Optimal vibration parameters for olive harvesting from finite element analysis and vibration tests

Several vibration harvesting parameters must be obtained through experiments due to the complexity of olive branches. However, the pure test method significantly reduces the efficiency of equipment development. Therefore, in this study, we proposes a research method based on a combination of finite element simulation and vibration tests to address this problem. SolidWorks was used to establish a three-dimensional model of an olive tree including some smaller branches, The natural frequency and modal vibration modes of olive trees were determined by modal analysis. Furthermore, the vibration parameters were determined by harmonic response analysis. Then, the vibration motor was tested at five frequencies (10, 15, 20, 25, and 30 Hz), and the results were compared with the transient analysis results. The results show that the vibration response is more intense in the medium frequency range (18.66–28.96 Hz). It is inefficient and uneconomical to harvest all olives by applying force to the trunk. It is more effective to apply vibration force to the lateral branch to lessen the damage inflicted to the tree. An excitation force of 5220 N at 25 Hz to the left branch is suitable for harvesting the olive fruit. The average correlation coefficient of the maximum resultant acceleration observed in the tests and its simulated value was 0.63, indicating that the model can predict the vibration response reliably. Finally, the results of the harmonic response analysis were verified by transient analysis. This study can serve as a reference for the design of vibration harvesters.