前胡种子物性参数测定及其离散元仿真模型参数标定

Measurement of physical parameters of Radix peucedani seeds and parameter calibration of discrete element simulation model

【目的】为确定前胡排种器离散元仿真所需的物性参数,对前胡种子物性参数进行测量及标定.【方法】采用空心圆筒堆积试验法与EDEM仿真结合的方法,结合图像处理技术测定前胡种子堆积角,基于响应面优化法对前胡种子物性参数进行标定,采用Plackett-Burman法从7组因素中筛选出了2组前胡种子堆积角影响显著的因素,再根据星点设计-效应面法试验原理,对前胡种子与前胡种子静摩擦系数、前胡种子与前胡种子滚动摩擦系数进行响应面分析试验.用效应面法预测影响显著因素的最佳参数组合.【结果】前胡种子密度为0.129 g/cm^3,前胡种子与尼龙板静摩擦系数为0.55,前胡种子与前胡种子静摩擦系数0.53,前胡种子与前胡种子滚动摩擦系数为0.05,将最佳参数组合进行仿真试验得到的堆积角与真实试验所得堆积角进行对比,相对误差在2.05%以内,在允许误差范围内.【结论】通过EDEM快速填充的方法建立了前胡种子离散元颗粒模型,为后续前胡的研究奠定了基础.通过空心圆筒法结合图像处理技术,获得了前胡种子堆积角均值为40.93°.

【Objective】 In order to solve the technical problems of the sowing of the Radix peucedani,it is crucial to develop a seed sowing device of R.peucedani.【Method】 Simulation of discrete element method is used to meet the requirements of the sowing of R.peucedani,and it is necessary to calibrate the physical parameters of the seed of R.peucedani.This work combine the method of hollow cylinder stacking test with discrete element method to measure the repose angle of 13 groups through image processing technology,and find out the average value.Further,based on the response surface method,the physical parameters of the seeds are calibrated.Plackett-Burman test was then utilized to screen 2 significant parameters from 7 parameters.The selected 2 parameters are the coefficient of static friction between the seeds,the coefficient of rolling friction between the seeds.Finally,according to the Central Composition Design,the response surface method was conducted on the parameters which have significant effect on the repose angle of the seed.The significant parameters include the coefficient of static friction(A) and the coefficient of rolling friction(B) between the seeds of R.peucedani,and the quadratic term A^2,B^2.Response surface method(RSM) was used to predict the optimal of significant parameters.【Result】 The density of the seeds was 0.129 g/cm^3,and the coefficient of static friction between the seeds and the nylon plate is 0.55 by instrument and test.The optimal coefficient of static friction between the seeds of R.peucedani is 0.53.And the coefficient of rolling friction between the seeds of R.peucedani is 0.05.Other parameters which have no significant effect choose the intermediate levels.【Conclusion】 The reliability of the optimum parameter combination is verified by Discrete element method.