Friction Of Grains Research Articles

Biometric parameters and physical-mechanical properties of wheat and barley grown on dry lands

In Uzbekistan, wheat is grown on more than 120,000 hectares of dry land, and barley on about 65,000 hectares. Due to the development of animal husbandry on dry lands, along with the grain of wheat and barley, straw is in great demand and it is important to harvest it without losing it. Research is underway to develop a device that would load the straw coming out of it into the back of the combine into large trailers when harvesting grain on dry land. For this purpose, the physical and mechanical properties of wheat and barley grown on dry lands were studied. In dry lands of Uzbekistan, the average grain length in different varieties is mainly in the range of 70-80 cm, and the ratio of grain to straw is in the range of 1: 1.17 - 1: 1.48. The coefficient of friction of grains and ears is 0.34 and 0.32, which is 1.2-1.7 times less than the coefficient of friction of stalks and sawdust. The critical flight speed is 2.0-4.0 m/s in straw sections up to 50 mm in length, 5.0-6.0 m/s in 100 mm, and 12.0-19.0 m/s in sections larger than 100 mm.

​Effect of Moisture Content on Engineering Properties of Green Gram for Designing of Agricultural Equipment

Background: Green gram is a popular pulse crop in India (with 2.02 MT production over a cultivated area of 4.26 Mha) and Odisha (20.8 lakh ha area with a yield of 10.60 lakh tonnes). The information on the engineering properties and its behavioural changes with moisture content is vital for handling and designing of different agricultural processing equipment. Methods: This work mainly focused on studying green gram variety’s (Sujata) engineering properties at five different moisture levels (within a moisture range of 10.58 to 45.45% (d.b.). Standard methods and procedures were followed in the study and the output results were compared with previous research work to justify the variation or anomaly in some cases. The curve estimation method (regression analysis) was followed to find the best-fit curve and equation for the parameters studied. Result: The geometric mean diameter (GMD) of grain increased from 3.75 to 4.12 mm within the moisture content (MC) range and the variation was statistically significant (p less than 0.05). Sphericity and surface area varied significantly from 0.83 to 0.82 and 44.13 to 53.45 mm2, respectively, within the range of moisture contents studied with a high correlation among the data. Mass of thousand grains augmented (44.13 to 53.45 g) with a rise in MC and the data followed logarithmic and inverse curves. Bulk and true densities of green gram declined significantly from 860 to 670 kg m-3 and 1330 to 1240 kg m-3 with an increase in the moisture content. The porosity of green gram increased significantly from 35.75% to 46.38% and the terminal velocity raised from 9.20 m s-1 to 11.10 m s-1 with an increase in MC. The dynamic angle of repose increased significantly from 30.95 to 46.57o with MC. A significant variation in the coefficient of internal friction (0.78 to 0.90) was observed for the grains. The coefficient of static friction of grain increased significantly for different surfaces (MS, SS, Plywood and GI) with a rise in MC. The MS surface produced the highest coefficient of static friction and SS had the least. The results confirmed significant effect of MC on all engineering properties of green gram.

Development of a plant for peeling rapeseed in the electromagnetic field of ultrahigh frequency

Currently, domestic industry uses imported raw materials. At the same time, supplies of rapeseed oil for export as raw materials account for about 80% of the production volumes. Therefore, import substitution of rapeseed oil due to an increase in its own production and a significant increase in the efficiency of processing technology with improved quality characteristics, the development of innovative technology and technical means to improve the quality of peeling of rapeseed is relevant. Depending on the grain structure, one of three methods of peeling is used: compression and shear, multiple or single blow, by abrasion of the shells. The rapeseed kernel has a fragile structure, so peeling with a multiple blow is irrational. Two requirements are imposed on the rape seed peeling process: high-quality separation of husk from the kernel and preservation of the integrity of the kernel. The article describes the developed design of the installation for peeling rape in an electromagnetic field, which allows the peeling process to be carried out at low operating costs. The process of peeling rape is possible by hydromechanical destruction and abrasion of husks on rotating abrasive disks and mutual friction of grains in the EMF microwave, followed by removal of the shells by blowing air through a hollow dielectric shaft with holes and a perforated cylindrical resonator. The article also describes the technological process of rape peeling and conducted a feasibility study on the implementation of the proposed installation. The economic effect of the use of a microwave installation for rape peeling is 124 thousand rubles/month with the volume of output 38.5 tons/month, profitability will increase by 3.7%.

