Authors

Abstract

The analysis of the clearing process of the cutting deck of a small plot wheat combine harvester requires the use of discrete element simulation methods. However, the current simulation test lacks the contact parameters such as wheat stalk and stalk-seed. In this paper, the wheat stalks and seeds at harvest time were taken as the research objects, and the calibration study of the discrete element simulation model parameters of stalks and stalk-seeds was carried out by means of mechanical test determination and EDEM software simulation. The stiffness coefficients of wheat stalks were determined by mechanical tests; the average values of wheat stalk stacking angle of 39.22° and wheat stalk-seed stacking angle of 44.41° were obtained by stacking angle tests. By the steepest climb test and binary regression test, the stalk normal stiffness coefficient was determined to be 5e+08N/m2 and tangential stiffness was determined to be 6.35e+08N/m2; the stalk-stalk collision recovery coefficient was obtained to be 0.551, static friction coefficient was obtained to be 0.797, and rolling friction coefficient was obtained to be 0.079 by the two-level analytical factorization test, the steepest climb test, and the three-factor response surface test. Based on this, the average value of wheat stalk-seed stacking angle was obtained to be 39.22° and the average value of wheat stalk-seed stacking angle was obtained to be 44.41° by the stacking angle test. On this basis, the coefficient of recovery of stalk-stalk collision was 0.434, the coefficient of static friction was 0.884, and the coefficient of rolling friction was 0.339 obtained by the three-factor response surface test. Three validation experiments were carried out by substituting the obtained parameters into the simulation test, and the error values were close to the error value %0.255 in the model, which proved that the experimental data were reliable.

Abstract in Chinese

小区小麦联合收获机割台清理过程的分析需要使用离散元仿真方法。但目前仿真试验缺乏小麦茎秆、茎秆-籽粒等接触参数。本文以收获期的小麦茎秆、籽粒为研究对象，通过力学试验测定和EDEM软件仿真的方式对茎秆和茎秆-籽粒的离散元仿真模型参数展开标定研究。通过力学试验测定了小麦茎秆的刚度系数；通过堆积角试验，得到小麦茎秆堆积角的平均值为39.22°及小麦茎秆-籽粒堆积角的平均值为44.41°。通过最陡爬坡试验和二元回归试验，确定了茎秆法向刚度系数为5e+08N/m2和切向刚度为6.35e+08N/m2；通过二水平析因试验、最陡爬坡试验和三因素响应曲面试验获得了茎秆-茎秆的碰撞恢复系数为0.551、静摩擦系数为0.797、滚动摩擦系数为0.079；在此基础上，通过三因素曲面响应试验获得了茎秆-籽粒的碰撞恢复系数为0.434、静摩擦系数为0.884、滚动摩擦系数为0.339。将得到参数代入仿真试验中进行三次验证实验，误差值接近模型中的误差值%0.255，证明试验数据可靠。