Damping Properties of Plum Trees Shaken at Their Trunks

Horváth, Ernő; Sitkei, György

doi:10.13031/2013.17936

Cited by 20 publications

(8 citation statements)

References 6 publications

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“…The variations in A.t. as a function of clamping heights is in line with data obtained by Horvath and Sitkei (2005), who noted that energy dissipation is high, especially in low clamping due to soil damping, as well as to tree canopy damping in the air. The transmitted resultant acceleration value increased by approximately 2% when the clamping head was positioned in the upper part of the trunk, rather than the lower part.…”

Section: Discussionsupporting

confidence: 91%

Assessment of aerial and underground vibration transmission in mechanically trunk shaken olive trees

Sola-Guirado

Bernardi

García

et al. 2018

J Agricult Engineer

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The present study analyses the transmission of vibrations generated from a multidirectional trunk shaker to olive tree structure considering both the aerial zone (trunk and branches) and the underground zone (the coarse root). The vibration characterization was conducted by measuring acceleration on several points of the tree during harvesting operations. The influence of two different heights of shaker head clamping was analysed. In addition, a dynamic probing was performed in order to evaluate soil compaction. The results showed that the vibration performed by the trunk shaker head, corresponding to an acceleration resultant of approximately 77 ms–2 with a dominant vibration frequency of 18 Hz, increased up to 106% in branches and decreased up to 90% in trunks. At root level, where the analysis was carried out at 1/3 and 2/3 of the coarse root length, the acceleration values diminished significantly to 17 ms–2 and 12 ms–2, respectively. Soil dynamic resistance was lower (36 kg cm–2) near the trees than between the trees (53 kg cm–2). The vibration transmission to the aerial and the underground parts diversely influences the dynamic behaviour of the olive tree, considering an operational frequency of a commercial trunk shaker. The assessment of vibration transmission to the aerial part could contribute to improve fruit detachment and reduce branch breaking and leaf detachment. While vibration transmission to the underground part rises new challenges considering soil compaction in olive groves.

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Section: Discussionsupporting

confidence: 91%

Assessment of aerial and underground vibration transmission in mechanically trunk shaken olive trees

Sola-Guirado

Bernardi

García

et al. 2018

J Agricult Engineer

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show abstract

“…This damping component showed a marked nonlinearity and was inversely proportional to the frequency. The elevated value of the initial damping could be explained because the mass of the soil that vibrates with the tree-soil system absorbs most of the energy according to the largest amplitudes in the tree-soil vibrating system (Horvath and Sitkei 2005). The increase in the excitation frequency produces a decrease in the damping ratio, indicating that the viscous damping component has a reduced relative importance and, as pointed out by most of the authors, that the aerodynamic damping of the tree has an even more important role in forced vibration, where the amplitude of the movement is reduced.…”

Section: Discussionmentioning

confidence: 99%

Dynamic analysis of olive trees in intensive orchards under forced vibration

García

Blanco-Roldán

Gil-Ribes

et al. 2008

Trees

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The mechanical harvesting of fruit for oil production in an intensive olive tree orchard is generally accomplished by applying vibration to the tree's trunk. This vibration is consequently transmitted to the branches, causing the fruit to detach. Although this practice is commonly used, the effects on tree behavior under forced vibration are not firmly established. Dynamic analysis was performed on 17 olive trees (Olea europaea L.) growing in an intensively-managed orchard using modal testing techniques. Modal parameter identification was focused inside the range excitation frequency used by the most commonly available trunk shakers on the market. The olive trees featuring a low morphological variability and modal parameters were obtained for a representative olive tree. The first two modes of vibration of the main tree frame were identified with damping ratios of 26.9 and 17.1% and natural frequencies of 20.2 and 37.7 Hz, respectively. A third mode of vibration of less importance was found at a higher frequency. Therefore, many local modes of vibration were detected near these natural frequencies, primarily located on secondary branches. During the testing, the olive trees behaved like a damped harmonic oscillator with predominantly mass damping in these modes.

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“…The trunk shaker (Topavi) clamped the trunk at 0.9 m, and the displacements measured at 1.8 m above the ground were substantially higher (38-66 mm), and finally, the SMTA shaker was the equipment that clamped the trunks at the highest point (1.9 m) and reached the highest amplitudes, 125-170 mm; this high displacement can only be achieved, without the risk of breaking the trunk, when the clamping point is far from the ground. Moreover, this elevated clamping point allows the use of low power shakers, as demonstrated by [18]. In Table 2 the main parameters are summarized.…”

Section: Comparison Of the Vibrations Reached With Each Equipmentmentioning

confidence: 99%

“…When the shaker must be applied to the trunk closer to the ground, the amplitudes must be reduced to between 20-30 mm. As a consequence, to obtain a good detachment percentage, the frequency must be increased (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25), but the shakes must be of short duration, of less than 10 s to avoid excessive defoliation [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Mechanical Harvesting of Ornamental Citrus Trees in Valencia, Spain

et al. 2019

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Citrus trees are used as ornamental plants in several Spanish cities. They give a nice color to the streets and a nice scent in the flowering stage, but when the fruits fall, they dirty the roads and pavements, and can cause accidents; this is the reason why gardeners must detach and collect the fruits. This task is being done manually, but it is quite inefficient and expensive. In this study, three types of machines have been used to mechanize this task: a trunk shaker with umbrella, a trunk shaker hitched to an orchard tractor, and an experimental smaller sized shaker that can be attached to small and pedestrian tractors. The shaking patterns used by each equipment, detachment percentages, mobility constraints, and tree damage have been measured, and reduction costs have been estimated. After three years of study, the system has been fully accepted by both gardeners and citizens.

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Damping Properties of Plum Trees Shaken at Their Trunks

Cited by 20 publications

References 6 publications

Assessment of aerial and underground vibration transmission in mechanically trunk shaken olive trees

Assessment of aerial and underground vibration transmission in mechanically trunk shaken olive trees

Dynamic analysis of olive trees in intensive orchards under forced vibration

Mechanical Harvesting of Ornamental Citrus Trees in Valencia, Spain

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