Investigation of the vibration effect of using single or double eccentric mass in the trunk shakers used in fruit harvesting

Trunk shakers are widely used in the harvesting of tree fruits. The vibration produced by trunk shakers is obtained by rotating eccentric masses. In trunk shakers, a single eccentric mass is used as well as a double eccentric mass. However, there is no study on their effectiveness relative to each other if these eccentric masses are used single and double. In this study, the vibration effect of eccentric masses in trunk shakers is compared when they are operated in axial or parallel positions as a double mass instead of a single mass. For this purpose, a trunk shaker was designed for a stiff trunk tree and manufactured after modeling in 3D. The 3D model of the trunk shaker is simulated in ANSYS software. Afterward, experiments are carried out with the manufactured trunk shaker assembly. A trunk model (steel pipe) is vibrated by operating the eccentric masses at frequencies of 16.5 Hz and 25 Hz. Vibration graphics are obtained by making measurements for 2 s in the x and y axes directions at two different points of the tree model. The vibration results obtained in the simulations in ANSYS software are compared with the results obtained in the experimental study. In both simulations and experimental studies, it has been found that when double mass is used instead of single mass on trunk shakers, there is a decrease in the vibration values ​​they produce. The vectorial resultant of the acceleration values ​​produced by the masses at different positions in the x and y axes were compared proportionally. When the dual mass is used instead of a single mass, the greatest reduction in acceleration was obtained in dual-mass experiments (−14.6 % in experiments and −14.2 % in simulations) placed in parallel positions at 25 Hz frequency. These results show that the positions of the eccentric masses as well as their frequencies are critical for harvesting in a shorter time without damaging the tree trunk. It was concluded that the use of single eccentric mass trunk shakers may be more efficient for fruit harvesting on trees with very stiff trunks.