颗粒肥料离散元仿真边界参数系统化研究

离散元边界参数对仿真精确性具有重要的影响。为提高离散元仿真精度,以大颗粒尿素颗粒为研究对象,利用Plackett-Burman休止角仿真试验进行了重要边界参数的筛选,确定影响显著的参数依次为尿素颗粒间滚动摩擦因数、颗粒间静摩擦因数和颗粒与ABS板间静摩擦因数,且3种边界参数影响尿素颗粒堆积特性,休止角随着3种边界参数的增大而增大。利用自制静摩擦因数测量仪和虚拟仿真标定方法分别对颗粒与ABS板间的静摩擦因数、颗粒间静摩擦因数和颗粒间滚动摩擦因数进行研究,并对确定值进行了堆积过程的仿真和试验验证,仿真休止角与实际试验休止角相对误差仅为0.36%,不同含水率下的实际试验休止角与标定参数下的仿真休止角相对误差均不大于3.25%,表明仿真确定的边界参数和仿真模型的有效性。

Systematic Study on Boundary Parameters of Discrete Element Simulation of Granular Fertilizer

The discrete element boundary parameters have an important influence on the simulation accuracy. In order to improve the simulation accuracy, big urea particles were taken as the research object, the macroscopic phenomenon of the repose angle which reflected stacking process of granular particles was chosen, and the Plackett-Burman screening test was used to select the factors which was important based on the angle of repose. The order of importance for determining the effect was the rolling friction coefficient between urea particles, the static friction coefficient between urea particles and the static friction coefficient between particles and ABS plates, and the three boundary parameters influencing the accumulation of urea particles, the angle of repose was increased with the increase of the three boundary parameters. The static friction coefficient, the static friction coefficient between particles and ABS plate and the coefficient of rolling friction between particles were studied by self made static friction coefficient measuring instrument and virtual simulation calibration method, respectively. And the simulation and test verification of accumulating process of determined values were carried out. The relative error between the simulation repose angle and the actual test repose angle was only 0.36%. The relative error between the calibrated simulation repose angle and the actual test repose angle with different water contents was not more than 3.25%. The test results verified the validity of the boundary parameters and the simulation model. A new method for calibrating urea particle simulation boundary parameters was proposed. The validity of the calibrated discrete element model and boundary parameters of the urea particles was improved. The calibrated discrete element model and boundary parameters of the urea particles and calibration method can be applied to the dynamic simulation of the fertilizer distributor.