Assessment of Engineering Properties of Proso Millet (Panicum miliaceum)

Engineering properties of grain and kernel are required to design crop production, material handling and processing equipment. A study was conducted to determine the properties of grain and kernel of Panicum miliaceum at different moisture contents in range of 6.5−26.5 % (d.b.). The length, width, thickness and geometric mean diameter of Panicum miliaceum were observed in the range of 2.22−2.36 mm, 2.08−2.24 mm, 1.93−2.21 mm, 2.07−2.27 mm for grain and 1.87−1.98 mm, 1.73−1.97 mm, 1.63−1.80 mm, 1.74−1.91 mm for kernel, respectively. Sphericity ranged between 0.93−0.97 for the grain, and 0.93−0.96 for the kernel. Surface area, volume and thousand-grain weight increased from 12.73 mm2 to 15.64 mm2 , 4.25 mm2 to 5.80 mm3 , 5.25 g to 6.70 g for grain; and 8.94 mm3 to 11.14 mm2 , 2.50 mm3 to 3.50 mm3 , 3.21 g to 4.15 g for kernel, respectively. True density of grain and kernel increased with increase in moisture content. Bulk density decreased from 765.5 kg.m-3 to 697.57 kg.m-3. Similarly, in case of kernel, bulk density decreased from 845.33 kg.m-3 to 724.97 kg.m-3. Terminal velocity of grain and kernel ranged from 1.68 m.s-1 to 2.77 m.s-1 and 0.80 m.s-1 to 1.89 m.s-1, respectively and increasing trend was observed with moisture content. The coefficient of internal friction of grain and kernel increased with increase in moisture content from 0.48 to 0.68 and 0.69 to 0.90, respectively. The geometric, gravimetric, aerodynamic and frictional properties of grain and kernel of Panicum miliaceum at different moisture contents were found to be different at 5 % significance level.

METHOD OF DETERMINING WEAR OF FAN BLADES CRUSHER GRAIN

It is scientifically proven that the main factors affecting the productive potential of the animals, are the structure of fodder farms, the quality of feed and methods of feeding. It is known that concentrated fodder are an important component in the diet of animals and contribute to a stronger manifestation of their productive potential. For grinding grain into livestock is usually used crusher with different working bodies. The most widely is spread hammer mill grain crusher. This happens due to the simplicity of their construction and relatively high resource of working bodies. Currently, for farmers are of great interest the small-sized feed factories and units, which include crusher grain with a fan. However, along with the obvious advantages of hammer crusher, like with forced feeding of material and with pneumatic, have a number of disadvantages, one of which is the increased wear of their working bodies: hammers, screens, fan blades. The greatest interest from the point of reducing wear represent fan blades, as changing their shape, it is possible to reduce or increase the intensity of wear. In addition, they are more prone to wear, since all of the crushed material passes through them with great speed, while in the grinding chamber, the amount of grain distributed over a larger number of hammers, and the relative velocity of grains in it decreases. The analysis showed that the intensity of wear of working surfaces of the blades of the fan depends on the coefficient of friction of grains on the blade, the angle of the blade to the radius of the rotor disc, and the greatest influence on friction force has a peripheral speed of the blades. To increase the service life of the blades and reduce the intensity of wear and tear it should be choosen the correct form of the smallest possible radius of curvature. The method is proposed on the basis of which it is possible to calculate the amount of wear of fan blades, taking into account its aerodynamic characteristics.

The Formation and Behaviour of Residual Stresses with Finished Surfaces

The single tool grains affect the workpiece surface during grinding in the separated areas of deformation. The elastic and consequently plastic deformations occur at the engagement of grains. The friction of grain and material likewise the friction of elementary chip and grain acts simultaneously. These phenomena are accompanied with an origination of great amount of heat and high pressures and that is the reason for residual stress origin and formation in the ground surface. The residual stress is an important factor in influencing usable properties of machine parts. The stress influences not only the dynamical load capacity of surface but the durability and quality of design units as well. This stress is considered as the source of so called technological notches, having an influence on corrosion resistance, wear resistance, and dimension stability of machine parts.

