This study aimed to improve the measurement accuracy of the discrete element method (DEM) simulation parameters of sorghum seeds for enhanced model accuracy. We measured the intrinsic and contact parameters of sorghum seeds, extracted the outline of the seeds by 3D scanning, and used the multi-spherical particle model filling method in the EDEM (Version 2020) software to obtain the simulation model of the seeds. By simulating the free-fall, slope slip, slope rolling, and rolling experiments of sorghum seeds–photosensitive resin material, we calibrated the collision restitution coefficient of the sorghum seeds–photosensitive resin material to 0.690, static friction coefficient to 0.345, and rolling friction coefficient to 0.040. Through the steepest ascent search and central composite design experiments, we calibrated the collision restitution coefficient of sorghum seeds–sorghum seeds to 0.400, the static friction coefficient to 0.450, and the rolling friction coefficient to 0.043. The angle of repose of the parameter combination and the angle of repose of the physical experiment (33.82°) were verified, and the relative errors of the coefficients were 0.7%, 0.25%, and 0.3%, respectively, indicating that the established model had a high simulation accuracy and reliability. These results show that the established sorghum seeds model and the optimally calibrated parameter combination are effective for DEM studies on sorghum seeds.

Due to a lack of an accurate model in finite element simulation of mechanized harvesting of wild chrysanthemum, the stem of wild chrysanthemum in the harvesting period is taken as the research object. ANSYS Workbench 19.0 software and LS-DYNA software (LS-PrePOST-4.3-X64) are used to calibrate the finite element simulation model of wild chrysanthemum stem cutting. The stem diameter distribution at the cutting height of the chrysanthemum is obtained. The maximum shear forces at different diameters (7 mm, 8 mm, 9 mm, 10 mm, and 11 mm) within the cutting range are determined as 120.0 N, 159.2 N, 213.8 N, 300.0 N, and 378.2 N, respectively, by using a biomechanical testing machine and a custom-made shear blade. The Plastic_Kinematic failure model is used to simulate the cutting process by the finite element method. The Plackett–Burman test is employed to screen out the test factors that significantly affect the results, namely, the yield stress, failure strain, and strain rate parameter C. The regression model between the shear force and significant parameters is obtained by central composite design experiments. To obtain the model parameters, the measured values are substituted into the regression equation as the simulation target values. In other words, the yield stress is 17.96 MPa, the strain rate parameter C is 87.27, and the failure strain is 0.0387. The maximum shear force simulation test is carried out with the determined parameters. The results showed that the maximum error between the simulated and the actual value of the maximum shear force of wild chrysanthemum stems with different diameters is 7.8%. This indicates that the calibrated parameters of the relevant stem failure model can be used in the finite element method simulation and provide a basis for subsequent simulations.

Using discrete element simulation to reveal the interaction between seed and seed metering devices (SMD) is an important method for developing SMDs. However, due to the lack of discrete element modeling (DEM) parameters of adzuki bean seeds (ABS) in existing literature, it is difficult to develop a suitable SMD. In this study, the DEM parameters of ABS were determined by a combination of physical tests and virtual calibration. Initially, the intrinsic parameters, contact parameters, and angle of repose (AOR) of ABS were measured. The parameters significantly affected AOR were then screened out by Plackett–Burman test. Furthermore, the Steepest Ascent test was used to determine the optimal interval value of significant parameters. Finally, the optimal values of significant parameters were obtained by the Box–Behnken test with an AOR of 23.93° and an error of 0 as targets. The results showed that the coefficient of static friction of ABS–ABS, coefficient of static friction of ABS-photosensitive resin plate, and coefficient of rolling friction of ABS–ABS significantly affected the AOR, and their optimal values were 0.302, 0.282, and 0.043, respectively. The verification test showed that the relative error between simulated and measured values of AOR was 0.67%. This indicated that the determined DEM parameters were accurate and reliable. The results from the study can provide a reference for the selection of DEM parameters in the mechanized seeding process of ABS.

Discrete element simulation is an effective method to reveal the interaction between tillage components and work objects. However, due to the lack of discrete element modelling parameters of maize root and its mixture with soil, existing tillage models cannot accurately simulate the farmland environment under a no-tillage system. This study developed single maize root (SMR) with different diameters and maize root-soil mixture (MRSM) DEM models based on calibrated parameters through the angle of repose (AOR) tests. First, the Plackett–Burman and the steepest climb tests were performed to identify the range of essential parameters for the AOR of the SMR. Then, the optimal parameters for the SMR and MRSR models were obtained by Box–Behnken design (BBD) testing. The results showed that the static friction coefficient of SMR-SMR and the rolling friction coefficient of SMR-SMR and SMR-steel significantly affected the AOR. In addition, the AOR of MRSM was extremely sensitive to the restitution coefficient and surface energy coefficient of root soil. Based on optimal parameters, the relative errors between the simulated and measured AOR and pixel peak values of the piles’ contour curve were less than 5% for SMR and MRSM. The error of the dynamic AOR of the measured and simulated MSRM was less than 10%. These results indicate that the parameter calibration method and the developed models can be valuable references for DEM simulation for maize stubble and tillage.