Analysis of damage caused by drop impacts for mulberry fruits: An dropping experiment and numerical simulation

Abstract

AbstractIn the process of mechanized production of mulberry, falling collision damage is one of the main damage forms, which causes serious damage and accelerates fruit decay. Through the drop collision test and simulation analysis of mulberry fruit, the relationship between drop conditions and fruit damage degree was established, so as to provide reference for reducing fruit falling damage. The drop test is carried out. The relationship between factors and indicators is established. The drop height, fruit plate angle, fruit plate material, and drop direction were taken as factors, and then the energy loss was selected as indicator. The drop process of mulberry fruit is analyzed by numerical simulation, and the maximum stress and deformation of mulberry fruit are analyzed. With the increase of the drop height, the kinetic energy of the fruit increases. When the fruit plate material is pearl cotton, the drop height changes from 200 to 1000 mm, the energy loss of fruit falling increases from 4.42 × 10−0.3 J to 2.14 × 10−0.2 J. When the drop height of fruit is 200 mm, the angle of fruit plate is 30°, and the material of fruit plate is pearl cotton, the minimum energy loss of fruit is 3.39 × 10−0.3 J, the fruit damage was the least. This study can provide a reference to reduce the damage of mulberry fruit in the process of mechanical harvest and transportation.Practical ApplicationsThe existing mulberry harvesting methods are manual harvesting, while the vibration harvesting methods have high harvesting efficiency and serious damage. When the harvesting parts hit the tree trunk, the mulberry fruit will leave the tree and falls onto the fruit‐receiving device in the process of mechanical harvesting. There will be a collision and falling of the mulberry, which may cause serious damage. Therefore, in the process of mulberry fruit harvest, transportation, the falling, and collision damage is the main damage form.At present, there is few research on the drop impact damage test of mulberry fruit. In this study, the effects of mulberry falling direction, fruit plate material and drop height on mulberry damage were discussed by drop experiment. Then, the optimization results were carried out. The change and distribution of stress and strain in the process of collision were analyzed by numerical simulation, and the relationship between falling conditions and damage level was established. It is important to analyze the dynamic characteristics of mulberry in the process of drop. This study can be applied as a reference to reduce mulberry fruit impact damage, and provide a theoretical reference for the design of mulberry vibration harvesting machinery.