Structuring in complex plasma for nonlinearly screened dust particles

An explanation is proposed for the recently discovered effect of spontaneous dusty plasma structuring (and the appearance of compact dust structures) under conditions of nonlinear dust screening. Physical processes are considered that make homogenous dusty plasma universally unstable and lead to the appearance of structures. It is shown for the first time that the efficiency of structuring increases substantially in the presence of plasma flows caused by the charging of nonlinearly screened dust grains. General results are obtained for arbitrary nonlinear screening, and special attention is paid to the model of nonlinear screening often used since 1964. The growth rate of structuring instability is derived. It is shown that, in the case of nonlinear screening, the structuring has a threshold determined by the friction of grains against the neutral gas. The theoretically obtained threshold agrees with recent experimental observations. The dispersion relation for dusty plasma structuring is shown to be similar to the dispersion relation for gravitational instability with an effective gravitational constant. The effective dust attraction caused by this instability is shown to be collective, and the dependence of the effective gravitational constant on the dust-to-ion density ratio is found explicitly for the first time. It is demonstrated that the proposed method of calculation of dust attraction by using the effective gravitational constant is the most efficient and straightforward. Understanding of the role of nonlinear screening gives deeper physical grounds for the theoretical interpretation of the observed phenomenon of dust crystal formation in complex plasmas.

Handling, frictional and technological properties of wheat as affected by moisture content and cultivar

In order to optimize the processes such as planting, harvesting, handling, threshing, cleaning, sorting, conveying, drying and storing and to reduce the quantitative and qualitative losses of grains and seeds, their physical properties need to be known. In this research, several physical properties of five wheat cultivars (Pehlivan, Kızıltan-91, Çeşit-1252, Bayraktar-2000 and Kırik) were determined as a function of moisture content. The values of the length, width, thickness, geometric mean diameter, sphericity, projected area, thousand grain mass, terminal velocity, angle of repose and dynamic coefficient of friction of grains increased as the moisture content increased. The values of bulk density, true density and rupture force of grains decreased as the moisture content increased. On the other hand, the values of porosity and deformation at rupture point of grains did not show any regular variation with the moisture content.

Design, fabrication and performance of a motorized cowpea thresher for Nigerian small-scale farmers

Based on the results of measurements of moisture content of grains, cowpea grain and pod sizes, grain-pod ratio, angle of friction of grains and some information from literature, a motorized cowpea thresher using a star-shaped beater to which beater belts were attached was designed and locally built. Five varieties of cowpea, K59, Ife-Brown, IT84E-124, Ife-Bimpe and TVX 715 which are fairly representative of the most popular varieties in Nigeria were selected for the measurement of design parameters. The statistical design used in studying the effect of variety on length, width, thickness, equivalent diameter, sphericity, pod weight and grain-pod ratio with 30 replications, moisture content with 3 replications and angle of friction with 5 replications was complete randomized design (CRD). The moisture content for the grain varieties ranged from 11.06 to 12.02% w.b while the size and shape measurement parameters namely; length, width, thickness, equivalent diameter and sphericity ranged from 8.22 to 10mm, 6.04 to 6.83 mm, 4.36 to 5.38 mm, 6.00 to 7.09 mm and 0.71 to 0.79 respectively for grains. For the pods, the length, width and thickness ranged from 124.78 to 194.93 mm, 7.28 to 9.15 mm and 5.27 to 7.86 mm respectively. The pod weight and grain-pod ratios ranged from 1.96 to 3.39 and 0.75 to 0.86 respectively for all the varieties tested while the angle of friction of grains on mild steel ranged from 23.6 to 26.6o. The results of the study as indicated by analysis of variance (ANOVA) show that there is highly significant effect (P ≤ 0.01) of variety on all the grains and pods measurement parameters except angle of friction where non-significance was observed. Skewness and kurtosis analysis indicates that the frequency distribution curves for grains and pods measurement parameters generally approximated those of the normal distribution. Based on the optimum machine parameters, the machine throughput was determined to be 101.19, 110.86, 74.33, 75.81 and 102.09 kg grains/hour for K59, Ife-Brown, IT84E-124, Ife-Bimpe and TVX 715 respectively. Preliminary performance evaluation tests carried out on the fabricated thresher using IT84E-124 as the test material at recommended beater and fan speeds of 500 rpm and 1400 rpm respectively indicated average threshing efficiency of 96.29%, percentage damage of 3.55% and percentage threshed and undamaged grains of 92.74%. A cleaning efficiency and loss of 95.60 and 3.71% respectively was observed indicating that with the use of a star-shaped beater, drudgery and cost can be reduced to a minimum and yet achieving good quality products. Key words: Design, fabrication, thresher, cowpea, performance evaluation.

