scholarly journals Analysis of efficiency of drilling equipment use in mining operations

2021 ◽  
Vol 315 ◽  
pp. 02018
Author(s):  
Yuriy Masaev ◽  
Vladislav Masaev ◽  
Yuriy Drozdenko
Keyword(s):  
Mechanical Properties ◽  
Energy Intensity ◽  
Physical And Mechanical Properties ◽  
Structural Features ◽  
Ore Deposits ◽  
Mining Operations ◽  
Drilling Equipment ◽  
Wide Range ◽  
Mine Workings ◽  
Underground Method

When developing coal and ore deposits by underground method, it is necessary to carry out a large volume of preparatory mine workings using drilling and blasting operations. Minerals are found in rocks under various conditions and their physical and mechanical properties change in a wide range. Under such conditions, it is necessary to use drilling machines this different to the principle of action and structural features. The article considers geometric parameters of roc cutters, peculiarities of drilling modes, affecting energy intensity and drilling productivity in rocks with different strength coefficient.

Structure and properties of compact articles from high-alloyed iron powder with adding of boron nitride

2020 ◽  
pp. 39-48
Author(s):  
B. O. Bolshakov ◽  
◽  
R. F. Galiakbarov ◽  
A. M. Smyslov ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Grain Boundary ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Operating Conditions ◽  
Structure And Properties ◽  
Steam Turbines ◽  
Friction Forces ◽  
Wide Range

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.

Control of properties and structure of steel vessels by cooling in various media at the outlet of rolling and pressing lines

2021 ◽  
pp. 34-38
Author(s):  
R. L. Shatalov ◽  
V. A. Medvedev
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
Metal Structure ◽  
Machine Building ◽  
Regression Equations ◽  
Wide Range ◽  
Industrial Mineral ◽  
Cooling Media ◽  
Technological Limitations ◽  
Non Destructive

When controlling the mechanical properties and structure of vessels made of carbon structural steels manufactured by hot deformation on rolling and pressing lines (PPL) of machine-building enterprises of Russia, such cooling media as water, I20 industrial mineral oil, air are used. The applied cooling media are able to provide the workpieces with a given structure with a wide range of mechanical properties. However, the cooling media have a number of technological limitations and conditions of the use, non-compliance with which leads to reject. When cooled in oil, the probability of ignition is high; when cooled in water, hardening cracks may form, and air is not always able to provide the required rate and uniformity of heat transfer to the environment. The efficiency of control of physical and mechanical properties and structure of deformed vessels made of 50 steel by cooling in TERMAT polymer aqueous solutions in different concentrations on PPL of the plant of JSC NPO Pribor was studied. The effect of varying the concentration from 2 to 9% of TERMAT polymer on the formation of metal structure, as well as physical and mechanical properties of hot-deformed vessels was studied. The results of testing the strength and plastic characteristics of vessels by destructive and non-destructive control methods are presented. According to the results of physical and mechanical properties, regression equations were obtained with at least 95% reliability of R2, which establish the relationship between the controlled plastic and strength parameters of the vessel metal`s properties. The conducted researches allowed to compare the indicators of the main physical and mechanical properties of steel vessels at the PPL outlet and to propose methods of inhomogeneity control that reduce time and material costs by 5–10% during the tests.

scholarly journals Fabrication and Characterization of Polylactic Acid Electrospun Scaffolds Modified with Multi-Walled Carbon Nanotubes and Hydroxyapatite Nanoparticles

