Determination of discrete element model parameters required for soil tillage
Determination of discrete element model parameters required for soil tillage
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DOI：
10.1016/j.still.2006.03.006
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发表时间：
2007-01-01
影响因子：
6.5
通讯作者：
Shmulevich, I.
中科院分区：
文献类型：
--
作者：
Asaf, Z.;Rubinstein, D.;Shmulevich, I.
土壤耕作过程中发生的动力相互作用包括高速率的塑性变形和土壤破坏，其特征是土壤颗粒的流动。离散元法（DEM）似乎是一种很有前途的方法来建立一个高保真模型来描述土壤-工具的相互作用。使用DEM对这种相互作用的正确预测取决于模型参数。然而，目前还没有确定离散单元模型参数的可靠方法。在这项研究中，参数的确定是基于现场测试，包括使用不同的渗透工具进行的下沉测试。在每次测试的基础上，绘制出力与位移的关系图，或所谓的“真实曲线”。根据现场试验建立了离散单元模型。从力与位移的模拟结果中得到“仿真曲线”图。为了使实际曲线与仿真曲线之间的面积差最小，采用了一种基于Nelder-Mead优化算法的逆解技术。这一特殊问题的优化结果对参数的初始估计很敏感。为了获得唯一解，初始估计值必须足够接近参数的适当值。提出了能量法和弹塑性法则来确定优化过程的初始估计。所描述的方法得到了实验和数值验证；实验结果与离散元模拟结果具有较好的相关性。(c) 2006 Elsevier B.V.版权所有
The dynamic interaction that occurs in the soil tillage process includes a high rate of plastic deformation and soil failure, characterized by flow of the soil particles. The discrete element method (DEM) seems to be a promising approach for constructing a high-fidelity model to describe soil-implement interaction. Proper prediction of this interaction using DEM depends upon the model parameters. However, there is no robust method for determining the parameters for discrete element models. In this study, the determination of parameters was based on in situ field tests, which consisted of sinkage tests performed with different penetration tools. Based on each test, a plot of force versus displacement, or a so-called "real curve," was drawn. Discrete element models were built in correspondence with the field tests. "Simulation curve" plots were obtained from the results of the simulation of force versus displacement. In order to minimize the area difference between the real and simulation curves, an inverse solution technique using the Nelder-Mead algorithm of optimization was employed. The optimization results of this particular problem are sensitive to the initial estimate of the parameters. In order to achieve a unique solution, the initial estimate must be close enough to the proper value of the parameters. An energy method and elastic-plastic rule were developed to determine the initial estimation for the optimization process. The described methodology was verified experimentally and numerically; good correlation was achieved between the soil mechanical behavior obtained by experiments and the discrete element simulations. (c) 2006 Elsevier B.V. All rights reserved.