A Viscometric Approach to the Design of a Seed Dressing Mixer

A new design of mixer for seed dressing is presented. The main objective in the design was to provide a uniform stress field without high shear spots or eddy zones. The approach was to adopt the concept of rotational cylinder viscometry and apply the analysis of shear stresses and shear rates to a vertical axis mixer. The resulting design consisted of a stationary outer chamber with an inner rotor. Flights mounted on the rotor, interleaved with baffles attached to the inside of the chamber wall to ensure that all the seed was circulated through the treatment zone. The clearances and speeds were carefully evaluated to make sure that maximum intensity of mixing was achieved without any danger of damage to the seed. The shear rate at the flight tip was evaluated as 41 s 1. Power predictions were estimated on a basis of friction of grain on the moving surfaces and gave an overestimate of 23% but nevertheless proved to be useful in choosing a drive motor. Tests in the laboratory correlated well with those in the full-scale test machine on the basis of three criteria: the mean residence time of the seed in the mixer, the visual appearance of uniformity of the chemical treatment and the measurement of damage. The mean residence time varied from 22 s at a rate of 29 t/h to 88 s for a rate of 5 t/h. The uniformity was judged to be as good as that achieved by other commercial mixers and the amount of damage caused to the seed was found to be statistically insignificant. The commercial model is a very compact machine compared to other seed dressers. It mixes grain thoroughly with a mean residence time of under 1 min and causes no significant damage to the grain.

VERTICAL LOADING OF TEMPERATURE CABLES

ABSTRACT One of the most popular methods of determining potential locations of spoilage in stored grains is through constant monitoring of the internal temperatures of the grain mass. Distinctive increases of the local temperatures in the grain are a good indication of potential spoilage problems. Daily inspection of the internal temperature of the stored grain can detect the presence of a hot spot before any grain is seriously deteriorated. The operator can then choose to aerate the grain to cool the hot spot or remove the grain from the bin. Daily monitoring of temperatures requires that sensing elements be placed within the grain mass. A common method of monitoring temperatures in a mass of stored grain utilizes thermocouples attached at regular intervals to high-strength steel cables. The entire assembly including the thermocouples and the cables is coated with a protective jacket. Temperature-sensing cables are available in many types, differing in surface material, size and cross-sectional shape. These cables are typically suspended from a grain bin roof in a standard pattern so they form a three-dimensional matrix of temperature monitoring points. Article was submitted for publication in January 1990; reviewed and approved for publication by the Structures and Environment Div. of ASAE in July 1990. Presented as ASAE Paper No. 89-4002. This work is published with the approval of the Director of the Kentucky Agricultural Experiment Station and designated as Paper No. 89-2-113. Major funding for the research reported in this article was provided by the Farm and Industrial Equipment Institute, Chicago, IL, and the University of Kentucky Agricultural Experiment Station. Part of the equipment used in this research was donated by Brock Mfg. Co., Inc., Milford, IN; Butler Mfg. Co., Kansas City, MO; Chief Industries, Inc., Grand Island, NE; Clayton & Lambert Mfg. Co., Buckner, KY; Floss Food Technology Corp., Eden Prairie, MN; and Mix-Mill Mfg. Co., Inc., Bluffton, IN. The authors are C. V. Schwab, Assistant Professor, Agricultural Engineering Dept., Iowa State University, Ames; R. A. Curtis, Research Assistant, Agricultural Engineering Dept., University of Kentucky, Lexington; S. A. Thompson, Associate Professor, Agricultural Engineering Dept., University of Georgia, Athens; and I. J. Ross, Professor and Chairman, Agricultural Engineering Dept, University of Kentucky, Lexington. These cables are subject to vertical frictional loading during filling, storing, and emptying operations. Since these cables are supported by the roof of a grain bin, designers require design guidelines for estimating the magnitudes and characteristics of the vertical loading. The loads imposed on temperature sensing cables have caused localized failures in certain components of grain bins as reported by Wickstrom (1980). The purpose of this study was to compare five different types of commercially available temperature sensing cables to determine the apparent coefficient of friction of wheat on the cables and the magnitude of vertical loading in a full-scale grain bin during both static and dynamic unloading conditions. The effects of emptying flow rate, starting grain height, detention time, and the radial position of the cables in the bin were determined. EXPERIMENTAL METHODS The experiments consisted of two parts: a laboratory study to determine the apparent dynamic coefficient of friction of grain on the cable surfaces; and a full-scale bin study to measure vertical frictional loading on the cables. Five types of temperature cables which represent several of the variations in commercially available cables were used in the experiments. The different dimensions and surfaces materials of the cables are given in Table 1 and the physical appearance is shown in figure 1. The cables used for the laboratory study were short sections identical to the cable specimens used in the bin study. The grain used was soft red winter wheat at 11.9% moisture content (wet basis) with an uncompacted bulk weight of 772.6 kg/m^. The influences of different variables on parameters measured were determined using analysis of variance technique in SAS (1982). The laboratory study was conducted to determine the apparent coefficient of friction of wheat on the temperature cables at different normal pressures. The magnitude of the

