摘 要

林果产业是现代林业的重要组成部分，其发展遍布全国各地。随着林果机械化采收技术的广泛应用，对果树的固有特性和振动特性需要进行更加深入的研究。通过研究激振参数对果树枝干的位移、加速度等动态响应关系的影响，设计出高效率的林果振动采收系统。

本次试验分别对两种不同树型进行测试，一种主干树型，一种Y型果树。通过使用锤子敲打银杏树主干的激振方法测得果树的固有特性，计算得主干果树的阻尼比为0.03、固有频率为2.03 Hz，可以确定果树的基频为2.03 Hz，经过对比分析得出以下结论：1）当频率为2.03 Hz时，各测点的三个方向都达到波峰；2）在0～5 Hz范围内，各测点三个方向的能量都有很大的波动，当频率超过10 Hz，各测点的三个方向能量波动都逐渐减弱。用同样方法测得Y型果树的阻尼比为0.05、固有频率为1.88 Hz，分析得出以下结论：1）当频率在6 Hz左右时，各测点的三个方向都达到波峰；2）在6~10 Hz范围内，各测点三个方向的能量波动较平稳，当频率超过10 Hz，各测点的三个方向能量波动较大；3）在12 Hz左右各个测点急速达到波峰。

利用激振电机提供激振力的方式测试两种果树加速度响应，分析主干树型得出结论：1）p4点在三个方向的响应最大，在z向四个测点的响应幅度都差不多基本一致。3）越是在末梢的点响应越大，证明振动的越激烈。分析Y型果树得出结论：1）两个侧枝及主干最靠近激振点的测点在x方向的加速度响应都会在23 Hz时产生激增现象，振幅最大有157.44 m/s²；2）侧枝一和侧枝二的接近末梢的两个测点的加速度变化趋势都是相同的，先缓慢上升达到一个峰，再逐渐下降，其中侧枝一在下降之后还有缓慢上升的趋势；3）侧枝二在z向的响应最大，侧枝一在y向的响应最大；4）侧枝二的c2、c3在12.34 Hz和23.13 Hz三个方向同时达到峰。

关键字：固有特性；振动采收；激振频率；加速度响应

Experimental study on natural characteristics and vibration response of fruit trees

ABSTRACT

Fruit and forest industry is an important component of modern forestry that development spreads all over the country. With the widespread application of fruit mechanical harvesting technology, the natural characteristics and vibration characteristics of fruit trees need to be studied more deeply. By studying the influence of vibration parameters on the dynamic response of the branches and trunks of the fruit stem, the high efficiency fruit vibration harvesting system is designed.

In this experiment, two different tree types were tested, a trunk tree type and a Y-type tree. The natural characteristics of fruit trees were measured by hammering the trunk of ginkgo tree, and the damping ratio of main fruit tree was 0.03, and the natural frequency was 2.03 Hz. The basic frequency of fruit tree was 2.03 Hz, Through comparative analysis the following conclusions: 1) When the frequency is 2.03 Hz, the three directions of the measuring point is reaching the peak; 2) In 0 ~ 5 Hz range, three directions of each measured energy has great fluctuation, when the frequency is more than 10 Hz, the three direction of energy fluctuation of each measuring point are decreased. With the same method measured Y fruit damping ratio is 0.05, the natural frequency is 1.88 Hz, analysis the following conclusions: 1) When the frequency is about 6 Hz, the three directions of the measuring point is reaching the peak; 2) In the range of 6~10 Hz, the energy fluctuations in three directions respectively were stable, when the frequency of more than 10 Hz, each measuring point of the three direction of energy fluctuations; 3) At about 12Hz of all measuring points rapidly and reached the peak.

Providing exciting force using vibration motor way to test the two fruit tree trunk acceleration response analysis concluded: 1) Four points overall tree trunk acceleration are increased with the increase of frequency response of p4. 2) In the three directions, from z to four measured response amplitude some are almost consistent. 3) More in the peripheral response more proof vibration more intense. Analysis of type Y fruit trees leads to conclusions: 1) The trend of the acceleration of a branch and branch two measuring points two closer to the endings are the same, to reach a peak and then rose slowly decline, a decline in the collateral and after a slow upward trend; 2) In response to z two branches, a branch in the direction of y the maximum response; 3) Collateral two c2, c3 and 12.34 Hz and 23.13 Hz reached the peak in three directions.

Keywords: Inherent characteristics; Vibration harvesting; Excitation frequency; Acceleration response

目录

1 绪论………………………………………………………………………………………………………………...1

1.1研究背景、目的与意义……………………………………………………........... ………………………….1

1.2国内外研究状况…………………………………………………………….....................................................1

1.2.1果树系统建模……………………………………………………………………………………………..1

1.2.1.1 国外研究现状……………………………………………………………………………………..1

1.2.1.2 国外研究现状……………………………………………………………………………………..2

1.2.2 振动响应试验研究……………………………………………………………………………………….2

1.2.2.1 国外研究现状……………………………………………………………………………………..2

1.2.2.2 国内研究现状…………………………………………..................................................................4

1.3 本课题主要内容……………………………………………............................................................................5

1.4 本章小结…………………………………………………………………........................................................5

2 果树振动动态特性测试系统……………………………………………………...................................................6

2.1 测试系统总体方案…………………………………………………………………………………………....6