Breakage behaviour of single rice particles under compression and impact

Evolution characteristics of micromechanics provides insights into the microstructure of pharmaceutical tablets fabricated by bimodal mixtures

This research focuses on the evolution of mechanical behavior of bimodal mixtures undergoing compaction and diametrical compression. The clusters were built and discrete element method (DEM) was used to investigate the densification process and micromechanics of bimodal mixtures. Additionally, a more comprehensive investigate of the respective breakage of the bimodal mixtures has been carried out. On this basis, qualitative and quantitative analysis of the compressive force, force chain, contact bonds and density field evolution characteristics of the clusters are investigated during the compression process. The entire loading process of the clusters is divided into three stages: rearrangement, breakage and elastic-plastic deformation. Additionally, there are differences in the evolution of micromechanics behavior of different particles in the bimodal mixture, with pregelatinized starch breakage and deformation occurring before microcrystalline cellulose. With the tablet deformation, the fragmentation process of the tablet started at the point of contact and extended toward the center, and the curvature of the force chain increased. This approach may potentially hold a valuable new information relevant to important transformation forms batch manufacturing to advanced manufacturing for the oral solid dosage form.

Moisture-Dependent Physical-Mechanical Properties of Maize, Rice, and Soybeans as Related to Handling and Processing

Knowledge of physical and mechanical properties of cereal grains is important for designing handling and processing equipment. However, there is still a lack of knowledge on the influence of moisture content on the physical-mechanical properties as related to machine design. The aim of this study was to investigate and describe the changes in select physical-mechanical properties of maize, rice, and soybeans at various moisture content (10%, 14%, 18%, 22%, 26%; wet basis) and their compression behavior at two loading rates of 1.25 mm/min and 125 mm/min. The measured physical and mechanical properties include size, shape, and breakage force of single kernels. It was found that an increase in moisture content increased the kernel size, altered the kernel shape, and decreased the bulk density. The effects of moisture content and loading rate on breakage force, stress, and energy varied depending on the grain type. Our results indicated that an increase in moisture content changed the mechanical behavior of grain kernels from brittle to viscoelastic. To prevent kernel damage during processing and handling, the measured force and stress during compression can be used as the limit value for designing equipment.

Discrete Element Simulation Study of the Accumulation Characteristics for Rice Seeds with Different Moisture Content

To study the accumulation characteristics of rice seeds with different moisture content, an accurate model of rice seeds was established by 3D scanning technology. The accumulation state of rice seeds by the “point source” accumulation method was analyzed by proportioning and measuring the simulation parameters with different moisture content. The accumulation process was simulated at 10.23%, 14.09%, 17.85%, 21.77%, 26.41% and 29.22% moisture content, respectively. The velocity and force state of the seeds were visually analyzed by using the accumulation process with a moisture content of 29.22%. The accumulation process was divided into four stages according to the velocity characteristics of the seeds. The average force and kinetic energy of the rice seeds outside the cylinder were obtained, and the average force of the rice seeds outside the cylinder was proved to be the direct cause of the velocity change during the accumulation process. The mechanical characteristics of rice seeds in the quasi-static accumulation stage were partitioned and systematically analyzed. The force distribution of the “central depression” structure of rice seeds with a moisture content of 10.23%, 14.09% and 17.85% on the horizontal surface appeared. The higher the moisture content of rice seeds, the more likely the typical “circular” force structure appeared, and the more uniformly the force on the horizontal surface was distributed in the circumference direction.