Crab Apples Tree Structure Model Of Viscoelastic Vibration Research

This research was raised under the prosperity background of the development of modern fruit industry. In order to change the traditional of picking fruit totally by artificial work. Integrated the conception of mechanizing production into fruit picking industry, not only improve the efficiency of picking, but also decrease the labor of cost price. All these had made great contribution to the adaption of fruit to the fierce market competation. In the process of applying mechanization picking technology, there were many problems slow down its promotion. One of typical problems was the quality picked by machine can not satisfy related standard, the other one was the damage to fruit trees. Therefore, higher requirements were put forward on mechanical harvest.This paper mainly focus on the fruit trees. The trunks and branches of fruit trees were studied by means of one dimension Euler Bernoulli beam theory of elastomer. The branches of the simplified model was established, together with the equation of fruit tree branches. Correlation property parameters of fruit trees were measured based on the former theoretical equation. By designing experiments body characteristics of Crab apples, elastic modulus and damping were determined to draw relevant conclusions are as follows:a) The major and minor axis of cross section circle of branches had high linear correlation, so the fruit tree model can be substituted by cylinder. Through the calculation and comparison of attenuation in cross section circle area of the trunk and lateral branch, the trunk section round rate was smaller than lateral branch. Therefore, the trunk can be regard as uniform circle beam, while the lateral branch was regarded as variable cross-section circle beam.b) The bending elastic modulus of crabapple trees related to the tree diameter, with the increase of branch diameter, bending elastic modulus and stiffness increase,too. The compressive strength limit of branch horizontal stripes also increase. What else, there was highly linear relation among the diameter and the compressive strength limit of branch horizontal stripes. When the diameter of branch surpass 36 mm,the branch can be equal to material of linear elastic, while it less than 20 mm,the branch should be regarded to somehow non-linear elastic material.c) The damping coefficient increase with the increase of diameter in crabapple’s branch. The damping close to the ground was far greater than that of far from the end.The paper by room resonance experiments and impact tests obtained dynamic response of fruit trees, its conclusions are as follows:a) The resonant frequency of fruit trees should be around 10 Hz.b) Impact test results impact energy transmitted mainly by fruit trees along the main directions. Analysis of fruit trees trunk transfer rate shock attenuation distribution from 350 m / s to 90 m / s. Trunk consumes most of the impact energy. And by contrast with the rigid body and an elastomer impact signal can be seen that the diameter of the thicker portion of fruit trees belonging to rigid impact, and part of it is relatively thin elastomeric shock, the results corroborate the conclusions in Chapter 3.c) The impact energy is passed along the trunk section will be diverted to the branches, split number and angle of the branches and trunk of energy related, the greater the angle, the less energy shunt, smaller branches to the trunk portion in response to the impact caused by. Therefore, when using an impact-type pickers, should choose a different impact loads to the tree-shaped, improve picking rate while reducing the impact of damage to fruit trees; but also reminds us that in the planting of fruit trees pruning stage should be considered to ensure that fruit geometric characteristics of growth and bring greater efficiency to pick.d) Experimental observation by plane and perpendicular to the branches of fruit trees fruit tree branches plane parallel to the impact of the effect seen when the impact direction parallel to the plane of fruit branches, fruit tree branches bring maximum acceleration, which indicates the impact of using this kind of approach can maximize the impact energy from the trunk to the branches split, making the branches maximum acceleration response, in favor of fruit drop. Therefore, when the harvest field, should adopt parallel to the plane of the direction of the impact of the branches, so you can make picking efficiency.