AN OPTIMAL MISTING METHOD FOR COOLING LIVESTOCK HOUSING

ABSTRACT The stress ratio (K) used in Janssen's equation for calculating grain pressure was determined for soybeans by four different methods. Static stresses were measured in a 0.91 m diameter x 2.743 m high model galvanized smooth steel bin. The four methods were: 1) measure vertical loads on the floor and wall separately; 2) measure vertical and hoop strains in the bin walls with six, two-element, rosette gages evenly spaced around the bin circumference at 15.2 cm above floor, 3) measure horizontal and shear loads at the bin wall with three ring load cells placed at different heights on the model bin wall (15.2, 61.0, and 106.7 cm above the floor); and 4) directly measure vertical and horizontal stresses within the grain mass using in-mass transducers (IMTs) at four different heights at the bin center (15.2, 61.0, 106.7, and 152.4 cm above the floor). A total of 18 replications were performed. For grain depths less than H/D = 2.8, K-ratio decreased with increasing depth of soybeans. At depths about three times the bin diameter (U/D = 3.0), the K-ratio approached a constant value that may be approximated by KQ = 1 - sin p, where p is the angle of internal friction of grain to grain.

EXPERIMENTAL DETERMINATION OF JANSSEN'S STRESS RATIO BY FOUR METHODS FOR SOYBEANS UNDER STATIC CONDITIONS

ABSTRACT The stress ratio (K) used in Janssen's equation for calculating grain pressure was determined for soybeans by four different methods. Static stresses were measured in a 0.91 m diameter x 2.743 m high model galvanized smooth steel bin. The four methods were: 1) measure vertical loads on the floor and wall separately; 2) measure vertical and hoop strains in the bin walls with six, two-element, rosette gages evenly spaced around the bin circumference at 15.2 cm above floor, 3) measure horizontal and shear loads at the bin wall with three ring load cells placed at different heights on the model bin wall (15.2, 61.0, and 106.7 cm above the floor); and 4) directly measure vertical and horizontal stresses within the grain mass using in-mass transducers (IMTs) at four different heights at the bin center (15.2, 61.0, 106.7, and 152.4 cm above the floor). A total of 18 replications were performed. For grain depths less than H/D = 2.8, K-ratio decreased with increasing depth of soybeans. At depths about three times the bin diameter (U/D = 3.0), the K-ratio approached a constant value that may be approximated by KQ = 1 - sin p, where p is the angle of internal friction of grain to grain.

Role of Grains in the Drift of Plasma and Magnetic Field in Dense Interstellar Clouds

The magnetic flux through an interstellar cloud or through a part of the cloud must decrease considerably by the drift of plasma and magnetic field in order that stars form in the cloud. Because most grains are negatively charged in dense clouds (Elmegreen 1979; Umebayashi and Nakano 1980), they retard magnetic flux leakage in addition to ions (Elmegreen 1979). We investigate this effect for different situations and obtain the following results (for details, see Nakano and Umebayashi 1980): 1.For nearly spherical clouds of mass ≳ 103M⊙ sustained by magnetic force the friction of grains is efficient at nH⊙ ≳ 105 cm−3, and the magnetic flux leakage time tB is greater than a few million years at any density. Grains drift as fast as ions and electrons.2.For spherical clouds of smaller mass and disk-shaped clouds, tB becomes much smaller and the drift of grains is much slower than ions and electrons at nH ≳ 106 cm−3.3.Thus magnetic flux leakage occurs mainly in the condensations described in 2, and the abundance of heavy elements in stars deviates little from that of the parent clouds because of small grain drift.

Kinetic Friction of Grains on Surfaces

Kinetic Friction of Grains on Surfaces

Determining Static Coefficients of Friction of Grains on Structural Surfaces

Determining Static Coefficients of Friction of Grains on Structural Surfaces