Calibration of Simulation Parameters for Fresh Tea Leaves Based on the Discrete Element Method

Abstract

To address the problem of a lack of accurate parameters in the discrete element simulation study of the machine-picked fresh tea leaf mechanized-sorting process, this study used machine-picked fresh tea leaves as the research object, established discrete element models of different fresh tea leaf components in EDEM software version 7.0.0. based on the bonded particle model using three-dimensional scanning inverse-modeling technology, and calibrated the simulation parameters through physical tests and virtual simulation tests. Firstly, the intrinsic parameters of machine-picked tea leaves were measured using physical tests; the physical-stacking tea leaf test was conducted using the cylinder lifting method, the tea leaf repose angle being 32.62° as measured from the stacking images using CAD. With the physical repose angle as the target value, the Plackeet–Burman test, the steepest-ascent test and the Box–Behnken optimization test were conducted in turn, and the results showed that the static friction coefficient between tea leaves, the rolling friction coefficient between tea leaves and the static friction coefficient between tea leaves and PVC have a major effect on the repose angle, and the optimal combination of the three significant parameters was determined. Finally, five simulations were conducted using the optimal combination of parameters, the relative error between the repose angle measured by the simulation test and the physical repose angle being just 0.28%. Moreover, the t-test obtained p > 0.05, indicating that there was no significant difference between the simulation test results and the physical test results. The results showed that the calibrated discrete element simulation parameters obtained could provide a reference for the discrete element simulation study of fresh tea leaves.

Parameter Calibration of Discrete Element Model of Wine Lees Particles

“…Currently, in the field of agricultural engineering, many scholars have conducted a lot of research on the calibration of discrete element model parameters of particles. Yunxia Wang, Fanyi Liu, and Tao Wu calibrated the discrete elemental model parameters of corn seeds, wheat, and clayey soil, respectively, based on angle of repose simulation experiments [6][7][8]; Xu Bing established a non-spherical particle model of buckwheat seeds using the auto-filling method and parameterized it using a discrete element model [9]. Wang Long designed a device to simultaneously determine the angle of repose and angle of accumulation of materials and calibrated the contact parameters of cotton seeds through physical and simulation tests [10].…”