林木风倒动态模型的建立与分析

Establishment and Analysis of Dynamical Model for Windthrow of Trees

基于一些理想化的假设,将林木简化成一根无质量弹性杆连结,给出林木的动态微分方程以及模型边界条件,考虑树干底部弯矩和风力的关系,描述树干底部弯矩和风力关系的物理意义,推导出无阻尼和有阻尼情况下林木的简化动态模型,最后给出位移的计算表达式。数值仿真结果表明该模型能足够好的满足初始假设,且计算量小。从数值结果的对比分析中得出一些有意义的结论,可为后续研究提供理论基础。

Windthrow is a major reason of making the gaps,which is a factor of ecology turbulence.So it is very important to analyze the mechanism of windthrow theoretically and practically.In this paper,the dynamical model of the windthrow of trees was established.Based on some idealized hypothesis,the tree was treated as a massless elastic stick and the dynamical model and the boundary conditions of model were obtained.Considering the relations between the bending moment of the bottom and wind,we described the physical meaning of the bending moment of the bottom and wind.Meanwhile we deduced the simplified dynamical model with and without damping.At last,the displacement expression of calculation was obtained.The numerical simulation showed that the model can perfectly meet initial hypothesis and require less computation.From the numerical results and comparison between these results,some conclusions of significance were drawn,which can provide theoretical basis for subsequent research.