scholarly journals Prospects for energy-saving methods of crushing brittle materials

2021 ◽  
Vol 64 (6) ◽  
pp. 442-446
Author(s):  
A. G. Nikitin ◽  
A. R. Fastykovskii ◽  
M. E. Shabunov ◽  
N. M. Kurochkin ◽  
I. A. Bazhenov
Keyword(s):  
Energy Consumption ◽  
Brittle Materials ◽  
Compression Fracture ◽  
Metallurgical Industry ◽  
Complex Stress ◽  
Complex Stress State ◽  
Shear Stresses ◽  
Crushed Material ◽  
Main Indicator ◽  
Processed Material

Crushing machines are part of the charge departments of blast-furnace and steel-making shops of metallurgical enterprises. One of the main indicator of the crushing process is its energy efficiency. It is determined by the mass of crushed material when consuming a  unit of electricity. The article considers various methods of crushing brittle materials and the design of crushing machines for their implementation. The  analysis of the crushers has shown that impact crushers are the most energy-efficient. However, due to a significant drawback (the yield of a  suitable product is very small), they are practically not used in the metallurgical industry, in which high requirements are imposed on the finished product fractional composition. In the metallurgical industry, compression crushers are widely used with approximately the same specific energy intensity, that is, with the same energy consumption for the destruction of a unit volume of material of equal strength. Compression fracture is the most energy intensive crushing method known. In single-roll crushers, a  piece of material is fed into the gap between a roll and a solid, stationary plate. During the operation a complex stress state is generated in the destructed material. Compressive forces act on a piece of crushed material, causing normal compressive stresses in it, and an internal torque, causing shear stresses. This is achieved by the reduction in energy on crushing by 20 – 30 % in comparison with crushers operating in compression (all other things are equal). The  authors describe the design of a crusher, in which the destruction of the processed material occurs due to the forces acting on the crushed piece in one plane towards each other. In this case, only shear stresses arise in the processed piece. The use of crushers, in which the destruction of the processed material occurs due to generation of only tangential stresses in  a  piece, can reduce the energy consumption per unit of finished product by almost a half. The design of such crushers is a promising direction in the development of machines intended for crushing.

scholarly journals POWER ANALYSIS OF THE PROCESS OF BRITTLE MATERIALS DESTRUCTION IN UNIVERSAL CRUSHING MACHINE WITH ROLL LOCKER

2019 ◽  
Vol 62 (4) ◽  
pp. 303-307
Author(s):  
A. G. Nikitin ◽  
Yu. A. Epifantsev ◽  
K. S. Medvedeva ◽  
P. B. Gerike
Keyword(s):  
Energy Consumption ◽  
Power Analysis ◽  
Electric Energy ◽  
Metallurgical Industry ◽  
Complex Stress State ◽  
Simultaneous Action ◽  
Drive Power ◽  
Energy Unit ◽  
Crushed Material ◽  
Roll Crusher

The processing of friable materials used in metallurgical industry for production of definite size classes requires operation of crushing machines, including single-roll machines. Parameters of crushing process are degree and efficiency of crushing. The crushing degree is estimated by the ratio of dimensions of the initial crushing and resulting pieces and depends on the size of gap between the roll and the fixed jaw. Crushing efficiency is determined by mass of material crushed by consumed electric energy unit, and depends mainly on strength of crushed material. In order to reduce energy consumption needed for crushing, a single-roll crusher was developed at Siberian State Industrial University with forced feeding of crushing piece into the fracture zone due to the locker located on the roll. Forces of technological resistance appearing during machine operation are the main initial values for machine drive power and structural elements strength testing, thus, the operation power analysis is an integral stage in the design of any machine, including a crushing one. In the present work, forces acting on a crushing piece from roll side and fixed jaw in vertical and horizontal planes are identified. Based on the results obtained, it was determined that internal compressive forces acting on piece of crushing material cause action of normal compressive stresses in a piece, as well as an internal torque effect, which causes shearing stresses action, i.e. a complex stress state is generated in a fractioned piece with simultaneous action of normal and shearing stresses, under which action a fractioning piece is destroyed. Thus reduction in energy consumption for crushing is achieved, with all other conditions being equal. It reduces energy consumption of a single-roll crusher with forced feeding of material into the crushing zone.

