Mechanical Instability of Heavy Column with Rotational Spring

IF 1.5 4区 工程技术 Q3 MECHANICS
Tohya Kanahama, Carol Lee Chalermsin, Motohiro Sato
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引用次数: 0

Abstract

In previous research on the mechanical instability of trees based on mechanical theory, wild tree has been modeled as a cantilever which was perfectly attached to the ground. However, experimental research has identified two failure modes, including root turnover and self-buckling of the trunk. This suggests that the imperfect fixation caused by root-soil interaction must be considered when discussing tree stability. The purpose of this study is to clarify the self-buckling characteristics of wild trees considering soil instability. To account for the resistance moment caused by the interaction between the root and soil, trees as cantilevers fixed to the ground by a rotational spring were modeled. In this model, the self-buckling problem was formulated considering the rotational rigidity of the spring, and the formula derived for the critical height and buckling mode. As a result, the formula for critical height considering rotational rigidity was obtained, and it was found that the buckling modes can be classified into the rigid-body mode and beam mode based on the rotational rigidity. By comparing this result with the statistical law based on the measurement of real trees reported in previous research, it was determined that real trees were designed based on beam mode. This suggests that the wild tree skillfully balances the moment of resistance caused by the interaction between the root and soil to prevent “uprooting,” which is extremely fatal for trees. Moreover, it was also found that the safety factor of trees for self-buckling is ensured enough to prevent the beam mode.
带旋转弹簧的重柱的机械不稳定性
在以往基于力学理论对树木机械不稳定性的研究中,野生树木被建模为完全固定在地面上的悬臂。然而,实验研究发现了两种失效模式,包括根部翻转和树干自弯曲。这表明,在讨论树木稳定性时,必须考虑根与土壤相互作用造成的不完全固定。本研究的目的是在考虑土壤不稳定性的情况下阐明野生树木的自弯曲特性。为了考虑根系与土壤之间相互作用产生的阻力矩,研究人员将树木作为悬臂,通过旋转弹簧固定在地面上。在该模型中,考虑到弹簧的旋转刚度,提出了自屈曲问题,并推导出临界高度和屈曲模式公式。结果得到了考虑旋转刚度的临界高度公式,并发现根据旋转刚度,屈曲模式可分为刚体模式和梁模式。通过将这一结果与之前研究报告中基于真实树木测量的统计规律进行比较,确定真实树木是基于梁模式设计的。这表明,野生树木巧妙地平衡了根部与土壤之间相互作用产生的阻力矩,从而避免了对树木极为致命的 "连根拔起 "现象。此外,研究还发现,树木自我屈曲的安全系数足以确保防止横梁模式。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Journal of Mechanics
Journal of Mechanics 物理-力学
CiteScore
3.20
自引率
11.80%
发文量
20
审稿时长
6 months
期刊介绍: The objective of the Journal of Mechanics is to provide an international forum to foster exchange of ideas among mechanics communities in different parts of world. The Journal of Mechanics publishes original research in all fields of theoretical and applied mechanics. The Journal especially welcomes papers that are related to recent technological advances. The contributions, which may be analytical, experimental or numerical, should be of significance to the progress of mechanics. Papers which are merely illustrations of established principles and procedures will generally not be accepted. Reports that are of technical interest are published as short articles. Review articles are published only by invitation.
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