Determination of properties of black pepper to use in discrete element modeling

Virtual parameter calibration of pod pepper seeds based on discrete element simulation

In order to achieve numerical optimization of the pod pepper seed sowing device, the contact parameters of pod pepper seeds were calibrated, with the angle of repose used as the response value. A set of discrete element method (DEM) models of pod pepper seeds was developed to simulate the formation of seed repose angles using reverse engineering reconstruction techniques. An eight-factor, three-level response surface experiment based on the Box-Behnken central combination test method was performed to study the effects of various factors on the angle of repose of seeds. The angle of repose obtained from physical experiments with a value of 27.56° was taken as the target value. The optimal combination of parameters is obtained as follows: seed Poisson's ratio of 0.22, seed shear modulus of 15.47 MPa, seed-to-seed static friction coefficient of 0.25, seed-to-seed rolling friction coefficient of 0.67, seed-to-seed collision recovery coefficient of 0.64, seed-to-steel-plate static friction coefficient of 0.55, seed-to-steel-plate rolling friction coefficient of 0.45, and seed-to-steel plate collision recovery coefficient of 0.34. A two-sample t-test of the angle of repose obtained by the cylinder lifting method and the pumping plate method against the target value yielded P > 0.05, indicating the reliability of the simulation experiments.

Determination of mechanical properties of Zanthoxylum armatum using the discrete element method

Using the discrete element method (DEM) to investigate the behavior of particles is a crucial strategy in the research and development of novel equipment. Green pepper (Zanthoxylum armatum) is a globally renewable plant-derived medicinal and food homologous commodity with a wide range of uses and great demand, but the mechanical properties needed to develop its processing equipment are scare. Thus, this case of study aimed to systematically explore the necessary input parameters to model green pepper, and to provide new insights for the guidance of future industrial applications worldwide. On the basis of the experimental measured physical properties, the contact properties of green pepper on zinc-coated steel were fist calibrated, and then used to determine the contact properties between particles. The differences between the experimental and simulation results were analyzed for selection and verification of the contact properties accurately. Difference analysis confirmed that the coefficient of restitution, coefficient of static friction and coefficient of rolling friction for contact between the particle and zinc-coated steel have values of 0.392, 0.650, and 0.168, and those coefficients for particle-to-particle contact have values of 0.199, 0.710, and 0.184, respectively. Discoveries in this work may contribute to the research and development of production equipment for green pepper.

Numerical Analysis of the Relationship between Friction Coefficient and Repose Angle of Blast Furnace Raw Materials by Discrete Element Method

In recent years, the discrete element method (DEM) has been widely used to study the factors affecting the repose angle and calibrate particle parameters for simulations. In this paper, DEM is used to study the effects of the coefficient of rolling and static friction of pellet, sinter and coke particles on the repose angle. By comparison of the results of simulations and physical experiments, the coefficients of rolling and static friction suitable for simulation work are determined. The results demonstrate that repose angle increases with the coefficient of rolling and static friction, but the rate of increase gradually decays, when the coefficient of rolling friction exceeds 0.4 or the coefficient of static friction exceeds 0.35. The coefficient of static friction has a greater impact on the repose angle than the coefficient of rolling friction. The rougher of the base surface, the larger the repose angle of the formed particle piled. It can be concluded that appropriate coefficient of rolling and static friction for simulations can be obtained by the outlined procedure.

Measurement and Calibration of the Parameters for Discrete Element Method Modeling of Rapeseed

The discrete element method (DEM) for modeling the behavior of particulate material is highly dependent on the use of appropriate and accurate parameters. In this study, a seed metering DEM simulation was used to measure, calibrate, and verify the physical and interactional parameters of rapeseed. The coefficients of restitution and static friction between rapeseeds and three common materials (aluminum alloy, acrylic, and high-density polyethylene) were measured using free drop and sliding ramp tests, respectively. The angle of repose was determined using a hollow cylinder experiment, which was duplicated using a DEM simulation, to examine the effects of static and rolling friction coefficients on the angle of repose. Response surface optimization was performed to determine the optimized model parameters using a Box–Behnken design test. A metering device was made with three materials, and rapeseed seeding was simulated at different working speeds to verify the calibrated parameters. The validation results showed that the relative errors between the seed metering model and experiments for the single qualified seeding, missed seeding, and multiple seeding rates were −0.15%, 3.29%, and 5.37%, respectively. The results suggest that the determined physical and interactional parameters of rapeseed can be used as references for future DEM simulations.