ANALYSIS OF RESEARCH AND DESIGN MODELS FOR THE PUNCHNING SHEAR OF FLAT RC SLABS

2010 ◽  
Vol 2 (3) ◽  
pp. 93-100
Author(s):  
Gediminas Marčiukaitis ◽  
Remigijus Šalna
Keyword(s):  
Shear Strength ◽  
Theoretical Calculations ◽  
Theoretical Models ◽  
Complex Stress ◽  
Complex Stress State ◽  
Punching Shear ◽  
Shear Stresses ◽  
Test Results ◽  
Design Models ◽  
The Difference

The paper presents the review and analysis of the existing methods and models for calculating punching shear strength. The analysis of the existing design methods has showed that there is no unified theory about calculating punching shear strength. The models are similar in the way that fictitious shear stresses act in the fictitious shear area and are mainly obtained from the test results that may differ in their values. Therefore, the difference between the results obtained employing various calculation methods can be as high as 1,37 times, whereas the difference between the results of theoretical calculations and test research may vary up to 1,8 times. These facts clearly demonstrate that punching shear phenomena are not completely analyzed and require additional researches. The paper also proposes an in-deep analysis of famous analytical punching shear calculation models suggested within the last 50 years like Kinnunen and Nylander (1960), Moe (1961), Breastrup et al. (1976), Georgopoulos (1989), Broms (1990), Hallgren (1998), Menetrey (2002) and Theodorakopoulos (2002). The development of the above mentioned design models, the main assumptions and an algorithm for calculating punching shear strength are discussed in the article. The review of the existing models for calculating punching shear strength has also revealed that two main model types can be distinguished: type 1 – failure occurs when the compression zone is cut by shear and compression stress; type 2 – failure occurs when tensile stresses in concrete punching cone exceeds its tensile strength. A comparison between theoretical models and test results performed by different authors demonstrate that more accurate results can be obtained by calculating punching shear strength using the first types of models. The analysis has revealed it is purposeful to search for more effective reinforcing methods that can change the character of failure from brittle to plastic. A more effective replacement of reinforcement and the behaviour of concrete taking into account complex stress state in the failure zone should be applied.

scholarly journals INFLUENCE OF TEST CONDITIONS ON STRENGTH PROPERTIES OF THIN-WALL RUBBER PRODUCTS

2020 ◽  
pp. 78-84
Author(s):  
D. Kudelin ◽  
T. Nesnolovskaya
Keyword(s):  
Stress State ◽  
Uniaxial Tension ◽  
Stress Concentrator ◽  
Strength Properties ◽  
Complex Stress ◽  
Complex Stress State ◽  
Complex Stressed State ◽  
Shear Stresses ◽  
Thin Wall ◽  
Element Analysis

A computer simulation of the loading of the rubber membrane by a spherical indenter is performed using a finite element analysis package. It is shown that in the complex stress state rubber based on crystallize rubber IR are significantly inferior in strength properties as in the absence and in the presence of stress concentrator to rubber based on amorphous rubber SBR, while in uniaxial tension they are superior. It is revealed that in the complex stress state, rubbers based on IR rubber filled with 40 parts by weight of carbon black N339 have low resistance to shear stresses, inferior to SBR and BR vulcanizates, which results in low strength properties of rubbers based on it in comparison with strength characteristics determined under uniaxial tension. An analysis of the strength properties of rubbers in the presence of a stress concentrator shows that in a complex stress state, rubbers based on amorphous SBR rubber have the maximum tear resistance, exceeding IR and BR vulcanizates by this indicator, respectively by ~ 4 and 2 times. Under uniaxial tension, the most important factor is the ability of the material to orientation hardening, due to the regularity of the rubber structure and the presence of reinforcing filler, and in the complex-stressed state, the most important factor is a density of the nodes of the fluctuation mesh from the point of view of strength properties.

FEM Analysis and Experimental Study for Bond Strength of High-Strength Coating by Wedged Load Test Method

2010 ◽  
Vol 152-153 ◽  
pp. 1058-1061
Author(s):  
Zhou Wei ◽  
Xiao Xia Zhang
Keyword(s):  
Bond Strength ◽  
Adhesion Strength ◽  
Fem Analysis ◽  
High Strength ◽  
Pressure Head ◽  
Optical Microscope ◽  
Complex Stress ◽  
Complex Stress State ◽  
Load Test ◽  
Test Method

A wedged load test method is used to evaluate the adhesion strength of high-strength coatings, which have been processed with various sintering parameters. In this test, for stress concentration at cut tip, cracks are always induced and expanded rapidly cross the interface between coating and substrate. Macro-fracture and SEM image of coating interface of high-strength coating are characterized using optical microscope and scanning electron microscopy (SEM), respectively. In order to evaluate the bonding properties between coating and substrate effectively, corresponding finite element (FE) analysis has been conducted to evaluate the adhesion strength of high-strength coating. And stress distributions cross the interface of high-strength coating are obtained. The stress analysis can help to evaluate the bond strength of high-strength coating. Because of small specimen and contact relationship between wedged pressure head and wedged cuts, complex stress state is affected by many factors resulting from interface, and also by the thickness of coating.

