Research on the Relationship Between the Frequency Spectrum Characteristics and the Vibration Responses of a Ginkgo biloba Tree

The most effective method of the fruit harvesting is the mechanical harvest. Under forced vibration, not only the excitation amplitude, frequency, duration, but also the inherent frequency spectrum characteristics of the fruit trees affect the removal of fruits. The frequency spectrum of different testing positions on a Ginkgo biloba tree under the impact excitation was tested in the laboratory. The acceleration responses under the harmonic excitation were measured at the frequency of the peak and trough points in the frequency spectrum curves. Results of this research indicate that the frequency spectrum presented the consistency on the same branch but distinction among different branches. There was a correspondence between the frequency spectrum characteristics and the vibration responses. The vibration responses could be strengthened at the resonant frequency. Our results indicate that it was difficult to induce the strong vibration response of all the branches at the single frequency during the practical mechanical harvesting of fruits.