树木表面裂纹形成的生物力学机制

Mechanics and Modeling of Crack Formation in Tree Epidermis

树木生长过程中会产生很大的生长应力,这些力与植物的生长过程有哪些关联?回答这个问题,有必要对应力与树木生长之间的关系进行研究。受近年来植物细胞力学研究的启发,本文采用连续介质弹性壳的力学模型,分析了树皮在树木生长过程中的应力状态,从材料强度的角度,解释了树皮表面纵裂的力学根源。同时,结合线弹性断裂力学的分析方法,并考虑了树木材料的各向异性材料力学性质,给出了树皮表面裂纹张开位移随树木生长膨胀压力变化的规律。研究结果定性地解释了树木表面纵裂的规律:通常树皮表面裂纹沿树高逐渐变窄变稀,裂纹的长度和裂尖张开位移均沿树木的高度方向减小。本文定性地阐明了树木生长应力与树皮表面纵裂形貌之间的关联,为探索多学科的研究方法提供了更多的参考依据。

Tree stems are under tremendous mechanical forces generated by turgor pressure.What is the link between biological and mechanical processes？ In order to answer this question,it is necessary to understand the mechanics of growth.Inspired by the recent research of the cell wall mechanics,the pressure vessel model has been proposed to analyze the stress state of stem epidermis.From the point of view of material strength,we give rational illumination of the axial crack in the tree epidermis.Based on linear elastic fracture mechanics,we set up a relationship between the crack open displacement in the tree bark and turgor pressure.Here the anisotropic material mechanical properties are considered for the tree.The numerical results give a qualitative interpretation for axial crack on the tree surface that the crack becomes narrow and sparse along the tree from the ground and the length and open displacement of the crack decrease along the tree.To capture and explain the biological process,the use of mechanical modeling approaches in plant emphasize the need for fostering interdisciplinary research.