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Purpose: This research investigates the behavior of granulated sugar particles of different sizes in a rotating drum at varying speeds, using the discrete element method (DEM) as a mathematical modeling approach. Design/methodology/approach: The study conducted a data scan to determine both static and rolling friction coefficients. Based on benchmark studies, the Hertz–Mindlin contact model with rolling history elastic-plastic spring-dashpot (EPSD) and CDT (directional constant torque) models were employed to simulate the behavior of granulated sugar particles in a rotating drum under varying speeds. Findings: In this research, the static and rolling friction coefficients presented the best values for granulated sugar near 0.60 and 1.5, respectively, applying the CDT model. The method demonstrated great accuracy in replicating experimental data. Originality/value: This study enables comprehension of the behavior of the particles and particle system in a rotating drum at different speeds. The method may develop models that characterize and predict the main effects of particle systems to reduce project time and expense, especially in the food industry. [ABSTRACT FROM AUTHOR]

In order to systematically obtain the excavation characteristic parameters for ginger harvesting, experimental analysis was conducted on the discrete elemental parameters in a particle simulation model of the ginger-soil system. Through stacking tests, the surface energy of soil-ginger tuber JKR was determined to be 3.7 J/m², the coefficient of static friction of soil-steel (65 Mn) was 0.56, the coefficient of rolling friction was 0.03, and the coefficient of restitution of collision was 0.40. Utilizing normal and lateral compression tests conducted on the soil body, the soil base parameters required for the Bonding model were determined. Subsequently, a three-dimensional model of ginger root and stem was constructed using these parameters. With the aid of 3D scanning technology, a discrete element parameter model was established for the ginger field during the harvesting period. On the basis of the measured parameters, a three-dimensional model of ginger rhizome was established and finally a discrete parameter model of ginger field was constructed in the harvesting period. The calibration parameters are highly reliable after the model's tightness and field harvesting test, which provides reliable data support for the soil flow and the force of the soil-touching parts during the later simulation of ginger harvesting and digging operation. [ABSTRACT FROM AUTHOR]

In view of the lack of accurate models for discrete element simulation in the current research and development process of forage harvesting and crushing machinery, the contact parameters were calibrated based on Hertz-Mindlin (no slip) contact model by EDEM simulation software with alfalfa stalk at primary florescence as the research object. Based on the angle of repose, the restitution coefficient, static friction coefficient, rolling friction coefficient of alfalfa stalks were determined through the Placket-Burman test, steepest ascent test and Box-Behnken test. The simulation test of the repose angle was carried out with the determined contact parameters. The results showed that the relative error between the simulated repose angle and the physical test repose angle was 0.48%, which indicated that the calibrated contact parameters could truly reflect the physical characteristics of alfalfa stalks at the primary florescence. It provided a reliable model and parameter calibration method for the discrete element simulation in the research and development process of forage machinery, and also provided a reference for the research and optimization design of forage harvesting, crushing and processing machinery. [ABSTRACT FROM AUTHOR]

In view of the large difference in moisture content of cotton stalk in autumn in Xinjiang, the existing process of obtaining discrete element simulation parameters of cotton stalk is low in accuracy and complicated in operation, leading to the problems of poor universality and low accuracy in regard to the discrete element simulation parameter-calibration method in the process of mechanized transportation, throwing and returning to the field. Therefore, the experimental study on cotton stalk with different moisture content was carried out with the accumulation angle as the response value, so as to construct a parameter model that can quickly and accurately calibrate cotton stalk with different levels of moisture content. The model has high applicability and flexibility, and it can be widely used in the simulation test of various cotton field-operation machinery, such as a residual film-recycling machine, cotton picker, crushing and returning machine and other equipment. The water content–accumulation angle model was established by the cylinder-lifting method, and the correlation coefficient of the model was 0.9993. Based on EDEM 2020 software, the Hertz–Mindlin model was used to simulate the stacking angle of cotton stalk, and the rolling friction coefficient, static friction coefficient and collision recovery coefficient between cotton stalk and cotton stalk–steel were obtained. Through the Plackett–Burman test, climbing test and Box–Behnken test, three significant parameters, namely the rolling friction coefficient, static friction coefficient and static friction coefficient between cotton stalk and steel, were selected from discrete element simulation parameters to characterize the moisture content of cotton stalk, and the accumulation angle–discrete element parameter model was established. The p-value of the model was less than 0.0001, and the relative error was only 2.67%. Based on the moisture content–stacking angle model and the stacking angle–discrete element parameter model, the moisture content–discrete element parameter model was constructed. The model was verified by the cylinder-lifting method and the plate-drawing method, and the relative error was only 2.79%. Finally, the model was further verified by comparing the effect of the throwing uniformity between the mechanical simulation test and field test, and the relative error was only 4.75%. The test proves that the moisture content–discrete element parameter model is accurate and reliable, not only providing the design basis and support for the mechanization research of cotton stalk conveying and returning to the field in Xinjiang but also providing ideas for the calibration of discrete element simulation parameters of other crop straws. [ABSTRACT FROM AUTHOR]

To enhance the simulation efficiency of the EDEM discrete element numerical simulation software for coal powder mineral particles, experimental data on the rest angle of coal powder particles were collected as the response variable. Five parameters related to coal powder particles within the Hertz-Mindlin no-slip contact model were selected for investigation. Initially, the Plackett-Burman experiment identified three parameters: collision restitution coefficient, static friction coefficient, and rolling friction coefficient, significantly influencing the resting angle. Subsequently, the steepest ascent experiment determined the significant parameter ranges as follows: the collision restitution coefficient ranged from 0.20 to 0.40, the particle-particle static friction coefficient ranged from 0.30 to 0.50, and the particle-particle dynamic friction coefficient ranged from 0.06 to 0.10. Finally, the second-order regression model for the angle of repose and the saliency parameters was developed and optimized using the Box-Behnken experimental design. The following parameter combination was obtained: the collision recovery coefficient was 0.30, the particle-particle static friction coefficient was 0.49, and the particle-particle dynamic friction coefficient was 0.09. This study aimed to compare the angle of repose between the simulation experiment and the actual experiment. The relative error was only 1.02%, indicating that the simulation experiment achieved the optimal parameter combination. [ABSTRACT FROM AUTHOR]

Oil peony is an important oil crop that is primarily sown by using artificial methods at present. Its seeder encounters the problems of low efficiency of seeding that significantly limits the highly efficient mechanized production of high-quality peony oil. In this study, Fengdan white oil peony seeds were used as the research object and repose angle as the response value to establish a discrete element model (DEM) and parameter calibration. The range of parameters of oil peony seeds was first obtained through an experiment, and their repose angle was obtained by an inclinometer. A three-dimensional DEM of oil peony seeds was then established. The Plackett–Burman (PB) test was utilized to screen the parameters that had a significant influence on the repose angle, and the steepest ascent (SA) test was applied to determine their optimum range of testing. Following this, based on Box–Behnken (BBD) test results, a second-order regression model between the important parameters and the repose angle was constructed. Finally, the absolute minimum difference between simulated and measured repose angles was utilized as the objective of optimization to obtain the following optimum combination of parameters: The values of the seed–steel collision recovery coefficient (CRC), seed–seed static friction coefficient (SFC), seed–steel SFC, and seed–seed rolling friction coefficient (RFC) were 0.704, 0.324, 0.335, and 0.045, respectively. This optimal combination of parameters was confirmed through simulations, and the error between simulated and measured repose angles was only 0.67%, indicating that the calibrated DEM of oil peony seeds was reliable. [ABSTRACT FROM AUTHOR]

