Finite elements modeling of olive tree mechanical harvesting using different shakers

The aim of this study is the optimization of stem shaking conditions in the mechanical harvesting of olive fruits. In order to study the influence of different shakers on the dynamic response of “Chemlali”, the main olive variety in Tunisia, a finite element numerical modeling was undertaken. The olive tree is modeled by three-dimension beams. Each beam has two nodes and 6 freedom degrees for each node. The structure is built by 560 elements and 561 nodes. For each part of the tree, the wood’s mechanical characteristics are determined experimentally. Orbital and multidirectional shakers were the mechanical harvesting tools tested. For each type, we developed the excitatory force equation as a function of the shaker’s characteristics: the eccentric value, the unbalanced weights and their rotation frequencies. In this paper, we present the structure response in relation to the shaker’s type, its placement and its excitation frequencies. This response was controlled, firstly by the acceleration and displacement values at the ends of secondary branches, and secondly by the reaction force at the peduncles level. These results are useful for the design of new shakers adapted to the studied olive variety.