Energy Transfer Characteristics of Walnut Trunk and Branches in Mechanical Vibration Picking

In order to study the dynamic characteristics of thin bark walnut tree with obvious trunk after artificial pruning under external vibration excitation load, the energy transfer law of mechanical vibration picking was revealed. A dynamic model of the vibration system of walnut tree-picker was established, and the operation mode of the symmetrical double-eccentric walnut picker gripping the trunk was adopted. The field vibration energy transfer test was carried out by installing a three-axis vibration monitoring sensor according to the prescribed path and monitoring point. Combined with the vibration displacement response data of the trunk, the results showed that when stimulated by symmetrical double eccentric vibration, the movement process of the walnut trunk oscillated and reciprocated along the Z direction of the clamping position. According to the variation rules of vibration displacement and kinetic energy amplitude of the forced vibrating branches of walnut tree obtained by the three-axis vibration monitoring sensor, the mechanical energy was converted into kinetic energy during the picking process of walnut vibration, and transferred from the excitation position of the trunk to the free end of the branch in the form of energy waves. In the transmission process, kinetic energy was obtained at each monitoring point in turn, and the longer the transmission distance was, the more the kinetic energy attenuation was. In addition, the branch wobbled and bent in the process of spatial movement, resulting in a small range of instantaneous restorable deformation in the growth direction. Due to the influence of short branch length and other factors, the up and down swing amplitude was larger than the left and right swing amplitude, which was opposite to the spatial swing amplitude of branches and lateral branches. The analysis of the mean value of forced kinetic energy of the farthest branch under excitation frequency of 13~30Hz showed that when the picker operated at 23~25Hz excitation frequency, the mean value of kinetic energy obtained by the farthest branch of the test walnut tree was the largest.The research results can provide a theoretical basis for the selection of working parameters of the vibrating picker for walnut trunk. © 2024 Chinese Society of Agricultural Machinery. All rights reserved.