颗粒结构化排列玉米秸秆离散元模型与防堵作业验证

Modeling and Validation of Structured Particle-arranged Flexible Corn Stalk Discrete Element Model for No-till Seeding

摘要:

针对现有玉米柔性秸秆模型难以精确模拟免耕播种防堵装置作业指标及工况等问题，本文设计了一种内瓤颗粒等距均匀粘结、双球形外皮颗粒与之稳定配合的椭圆柱状玉米柔性秸秆模型，可应用于秸秆随机铺放在土壤条件下防堵装置作业精确模拟。通过对秸秆样本和分离后外皮、内瓤分别进行剪切试验，以峰值力、位移和功耗为指标开展了多因素颗粒粘结参数标定，验证试验结果表明该模型能准确反映实际切割工况下内瓤、外皮及秸秆的力学特性与切割指标。为进一步验证模型对切断式防堵装置作业的模拟精度，构建了秸秆随机铺放于土壤的仿真和土槽模型，开展作业过程模拟。试验结果表明，该模型可较为准确地模拟缺口圆盘作业后秸秆残留、断裂情况，秸秆切断和压入土壤数量平均误差分别为12.04%、7.73%，缺口圆盘牵引力和下压力平均误差分别为5.14%、7.41%。研究结果为切断式防堵装置优化和柔性秸秆模型改进提供参考。

Abstract:

Aiming to address the challenge that existing flexible corn stalk models struggle to accurately simulate the operational indicators and working conditions of no-tillage anti-blocking devices, an elliptical cylindrical flexible corn stalk model was presented. The model features equidistantly and uniformly bonded pith particles, which stably coordinate with double-spherical husk particles, enabling precise simulation of anti-blocking device operations under conditions where stalks were randomly laid on the soil. Shear tests were conducted on stalk samples and separated husk and pith components to calibrate particle bonding parameters under multiple constraints, using peak force, displacement, and power consumption as indicators. Validation tests showed that the model accurately reflected the mechanical properties and cutting indices of pith, husk, and stalks under actual cutting conditions. To further verify the simulation accuracy for cutting-type anti-blocking device operations, both simulation and soil bin models with randomly distributed stalks on soil were constructed to simulate the operation process. Tests indicated that the model can relatively accurately simulate stalk residue and fracture conditions after notched disc operation. The average errors in the number of cut stalks and stalks pressed into the soil were 12.04% and 7.73%, respectively, while the average errors in the draft force and down force of the notched disc were 5.14% and 7.41%, respectively. The development of this model was expected to provide references for the optimization of cutting-type anti-blocking devices and the improvement of flexible stalk models.