基于离散元仿真参数的微型薯物料测定

Discrete element simulation parameters-based measurement of materials for potato minituber

以脱毒微型马铃薯(简称“微型薯”)“大西洋”“中薯5号”和“华薯1号”为研究对象,以离散元软件EDEM中微型薯仿真研究所需的相关参数为目标,测定3种微型薯的物理力学特征参数和接触力学参数。采用响应曲面法设计试验,以静摩擦系数、滚动摩擦系数为试验变量,以堆积角为试验指标,将上述测定后的参数输入EDEM进行仿真,求取微型薯之间的滚动摩擦系数。以堆积角为响应值,使用圆筒提升法验证仿真结果的可信度。结果表明:与试验实际堆积角相比,不同品种的微型薯仿真结果差异均低于3%,仿真结果可靠。

Parameters of physical and mechanical characteristics are indispensable in designing potato minituber related mechanical equipment planter and classifier.Parameters of the contact mechanics are indispensable in developing simulation technology as well.The virus-free potato minitubers(referred as“minituber”)including“Daxiyang”,“Zhongshu No.5”and“Huashu No.1”and the relevant parameters required for discrete element software EDEM in potato minituber were used to measure physical parameters and contact mechanical parameters of three kinds of potato minitubers.Self-made equipment was used to measure and calculate the triaxial dimensions,weight,radius of curvature,density,Poisson's ratio and shear modulus.The contact mechanical parameters of three kinds of minitubers and three materials(steel plate,ABS and the same variety potato minitubers)including the collision recovery coefficient were measured by using a self-made collision device.The static friction coefficient was measured by using the method of sliding on an inclined plane.The combination of rolling on an inclined plane and high-speed photography was used to record the rolling distance and measure the rolling friction coefficient of potato minituber,steel plates or ABS.The response surface method was used to design the test by using coefficient of static friction and coefficient of rolling friction as test variables,and the stacking angle as test index.The parameters measured in the above experiment were input into the EDEM for simulation to obtain coefficient of the rolling friction in minitubers.Using the stacking angle as the response value,and the credibility of the simulation results was verified by raising a round pipe slowly.Results showed that density,shear modulus and Poisson’s ratio had little correlation with the basic parameters of physical characteristics of minitubers.The triaxial dimensions,weight and radius of curvature were quite different.The varieties were different as well.The contact mechanical parameters of the three types of minitubers and their own same variety were lower than those of the steel plate and ABS.The coefficients of static and dynamic friction of the three types of minitubers and ABS were higher than that of the steel plate.The collision recovery coefficient showed the opposite trend.ABS was lower than the steel plate.The contact mechanical parameters of“Daxiyang”were higher than those of“Zhongshu No.5”and“Huashu No.1”.Among the three materials,the contact mechanical parameters with the steel plate were the largest,indicating that its elastic recovery performance is the best,with relatively large friction and relative difficulty to be damaged.The fluidity and the mechanized seeding performance was poor.The difference of contact mechanical parameters between“Zhongshu No.5”and“Huashu No.1”was small.The measurement results of different varieties of minitubers were quite different.Users can select the required parameters in the text according to their needs.The variety should be fully considered in the design and simulation calculations.Compared with the actual accumulation angle of the experiment,the simulation results of different varieties of potato minituber were less than 3%,indicating that the results are reliable and the actual parameters of the minituber particles measured can be used as simulation parameters in the EDEM software.