부산대학교 도서관

Purpose: Measurement and analysis of vibration characteristics of plants are of great significance in plant health monitoring, wood material characteristic determination, etc. Currently, vibration characteristics of plants are mainly measured by contact sensors, which need a relatively complex installation procedure, and what's worse, may affect accuracy of test results.Methods: In this study, vibration characteristics of Radermachera sinica, including natural frequencies and equivalent damping ratios, are contactlessly measured by a laser Doppler vibrometer (LDV). A mechanical model is developed to simulate the vibration of a plant. By combining this mechanical model with experimental data, the material damping coefficients of the vibrating plant can be determined. Finite-element analysis (FEA) is conducted, and the simulating results are compared with the mechanical model.Results: Vibration data of the healthy plant with leaves (Group 1), healthy plant without leaves (Group 2), and diseased plant without leaves (Group 3) are measured and vibration characteristics are obtained by analyzing measurement data of LDV. The experiment results show that the natural frequencies of Radermachera sinica in Group 2 and Group 3 are 1.60 and 2.84 times of that in Group 1, respectively, while the equivalent damping ratios in Group 2 and Group 3 are 0.52 and 1.24 times of that in Group 1, respectively. Furtherly, the material damping coefficient is predicted by the mechanical model, and the result shows that the material damping coefficient in the diseased plant is 1.2 times of that in healthy plants. The results obtained from the FEA align well with the predictions of the mechanical model, thereby confirming the accuracy of the mechanical model.Conclusion: The non-contact vibration measurement technique, combined with the mechanical model proposed in this paper, may offer a new approach to identify the health status and determine the material damping of Radermachera sinica and other plants.