Biomimetics ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 43
Author(s):  
Athanasios Kotrotsos ◽  
Prokopis Yiallouros ◽  
Vassilis Kostopoulos
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Polylactic Acid ◽  
Physical And Mechanical Properties ◽  
Polymeric Materials ◽  
Cost Effective ◽  
Electrospinning Process ◽  
Wide Range ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The solution electrospinning process (SEP) is a cost-effective technique in which a wide range of polymeric materials can be electrospun. Electrospun materials can also be easily modified during the solution preparation process (prior SEP). Based on this, the aim of the current work is the fabrication and nanomodification of scaffolds using SEP, and the investigation of their porosity and physical and mechanical properties. In this study, polylactic acid (PLA) was selected for scaffold fabrication, and further modified with multi-walled carbon nanotubes (MWCNTs) and hydroxyapatite (HAP) nanoparticles. After fabrication, porosity calculation and physical and mechanical characterization for all scaffold types were conducted. More precisely, the morphology of the fibers (in terms of fiber diameter), the surface properties (in terms of contact angle) and the mechanical properties under the tensile mode of the fabricated scaffolds have been investigated and further compared against pristine PLA scaffolds (without nanofillers). Finally, the scaffold with the optimal properties was proposed as the candidate material for potential future cell culturing.

scholarly journals Prosthodontic Applications of Polymethyl Methacrylate (PMMA): An Update

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2299 ◽  
Author(s):  
Muhammad Sohail Zafar
Keyword(s):  
Mechanical Properties ◽  
Polymethyl Methacrylate ◽  
Physical And Mechanical Properties ◽  
Mechanical Reinforcement ◽  
Occlusal Splints ◽  
Dental Prostheses ◽  
Wide Range ◽  
Dental Applications ◽  
Artificial Teeth ◽  
Orthodontic Retainers

A wide range of polymers are commonly used for various applications in prosthodontics. Polymethyl methacrylate (PMMA) is commonly used for prosthetic dental applications, including the fabrication of artificial teeth, denture bases, dentures, obturators, orthodontic retainers, temporary or provisional crowns, and for the repair of dental prostheses. Additional dental applications of PMMA include occlusal splints, printed or milled casts, dies for treatment planning, and the embedding of tooth specimens for research purposes. The unique properties of PMMA, such as its low density, aesthetics, cost-effectiveness, ease of manipulation, and tailorable physical and mechanical properties, make it a suitable and popular biomaterial for these dental applications. To further improve the properties (thermal properties, water sorption, solubility, impact strength, flexural strength) of PMMA, several chemical modifications and mechanical reinforcement techniques using various types of fibers, nanoparticles, and nanotubes have been reported recently. The present article comprehensively reviews various aspects and properties of PMMA biomaterials, mainly for prosthodontic applications. In addition, recent updates and modifications to enhance the physical and mechanical properties of PMMA are also discussed.

scholarly journals Physical and mechanical properties of the rocks of the Starobinsky deposit forming the Third potash layer and its roof

2021 ◽  
Vol 65 (4) ◽  
pp. 484-494
Author(s):  
A. B. Petrovsky ◽  
V. Ya. Prushak ◽  
E. A. Lutovich
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
Geological Structure ◽  
Mining Operations ◽  
The Third ◽  
Composition And Structure ◽  
Mining Conditions ◽  
The Stability ◽  
Roof Falling ◽  
Main Factor

The geological structure and the physical-mechanical properties of rocks composing and overlapping the Third potash formation in the areas of the mine field mine No. 4 JSC Belaruskali, which are scheduled to practice, are studied. The geological sections of the Third potash layer and its roof were built, the thickness of sylvinite and halite layers was measured, the roof falling of the rocks of the layer with a height of up to 20 m was assessed, and the type of immediate roof was determined by the composition and structure of its constituent rocks. It was established that the strength under uniaxial compression of both sylvinite and halite layers for the areas under consideration differs slightly. Therefore, to solve engineering problems of ensuring the stability of mine workings and to calculate fastening parameters, strength values averaged over the groups of layers can be used that correlate well with the percentage of weak and clay interlayers. The same applies to Poisson’s ratio, the values of which for various layers of formation are slightly different and can be taken by their averaging. It is shown that the main factor that negatively affects the strength of rocks occurring in the roof of the Third potash seam is the presence of weak and clay interlayers, which increases with depth. The introduction of the obtained results allows us to improve the calculation accuracy of securing mining parameters, to reduce the costs of their maintenance, and to improve the safety of mining operations in developing the Third potash formation in complex geological and mining conditions.

