A Calibration of the Contact Parameters of a Sesbania Seed Discrete Element Model Based on RSM

Abstract

In order to simulate and analyze the mechanized seeding process of sesbania seeds by using a discrete element method and improve the reliability of the discrete element simulation test, the contact parameters of sesbania seeds were calibrated in combination with the actual seed drop test and the simulated seed drop test. Through measurements, the intrinsic parameters of the sesbania seed were determined, and the discrete element simulation model of the sesbania seed was established. A measuring device that can simultaneously measure the resting angle and the stacking angle of the population was designed. The rest angle error and the stack angle error of the actual seed drop test and the simulated seed drop test were used as test indicators. The Plackett–Burman test screened out the contact parameters that had a significant effect on the test indicators. The response surface method (RSM) was used to carry out the three-factor quadratic rotation orthogonal combination test, and the mathematical regression model between the significant contact parameters and the test indexes was established. The optimal combination of contact parameters was determined using the multi-objective optimization method as follows: collision recovery coefficient between seeds of 0.463, static friction coefficient between seeds of 0.520, and rolling friction coefficient between seeds of 0.072. The discrete element model and calibration parameters of sesbania seeds were tested and verified using a fluted roller feed mechanism. The results showed that the average relative error between the measured value and the simulated value of the mass flow rate of the sesbania seeds was 2.74%, less than 5%, indicating that the discrete element simulation model of sesbania seeds and the calibration results of the contact parameters had high accuracy and reliability, which could be used for the discrete element simulation test of sesbania seeds.