The discrete elemental parameters of pod pepper seeds were calibrated for future numerical optimization of the pod pepper seed cleaning device. The study concentrates on calibrating the intrinsic and contact parameters of pod pepper seeds utilizing the discrete element method. Compression tests were performed to ascertain intrinsic parameters such as Poisson's ratio and the seeds' elastic modulus. The static friction coefficient and collision restitution coefficient between the seeds and steel plates were identified through incline and free-fall tests. Plackett–Burman, steepest ascent, and Box–Behnken experiments were performed to establish a second-order regression model correlating significant parameters with the angle of repose. The optimal parameter combination, based on the measured angle of repose (32.45°), yielded static friction coefficients between seeds, rolling friction coefficients between seeds, and static friction coefficients between seeds and steel plates of 0.608, 0.018, and 0.787, respectively. The two-sample t-test of the physical and simulated repose angles yielded p > 0.05, and the relative error of the physical and simulated repose angles was 0.68%, which confirmed the reliability of the calibration parameters. The findings indicate that the calibration method for pod pepper seeds effectively informs the calibration of parameters for other irregular crops. [ABSTRACT FROM AUTHOR]

Physical property parameter measurements and simulation model parameter calibrations of Pak Choi seeds were conducted to address the lack of accurate parameters for discrete elemental seed discharging simulation tests in the seed-metering device. Firstly, physical tests were utilized to determine the basic physical parameters and contact parameters of Pak Choi seeds. The results of these physical tests served as the basis for determining the range of simulation parameters. The Plackett-Burman test was employed to screen out factors that significantly affected the simulated angle of repose from the test parameters, including static friction coefficient between Pak Choi seeds-Pak Choi seeds and rolling friction coefficient between Pak Choi seeds- Pak Choi seeds. The optimal interval of these two factors was determined using the Steepest Climb Test. Subsequently, the regression equation between the significance parameters and the angle of repose was obtained through the Central Composite Designs test, and the best parameter combinations were obtained with the measured stacking angle of 24.3° as the optimisation target value: Pak Choi seeds-Pak Choi seeds static friction coefficient of 0.486, Pak Choi seeds-Pak Choi seeds rolling friction coefficient of 0.104. Finally, simulation and bench comparison tests were carried out for stacking angle and Pak Choi seed discharger performance evaluation. The relative error of the angle of repose was found to be 0.288%, while average relative errors for qualified sowing rate, replanting rate, and missed sowing rate were all less than 5%. These results demonstrate that calibrated Pak Choi seed simulation parameters are reliable and can serve as a reference for design optimization of Pak Choi seed dischargers in academic research writing standards. [ABSTRACT FROM AUTHOR]

To analyze the interaction between the surface soil and the soil-contacting component (65 Mn) in the camellia oleifera forest planting area in Changsha City, Hunan, China, in this study, we conducted discrete element calibration using physical and simulation tests. The chosen contact model was Hertz–Mindlin with JKR cohesion, with the soil repose angle as the response variable. The repose angle of the soil was determined to be 36.03° based on the physical tests. The significant influencing factors of the repose angle determined based on the Plackett–Burman test were the soil–soil recovery coefficient, soil–soil rolling friction coefficient, soil-65 Mn static friction coefficient, and surface energy of soil for the JKR model. A regression model for the repose angle was developed using the Box–Behnken response surface optimization method to identify the best parameter combination. The optimal parameter combination for the JKR model was determined as follows: surface energy of soil: 0.400, soil–soil rolling friction coefficient: 0.040, soil-65 Mn static friction coefficient: 0.404, and soil–soil recovery coefficient: 0.522. The calibrated discrete element parameters were validated through experiments on the repose angle and steel rod insertion. The results indicated that the relative errors obtained from the two verification methods were 2.44% and 1.71%, respectively. This research offers fundamental insights for understanding the interaction between soil and soil-contacting components and optimizing their design. [ABSTRACT FROM AUTHOR]

The transplantation of seedlings represents a pivotal stage in plug tray seedling cultivation. Conventional end effectors used in transplanters are primarily tailored for seedlings with well-established root systems and tightly bound substrates. However, when the substrate lacks sufficient root wrapping and remains loose, independent seedling removal devices utilising blowing or suction methods are often employed. This results in structural complexity and increased costs for the transplanter. To address the challenge of grasping loose substrate, this study advocates for a novel approach utilising a diagonal oblique-insertion type end effector. Through repose angle trials, discrete element simulation parameters were calibrated. Subsequently, leveraging these calibrated simulation parameters, the end effector was optimisation through orthogonal experiments. Findings reveal that the relative error between simulated and actual repose angles is minimised under specific conditions, with the shear modulus at 8.2 × 106 Pa, the particle-particle rolling friction coefficient at 0.234, the particle-steel static friction coefficient at 0.36, and the JKR surface energy at 0.347 J m−2. Employing these simulation parameters for end effector optimisation, it was determined that the average substrate integrity rate reaches 79.26% with an end effector featuring 5 tines, a gripper positioned 2.5 mm from the edge of the hole, and a gripper ascent speed of 0.056 m s−1. The average relative error between actual grasping experimental and simulation results was observed at 10.21%, indicating the suitability of these discrete element parameters for optimising simulations of end effectors for transplanters. Furthermore, the end effector devised in this study demonstrated efficacy in transplanting loose substrates. • A diagonal oblique-insertion type end effector was designed. • Calibration of discrete element parameters for substrate using repose angle test. • Optimisation of end effector using discrete element simulation. [ABSTRACT FROM AUTHOR]

Particulate precipitation, deposition, and accumulation, including the formation of salt and mineral crystals, frequently occur in a wide range of subsurface applications involving multiphase flow through porous media. Consequently, there has been a considerable emphasis on researching and understanding these phenomena. However, modeling particle dynamics in flows through porous media with low Reynolds numbers has always been a challenging problem as it requires resolving fluid flow around the moving solid particles, the solid–solid contact mechanics, and the solid–fluid coupling. The discrete element method coupled with fluid solvers has been widely used to study particle-laden flow. Most fluid-solid numerical schemes involve solving the full or generalized Navier–Stokes equations, which often yields relatively accurate fluid-solid interactions at the cost of computation time and particle shape limitations. In this paper, we present a novel method to study mono-layered particle-laden flow by coupling the level set discrete element method (LS-DEM) with Hele-Shaw flow model. Utilizing the Hele-Shaw flow model allows us to simplify flow computation, while incorporating LS-DEM enables the simulation of arbitrarily shaped particles. Cases of mono-layered particle flow through a simplified micromodel geometry are studied and validated against published experimental results. Moreover, the effects of particle friction and shape on clogging statistics are investigated. [ABSTRACT FROM AUTHOR]

Considering a 3D sheared granular layer through a discrete element modeling, it is well known the rolling resistance influences the macro friction coefficient. Even if the rolling resistance role has been deeply investigated previously because it is commonly used to represent the shape and the roughness of the grains, the rolling viscous damping coefficient is still not studied. This parameter is rarely used or only to dissipate the energy and to converge numerically. This paper revisits the physical role of those coefficients with a parametric study of the rolling friction and the rolling damping at different shear speeds and different confinement pressures. It has been observed the damping coefficient induces a frictional weakening. Indeed, competition between the rolling resistance and the rolling damping occurs. Angular resistance aims to avoid grains rolling, decreasing the difference between the angular velocities of grains. Whereas, angular damping acts in the opposite, avoiding a change in the difference between the angular velocities of grains. In consequence, grains stay rolling and the sample toughness decreases. This effect must be considered to not overestimate the frictional response of a granular layer. [ABSTRACT FROM AUTHOR]

