Finite Element Analysis of Coffea arabica L. var. Colombia Fruits for Selective Detachment Using Forced Vibrations

This study provides a forced vibration analysis to evaluate the stresses at the pedicel interfaces of the fruit-peduncle system of Coffea arabica L. var. Colombia by means of finite element analysis. The real topology of the fruit-peduncle system was developed from a proposed numerical procedure to complete a dynamic analysis. The Young’s modulus of the fruit was approximated from firmness indices for all stages of ripening. Numerical computations were performed in the frequency range of 0 to 400 Hz and three vibration modes were identified in this bandwidth. Results show that the second natural frequency (128 Hz) is acceptable for stimulating the detachment of ripe fruits because the fruit-pedicel-peduncle system induces bending in the fruit interface. As a final conclusion, we determine that dynamic excitations between 120 and 150 Hz could permit selective stimulus of ripe fruits, since other ripening stages were not stimulated in this frequency range