Detachment patterns and impact characteristics of litchi fruit during vibrational harvesting
Detachment patterns and impact characteristics of litchi fruit during vibrational harvesting
复制标题
振动采收荔枝果实脱离模式及冲击特性
DOI：
10.1016/j.scienta.2021.110836
复制
发表时间：
2022
影响因子：
4.3
通讯作者：
Lu Huazhong
中科院分区：
文献类型：
--
作者：
Wang Yanfei;Wang Weizu;Fu Han;Yang Zhou;Lu Huazhong
• A program was developed to analyze the fruit motion in high-speed videos. • Most litchi fruit were detached at quasi-static tilting test without traction. • Stress exceeding ultimate stress was a main detachment reason. • Inducing large tilting angles was advantageous for increasing detachment speed. A high-speed camera was used to study the motions of litchi fruit during vibrational harvesting to investigate fruit detachment patterns. The quasi-static traction and tilting tests, as well as vibrational detachment tests using frequencies of 9, 12 and 15 Hz and amplitudes of 100 and 130 mm, were conducted on ‘Huaizhi’ litchi. A MATLAB program was developed to estimate the motion parameters of the fruit during shaking. The quasi-static tests indicated that the detachment force decreased as the tilting angle increased from 0° to 60° and that most fruit would detach at a certain tilting angle (average value of 62.6°) without traction. The vibrational detachment tests suggested two main reasons for fruit detachment: the stress exceeded the ultimate stress at the fruit–stem junction and fatigue induced by the alternating stress at the junction. Inducing a large tilting angle during shaking was advantageous for creating a high degree of stress at the fruit–stem junction and for achieving a high detachment speed. In general, appropriate increases in the vibration amplitude and frequency decreased the degree of fruit damage by causing fewer impacts. In this study, 12 Hz/130 mm and 15 Hz/100 mm were the optimal parameter combinations to achieve limited litchi fruit damage and high detachment speeds.
