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应力波在落叶松活立木中的传播规律(PDF/HTML)

《南京林业大学学报(自然科学版)》[ISSN:1000-2006/CN:32-1161/S]

Issue:
2017年03期
Page:
133-139
Column:
研究论文
publishdate:
2017-05-31

Article Info:/Info

Title:
Stress wave propagation patterns in larch standing trees
Article ID:
1000-2006(2017)03-0133-07
Author(s):
LIU Fenglu1 JIANG Fang1* WANG Xiping2 ZHANG Houjiang1 LIU Xingkai1
1 School of Technology, Beijing Forestry University, Beijing 100083, China;
2 USDA Forest Products Laboratory, Madison, Wisconsin 53726, USA
Keywords:
stress wave larch standing trees COMSOL Multiphysics numerical simulation orthotropy
Classification number :
S781.23
DOI:
10.3969/j.issn.1000-2006.201609032
Document Code:
-
Abstract:
【Objective】The primary purpose of this study was to explore the propagation patterns of stress waves traveling in larch standing trees, and pave a theoretical foundation for further study on the prediction and evaluation of the mechanical properties of these plantation trees.【Method】In this study, the wave fronts of stress waves propagating in standing trees were simulated, and the forms of two-dimensional and three-dimensional propagation patterns of the stress waves propagating in standing trees were studied by using COMSOL Multiphysics finite element analysis software, based on the stress wave propagation theory in a solid medium and the orthotropic assumption for standing trees. Finally, a field experiment for the measurement of stress-wave timing was conducted to verify the validity of the numerical simulation method.【Result】It was found that the wavefront at the starting stage was a sloping curve or surface, bending to input point of force pulse and with the increase in distance, the inclination of the wavefront decreased gradually until it was approximately vertical to the length direction, i.e., the wavefront gradually changed from a 3D wave to a quasi-plane wave. The rate of decrease of the wavefront inclination increased with decreasing tree diameter. The travel distance had no effect on the wave velocity, but the wave velocity generally increased with increasing diameter. Finally, the feasibility of the simulation method used for investigating the stress-wave propagation patterns in standing trees was verified.【Conclusion】The numerical simulation method is practicable for the study of the propagation patterns of stress waves in standing trees and the effects of the diameter and propagation distance on the wave velocity. The diameter as well as the propagation distance could influence the propagation patterns of stress waves in standing trees, but their effects on stress-wave velocity were different.

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Last Update: 2017-05-20