Modal properties of fruit-rachilla system of the macaw palm

The macaw palm has been domesticated due to its potential use in the production of biodiesel. One of the current challenges in this area is to determine the proper information and develop the technologies required for using macaw palm, allowing it to contribute to the sustainable production of feedstock for biodiesel industry. The principle of mechanical vibration can be employed for the detachment of fruits from a tree bunch, and it is therefore necessary to study the dynamic behavior of the macaw palm fruit-rachilla system during the vibration. Hence, the modal properties of the system were determined. A study on the dynamic behaviors was carried out using a deterministic finite element model, and the natural frequencies were obtained through a frequency-scanning test to evaluate the model. The mean relative error (MRE) between the measured and simulated natural frequencies was also used to evaluate the model. The natural frequencies, determined experimentally, varied between 26.21 and 33.45 Hz on average, whereas the simulated frequencies varied from 24.81 to 39.27 Hz. The overall MRE was 9.08%. Once the model was validated, a sensibility test showed that the density of fruit and the elasticity modulus are the parameters that most influence the natural frequencies of the fruit-rachilla system.