In addressing the challenges of high energy consumption and low efficiency in fertilization borehole drilling for clayey soils in southern orchards, this study utilizes the Discrete Element Method to establish a simulation model for clayey soils. Through this approach, we identify an optimal set of operational parameters that significantly reduces energy consumption. By utilizing simulation technology to model the drilling process, we analyzed the impact of rotation speed and feed rate on the torque and resistance of the drilling apparatus. Initially, this paper describes field measurements of particle parameters in soils from southern orchards. Subsequently, utilizing the Discrete Element Method and particle contact theory, we established a simulation model to represent the interactions between soil and soil, as well as soil and auger in the soil environment of the southern region. For the Southern orchard clay with a moisture content of 16.8% and a measured angle of repose of 35.55°, parameter calibration was performed. The contact model "Hertz-Mindlin with Johnson-Kendall-Roberts" was selected in EDEM. Using Design Expert, a regression model variance analysis was applied to the discrete element model parameters, leading to the determination of the optimal values for significant soil model parameters. The soil JKR surface energy is 5.85 J·m−2, with a soil–soil restitution coefficient of 0.65 and a soil–steel static friction coefficient of 0.5. Subsequently, discrete element simulation experiments on the drilling apparatus were conducted in EDEM, considering various rotation speeds and feed rates. The simulation analysis indicates that the torque consistently increases with higher rotation speeds, with a maximum relative error of 7%. The torque initially rises from zero to a maximum value, then gradually decreases to a low value, followed by a rapid increase to a higher value, and finally drops back down. This cycle repeats in the observed pattern. The total force experienced reaches its minimum average value of 200 N at a feed rate of 0.05 m/s. Simulation test results indicate that, among the three forces acting on the auger (vertical resistance, horizontal resistance, and lateral resistance), vertical resistance is the primary factor contributing to power consumption. As the rotation speed increases, the maximum value of vertical resistance continues to rise, while horizontal resistance and lateral resistance exhibit a declining trend. As the feed rate increases, the maximum values of resistance in all three directions also increase. When the feed rate exceeds 0.05 m/s, the maximum lateral resistance experiences a sharp increase. Through comprehensive analysis, the optimal operational parameters for borehole fertilization are determined to be a rotation speed of 100 r·min−1 and a feed rate of 0.05 m/s. The aim of this study is to reduce the energy consumption of borehole fertilization operations, minimize carbon emissions, and promote the sustainable development of orchard production. [ABSTRACT FROM AUTHOR]

Shellfish culture heavy soils are suitable for the cultivation of marine organisms and are essential for the development of marine fisheries. To study both the interaction between heavy soil particles and that between the soil and soil-engaging components of agricultural machinery in shellfish culture, the simulation parameters in the model were determined. To study the interaction between soil particles in the viscous soil of shellfish culture with moisture content of 26.51% ± 1%. Discrete element method is used to establish the accumulation simulation experiment; the contact parameters between soil particles were calibrated. The response surface optimization technique was used to create the accumulation angle regression model. To study the interaction between the soil and soil-engaging components, the static friction coefficient between the heavy soil and soil-engaging components was determined by static friction experiment. The contact parameters between the soil and soil-engaging components were calibrated by the slope simulation experiment; the rolling distance regression model was established by response surface optimization methodology. The findings demonstrate that the optimized soil model can simulate the actual soil, and reflect the interaction between the heavy soil particles, soil, and the soil-engaging components of agricultural machinery, which not only provides a theoretical basis for the design and optimization of soil-engaging components of agricultural machinery in heavy soil, but also provides a new way for the research and development of agricultural machinery in a complex environment. [ABSTRACT FROM AUTHOR]

Precision seeding technology is an important component of agricultural mechanization production. The precise regulation of seed movement behavior is the core of precision sowing technology and the key to improving the quality of single seed precision sowing. To accurately obtain the interaction law between seeds and soil after touching the soil, it is necessary to conduct comprehensive physical experiments to determine the simulation parameters of the seed and soil. This article takes coated cotton seeds as the research object, and the basic physical parameters of coated cotton seeds are measured through biological experiments. Based on the Hertz–Mindlin with bonding V2 contact model, a simulation model of compression between coated cotton seeds and soil is established. Using peak compression force as the response value, a combination of physical experiments and simulation simulations was used to calibrate the simulation parameters of the simulation mode of coated cotton seeds and soil. Through PB testing, it was found that four factors have a significant impact on the peak compressive force, and the parameter range was obtained. The Poisson's ratio of coated cotton seeds was 0.14–0.26. The static friction coefficient between coated cotton seeds and steel plate was 0.38–0.58. The static friction coefficient between soil and soil was 0.3–1.2. The rolling friction coefficient between soil and soil was 0.1–0.6. Through response surface experiments with four factors and three levels, regression models were established between various factors and response values, and the optimal combination of simulation parameters was determined: the Poisson's ratio of coated cotton seeds was 0.21; the static friction coefficient between coated cotton seed and steel plate was 0.47; the static friction coefficient between soil and soil was 0.34; and the rolling friction coefficient between soil and soil was 0.59. Based on the optimal parameter combination, the simulation of compression between coated cotton seeds and soil was continued, and the variation law of soil particle bonding bonds at different positions of coated cotton seeds during the compression process was obtained. This study provides a basis for exploring the interaction mechanism between the trencher seed soil of precision seeders and optimizing the design of critical components of cotton precision seeders. [ABSTRACT FROM AUTHOR]

During precision sowing, the contact process between the soil and seeds cannot be ignored. The constitutive relationship of soil is relatively complex, with characteristics such as high nonlinearity, while the contact mechanism between the soil and seeds is unclear. To better understand the contact between seeds and soil, it is necessary to establish a reasonable contact model. Ellipsoidal seeds, such as soybean, red bean, and kidney bean seeds, were adopted as research objects. In this paper, we used the discrete element method to establish an ellipsoidal seed–soil contact model. The JKR + bonding model was adopted for describing the adhesion between soil particles, and the Hertz–Mindlin new restitution (HMNS) model was used for ellipsoidal seed particles to eliminate the multiple contact point issue when modeling with the multi-sphere filling method. Moreover, both simulations and experiments were conducted to calibrate the interaction parameters between soil and seeds. The path of steepest ascent test and Box‒Behnken design (BBD) tests were also used, as well as direct shear tests. Thus, certain soil parameter values were obtained, namely the JKR surface energy was 4.436 J/m2, the normal stiffness per unit area was 2.86 × 106 N/m3, the shear stiffness per unit area was 5.54 × 105 N/m3, the critical normal stress was 1833 Pa, and the critical shear stress was 3332 Pa. In addition, the simulation parameters for ellipsoidal seeds were obtained from previous works. Moreover, to obtain more accurate ellipsoidal seed–soil interaction parameters, collision tests, static friction tests, and rolling friction tests were adopted. A single-factor test was used to calibrate the ellipsoidal seed–soil interaction parameters. The calibration results were as follows: the collision restitution coefficients of ellipsoidal seeds with soil were all 0.25. The static friction coefficient of soybeans with soil was 0.6, that of red beans with soil was 0.65, and that of kidney beans with soil was 0.5. The rolling friction coefficient of soybeans with soil was 0.1, that of red beans with soil was 0.14, and that of kidney beans with soil was 0.14. Finally, the rationality of parameter selection was verified through piling tests between ellipsoidal seeds and soil. The relative error of the angle of repose of soybean/soil was 2.99%, that of red bean/soil was 0.60%, and that of kidney bean/soil was 0.55%. Thus, the feasibility and rationality of the contact models between the ellipsoidal seeds and soil established in this paper, as well as the parameter selection, were verified. [ABSTRACT FROM AUTHOR]

In this study, the discrete element software EDEM was applied to establish a simulation model of non-uniform-sized particle units for Broussonetia papyrifera stalks, which aimed to address the low utilization rate of existing Broussonetia papyrifera harvesting machinery, the significant variation between the simulated model of Broussonetia papyrifera stalks and their actual appearance, as well as the absence of contact parameter calibration. Through a combination of the free-fall collision method, inclined plane sliding method, and inclined plane rolling method, numerical simulation was conducted to analyze the pattern of variations in contact parameters between Broussonetia papyrifera stalks and the steel material of the machinery. Accordingly, these parameters were calibrated. The results showed that the coefficient of restitution between Broussonetia papyrifera stalks and steel materials was 0.321, the static friction factor was 0.589, and the rolling friction factor was 0.078. With the parameters of contact between Broussonetia papyrifera stalks as variables and the experimentally measured pile angle as the objective of optimization, the steepest ascent experiment and the three-factor five-level rotation combination experiment were conducted. In this way, a second-order response model was constructed to analyze the relationship between the contact parameters and the pile angle. Through the optimization analysis of experimental data, it was determined that the coefficient of restitution between Broussonetia papyrifera stalks was 0.21, the static friction factor was 0.24, and the rolling friction factor was 0.03. Furthermore, the calibration results were validated through experimentation to show that the relative error between the obtained pile angle under the context of optimal parameter combination and the actual one was 4.11%. In addition, the relative error of mass flow rate in spiral transport was within a reasonable range, this study lays a foundation both theoretically and statistically for the simulation of contact parameters for Broussonetia papyrifera stalk harvesting processing, mechanical harvesting, and so on. [ABSTRACT FROM AUTHOR]

