基于EDEM的稻种离散元摩擦参数标定

Calibration of Friction Parameters of Seed Particle Models of Hybrid Rice Based on EDEM

混播制种是当前提高杂交水稻制种效率的有效途径之一。杂交水稻混播制种模式下,可以利用父、母本种子粒形或粒径差异对收获得到的父本、母本种子混合物进行机械化分选。为了进一步完善杂交水稻种子分选机械的设计,以玉针香父、母本种子颗粒模型间的摩擦参数为研究对象,进行种子的堆积角物理试验,并利用EDEM分析软件构建离散元模型,选取滚动摩擦因数和静摩擦因数作为试验因素,进行了预试验和两因素三水平全面仿真试验。利用MATLAB软件对父、母本种子堆积群外轮廓图像进行线性拟合求取堆积角值,并通过多次采样计算相对误差。采用双列排布的方式分别建立父本和母本种子的EDEM多球模型进行仿真试验,取定相对误差最小的试验组P2和Q2的种间滚动摩擦因数为标定值,再通过MATLAB对种间静摩擦因数的取值区间进行插值预测。结果表明:父本的种间滚动摩擦因数和静摩擦因数分别为0.11和0.575,母本的种间滚动摩擦因数和静摩擦因数分别为0.07和0.453。将标定后的摩擦参数进行堆积角验证试验,试验得到父本和母本种子堆积角仿真结果与物理试验结果无显著性差异,父本和母本种子的相对误差分别为0.67%和0.45%,进一步验证了标定试验的可靠性。这表明所建立的杂交水稻父本和母本种子颗粒模型及标定得到的摩擦参数可以为杂交水稻种子分选机械的动态仿真研究提供参考。

Mixed sowing is one of the effective ways to improve the efficiency of hybrid rice seed production.In this hybrid rice seed production mode,the male and female seeds can be mechanically storted according to the difference of shape or size between them.In order to further improve the design of hybrid rice seed sorting machine,the physical experiment of seed repose angle was carried out with the friction parameters between the models of the male and female seed particles of Yuzhenxiang as the research object.The discrete element model of the seeds was constructed by using the EDEM analysis software,and the coefficient of rolling friction and coefficient of static friction were selected as the test factors to conduct the pre-experiment and the two-factor three-level comprehensive simulation experiment.The value of the repose angle is obtained by linear fitting of the outer contour of stacking group with MATLAB software,and the relative error is calculated through multiple sampling.The EDEM multi ball models of male and female seeds were set up respectively in the way of double row arrangement for simulation test,and the coefficient of rolling friction between species of experimental groups P2 and Q2 with the smallest relative error was taken as the calibration value,and then the value range of the coefficient of static friction between species was interpolated and predicted with MATLAB.The results showed that the coefficient of rolling friction and coefficient of static friction between species of the male seeds were 0.11 and 0.575,respectively,and the coefficient of rolling friction and coefficient of static friction between species of the female seeds were 0.07 and 0.453,respectively.The calibrated friction parameters were tested to verify the repose angle,and there was no significant difference between the simulation results of the repose angle of male and female seeds and that of the physical test results.The relative errors of male and female seeds were 0.67%and 0.45%,respectively,which further verified the reliability of the calibration test.It is proved that the developed hybrid rice male and female seed particle models and the calibrated friction parameters can provide a reference for dynamic simulation studies of hybrid rice seed sorting machinery.