Authors

Abstract

The mechanized harvesting of mulberry is important for its production. In the process of harvesting, it is considered not only the mechanical damage of mulberry fruit but also its harvesting efficiency. It is very important to improve the vibration harvesting efficiency of mulberry. In this study, modal analysis of mulberry trees and harmonic response analysis of branches were carried out to determine the harvesting frequency of the branch's vibration and other parameters. The effects of excitation frequency and vibration position on the triaxial acceleration of the mulberry branch at different positions were analyzed by vibration test. Then the triaxial acceleration of branches at different positions was analyzed. The conditions of the mulberry fruit shedding were obtained through theoretical analysis. Through the 20-order modal analysis of mulberry, it is concluded that a better vibration effect can be achieved when the vibration frequency is controlled at 4-16 Hz. According to the harmonic response analysis, the best excitation frequencies are 5-6 Hz, 10-13 Hz, and 14-16 Hz. The harmonic response analysis of fruit branches was carried out, and the stress of fruit stalks at 5 Hz, 10 Hz, and 15 Hz were analyzed. The result shows that the maximum stress is 2.9252×107 Pa, the excitation position is the first-order branch, and the excitation frequency is 15 Hz. The frequencies obtained from modal analysis and harmonious response analysis were used to conduct experiments. When the excitation frequency was 15 Hz, the triaxial accelerations aX, aY, and aZ were 2.12 g, 4.16 g, and 3.99 g, respectively, which were more conducive to the shedding of mulberry fruits.

Abstract in Chinese

桑树机械化采收是桑树生产的重要环节。在桑树机械化振动采收过程中，既要考虑桑树果实的机械损伤，又要考虑桑树果实的采收效率。果实如果不及时采收，将直接影响果实品质，造成很大的经济损失。提高桑树振动采收效率具有十分重要的意义。本研究通过对桑树进行模态分析和对树枝进行谐波响应分析，确定树枝振动的收获频率等参数。通过振动试验，分析了激励频率和振动位置对桑树枝条不同位置三轴加速度的影响。然后对不同位置支路的三轴加速度进行分析。通过理论分析，得出了桑树果实脱落的条件。通过对桑树的20阶模态分析，得出当振动频率控制在4-16hz时，可以获得较好的振动效果。根据谐波响应分析，最佳激励频率为5-6Hz、10-13Hz和14-16Hz。对果枝进行谐波响应分析，对果柄在5Hz、10Hz和15Hz下的应力进行分析。结果表明:最大应力为2.9252x107Pa，激励位置为一阶支路，激励频率为15Hz。利用模态分析和协调响应分析得到的频率进行试验。当激励频率为15Hz时，三轴加速度aX为2.12g, aY为4.16g, aZ为3.99g。更有利于桑树果实的脱落