Effective excitation conditions for the intense motion of the ginkgo seed-stem system during mechanical vibration harvesting.

The degree of the motion response of the ginkgo seed-stem system during mechanical vibration harvesting determines the separation force obtained, thereby affecting harvesting efficiency. A response surface stochastic finite element analysis was carried out to obtain the modal shapes and the ranges of natural frequencies of the seed-stem systems. It was initially based on model updating and considering the inherent variability of the ginkgo seed-stem system, Then, the dynamic response of the ginkgo seed-stem system under different vibration parameters was investigated. The results showed that at low frequencies, only the first-order natural frequency could lead to resonance and cause the seed-stem system to swing violently. Under horizontal excitation, the main resonance of the system was at an excitation frequency close to the natural frequency. Under vertical excitation, the system had a sub-harmonic resonance at an excitation frequency close to twice the natural frequency. When the excitation acceleration was much larger than the gravitational acceleration, due to the increase in the excitation frequency, the seed-stem bounced violently, significantly increasing the inertial forces on the ginkgo seeds. Thus, vertical excitation is more likely to cause the intense motion response of the seed-stem system than horizontal excitation. This study not only proposes a correction method for the finite element model of the seed-stem system but it also clarifies the effective excitation conditions for the ginkgo seed-stem system. It provides theoretical guidance for the efficient mechanical vibration harvesting of ginkgo seeds. • Finite element model was corrected using the response surface methodology. • The modal variability of the ginkgo seed-stem system was investigated. • Sub-harmonic resonance of seed-stem systems can be triggered by vertical excitation. • The bounce of ginkgo seeds resulted in a significant increase in its inertia force. [ABSTRACT FROM AUTHOR]