Discrete element-based calibration of simulation parameters of Cyperus esculentus L. (tiger nut) planted in sandy soil

In order to obtain the characteristic parameters of discrete element simulation of Cyperus esculentus planted in the sandy soil of southern Xinjiang, a discrete element simulation model for C. esculentus particles was established on the basis of determining the characteristic parameters of C. esculentus. The discrete element simulation parameters of the C. esculentus were calibrated by a method combining measurement in real tests and EDEM discrete element simulation. The value range of calibration parameters was measured in real tests. EDEM discrete element simulation was applied to establish a curve fitting equation between the calibration parameters measured in real tests and the test evaluation parameters and obtained simulated values of the calibration parameters. The results show that coefficient of restitution, coefficient of static friction, and coefficient of rolling friction for C. esculentus particle to steel plate contacts are 0.454, 0.413, and 0.0675, respectively, and coefficient of restitution between C. esculentus particle to particle is 0.437. On the basis of calibrating the above parameters, simulation tests were designed using C. esculentus group stacking angle as an evaluation indicator, and Poisson's ratio of C. esculentus, coefficient of static friction, and coefficient of rolling friction between C. esculentus particle to particle as test factors. The test results show that using the real value of stacking angle as a target value, the optimal parameters have values of Poisson's ratio of 0.41, coefficient of static friction of 0.48, and coefficient of rolling friction of 0.05 between C. esculentus particle to particle. The parameters combination is simulated and verified. The mean value of stacking angle of C. esculentus is 30.02 degrees, and the error is 1.22%. The research findings provide a reference basis for simulation study and optimal design of the mechanized harvesting process of C. esculentus. Practical applications Cyperus esculentus L., commonly called tiger nut, is an emerging economic crop. The parameters of C. esculentus are studied by combining real tests and EDEM discrete element simulation in this paper. For example, coefficient of restitution, the static friction coefficient, and the rolling friction coefficient between C. esculentus particles. The above parameters were also studied between the C. esculentus particles to the steel plate. The results can provide reference for the research and optimization of the mechanized equipment in the whole production of C. esculentus, and also provide the basis for scholars to study the relationship between the content of components and physical characteristics of the C. esculentus.