Authors

Abstract

In the current paper, a coated cotton-seed discrete element model was established. Furthermore, we designed a device for the simultaneous determination of the repose and accumulation angles, and Plackett–Burman and central composite design (CCD) tests were performed with the repose and accumulation angles as the test indexes. The static friction coefficient between seeds (SFCC) and the dynamic friction coefficient between seeds (DFCC) were observed to have a significant influence on the indexes and were thus selected for the subsequent analysis (P < 0.05). Analysis of variance revealed the terms of these two parameters to have a significant effect on the relative error of the repose angle (RERA) and the relative error of accumulation angles (REAA) (P < 0.05). A solution to the proposed mathematical model was determined via the NSGA-Ⅱ genetic algorithm and the Pareto optimal solution set was obtained. Based on multi-objective optimization, the SFCC and DFCC were determined as 0.174 and 0.068, for RERA and REAA values of 1.715% and 1.712%, respectively. Simulations were then performed using the optimal parameters. Results of the T-test demonstrated that there were no significant differences between the simulated and physical test results.

Abstract in Chinese

本文基于EDEM软件建立了包衣棉种离散元模型，设计了一种可以对物料休止角与堆积角同时进行测定的装置，通过物理试验与仿真试验对棉种接触参数进行了标定。首先，利用Plackett-Burman试验筛选出了对棉种休止角和堆积角有显著性影响的接触参数，为种间静摩擦系数和种间动摩擦系数；然后以休止角和堆积角相对误差为指标，对这两个参数进行最陡爬坡试验，优化其取值范围，并基于中心组合试验建立了指标与显著性参数的回归数学模型，数学模型的拟合度较好；进而采用遗传算法(NSGA-Ⅱ)进行多目标寻优，得到当种间静摩擦系数为0.174，种间动摩擦系数为0.068时，棉种离散元模型的数学模型最优解较好；最后利用T检验得到休止角和堆积角的P值均大于0.05，表明仿真试验与物理试验值差异不显著，验证了最优参数组合的可靠性。