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For the evaluation of the necessary theoretical model for the study of the transmission of the shaken in the structure of citrus trees, based on the theory of the finite elements, with a view to the development of the citrus harvest mechanization, it is indispensable to have a group of data that is necessary to determine experimentally. These data are fundamentally physical mechanical properties of the material that compose the such tree as the volumetric density, the coefficient of Poisson, the modules of elasticity to torsion and flexion, the break limit, as well as the reason of reduction of the limb. The determination of these properties was carried out in limbs of the own trees that would serve from base to the studies of the experimental transmission of the shaken in these varieties of trees. [ABSTRACT FROM AUTHOR]

Most of the theoretical researches carried out in the world with a view to determining the vibration regimes for detachment of coffee cherries, have been directed to find the most appropriate vibration frequencies to achieve fruit detachment. In general, those frequencies were coincident with some of the natural frequencies of oscillation of the fruit-peduncle system. In general, the amplitude of the vibrations required for fruit detachment has been determined exclusively by an experimental way, being the results limited to the conditions of realization of the experiments. In the work, starting from the calculation of the bending moment in the abscission zone of the fruit-peduncle system, caused by the shaking action, and their comparison with the necessary bending moment for fruit detachment, the values of frequency and amplitude of the vibrations, that provide the selective harvest of coffee cherries, are determined. For the calculations a mathematical model of fruit-peduncle system dynamics with two degrees of freedom, proposed by the author, was used. As a result of the investigation it is predicted that in a vibration mode were fruit and peduncle moves out of phase, amplitudes in the order of 2...3 mm are enough to achieve fruit detachment with good results related with selective harvest. [ABSTRACT FROM AUTHOR]

Coffee harvesting with the aid of mechanical means becomes impracticable for the immense majority of coffee producers in the world, due fundamentally to that, in general, in the moment of the crop, the plants contain fruits in all their maturation status and have not been able to be developed machines that guarantee a selective detachment of the cherries during harvest operation. In a first study (Symposio do Café do Brasil. EMBRAPA), a modal analysis of coffee fruit-stem system was made. Starting from this analysis, the possibility of achieving the selective detachment of the fruits (removing of a high percent of mature fruits and low percent of immature ones) can be expected if the vibrating frequencies of the machines that use this work principle, are selected in the surrounding of a vibration mode "in contrafase" of the fruit-pedicelo-peduncle system. In this first study, an analysis of the first twelve vibration modes of different configurations of the fruit-pedicelo-peduncle system of coffee, was carried out. This study resulted enough for the analysis of configurations with one fruit for peduncle, but it was insufficient for an analysis of the behavior of configurations with two or three fruits for peduncle. In this paper an study of 25 vibration modes of fruit-pedicelo-peduncle system of coffee (coffea arabica) varieties "Red Caturra" and "Yellow Caturra" is presented. As a result of the study four variants of counter-phase vibrating mode of the fruit-pedicelo-peduncle system were founded, being able to recommend the more promissory mode for selective harvest of coffee. [ABSTRACT FROM AUTHOR]

One of the main difficulties during mechanical coffee harvesting by vibration, consists on the presence of a great percent of green fruits in the harvested mass, that which constitutes a non resolved problem at international level. In this paper, starting from the evaluation of mathematical models of the fruit-stem system dynamics, recommendations are offered about the vibration frequencies to apply in order to achieve a better selectivity during the detachment of ‘arabica caturra’ coffee cherries. [ABSTRACT FROM AUTHOR]