Experiments and FE-analysis of 2-D root-soil contact problems based on Node-To-Segment approach
Experiments and FE-analysis of 2-D root-soil contact problems based on Node-To-Segment approach
复制标题
基于节点到段方法的二维根-土接触问题的实验和有限元分析
DOI：
10.1016/j.sandf.2019.08.003
复制
发表时间：
2019
影响因子：
3.7
通讯作者：
A. Murakami
中科院分区：
文献类型：
--
作者：
H. Tomobe;K. Fujisawa;A. Murakami
需要准确预测根土系统的机械响应，以评估和减少山体滑坡、地表侵蚀和倒伏的风险。本文提出使用节点到段（NTS）方法和有限元方法来预测根部和土壤之间的接触现象，例如碰撞、滑动和分离。为了对此类复杂几何问题的变形获得可靠的预测，本文提出并实现了 NTS 方法中的稳定算法。所提出的算法避免了NTS方法中众所周知的配对算法的非唯一性问题，该问题一直是将该方法应用于根土系统的障碍。当前方法用于两个数值示例。第一个是验证示例，其中重新分析拉拔实验，以检查该方法对几何简单的根-土壤接触问题的适用性。结果表明，当前方法可以合理预测拉拔响应，并且还可以准确估计摩擦力和内聚力。第二个是现实问题的示例，其中进行了类似于桩加载问题的二维倒伏实验并进行了模拟，以证明 NTS 方法在具有复杂根部几何形状的植物规模问题中的准确性和适用性。模拟的位移与反力之间的关系与实验一致，使得根际应力轮廓和变形可视化。
Accurate predictions of the mechanical response of root-soil systems are required for assessing and reducing the risk of landslides, surface erosions, and lodging. The present paper proposes the use of the node-to-segment (NTS) approach with the finite element method for predicting contact phenomena between roots and soils, such as collision, sliding, and separation. To obtain reliable predictions for the deformation of such geometrically complex problems, a stabilizing algorithm within the NTS approach is proposed and implemented here. The proposed algorithm prevents the well-known non-uniqueness problem of the pairing algorithm in the NTS approach, which has been an obstacle to applying the approach to root-soil systems. The current method is employed for two numerical examples. The first is an example of validation, in which pullout experiments are re-analyzed to examine the applicability of the method to a geometrically simple root-soil contact problem. It is shown that the current method provides a reasonable prediction of the pullout response, and that both the friction and the cohesion can also be accurately estimated with it. The second is an example of a realistic problem, in which a 2-D lodging experiment, analogous to pile-loading problems, is conducted and simulated to demonstrate the accuracy and applicability of the NTS approach in plant-scale problems with complex root geometries. The relationship between the displacement and the reaction force of the simulation is consistent with that of the experiment, and it enables the visualization of the stress contour and deformation of the rhizosphere.