To simulate the bending behaviour of paddy straw at varied moisture contents after crop harvesting, we created a flexible paddy straw specimen model based on the Hertz–Mindlin with parallel contact bonding model using the discrete element model (DEM) approach. The research presented in this study aims to investigate a new approach called Definitive Screening Design (DSD) for parameterizing and screening the most significant parameters of the DEM model. This investigation will specifically focus on the three-point bending test as a means of parameterization, and the shear plate test will be used for validation purposes. In addition, the most influential DEM parameters were optimized using another Design of Experiments approach called Central Composite Design. The findings from the DSD indicated that parameters such as bonded disk scale, normal stiffness, and shear stiffness have the highest impact on the bending force, while the coefficient of static friction (Straw-Steel) has the least effect. The three bonding parameters were respectively calibrated with the loading rate (0.42, 0.5, and 0.58 mm s−1) and a good agreement between actual and simulated shear force at moisture content M1—35 ± 3.4%, M2—24 ± 2.2% and M3—17 ± 2.6%. Modelled stem helps simulate the straw with low error and increases the accuracy of the simulation. The validated model, with an average relative error of 5.43, 7.63, and 8.86 per cent, produced reasonable agreement between measured and simulated shear force value and loading rate. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of the lack of intrinsic and contact parameters when applying the discrete element method to simulate and analyze the key aspects of white kidney bean seed sowing, harvesting and clearing. The experiment took white kidney bean seeds as the research object, measured the intrinsic parameters of white kidney bean seeds by using the universal testing machine, and measured the collision recovery coefficient of 0.445, static friction coefficient of 0.452 and rolling friction coefficient of 0.091 between white kidney bean seeds and Q235 steel plate by physical test and EDEM discrete element simulation parameter calibration. The stacking experiment was carried out by the cylinder lifting method, numerical processing was performed with MATLAB, and the actual stacking angle of white kidney bean seeds was 31.28°. The steepest climbing test was designed with the interspecific contact parameters as factors and the relative error between the actual and simulated stacking angles as indicators. The optimal combination of the interspecific contact parameters of white kidney bean was determined by response surface optimization analysis, and the interspecific collision recovery coefficient of white kidney bean was obtained as 0.39, static friction coefficient was 0.53, rolling friction coefficient was 0.092. Using the optimal parameters for the simulation test, the relative error between the actual stacking angle of white kidney bean seeds and the simulated stacking angle was 1.63%, indicating that the calibrated simulated contact parameters were reliable and could provide reference for the discrete element simulation of white kidney bean seeds. [ABSTRACT FROM AUTHOR]

Discrete element method (DEM) parameters are the basis for modelling the motion of particle systems. To verify the practicality of calibrating DEM simulation parameters for micrometre-sized pollen particles, spherical micrometre-sized tomato pollen was selected as the research object for a parameter calibration experiment. Constitutive parameters such as the pollen morphology, diameter, and density were obtained through experimental measurements. Then, the contact and collision process of pollen was measured and analysed using an atomic force microscope, and Young's modulus, surface energy, and recovery coefficient of pollen were calculated using the Johnson-Kendal-Roberts (JKR) contact model. A Plackett-Burman test was designed, and the significant factors were determined using the DEM simulation test for Young's modulus of pollen grains, pollen-pollen static friction coefficient, and the pollen-polypropylene static friction coefficient for the plastic floor. The parameter range was reduced using the steepest climbing test. A regression equation was determined according to the results of the Box-Behnken response surface analysis. When this equation was solved, Young's modulus of pollen grains was 5.25 × 106 Pa, the pollen-pollen static friction coefficient was 0.466, and the pollen-polypropylene plastic static friction coefficient was 0.417. From the accumulation verification experiment the relative error between measurement and the simulation was 1.01%, which indicates that a calibration experiment of micrometre-sized pollen particle parameters is feasible. Furthermore, the parameters obtained here can be used to calculate and predict the pollen pollination process. • Adhesion force measured by atomic force microscopy and surface energy calculated. • Calibration of parameters of pollen using simulation by discrete element methods. • Results can provide basic data for discrete element simulation of tomato pollination. [ABSTRACT FROM AUTHOR]

The discrete element method (DEM) has demonstrated significant advantages in modelling feed-tool interaction. The selection of an appropriate contact model and its parameter calibration is crucial for developing effective DEM simulations. A DEM model of feed powder was developed to forecast powder compression and densification in feed pelleting by using the Edinburgh elasto-plastic adhesion contact model. Firstly, a calibration method of DEM parameters based on the Plackett–Burman (PB) and the central composite (CC) test was proposed to enhance calibration efficiency. Both experimentally and through DEM simulation of the uniaxial confined compression experiments, powder repose angle experiments, and powder static friction angle experiments were used to calibrate the DEM parameters. Extract the DEM parameters that have a significant impact on feed pelleting through PB testing. Then, the effects of these parameters on response were analysed using CC testing, and ascertain their optimal values. Finally, the single-hole open compression experiment and feed pelleting experiment were used to evaluate the accuracy of the parameters. The results show that the average relative error between the predicted ultimate compressive force in the open compression experiment and the measured value is 8.16%, and that of the torque of the pellet mill is 2.10%. Thus, it was shown that the modelling and calibration method can effectively predict the compression and densification of powder in the feed pelleting. • Different feed ingredient flours vary less in fluidity and more in compressibility. • Calibration of a DEM model using uniaxial compression and friction experiment. • Deformation was a combination of elastic and plastic processes. • DEM simulation results were in satisfactory agreement with laboratory investigations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The lack of discrete element method (DEM) models and calibration parameters for Cucurbita ficifolia seeds, as well as low accuracy and efficiency of common parameters calibration methods, hinder the application of DEM for computer simulation in air-suction directional seeding equipment. In this study, the DEM parameters of the seeds were calibrated. The angle of repose (AOR), intrinsic parameters, and partial contact parameters of the seeds were experimentally measured. The seed 3D models were reconstructed based on the three-view profile information. The parameters and their value ranges were filtered through the Plackett–Burman design and steepest ascent test. The response surface method (RSM) and machine learning were utilised for optimisation inversion of the parameters. The experiments showed that the geometric relative error of the seed model was 0.69–6.54%, which meets the modelling requirements for DEM. The seed–seed static friction coefficient, the seed–seed and the seed–PVC rolling friction coefficient were 0.341, 0.026, and 0.059, respectively, which were obtained by inverting the GA-BP regression model via the Genetic Algorithm. The simulated AOR was 26.64°, with a relative error compared to the actual AOR of 1.64%, which was better than the simulated AOR obtained by RSM optimisation. The greater the smoothing value setting in EDEM software, the less the particle filling, resulting in improved simulation efficiency but reduced model accuracy. The CPU + GPU(CUDA) solver showed high DEM solution efficiency. The results reveal that the method can be used to quickly and accurately construct a 3D model of the seed, and the parameter optimisation accuracy of GA-BP-GA is better than that of RSM. [Display omitted] • A fast and precise method for parameters calibration based on DEM was present. • The ficifolia seed parameters were calibrated and used to develop planters. • The CAD-based 3D modelling method was used to reconstruct the ficifolia seed model. • Machine learning was used to invert the optimal parameters, which was better than RSM. • The effect of solver and particle count on simulation error and runtime was studied. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We investigate the effects of morphological features on the angle of repose (Φ ) of granular materials using a three-dimensional discrete element method (3D-DEM). A commercially available DEM package called particle flow code (PFC3D) was used. The elliptical clumped particles were imported in the form of an STL file, which was modelled by controlling two morphological descriptors (i.e., β and ξ) using a multi-sphere (MS) approach. The β represents the maximum pebble-pebble intersection angle and ξ defines the ratio of smallest to largest pebble diameter within a clump. The results concluded show that the Φ increase with an increase in static friction coefficient became insignificant after µs = 0.8, whereas the Φ decrease with a decrease in the number of pebbles. In addition, the microscopic parameter in terms of coordination number (Z) shows an initial concave response and stabilized with a further subsequent increase in the number of pebbles. These results are of particular interest which could provide insights into the microscopic level of interactions at particulate levels of granular materials. [ABSTRACT FROM AUTHOR]

