中药浸膏粉离散元模拟参数标定方法研究

目的采用离散元法(DEM)模拟中药浸膏粉休止角,确定颗粒之间、颗粒与几何体之间的接触参数。方法以生甘草浸膏粉、独活浸膏粉、微晶纤维素(MCC)和乙基纤维素(EC)4种粉末为研究对象,在Hertz-Mindlin with JKR Cohesion接触模型和颗粒缩放的基础上,通过Plackett-Burman设计筛选出对休止角模拟测定影响显著的接触参数,进而通过最陡爬坡设计确定关键接触参数的最佳区域。根据Box-Behnken试验结果,建立接触参数和模拟休止角之间的回归模型,优选最佳接触参数值并验证。结果筛选得到的关键接触参数为颗粒-颗粒滚动摩擦系数、颗粒-颗粒恢复系数和颗粒-不锈钢恢复系数,所建回归模型对休止角的标定范围为33.30°～43.64°,4种粉末休止角模拟测定值与实验值的相对误差绝对值均小于2.0%,表明所建标定方法准确可靠。结论证明了通过宏观物性参数间接标定中药颗粒体系DEM微观力学参数的可行性,为混合、输送等中药制药过程的精确模拟奠定了基础。

Calibration of discrete element simulation parameters of Chinese medicine extract powders

Objective The discrete element method (DEM) was used to simulate the angle of repose of Chinese medicine extract powders. The contact parameters between particles and between particles and geometry were calibrated. Methods The licorice extract powder, the extract powders of Angelicae Pubescentis Radix (Duhuo), microcrystalline cellulose (MCC) and ethyl cellulose (EC) were taken as the research objects. DEM was performed based on the Hertz-Mindlin with JKR Cohesion contact model and particle scaling. The Plackett-Burman design was used to screen out the critical contact parameters that had significant impact on the simulation measurement of the angle of repose. Then, the steepest climbing design was used to determine the best area of critical contact parameters. After that, a regression model between the contact parameters and the simulated angle of repose was established according to the Box-Behnken test results, and the best contact parameter values were optimized and verified. Results The critical contact parameters selected were particle-particle rolling friction coefficient, particle-particle restitution coefficient and particle-stainless steel restitution coefficient. The calibration range of the built regression model was from 33.30° to 43.64°. The absolute values of the relative error between the simulated values and the experimental values of the angle of repose for four powders were all less than 2.0%, indicating that the established calibration method was accurate and reliable. Conclusion This article proved the feasibility of calibrating the DEM micromechanical parameters of the Chinese medicine particle system through the macroscopic physical parameter, and laid the foundation for accurate simulation of Chinese medicine pharmaceutical processes like powder mixing and conveying.