Modeling and simulation of the dynamic behavior of the macaw palm fruit-rachilla system

The macaw palm ( Acrocomia aculeata) is a palm tree native to tropical forests that stand out due to its great potential for oil production. This study was developed with the objective of constructing a high-fidelity model of the macaw palm fruit-rachilla system for the purpose of simulating its dynamic behavior when subjected to mechanical vibrations. The finite element method was used to determine the natural frequencies and modes of vibration of the system. The three-dimensional models of the fruit-rachilla systems were elaborated using CAD3D Fusion 360 software. The modal properties of the fruit-rachilla systems were obtained based on the models developed by varying the elasticity modulus values of the system. The parameters of greatest influence in the estimation of natural frequencies are the elasticity modulus, especially that of the fruit-rachilla joint, and the specific mass. The models that take into account the three-dimensional strains along the rachilla are the least sensitive to variations in the mechanical properties (elasticity modulus and specific mass) and are shown to be more representative of the actual physical system.

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 biofuel, in addition to several co-products that can be generated from its oil and pulp. One of the current challenges in this area is the harvesting, as there are no specific machines for this operation. Therefore, it is necessary to determine the appropriate information regarding the physical properties of the plant, so that it is feasible to develop the technologies necessary for the commercial scale application of macaw palm, allowing it to contribute to the sustainable production of raw material for the biofuel industry and other co-products. The principle of mechanical vibration can be used to shed fruit from trees when ripe, and it can be a method used for harvesting. Thus, as proposed in this study, it was necessary to study the dynamic behavior of the fruit-rachilla system during 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 from 26.21 to 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 was carried out, which showed that the density of fruit and the elasticity modulus are the parameters that most influence the natural frequencies of the fruit-rachilla system.

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.