In order to improve the accuracy of the parameters during the process of rice straw shredding and returning to the field in discrete element simulation, the stubble straw in the field after rice harvest were taken as the research object, and the contact parameters between straw and steel, straw and straw were measured through the slope test. Then based on simulation model and through the stacking angle and shear test, the bonding radius between straw model particles, tangential critical stress, normal critical stress, coefficient of restitution, static friction coefficient and dynamic friction coefficient were taken as the test factors, taking the shear resistance and radial stacking angle of straw as evaluation indicators, a multi-objective optimization simulation calibration experiment were conducted using the Box-Behnken experimental scheme. The results showed that the bonding radius between straw particles was 1.06 mm, and the normal critical stress of straw was 4.77x1010 Pa, tangential critical stress was 4.67x106 Pa, the collision restitution coefficient between straw and straw was 0.21, the static Friction coefficient was 0.19, and the rolling friction coefficient was 0.09. The results of the simulation test results under the optimal parameter combination conditions and the physical test showed that the relative errors of the shear resistance and radial stacking angle of straw in the simulation test and physical test were 1.7% and 2.8%, respectively. This study could provide reference for the discrete element simulation analysis between straw and straw, as well as between straw and agricultural machinery. [ABSTRACT FROM AUTHOR]

To apply the discrete element method (DEM) to simulate the interaction process between soda saline–alkali soil and subsoiling component in Northeast China, establishing the soda saline–alkali soil particle model and selecting more accurate simulation parameters are important. In this paper, we studied the soda saline–alkali soil of the Songnen Plain in China. First, we studied the geometric shape of soda saline–alkali soil particles and proposed a modeling method for single soil particles based on the multisphere combination method. Considering the cohesion of soda saline–alkali soil particles, the Hertz–Mindlin with JKR (JKR) model was used as the contact model between soil particles. Then, the calibration method was used to obtain simulation parameters of soils that are difficult to obtain experimentally. We conducted soil angle of repose (AoR) tests, the Plackett–Burman (PB) tests, and steepest ascent (SA) tests in turn to perform a sensitivity analysis for microscopic contact parameters and select the parameters that have a significant effect on the response value (static AoR), i.e., soil surface energy, soil–soil static friction coefficient, and soil–soil rolling friction coefficient. Then, the optimal combination of simulation parameters was obtained via the Box–Behnken (BB) tests, using ANOVA to optimize the multiple regression equation. Finally, the optimal parameter combination was verified by the AoR test and the direct shear (DS) test. The results showed that the parameters had good adaptability for the AoR test. However, the simulation results of the DS test were significantly different from the experimental values. Therefore, the contact model needs to be further modified by adding Bonding bonds between soil particles based on the JKR model and further correcting for Rayleigh time step, shear modulus, and surface energy. By comparing the simulation and the experimental results, it was found that the simulation results obtained from both the DS test and AoR test had relatively small errors relative to physical tests, the two trends are the same, and the values are similar. This verified the feasibility and effectiveness of the soda saline–alkali soil particle modeling method and parameter selection proposed in this paper. [ABSTRACT FROM AUTHOR]

Aiming at the lack of discrete element simulation models and parameters for rice polishing, grading, color sorting and other technologies and equipment, and the difficulty of guiding equipment design and optimization through simulation, this paper calibrates the simulation parameters of white rice based on angle of repose (AOR) test and simulation methods. Huanghuazhan and Dongnong 429 white rice were selected as research object. Numerical model of white rice was established by multi-sphere filling. According to physical test and references, the simulation parameter range of white rice particles was determined. Plackett-Burman test was used to screen parameters, and it was found that the particle-particle static friction coefficient and particleparticle rolling friction coefficient had significant effects on the AOR of white rice. The regression model between the AOR and the significance parameter was established according to the central composite design method. The simulation parameter combination that has significant influence on the physical AOR was determined through the optimization design, and verified by the simulation test. The simulation AOR was compared with the physical AOR, and the relative error of the two kinds of white rice was less than 3%. The results show that the calibration method proposed in this study can accurately simulate the physical AOR test, which can provide reference for discrete element simulation of white rice processing. [ABSTRACT FROM AUTHOR]

The EDEM software (Altair EDEM 2022.0 professional version 8.0.0) was used to create a discrete element model of silage to address the lack of silage evidence parameters and contact parameters between silage and conveying equipment when using the discrete element method to simulate and analyze crucial aspects of silage conveying and feeding. Physical tests and simulations were used to calibrate the significant parameters, and the silage stacking angle obtained from simulation and tests was then validated. The response value of the stacking angle (38.65°) obtained from the physical examination was used as the response value. The response surface (RSM) finding and the GA finding based on the genetic algorithm (GA) artificial neural network (BP) model were used to compare the significance parameters. The PB and steepest climb tests were used to screen the significant factors. Results indicate that the static friction coefficient between silage and silage, the rolling friction coefficient between silage and silage, and the static friction coefficient between silage and the steel body are significant factors affecting the stacking angle of numerical simulation; the parameter optimization effect of GA-BP-GA is superior to that of RSM; the optimal parameter combinations are as follows: 0.495, 0.194, and 0.420, respectively, and the simulated stacking angle is 39.1510°, which matches the empirical test result. The relative error between the simulated and stacking angles derived from the physical test was 1.3%. The results demonstrate that the silage model is reliable within the parameters derived from the calibration, and that the calibrated parameters can be used in other discrete element simulation studies of silage. [ABSTRACT FROM AUTHOR]

The discrete element method (DEM) is an effective tool for obtaining qualitative and quantitative information on particle motion, which aids in the design and optimization of agricultural equipment structures. The accuracy of the DEM simulation parameters significantly impacts the simulation results. This study employed a combination of high-speed camera measurement, DEM simulation, and validation tests to determine the material and interaction property parameters for fertilizer particles. The basic parameters (triaxial size, bulk density, density, and coefficient of static friction) and coefficients of restitution between fertilizer and material were measured for three fertilizer varieties. There was a significant difference in the angle of repose between various material plates and fertilizer particles. The calibration values of coefficients of restitution and coefficients of rolling friction between fertilizer particles were optimized using the Box–Behnken method. The angle of repose was significantly affected by the coefficient of static friction and the coefficient of rolling friction between the fertilizer particles. The determined values for the coefficient of restitution, coefficient of static friction, and coefficient of rolling friction between the fertilizer particles were 0.323, 0.381, and 0.173, respectively. The error in the angle of the repose test was less than 3.0%, and the variation coefficient for each row consistency was less than 1.68 percentage points under the optimal simulation parameters. DEM simulations of the angle of repose and each row consistency variation coefficient test using the measured parameters can accurately predict the experimental results. The findings of this paper provide a theoretical basis for the DEM study of fertilizer particles. [ABSTRACT FROM AUTHOR]

