Study On Vibration Transmission Characteristics Of Broussonetia Papyrifera Based On Main Branch Vibration Method

Mechanized harvesting of forest fruits has the advantages of high harvesting efficiency and low harvesting costs.Vibration type fruit harvesting machinery is the most common type of fruit harvesting machinery.The vibration type forest fruit harvesting machine causes fruit trees to vibrate,causing fruits to fall off under the action of inertia force and gravity.Therefore,the vibration response characteristics of fruit trees are of great significance for achieving efficient harvesting of vibration type forest fruit harvesting machines.The thesis takes tree construction as the research object and analyzes the influence of excitation frequency and excitation point on the acceleration response and vibration energy transfer of the branch vibration.The main research content and important conclusions of the thesis are as follows:(1)Establishing a dynamic model of the " main branch-crank slider type vibration harvester " and a " fruit handle-fruit " vibration model.It was found that the magnitude of the force on the excitation point of the main branch and the vibration energy consumed by the main branch are related to factors such as excitation frequency,amplitude,etc.The normal inertia force of the fruit is related to the excitation frequency,amplitude,mechanical properties,and geometric structure of the fruit branch and fruit at the connection point.(2)Designing a crank slider type vibration harvester according to experimental requirements to achieve independent adjustment of the amplitude and excitation frequency of the vibration harvester;The moment of inertia of the centering crank slider mechanism and the crank angle are functions with period π.(3)The analysis results of vibration acceleration response indicate that: 1)The influence of excitation point position and excitation frequency on the vibration acceleration response of fruit branches is interactive;2)When the distance between the excitation point and the base of the main branch increases with the increase of excitation frequency,the main branches and secondary branches can achieve better vibration acceleration response;3)When the excitation point is in the middle of the main branches,the overall vibration acceleration response of the main branches and the secondary branch is the best.(4)The analysis results of vibration energy transfer indicate that: 1)When the excitation point is close to the base of the main branches,a higher excitation frequency will increase the energy dissipation effect of the base of the main branches,and the ineffective vibration energy transmitted to the base of the main branches will also increase;2)The efficiency of transmitting vibration energy from the main branches to the secondary branches decreases with the increase of excitation frequency;3)The resistance of changes in the geometric structure of the main branches to the transmission of vibration energy increases with the increase of excitation frequency.