Dynamic simulation of the Chinese hickory tree under multi-directional forced vibration

Abstract. Vibratory harvesting is an appropriate and efficient way to harvest the Chinese hickory fruits. To detach the fruits from trees, a shaker with large power was used to shake the trunk of fruit trees. However, there were some shortcomings of this way to harvest fruits, such as low efficiency and damages to trees. In this paper, in order to develop an efficient shaker for mechanical harvest, a new vibratory harvesting with multi-directional applied forced was studied. Firstly, the natural frequencies of tree were obtained under modal analysis by finite element software (ANSYS). Secondly, two harmonic forces with orthogonal-directions, the same amplitude and the same frequency were used to impact on the main branch of tree to determine the influence of tree’s dynamic responses with respect to the force direction. Finally, a dynamic testing with vibratory was also implemented to find the relationship between the acceleration response and the mounted angle. Both from the simulation and testing, results show that the radial force may shake the loaded branch, while the axial force can drive the rest branches effectively. It illustrates that the multi-directional excitation is superior to a single-directional excitation for vibratory harvesting fruit.