scholarly journals MECHANICAL CHARACTERISTICS OF THE RUBBED MAIZE STRAW DURING SCREW CONVEYING

2021 ◽  
pp. 109-118
Author(s):  
Wulantuya ◽  
Wuyuntana ◽  
Hongbo Wang ◽  
Wenbin Guo ◽  
Chunguang Wang ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Internal Friction ◽  
Moisture Content ◽  
Mechanical Characteristics ◽  
Sliding Friction ◽  
Angle Of Repose ◽  
Flow Function ◽  
Coefficient Of Sliding Friction ◽  
Maize Straw ◽  
Internal Friction Coefficient

In order to reduce the power consumption of screw conveyor and to improve the productivity, this study investigated such mechanical characteristics of rubbed maize straw as coefficient of sliding friction, angle of repose, internal friction coefficient, cohesion, flow function value and compressible coefficient with respect to its moisture content and density. An experiment was designed and consists of a sliding friction characteristic test-bed, a direct shear apparatus, a self-made device with adjustable density and compression. The results showed that: the coefficient of sliding friction increases with the increase of moisture content and density; the angle of repose and internal friction coefficient each increases with increasing moisture content respectively; there is no significant effect between the moisture content and the cohesion of rubbed maize straw; the flow function value goes up with the increase of the moisture content; also the increase of the moisture content leads to the increased bulk density due to the reduced materials gap and the increased compression coefficient, which makes it hard to compress. The equation of pressure and density was found, and it is suitable for the analysis of compression characteristic of rubbed maize straw. The research results lay a theoretical foundation and a basis for the further study on mechanical properties of maize straw.

scholarly journals Study of the nature of the dynamic coefficient of internal friction of grainmaterials

2019 ◽  
Vol 135 ◽  
pp. 01102
Author(s):  
Dmitriy Savenkov ◽  
Oleg Kirischiev ◽  
Ylia Kirischieva ◽  
Tatiana Tupolskikh ◽  
Tatiana Maltseva ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Internal Friction ◽  
Agricultural Production ◽  
Mechanical Characteristics ◽  
Dynamic Coefficient ◽  
Bulk Materials ◽  
Dynamic Coefficients ◽  
Internal Friction Coefficient ◽  
Physical And Mechanical Characteristics

The article highlights the issues related to the study of physical and mechanical characteristics of bulk materials, namely internal friction coefficients in static and dynamic modes. An innovative device of the carousel type for determining the frictional characteristics of bulk materials is described, which allows to implement the tasks of practical determination of dynamic coefficients of internal friction. Presented the program, methodology and results of research on the practical study of the internal friction coefficient of typical bulk products of agricultural production in the range of linear velocities of displacement of layers from 0 to 2.79 m/s, the reliability of which is not lower than 0.878.

scholarly journals A Comparative Analysis of the Flow Properties between Two Alumina-Based Dry Powders

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Milene Minniti de Campos ◽  
Maria do Carmo Ferreira
Keyword(s):  
Internal Friction ◽  
Moisture Content ◽  
Ceramic Powder ◽  
Morphological Characteristics ◽  
Angle Of Repose ◽  
Wall Friction ◽  
Flow Index ◽  
Alumina Powder ◽  
Flow Properties ◽  
Angle Of Internal Friction

We measured and compared the flow properties of two alumina-based powders. The alumina powder (AP) is irregularly shaped and has a smooth surface and moisture content of 0.16% (d.b.), and the ceramic powder (CP), obtained after atomization in a spray dryer, is spherical and has a rough surface and moisture content of 1.07%. We measured the Hausner ratio (HR), the static angle of repose (AoR), the flow index (FI), the angle of internal friction, and the wall's friction angle. The properties measured using aerated techniques (AoR and HR) demonstrated that AP presents true cohesiveness (and therefore a difficult flow), while CP presents some cohesiveness and its flow might be classified as half way between difficult and easy flow. Their FI values, which were obtained using a nonaerated technique, enable us to classify the alumina as cohesive and the ceramic powder as an easy-flow powder. The large mean diameter and morphological characteristics of CP reduce interparticle forces and improve flowability, in spite of the higher moisture content of their granules. The angles of internal friction and of wall friction were not significantly different when comparing the two powders.

Influences of Change of Plasma on Strength Property of Eolian Sand

2012 ◽  
Vol 170-173 ◽  
pp. 830-835
Author(s):  
Chang Ning Jin ◽  
Yu Hong Zhang
Keyword(s):  
Friction Coefficient ◽  
Internal Friction ◽  
Strength Property ◽  
Friction Angle ◽  
Clay Particles ◽  
Fine Grained ◽  
Eolian Sand ◽  
Coefficient Increase ◽  
Fine Grained Soil ◽  
Internal Friction Coefficient

The plasma in the eolian sand, included silt particle and clay particle, change easily and hugely. For studying their influences on the strength property of eolian sand, mixed silt particles and clay particles into eolian sand in different proportions to measure the internal friction angle and cohesion under different forming and testing conditions. The result indicates that: for the same kind of test specimen under different test types, the changes of cohesion and internal friction coefficient are regular. For the same test type, the changes of both cohesion and internal friction coefficient of different test specimens are regular. Generally, when the content of silt particles and clay particles is lower than a certain value, the cohesion and internal friction coefficient increase accordingly and rapidly along with the increase of silt particles and clay particles; after the content of silt particles and clay particles is larger than this value, the cohesion and internal friction coefficient increase slowly or decline along with the increase of silt particles and clay particles. The change range of this value is approximately between 45%～65%, the content of silt particles and clay particles. For the purpose of this test, as to the transition of test specimens from typical sandy soil to fine grained soil caused by the increase of silt particles and clay particles, the change point of strength is at 45％ approximately, which is basically consistent with the compacting test and CBR test, etc.

