典型蓖麻蒴果离散元参数标定与分析

Calibration and Analysis of Discrete Element Parameters of Typical Castor

蓖麻蒴果离散元参数难以通过试验或文献直接获得,为获得蓖麻蒴果脱壳过程离散元参数需进行参数标定。以堆积试验为依据,对典型蓖麻蒴果离散元参数进行标定。选用通蓖11号和品种1987进行试验,以蓖麻休止角为响应值,应用Plackett-Burman试验对物料离散元参数筛选出显著因素。利用最陡爬坡试验逼近最优参数组合区间,设计中心组合试验,选取最优参数组合。结果表明:通蓖11号的显著因素为蓖麻-蓖麻静摩擦系数、蓖麻-蓖麻动摩擦系数与蓖麻-Q235钢静摩擦系数,3个系数最优组合值分别为0.59,0.04,0.33,虚拟试验休止角平均值与真实值比值为94.48%;1987品种3个系数最优组合值分别为0.44,0.02,0.14,虚拟试验休止角平均值与真实值比值为96.44%。对通蓖11号3个参数进行优化,优化后各系数为0.6,0.05,0.4,此时虚拟试验休止角平均值与真实值比值为98%,仿真程度提高;通蓖11号各系数均大于1987品种,其中蓖麻-蓖麻静摩擦系数占比为0.27、蓖麻-蓖麻动摩擦系数占比为0.60、蓖麻-Q235钢静摩擦系数占比为0.65。3个参数越大,脱壳时的最大速度越小,仿真时间越长,最大压力及脱壳率越大。标定后的参数可为蓖麻蒴果离散元建模及分析提供参考。

It is difficult to obtain the parameters of discrete element method(DEM) of castor capsule directly through experiments or literatures. In order to obtain the parameters of DEM of castor capsule shelling process, it is necessary to calibrate the parameters. Based on the accumulation test, the parameters of typical castor capsule were calibrated by discrete element method. Taking the resting angle of castor as the response value, the Plackett-Burman test was used to screen out the significant factors for the DEM parameters of materials. The steepest climbing test was used to approximate the optimal parameter combination interval, and the central combination test was designed to select the optimal parameter combination. The test results showed that the significant factors of Tongbi 11 were static friction coefficient of castor-castor, dynamic friction coefficient of castor-castor and static friction coefficient of castor-Q235 steel. The optimal combination values of the three coefficients were0.59, 0.04 and 0.33, and the ratio of the average angle of repose to the true value of the virtual test was 95%. The optimal combination values of the three coefficients of 1987 varieties were castor 0.44, 0.02 and 0.14, and the ratio of the average value of the angle of repose of the virtual test to the true value was 97 %. The three coefficients of Tongbi 11 were optimized, and the optimized coefficients were 0.6, 0.05 and 0.4. At this time, the ratio of the average angle of repose to the true value of the virtual test was 98%, and the degree of simulation was improved. All coefficients of Tongbi 11 were greater than those of 1987 varieties, among which the static friction coefficient ratio of castor to castor was 0.27, the dynamic friction coefficient ratio of castor to castor was 0.60, and the static friction coefficient ratio of castor to Q235 steel was 0.65. The larger the three parameters were, the smaller the maximum speeds were during shelling, the longer the simulation time were, and the greater the maximum pressure and shelling rate were. The calibrated parameters can provide a reference for the discrete element modeling and analysis of castor.