Application of the concept of the criterion of equivalence of complex stress state to simple tension for assessing the fatigue resistance of structural materials. Part 1. Review of some experimental data with the preparation of the necessary information for subsequent use

2021 ◽  
pp. 24-27
Author(s):  
P.N. Kozlov
Keyword(s):  
Stressed State ◽  
Fatigue Resistance ◽  
Numerical Data ◽  
Structural Materials ◽  
Complex Stress ◽  
Complex Stress State ◽  
Static Loads ◽  
Simple Tension ◽  
Long Time ◽  
Equivalence Criterion

A brief overview of the features of the fatigue resistance of some steels is given with the selection of terms, concepts and numerical data necessary for the subsequent compilation and verification of the equivalence criterion in relation to assessing the ability of structural materials to resist fatigue for a long time under the action of certain combinations of alternating and static loads. Keywords: regular loading cycle, extremely stressed state, static stressed state, bending, torsion, biaxial static tension. [email protected]

scholarly journals Design Process of Energy Effective Shredding Machines for Biomass Treatment

10.14311/1622 ◽  
2012 ◽  
Vol 52 (5) ◽  
Author(s):  
Juraj Beniak ◽  
Juraj Ondruška ◽  
Viliam Čačko
Keyword(s):  
Energy Consumption ◽  
Energy Saving ◽  
Design Process ◽  
Electric Energy ◽  
Point Of View ◽  
Processed Material ◽  
Material Saving

The shredding process has not been sufficiently investigated for the design of better, energy and material saving shredding machines. In connection with present-day concern about the environment, ecology, energy saving, recycling, and finding new sources of energy, we need to look at the design of shredding machinery, the efficiency of the machines that we using, and ways of improving them to save electric energy for their operation. This paper deals with sizing and designing shredding machines from the point of view of energy consumption and optimization for specific types of processed material.

scholarly journals NONLINEAR DEFORMATION-FORCE MODEL OF A CONCRETE BAR WITH NON-METALLIC COMPOSITE REINFORCEMENT IN THE GENERAL CASE OF A STRESSED STATE

2021 ◽  
Vol 3 (1) ◽  
pp. 6-26
Author(s):  
I. Karpiuk ◽  
◽  
Ye. Klymenko ◽  
V. Karpiuk ◽  
M. Karpiuk ◽  
...  
Keyword(s):  
Stress State ◽  
Stressed State ◽  
Bearing Capacity ◽  
Nonlinear Deformation ◽  
Complex Stress ◽  
Complex Stress State ◽  
Force Model ◽  
Metallic Composite ◽  
Aggressive Environment ◽  
Deformation Force

The article discusses a nonlinear deformation-force model of a concrete bar structure with a non-metallic composite reinforcement (NKA-FRP) in the general case of a stressed state, when all four internal force factors from an external load (namely, bending and twisting moments, transverse and longitudinal forces). A sufficiently deep and meaningful analysis of well-known studies on the selected topic is given. It has been established that the proposed nonlinear deformation-force model of a bar structure with FRP in the general case of a stressed state can be practically useful due to the possibility of its application in the design or reinforcement of beams, girders, columns and elements of rosette trusses of rectangular cross-section, which are operated under aggressive environmental conditions. This model can also be used to check the bearing capacity of existing FRP concrete bar structures, which operate not only under the influence of an aggressive environment, but also under conditions of a complex stress-strain state. In the course of the research, an algorithm was developed for determining the bearing capacity of the design section of a concrete rod with FRP under its complex stress state. General physical relations for the design section are given in the form of a stiffness matrix. The algorithm for calculating a concrete bar with FRP consists of a block for inputting the initial data, the main part, auxiliary subroutines for checking the conditions for increasing the load vector and depletion of the bearing capacity, as well as a block for printing the calculation results. At each stage of a simple static stepwise increasing load, the calculation is carried out by performing a certain number of iterations until the accuracy of determining all components of the deformation vector satisfies a certain predetermined value. The features and patterns of changes in normal and tangential stresses, generalized linear and angular deformations, as well as the equations of equilibrium of a concrete bar with FRP, which operates under the influence of an aggressive environment under conditions of a complex stress state, are also considered.

Micromechanical Analysis of SiC/Ti6Al4V Composite Under Complex Stress State

2022 ◽  
Author(s):  
Pengjian Zou ◽  
Xuming Niu ◽  
Xihui Chen ◽  
Zhigang Sun ◽  
Yan Liu ◽  
...  
Keyword(s):  
Stress State ◽  
Complex Stress ◽  
Complex Stress State ◽  
Micromechanical Analysis
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