scholarly journals Numerical Study of Particle Morphology Effect on the Angle of Repose for Coarse Assemblies Using DEM

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Jing Chen ◽  
Rui Gao ◽  
Yangzepeng Liu
Keyword(s):  
Particle Shape ◽  
Laboratory Tests ◽  
Sliding Friction ◽  
Numerical Study ◽  
Dominant Role ◽  
Particle Morphology ◽  
Angle Of Repose ◽  
Shape Effect ◽  
Shape Factors ◽  
Coefficient Of Sliding Friction

The morphologies of coarse particles are usually irregular and play a dominant role in the mechanical behaviors of the particle assemblies. This paper quantitatively studies the effect of particle shape on the angle of repose, which is an important macroscopic parameter for ballast materials, via laboratory tests and numerical simulations by means of the discrete element method (DEM). Forty ballast particle templates and four simply created clump templates are reconstructed using an image-based method and quantified with two shape factors, sphericity and convexity. A series of simulations are conducted with the coefficient of sliding friction between particles changing from 0.2 to 0.6 at an interval of 0.1 to study its influence on various shapes of particles, and an appropriate value of sliding friction coefficient is chosen for the comparison of particle shape effect. The results show that increasing sphericity and convexity can significantly decrease the angle of repose, and the real ballast model gives a more realistic angle of repose behaviors as that of laboratory tests compared to simply created models. By analyzing the characteristics of particle motions and contacts from a microscopic perspective, the mechanism of particle shape attributed to the formation of granular aggregation is also discussed and revealed in this research.

Measurements of internal friction coefficient of SiC and Al2O3 powders

1993 ◽  
Vol 28 (24) ◽  
pp. 6737-6740 ◽  
Author(s):  
R. Cortés ◽  
M. A. Martínez ◽  
C. Navarro ◽  
V. Sánchez-Gálvez
Keyword(s):  
Friction Coefficient ◽  
Internal Friction ◽  
Internal Friction Coefficient

scholarly journals Internal Friction and Compressive Deformation in the Primary Zone during the High-Speed Cutting of SiCp/Al Composites

2021 ◽  
Author(s):  
Xiaoxuan Lin ◽  
Wenyuan Yang ◽  
Daochun Xu ◽  
Wenbin Li ◽  
Simin Ma
Keyword(s):  
Mathematical Model ◽  
Friction Coefficient ◽  
Internal Friction ◽  
High Speed ◽  
Compressive Strain ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Compressive Deformation ◽  
Primary Zone ◽  
Internal Friction Coefficient

Abstract The present work proposes that there is internal friction and compressive deformation in the primary zone. Mathematical model was established, in which the internal friction coefficient and some compressive characteristics of serrated chips were calculated. High-speed orthogonal cutting experiment was performed on SiCp/Al composites at cutting speeds of 10–350 m/min and feed rates of 0.07–0.12 mm/r. The internal friction and compressive deformation in the primary zone were investigated by combing results obtained in the experiments with the mathematical model. The internal friction coefficient (0.21–0.47), compressive stress (185.4 MPa–226.9 MPa), and compressive strain rate (0.013×104 /s–0.554×104 /s) increased with increasing cutting speed. However, the compression value (17.3 µm–50.0 µm) and compressive strain (0.18–0.26) decreased with the cutting speed.

scholarly journals Transient Evolution of Rheological Properties of Dense Granular Inertial Flow Under Plane Shear

2021 ◽  
Author(s):  
Xuejie Zhang ◽  
Wei Wang ◽  
Xiaojun Liu ◽  
Kun Liu
Keyword(s):  
Shear Strength ◽  
Friction Coefficient ◽  
Internal Friction ◽  
Rheological Properties ◽  
Interfacial Friction ◽  
Flow State ◽  
Plane Shear ◽  
Inertial Flow ◽  
Internal Friction Coefficient ◽  
Contact Orientation

Abstract Exploration on the transient evolution of the rheological properties of dense granular inertial flow is essential for revealing how the balance is established between the boundary drive strength and the internal shear strength. In this paper, discrete element method simulations are performed to study the transient flow characteristics of a dense granular system under plane shear in the inertial regime. To this end, we quantitatively analyze the changes in the system’s flow state, interfacial friction coefficient, internal friction coefficient, and microstructure. Simulation results show that the evolution of the horizontal flow experiences three typical stages, namely transmission, adjustment, and stabilization. Meanwhile, the shear dilatancy caused by the vertical movement of particles, gradually loosens the filling state, weakens the spatial geometric constraint and the system’s tangential load-bearing capacity, thereby decreasing the interfacial friction coefficient and reducing the boundary drive strength. On the other hand, the variations in the anisotropies of both contact orientation and contact forces, increase the internal friction coefficient and improve the internal shear strength. Therefore, the evolution of flow state from initially static to finally stable reduces the boundary drive strength while enhances the internal shear strength, and eventually a balance between them is achieved. Distinguished from the micromechanical behaviors, under different shear velocities the internal shear strength always mainly originates from the anisotropies in contact orientation and in normal contact force. Moreover, the contribution of the anisotropy in contact orientation becomes more predominant with the increase of shear velocity.

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