Study of Selected Physical-Mechanical Properties of Corn Grains Important from the Point of View of Mechanical Processing Systems Designing

Abstract

Mechanical properties of corn grains are of key importance in a design of processing machines whose energy demand depends on these properties. The aim of this study is to determine the selected mechanical properties of corn grains and the rupture energy. The research problem was formulated as questions: (1) How much force and energy is needed to induce a rupture of corn grain maintaining good quality of the product of processing (mixing, grinding transport)? (2) Can empirical distributions of the studied physical-mechanical properties be described by means of probability distributions provided by the literature? (3) Is there a relationship between the corn grain size and the selected mechanical properties, as well as rupture energy? In order to achieve the goals, the selected physical properties (size, volume) of corn grains have been distinguished and a static compression test has been carried out on an Instron 5966 testing machine. The results indicate a significant scatter of the results in terms of size, grain shape, forces, energy, and deformation corresponding to the point of inflection, bioyiled point, and rupture point. It has also been indicated that empirical distributions of the analyzed properties can be described by means of distributions known from the literature, e.g., gamma, Weibull or lognormal distributions. It has been confirmed that mechanical properties such as force, energy, and stress that cause rupture depend on the grain size, more precisely, the grain thickness—there are negative relations between thickness and force, energy and stress in relation to the point of inflection, bioyiled point, and rupture point.

Energy-Dependent Particle Size Distribution Models for Multi-Disc Mill

“…The ratio between the gap dimension and rice grain dimension is low, so the grains are mostly ground between the first two discs to a size lower than the gap dimensions, and further size reduction is a result of impact. Size reduction due to impact in the case of rice can take place as well during flowing through holes, because the forces and energies for rice damage are relatively low [ 66 ], lower than corn [ 40 ]. The dominant stress in the mill as the resultant of the materials’ internal structure and mechanical properties, also affect the size reduction.…”

“…In the case of both these grains, comminution is used for obtaining flour, flakes, and semi-finished products for human nutrition and also for the preparation of animal feed [ 39 ]. Hence, it is reasonable to develop comminution models for these materials, which will contribute to improving the design of grinding mills as well as increasing the quality of the ground product and reducing the final energy consumption [ 40 ].…”

Optimization of the Sowing Unit of a Piezoelectrical Sensor Chamber with the Use of Grain Motion Modeling by Means of the Discrete Element Method. Case Study: Rape Seed

“…In reality, rape grains differ in terms of size (diameters in the range 1.8-2.2 mm) and shape as sometimes they do not make ideal spheres. Seeds of biological materials are characterized by significant shape diversity within one species and a wide range of values for one feature, as found in previous studies [43,44]. Diversity of the grain shapes has a significant influence on the grain flight destination point because the grain shape includes, among others the following: angle of impact with the sensor surface which affects the length of flying as well as inertia moments that cause rotation of the grain around its own axis upon collision.…”

Study of the Relationships between Multi-Hole, Multi-Disc Mill Performance Parameters and Comminution Indicators

“…Higher power consumption for corn comminution than for rice grinding results from the differences in the grain size, structure and mechanical properties. As described earlier [78,79], higher forces and energy are needed to break the corn grains than rice grains. In the case of rice comminution, the power consumption depends also on the batch dosing speed W. Generally, this dependance is quite obvious; the more material between the discs, the larger force (power) is needed to break the grains.…”