An appropriate contact mechanics model and parameters are key to achieving accurate results in discrete element analyzis. This is necessary to predict the process of contact collision between the soil and maize seed during deposition. In this paper, the contact process between maize seed and soil is analyzed using the maize seed variety (Liangyu 99) and maize-sowing field soil (with three different moisture contents) as research objects. Based on this, the contact process between maize seeds and soil has been analyzed, on the basis of which a mechanical model suitable for simulating the contact process between maize seeds and soil has been explored, and the selection of parameters between heterogeneous particles (maize seed and soil particles) has been investigated. The results showed that adhesion forces have a significant effect on the collision process between seed and soil particles. While the presence of tangential adhesion force can be replaced by increasing the static and rolling friction coefficients, the normal adhesion force cannot be compensated in this way. The Edinburgh Elasto-Plastic Adhesive (EEPA) model is selected in this paper to describe the contact between seed and soil particles. The significance of the input parameters in the EEPA model is investigated using the Plackett–Burman test. The parameters between soil and seed particles are optimized using the central composite design, and the optimal parameter combinations are obtained. The relative error between the simulation and test result of the slope test for the three soil moisture contents is within 5.4%, validating the accuracy of the calibrated parameters. [ABSTRACT FROM AUTHOR]

The article describes numerical modeling of sublevel stoping using the discrete element method. The study included development of a modeling procedure, creation and calibration of the numerical models, and the result analysis. The optimal design parameters of structural components of the mining system are found, which are promotive of reduced ore losses in sublevel stoping at the Khibiny apatite–nepheline deposits. Some behavioral patterns of rock mass during sublevel stoping are obtained. The mechanism of ore losses is described. [ABSTRACT FROM AUTHOR]

In order to improve the accuracy of the parameters needed in the discrete element method (DEM) simulation process of wet-sticky feed raw materials, the JKR contact model in DEM was used to calibrate and verify the physical parameters of wet-sticky feed raw materials. Firstly, the parameters that have a significant effect on the angle of repose were screened using a Plackett–Burman design, and the screened parameters were: MM rolling friction coefficient, MM static friction coefficient, and JKR surface energy. Then, the three screened parameters were selected as the influencing factors and the accumulation angle of repose was selected as evaluating indicator; thus, the performance optimization experiments were carried out with the quadratic orthogonal rotation design. Taking the experimentally measured angle of repose value of 54.25°as the target value, the significance parameters were optimized, and the optimal combination was obtained : MM rolling friction factor was 0.21, MM static friction factor was 0.51, and JKR surface energy was 0.65. Finally, the angle of repose and SPP tests were compared under the calibrated parameters. The results showed that the relative error of experimental and simulated tests in angle of repose was 0.57%, and the compression displacement and compression ratio of the experimental and simulated tests in SPP were 1.01% and 0.95%, respectively, which improved the reliability of the simulated results. The research findings provide a reference basis for simulation study and optimal design of related equipment for feed raw materials. [ABSTRACT FROM AUTHOR]

The velocity fluctuation affects the safe operation of the heat exchanger when the particles flow through the heat exchanger. The particle flow model of heat exchanger is established based on the discrete element method to investigate the correlation between surface roughness and particle velocity fluctuation. Many studies have used static friction coefficients to characterize the particle roughness. The particle velocity fluctuation in heat exchanger is analyzed, and the effects of the static friction coefficient on the particle velocity fluctuation are studied. The results showed that when the particles flow stably, the force chain structure between the particles is a process of breaking and rapidly reconstructing. This force characteristic of the particles causes the constant fluctuation of the particle velocity, which fluctuation frequency varies from 0.05 Hz to 0.08 Hz. The velocity fluctuations of the particles located at the top of the heat exchanger are particularly violent. The direction of the force chain distribution gradually moves horizontally with the increase of the static friction coefficient, and the velocity fluctuation in the vertical orientation becomes more intense. The amplitude of velocity fluctuation increases from 0.6 × 10−3 m/s to 1.3 × 10−3 m/s. The results are helpful to understand the dynamic behavior of particle in heat exchanger during flow and provide the basis for subsequent improvements. [Display omitted] • The transient characteristics of particle flow was studied. • The effects of static friction coefficient on velocity fluctuation were studied. • The effects of static friction coefficient on the force chain were studied. [ABSTRACT FROM AUTHOR]

Discrete element modelling (DEM) is a numerical method for examining the dynamic behavior of granular media. In order to build an accurate simulation model and provide more comprehensive soil characteristic parameters for the design and optimization of various soil contact machinery, in this paper, the discrete element simulation method (EDEM) combined with experimental approach is used to investigate the soil contact characteristic parameters in East Asia. In this study, Hertze-Mindlin (no slip) was used as a particle contact model by taking particle contact parameters and soil JKR (Johnson-Kendall-Roberts) surface energy as determinants, and repose angle, internal friction angle, and cohesive force as evaluation indexes. The method of Plackett-Burman, Stepest ascent, and Box-Behnken were used to gradually reduce the range of parameters needed for simulation until the most accurate value was determined. The results show that the restitution coefficient, static friction coefficient, and rolling friction coefficient between soil particles have significant effects on the DEM model, and their value of them are 0.596, 0.725, and 0.16, respectively. Based on these parameters used for the repose angle test and direct shear stress test, the value of repose angle is 31.97°, the internal friction angle is 27.61°, and the cohesive force is 33.06 kPa. The relative errors with the actual measured values are 9.54%, 1.87%, and 2.31%, respectively. In order to further test whether the simulation parameters of soil obtained by repose angle test and direct shear stress test are consistent with the real soil, comparison test between field test and discrete element simulation was used. The results show that the error in height of ridge between the simulated soil and the actual soil is 4.06%, which is within the acceptable range. It also indicates that the calibrated and optimized soil simulation model can accurately represent the real soil. The research provides theoretical basis and technical support for the study of soil contact parts by using the discrete element method, combined with repose angle test and direct shear stress test. [ABSTRACT FROM AUTHOR]

The contact parameters setting determines the accuracy of discrete element method (DEM) simulation analysis, while there is a lack of research on contact parameters of green onion seed. In this paper, the physical parameters of green onion seeds were measured by experiment, and the DEM parameters were calibrated by simulation. Based on EDEM software, the Hertz-Mindlin no-slip model was used to create the particle model of green onion seeds that takes on the shape of peltate with the irregular surface, and the repose angle was measured by the measurement method of lifted cylinder. Plackett-Burman test was designed to screen the significance of parameters, and the optimal range of significance parameters was further determined through the steepest climbing test. Then the regression model of seeds repose angle was obtained by Box-Behnken test and the optimal parameter combination was calculated: the static friction factor between seeds was 0.424, the rolling friction factor was 0.085, the static friction factor between seeds and steel was 0.310. The optimized repose angle in the simulation had an overall relative error of 0.54%, indicating that the contact parameters of the calibrated green onion seed had high accuracy. [ABSTRACT FROM AUTHOR]

To obtain the physical parameters and contact parameters of ramie stalk decorticating simulation, the structural dimensions, density, moisture content, elastic modulus, and contact parameters of the ramie stalk were measured in this study based on the phloem and xylem of the ramie stalk. The physical stacking angles of the phloem and xylem were measured by the cylinder lift method and the extraction of the partition method, respectively. The contact parameters between the xylem and phloem of the ramie stalk were directly calibrated. Additionally, the contact parameters of the phloem–phloem, phloem–Q235A steel, xylem–xylem, and xylem–Q235A steel were used as calibration objects, and the simulated stacking angle was used as the evaluation index. Then, the Plackett–Burman test was designed to screen for the parameters which were significantly affecting the simulated stacking angle. Furthermore, the steepest ascent test determined the optimal range of values for two significant parameters of the phloem and three significant parameters of the xylem. Based on the central composite design, the second-order regression equations between the significant parameters of the phloem and xylem and the stacking angle were established, respectively. The physical stacking angles of 37.93° for phloem and 27.17° for xylem were the target values to obtain the optimal parameter group. The results showed that the restitution, static, and rolling friction coefficients between the xylem and phloem were 0.60, 0.53, and 0.021, respectively. The static and rolling friction coefficients between the phloem and phloem were 0.41 and 0.056, respectively. The rolling friction coefficient between the xylem and Q235A steel was 0.033, and the static and rolling friction coefficients between the xylem and xylem were 0.44 and 0.016, respectively. The verification test showed that the relative error values were less than 2.11%, which further indicated that the modeling method and parameter calibration of the ramie stalk phloem and xylem models were accurate and reliable. They can be used for the subsequent calibration simulation tests of ramie stalk bonding parameters and ramie stalk decorticating simulations. [ABSTRACT FROM AUTHOR]

