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URI permanente desta comunidadehttps://thoth.dti.ufv.br/handle/123456789/3352
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Item Dynamic Behavior of Coffee Branches: an Analysis Using the Finite Element Method(Instituto de Tecnologia do Paraná - Tecpar, 2024-01-12) Melo Junior, Wellington Washington Andrade de; Santos, Fábio Lúcio; Scinocca, Francisco; Rosa, Pablo Antunes da; Magalhães, Ricardo RodriguesThe use of computational simulation techniques is an important tool for the coffee harvesting issues, particularly the finite element method. The method is widely used in the structural analysis of agricultural machinery, as well as in the analysis of the stresses and vibrations of coffee branches and peduncles during the harvesting process. The present study aimed to develop three-dimensional finite element models of the plagiotropic branches of the Catuaí Vermelho variety of Arabica coffee in different positions along the orthotropic branches of the plant; considering high-fidelity models. Additionally, by considering the branches’ experimental properties (physical-mechanical), the natural frequencies and vibration modes of the branches were determined by means of computer simulations. First, the geometric properties of the coffee branches were obtained by means of two images taken using a professional camera to obtain the input data of the virtual simulation. For the mechanical properties, it was used a semi-analytical digital scale, to obtain the mass of the specimens. The modulus of elasticity was determined using a universal testing machine. The variability in the simulated natural frequencies could be identified, which was on the order of 30% for the first frequency, regardless of the position of the branch in the plant. These values were lower for the other frequencies. Linear regression fits showed a coefficient of determination, and correlation tests were used to verify the relationship between the values obtained numerically and experimentally, which were validated by using experimental data using the modal analysis techniques.Item Physical and mechanical properties of the wood of coffee trunks and branches(Editora UFLA, 2020) Velloso, Nara Silveira; Magalhães, Ricardo Rodrigues; Santos, Fábio Lúcio; Nunes, Márcio Felipe Pinheiro Neri; Vicentini, BrunoKnowledge of the physical and mechanical properties of coffee plants is essential to the development of mechanisms that perform the harvesting of their fruits by the principle of mechanical vibrations; however, these properties have yet to be determined in the laboratory. In this context, the present study aimed to determine the mechanical and physical properties of coffee plants through tensile and compression tests by means of a universal testing machine. Elasticity modulus, Poisson’s ratio, and specific mass were determined for specimens developed from the trunks and branches of 20 samples whole coffee plants, Coffea arabica variety, Catuaí Vermelho cultivar. The elasticity modulus was determined by the slope of the secant line in the elastic region of the stress-strain curve. Poisson’s ratio was determined by direct measurements in regions previously marked on the specimens. The conventional specific mass was obtained by the ratio between the mass of specimens and their volume. The methodology allowed the studied properties and a database to be obtained, and they can be used as a basis for the development and operation of the mechanism used in the mechanical and semi mechanical harvesting of coffee fruits. The results obtained indicate the following values for elasticity modulus of the trunk, performed from compression tests: 1090.94 MPa in the longitudinal direction and 108.60 MPa in the cross-sectional direction. For elasticity modulus of the branches, performed from tensile tests in the longitudinal direction: 507.72 MPa. For Poisson’s ratio, determined by direct measurements: 0.25 for the trunk and 0.09 for the branches. And for specific mass: 1070.05 kg.m-3 for the trunk and 1036.33 kg.m-3 for the branches.