Navegando por Autor "Santos, Fabio Lúcio"

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Determination of physical and mechanical properties of the coffee branch: an experimental approach
(Universidade Federal de Lavras, 2022-06-09) Melo Júnior, Wellington Washington Andrade de; Santos, Fabio Lúcio; Scinocca, Francisco; Rosa, Pablo Antunes da; Magalhães, Ricardo Rodrigues
In order to reduce the human efforts during manual harvesting and increase the operational capacity and quality, the mechanization of the harvesting operation has been significantly increasing in the last few years for coffee crops. Therefore, for the design of coffee harvesting machines, the physical and mechanical properties of coffee branches are of utmost importance for harvesting machines projects. In this way, using an experimental approach, the present paper analyzes the variability of physical and mechanical properties in the coffee branches, of the Coffea arabica L., cultivar Catuaí-Vermelho (IAC 144). The branches were collected in different positions, along the orthotropic branch: upper, middle and lower parts of the plant. The mass, volume, spe-cific mass, and modulus of elasticity of the collected specimens were determined considering their position in the plant and position along the branches. According to the position in the plant, no significant differences were found between the specific mass averages for the upper, middle, and lower parts of the plant. The research obtained an average of 1.24 GPa with a standard deviation of 0.13 GPa for the elasticity modulus. A significant increase in the elasticity modulus could be noted in the branches from the top to the bottom of the plant in the present research.
Effect of the impact of rigid rods on coffee fruit detachment efficiency by mechanical vibrations
(Editora UFLA, 2020) Gomes, Ely Queiroz; Santos, Fabio Lúcio; Nascimento, Moysés; Velloso, Nara Silveira
The mechanization of field activities has been the response of coffee producers to the labor shortage, especially for fruit harvesting. The use of mechanical harvesters allows greater harvesting efficiency and ensures the economic viability of coffee plantations, which currently depend mainly on the reduction in production costs. The principle used for mechanized coffee harvesting is based on the principle of mechanical vibration. The objective of this study was to analyze the dynamic behavior of the coffee fruit-peduncle-branch system under mechanical vibration and the impact of the vibrating rods on the fruit detachment process in association with this behavior. Fragments of coffee branches containing fruits in the unripe and ripe stages were used in this experiment. These samples were subjected to different frequencies (20, 30, 40, and 50 Hz) and amplitudes (0.002, 0.003, and 0.004 m). Another variable analyzed was the form of vibration transmission to the fruits, with the vibrations being transmitted to the samples with or without the impact of the fiberglass rods. The fruit detachment efficiency increased as the ripening stage progressed from unripe to ripe. A higher detachment efficiency occurred with the increase in vibration frequency and amplitude because of the higher vibrational energy imposed on the fruit. The detachment efficiency was low when the vibration was transmitted without the impact of the rods. Conversely, the vibration in combination with impact achieved a mean detachment efficiency of approximately 90%.
Modelagem e validação de um cafeeiro por elementos finitos utilizando escaneamento 3D e análise modal experimental
(Universidade Federal de Lavras, 2023-10-06) Silva, Davidson Silveira e; Magalhães, Ricardo Rodrigues; Santos, Fabio Lúcio
O café é um dos produtos mais importantes na economia brasileira, sendo o país o maior exportador do grão do mundo. Estudos voltados para simulações nas etapas de colheita mecanizada tem sido de grande interesse, tanto na academia quanto na agroindústria. Neste sentido, este trabalho tem como principal objetivo obter um modelo computacional dos ramos, empregando técnicas de escaneamento e validação experimental através de análise modal. Para isso, ramos de um cafeeiro Catuaí Vermelho foram escaneados e simulados computacionalmente para obtenção de um modelo computacional que represente o comportamento estático e dinâmico dos ramos. Previamente foi realizada a avaliação de quanto o modelo escaneado foi representativo aos dados obtidos experimentalmente. A massa específica e o módulo de elasticidade dos ramos selecionados foram obtidas em laboratório e utilizadas também como parâmetros para as simulações. Para a obtenção dos resultados de análises estática e modal, os modelos geométricos dos ramos foram simulados via Método dos Elementos Finitos (MEF). A validação do procedimento adotado deu-se por meio de experimentos, os quais certificaram que os três primeiros modos de vibração dos ramos ensaiados foram similares, observando-se desvios variando entre 2 e 20%. A análise estatística adotada indicou tendência de comportamento similar entre os ramos simulados e os resultados experimentais. Com base nos resultados obtidos, concluiu-se que é possível prever o comportamento dinâmico e estático de ramos de um cafeeiro a partir do escaneamento tridimensional e simulações numéricas via MEF. Isto pode ser considerado um avanço tecnológico, uma vez que normalmente são obtidos modelos simplificados por coordenadas geométricas.