In this study, to obtain the contact parameters of particulate materials accurately and quickly in residual film mixture after sieving, the contact parameters of particulate materials were calibrated via a physical test and simulation test. By using the self-made dynamic angle of a repose measurement test bench, the dynamic angle of repose of the particulate materials was measured at 41.32°, and the standard deviation was 1.33°. A discrete element simulation of the dynamic angle of the repose test was performed via an EDEM screening experiment design through a simulation of a combination of different parameters, with the dynamic angle of repose as the response value. Through simulation experiments, three significant influencing factors, as well as the level range of each factor, were confirmed. By using the response surface experiment, a mathematical model of the dynamic angle of repose and the three most influential parameters was created. The analysis of variance showed that the determination coefficient R2 and the correction determination coefficient R2adj were 0.9824 and 0.9598, respectively. The model had a good fit. The variable coefficient was 2.06% and the lack of fit was non-significant, which showed that the regression model was very significant, and the dynamic angle of repose could be predicted according to the model. By solving the optimization for the mathematical model, the optimal combination of parameters with three important influencing factors were obtained. The results showed that the coefficient of the static friction between soil and soil was 0.38, the coefficient of the rolling friction between soil and soil was 0.08, and the coefficient of the static friction between cotton residue and cotton residue was 0.33. The relative error of the dynamic angle of repose between the simulation with the optimal parameter combination and the physical test value was 2.64%. The results could provide a reference for the calibration of the discrete element model parameters of other agricultural particulate material, as well as provide a theoretical basis for the design of related collecting and conveying machinery. [ABSTRACT FROM AUTHOR]

Numerous powder manufacturing industries such as food and pharmaceutical require the use of mixers to ensure that loaded materials meet a certain level of uniformity to procure an end-product of a high standard. Studies concerning mixing issues still do not fully cover the choice of the optimal mixer parameters. In this paper, we investigated the effects of filling configuration and the number of paddles on the mixing rate in a single-shaft paddle mixer. We used bi-colored corn grains as solid particles and employed discrete element simulations using LIGGGHTS-PUBLIC®. To calculate the static friction, rolling friction, and the coefficient of restitution, we applied the box discharging technique. The coordinates-based mixing rate so-called nearest-neighbor index was employed to quantitatively examine the different mixing rates along the mixing period according to two variables, namely, filling type and paddle number. Filling one type of particles then filling the other type on top of it in the mixer achieves better mixing efficiency compared with sidewise filling of particles. The use of a high number of paddles improves the mixture uniformity, while using more than five paddles has no further impact on the mixture. Also, mixing is more efficient when dealing with particles that have the same or different number of clumps, whereas mixing spherical grains with five-sphere clump grains decreases the mixing efficiency considerably. [ABSTRACT FROM AUTHOR]

The discrete element parameters of pod pepper (Capsicum annuum) were calibrated for the future numerical optimisation for a pod pepper harvester. A group of discrete element method (DEM) models for pod pepper was established through reverse engineering reconstruction technology to simulate the formation of repose angle. The intrinsic parameters and some contact parameters of pod pepper were obtained through direct measurement. The measured repose angle of pod pepper was determined through bench tests of the cylinder lifting method. Based on these parameters and the DEM simulations, the contact parameters of pod pepper that were difficult to measure directly were calibrated through response surface methodology (RSM). These parameters included: static friction coefficient between pod pepper and pod pepper 0.21, rolling friction coefficient between pod pepper and pod pepper 0.10. These optimal parameters were applied to simulate the formation of pod peppers' repose angle in the two verification tests, and the relative errors between the verification repose angle and the measured repose angle were both within 3.35%. The results showed that the calibration methods for pod pepper were suitable to guide the parameter calibration of other irregular shaped crops. • Physical parameters of pod pepper were determined through direct measurements. • A well representative DEM model group of pod peppers was established. • The contact parameters of pod pepper were calibrated based on DEM and RSM. [ABSTRACT FROM AUTHOR]

A proper burden and porosity distribution of the bed in the upper shaft are important prerequisites for realizing a stable and efficient operation of the ironmaking blast furnace. The discrete element method was used to investigate the effects of the static friction coefficient between burden particles and shaft angle on the burden profile and porosity distribution in the bed formed by charging the burden with a bell-less charging equipment. The results indicate that a large static friction coefficient makes the particles stay closer to the impact point (i.e., where they fall) from the rotating chute. A large mixed region of the burden bed decreases the gas permeability, and an increase in the burden particle roughness will worsen this problem. The burden surface shape becomes flatter with an increase in the shaft angle. These findings explain the effect of particle properties and wall geometry on the inner structure of the burden bed. [ABSTRACT FROM AUTHOR]

To solve the problem of the lack of an accurate model for mechanized transportation and grading of walnut kernels, this paper took the shelled walnut kernels as the research object and calibrated the parameters of the discrete element model of walnut cracking kernels with the discrete element simulation software EDEM. The physical parameters of cracking kernels were measured by experiments, and the Hertz–Mindlin model was used to simulate the repose angle of cracking kernels. The contact parameters, such as the particle collision recovery coefficient, the static friction coefficient, and the rolling friction coefficient, were determined by the two-level factor test, steepest ascent test, and response surface test, respectively. Subsequently, the Hertz–Mindlin model with bonding contact was exploited to conduct the simulation of cracking kernels bending test based on the calibrated contact parameters. Finally, the normal contact stiffness, tangential contact stiffness, critical tangential force, and normal force of cracking kernels were determined by response surface analysis. It was shown that the relative error between the simulated values and the experiment results was 3.00 ± 1.31%. These results indicated that the calibrated parameter values are reliable, and could be used for the mechanized transportation and grading of walnut kernels. [ABSTRACT FROM AUTHOR]

To improve the accuracy of the discrete element research, physical and simulation experiments were used to calibrate the cotton stalk contact parameters. Based on the stalk-stalk and stalk-steel contact mechanics, the parameters were measured in physical experiments, and the discrete element simulation software was used to build the stalk model. In the simulation process, the Plackett-Burman experiment was used to screen three significant factors from six initial factors. The steepest Plackett-Burman experiment was used to determine the optimal interval of the significant factors. A second-order regression model of the significant factors and the angle of repose was established according to the Central Composite design experiment. The best parameter combination of the significant factors was then obtained: the coefficient of static friction on stalk-steel contact was 0.31, the coefficient of static friction on stalk-stalk contact was 0.62, and the coefficient of rolling friction on stalk-stalk contact was 0.02. The relative error between the physical angle of repose and the simulated angle was 3.27%, indicating that it is feasible to apply the simulation experiment instead of the physical one. It offers insights into cotton stalk contact parameter settings and film-stalk separation in the simulation. [ABSTRACT FROM AUTHOR]

