Research On Vibration Response Characteristics And Separation Deformation Law Of Fruit-Branch System

At present,manual harvesting is the primary harvesting method for forest fruits.However,there are problems with low harvesting efficiency and high harvesting cost in the manual harvesting of fruits.Mechanized harvesting of forest fruits is an effective way to solve the above issues.Vibratory harvesting machinery is the leading way of mechanized harvesting,which is based on the principle that the fruit oscillates under vibration,and the fruit stalk breaks under inertia force to achieve the purpose of fruit shedding.Therefore,the experiment can provide a theoretical reference for the efficient harvesting of vibratory forest fruit harvesting machinery by studying the force on the fruit under vibration.This thesis investigates the vibration response characteristics and separation deformation law of the fruit-branch system of apples by combining simulation and experiment with apple trees as the research object.The test was conducted to obtain the optimal vibration parameters for harvesting apples,which enables precisely harvesting apples.The primary research of this thesis is as follows:(1)The thesis establishes a mathematical model for the vibration of short-stalked and long-stalked fruits and analyzes the main factors affecting the separation force of the fruit stalk.The analysis showed that the normal inertia force generated by the fruit under vibration was the key to fruit detachment.The normal inertia force is related to the vibration frequency and vibration amplitude.The higher the vibration frequency and the greater the vibration amplitude,the greater the separation force between the fruit stalks,and the easier the fruit will fall off.(2)To achieve the purpose of analyzing the vibration response characteristics of the fruit-stalk-branch system,the experiments measured the dimensions of apple branches and their fruit,the fruit stalk separation force,the bending modulus of elasticity,density,moisture content,and other mechanical properties of branches,respectively,to provide practical and reliable data support for the vibration simulation of fruit trees.(3)The experiment first established a three-dimensional model of the fruit stalk branch of an apple and then conducted a modal harmony response analysis on the three-dimensional model in ANSYS Workbench to obtain the best vibration frequency of3.15 Hz for the fruit tree.Finally,the experiment was carried out by stress analysis of the fruit-stalk-branch system at different angles in ABAQUS,and the separation deformation law of the fruit stalk was derived.As the apple’s swing angle increased,the fruit’s inertia force increased.(4)The experimental design electronic fruit model was subjected to a vibration test with a vibration frequency of 1～4Hz and vibration amplitude of 0～20mm as the test variables,and the vibration acceleration and rotation angle of the apple were recorded.The test results showed that the vibration acceleration of the apple increased with the increase of vibration frequency,and the rotation angle showed a trend of first increasing and then decreasing;with the growth of vibration amplitude,the apple’s vibration acceleration and rotation angle also increased.At the vibration frequency of 3Hz and amplitude of 20 mm,the maximum separation force on the apple was 18.71 N.