with the actual results, which verified the validity and accuracy of the simulation model. The result also indicates that the simulation model could be a better alternative to the physical test, which can reduce the development cycle and the number of physical prototype test. The research output will play a significant role in carrying out the optimization design of the corn husker and provide a new method to develop a new husking mechanism.