To carry out simulation research on tire-soil interaction, EDEM software was used to calibrate the test soil and the contact parameters between the tire and soil. The soil contact model was the Edinburgh Elasto-Plastic Adhesion (EEPA) model. Using the soil repose angle as the repose value, the contact plasticity ratio, the soilsoil rolling friction coefficient, and the Tensile exp value were respectively calculated using the Plackett-Burman test, the steepest climbing test, and the Box-Behnken test, and the optimal combination of parameters was found to be E = 0.08, B = 0.1, and F = 4.8. The values of the remaining parameters were as follows: a soil-soil static friction coefficient of 0.45, a restitution coefficient of 0.5, a surface energy of 4, and a tangential stiffness multiplier of 0.35. Based on the slope sliding method, the coefficient of static friction between soil and rubber was calculated as 0.88. On this basis, a central combination test was designed to calibrate the rubbersoil rolling friction coefficient and coefficient of restitution, the optimal combination of which was found to be H = 0.18 and I = 0.55. A soil tank model was created using the optimal parameters, and the correctness of the established soil discrete element model and rubber-soil contact parameters was validated by comparing the simulation results and the results of an experiment of the tire driving process. [ABSTRACT FROM AUTHOR]

In order to improve the calculation efficiency of a discrete element EDEM (Discrete Element Method) numerical simulation software for micron particles, the particle model is linearly enlarged. At the same time, the parameters of the amplified particles were calibrated according to the Hertz-Mindlin with JKR (Johnson-Kendall-Roberts) contact model to make the amplified particles have the same particle flow characteristics as the actual particles. Actual tests were utilized to gather the angle of repose of the microfine iron tailings, which was then used as a reference value for response surface studies based on the JKR contact model from six factors connected to the fine iron tailings particles. The Plackett-Burman test was used to identify three parameters that had a significant effect on the rest angle: static friction factor; rolling friction factor; and JKR surface energy. The Box-Behnken experiment was used to establish a second-order regression model of the rest angle, and the significant parameters and the optimized parameters were: surface energy JKR coefficient 0.459; particle-particle static friction coefficient 0.393; and particle-particle dynamic friction coefficient 0.393, with a dynamic friction coefficient between particles of 0.106. By entering the parameters into the discrete element program, the angle of repose generated from the simulations was compared with the real test values, and the error was 1.56%. The contact parameters obtained can be used in the discrete element simulation of the amplified particles of fine-grained iron tailings, providing an EDEM model reference for the numerical simulation of fine-grained iron tailings particles. There is no discernible difference between the actual and simulated angles. [ABSTRACT FROM AUTHOR]

To obtain the cold soil of different soil layers in northwest China and the discrete element simulation parameters with contact components (Q235 steel), an accurate EDEM simulation model was constructed. The cold soil was divided into three layers, and Hertz-Mindlin (no slip） was used as contact model. The stacking angle test and straight shear test were used, and the significant factors were determined by the Packett-Burman method. The narrowing range was determined by the steepest climbing test, and the Box-Behnken response surface analysis method was used to determine the regression equation. The elastic recovery coefficient, the rolling friction factor and the static friction factor between different layers of soil particles were determined gradually. Through soil slip test and two-factor universal rotation center combination simulation test, the values of elastic recovery coefficient, static friction factor and rolling friction factor between soil particles and scrapers of different soil layers were obtained. The results show that the relative error is 5.78%, and the simulation parameters and research methods of layered cold soil calibration are verified. [ABSTRACT FROM AUTHOR]

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Simulation can be used to visualize the mechanical classification of walnuts. It can collect microscopic information about walnuts in the classification roller and guide its optimization design. In this process, simulation parameters are essential factors that ensure the effectiveness of the simulation. In this study, the crucial parameters of thin-skinned walnut particles in classification simulation were determined by combining the discrete element method (DEM) and physical tests. Firstly, the moisture content, shear modulus, stacking angle, and some contact parameters in the shell and kernel were obtained by drying test, compression test, cylinder lifting test, and physical test of contact parameters, respectively. A walnut model was constructed using reverse modeling technology. Then, the ranges of the rest contact parameters were determined using simulation inversion based on the Generic EDEM Material Model database. Second, the parameters significantly influencing the stacking angle were screened via the Plackett–Burman test using contact parameters as factors and stacking angle as the index. The results revealed that the walnut–walnut static friction coefficient, walnut–walnut rolling friction coefficient, and walnut–steel plate static friction coefficient significantly affect the stacking angle. The steepest ascent experiment produced the optimal value intervals of crucial parameters. Besides, a quadratic regression model of important parameters was built using the Box–Behnken test to achieve the optimal parameter combination. The stacking and classification experiments verified that the stacking angle and morphology are mostly similar under calibration parameters without any considerable differences. The relative error was only 0.068%. Notably, the relative error of the average staying time of walnut in the classification roller was 0.671%, and the dimensionless distribution curves of stay time were consistent. This study provides technological support to the simulation analysis of walnut classification and recommends novel methods and references to determine the parameters of other shell materials. [ABSTRACT FROM AUTHOR]

Rotary drums are widely used in industry, however, determining granular dynamics within them is still a complex task, thus remaining a focal point of research over the years. In this context, experimental techniques require numerical support to obtain data that is not easily acquired experimentally. One well-established numerical technique for studying particulate systems is the Lagrangian approach embed with Discrete Element Method (DEM). Although, DEM has limitations related to the definition of input parameters. It is crucial that DEM input parameters be measured and/or calibrated to reliably represent the granular behavior. These parameters are related to particle properties such as density, Young's modulus, Poisson's ratio, among others, and particle interactions, such as coefficients of restitution, static friction, and rolling friction. This study explores the experimental determination of interaction parameters preceding the acquisition of DEM input parameters in a rotary drum. Statistical analysis highlights the importance of each parameter and their combined interactions with the static angle of repose. The granular materials used were: soybeans, glass beads, polyacetal, 6 mm steel, and 4 mm steel. The coefficient of restitution was determined via free-fall methodology using equipment that verifies particle trajectory, static friction coefficient through equilibrium between weight and resistance forces, rolling friction coefficient using a launching device on surfaces of different roughness, and static angle of repose in a rectangular box with sections where particles rested. After removing the partition, angles were measured at both top and bottom sections. Regression techniques using a neural network created in Python were employed for both measurements. Experimental investigations and numerical simulations using DEM indicated that the coefficient of restitution depends on the thickness and type of material of the flat surfaces, showing an asymptotic behavior with increasing surface thickness. The static friction coefficient increased on rougher surfaces and in particles with greater imperfections. Rolling friction coefficient also increased on rough surfaces. Analysis of the angle of repose revealed that granular properties influence the response, such as static and rolling friction coefficients, whereas the coefficient of restitution had no significant influence. Neural network correlation coefficients exceeded 0.95, indicating a strong association between the variables. Our findings revealed that mathematical models can be used in conjunction with static repose angle experiments to calibrate DEM parameters for more robust and complex simulations. This research also quantifies and provides insights into the interactions between DEM parameters in direct measurement experiments, promoting more efficient calibration for future research. [Display omitted] • Restitution coefficient varies with surface thickness and material. • Increased surface roughness and imperfections raise static friction coefficients. • Rougher surfaces and smaller particles lead to higher rolling friction coefficients. • Granular properties, diameter, and density affect the static angle of repose. • Artificial Neural Networks have been employed for DEM parameters determination. [ABSTRACT FROM AUTHOR]

In view of the fact that the existing cotton stem simulation models are simplified and have a large discrepancy from the actual appearance and the contact parameters have not been calibrated. In this study, the simulation model and numerical simulation had been established using the discrete element software EDEM. Then a second-order response model between contact parameters and repose angle had been constructed. The test result showed that the static friction coefficient, rolling friction coefficient, and coefficient of restitution between cotton stems were crucial factors affecting the repose angle. The determination coefficient corrected determination coefficient and p-value of the second-order response model were R²=0.959, R²adj =0.921, and p<0.0001 respectively. The error values of the comparison between the simulation test results and the corresponding physical test values were all less than 10%, which showed that the model was reliable and had high interpretation and predictability, this study can provide a certain theoretical basis and data support for the setting of contact parameters in the data simulation of cotton stem harvesting and processing, mechanically-harvested film residue crushing and film stem separation, etc. [ABSTRACT FROM AUTHOR]