MODELING THE STRESS STATE OF THE BACKFILLING MASS WITH DIFFERENT PHYSICAL AND MECHANICAL PROPERTIES

2021 ◽  
pp. 7-18
Author(s):  
Mykhailo Petlovanyi ◽  
◽  
Kateryna Sai ◽  
Keyword(s):  
Mechanical Properties ◽  
Numerical Modeling ◽  
Stress State ◽  
Physical And Mechanical Properties ◽  
Practical Significance ◽  
Mining Operations ◽  
Mining Depth ◽  
Compressive Stresses ◽  
A Value ◽  
Backfilled Stopes

Purpose. Analytical researches of the stress state of the backfilling stopes with different physical and mechanical properties using numerical modeling to determine possible zones of stability losses and predict their failure. Methods. Numerical modeling of the formation of stresses around a high stopes was carried out for the conditions of mining iron ore reserves in the depth intervals of 740-1040 m of the Pivdenno-Bilozerske deposit, where mining operations are actively carried out using the finite element method in the SolidWorks 2016 software package with reliable substantiation of the parameters of the developed geomechanical model. Results. Numerical simulation of the stress state of the backfilling mass are carried out at variable values of the modulus of its elasticity and the mining depth. It was found that with the existing actual physical and mechanical properties of the backfilling mass during the development of the Pivdenno-Bilozerske deposit, the danger of its failure is predicted at depths of more than 890 m. In the center of the filling array, the stress values change linearly, and at the junction of the roof with the side of the backfilled stopes – polynomial. It was found that an increase in the modulus of elasticity of the backfilling mass allows to reduce the compressive stresses only at the junction of the roof with the side of the backfilled stopes to a value of 800 MPa. Scientific novelty. With an increase in the depth of development, despite an increase in the elastic modulus of the fill, the values of stresses increase, which eliminates the need to increase it with a decrease in the mining depth it was found. Practical significance. The results obtained make it possible to correct the technology of formation of a backfilling mass in the primary stopes, taking into account the formation of stresses on its contour and, with an increase in the mining depth, to form a backfilling mass with viscoplastic properties.

scholarly journals Research of dimensional-mass characteristics and physical and mechanical properties of bulbs and heaves of seed onion (Stuttgarter Risen variety) in the period of selection

2020 ◽  
pp. 72-75
Author(s):  
Alexander Gennadievich Aksenov ◽  
Aleksey Viktorovich Sibirev
Keyword(s):  
Mechanical Properties ◽  
Average Distance ◽  
Physical And Mechanical Properties ◽  
Large Change ◽  
Average Value ◽  
Wide Range ◽  
Working Bodies ◽  
Object Of Study ◽  
Range Of Variation ◽  
Left Middle

The aim of the research was to determine the size-mass and physico-mechanical properties of bulbs and heaves of seed onion of the Stuttgart Riesen variety during the selection period. The results of studies of the size-mass characteristics of bulbs and roll onion sets of the Stuttgart Riesen variety from the standpoint of creating the working bodies of machines for its cultivation and harvesting are presented. The results of previous studies of onion sets of other varieties are considered. The technique and equipment used in the research are described. The results of the studies are presented in the form of distribution histograms, the analysis of the studies was carried out by the method of variation statistics. Object of study: bulbs and roll onion sets of the Stuttgart Riesen variety. It is established that the value of the onion set form index lies in the range of 0.,82- 1,10. An analysis of the results shows that more than 90% of the bulbs have a rounded shape, approaching the shape of a sphere, the rest are flat-rounded. The main values of the width of the onion-set roll are in the range 53.,0 65,0 cm, with an average value of 59 cm, in addition, we can conclude that there is no large change in thickness in the cross section of the roll, while the average value of the thickness of the roll (left , middle, right) is within 5.4; 6.7; 5.2 cm with an average value of 6.4 cm. The average distance between the onion set rolls during the selection period is 113.4 cm, the maximum is 121 cm, and the minimum is 111.2 cm. The mass of a heap of 1 running meter of onion set roll characterizes the density of the onion set roll is 12.82 kg. However, the minimum and maximum values of this indicator have a wide range of variation from 12.0 to 15.0 kg.

scholarly journals The Emerging Role of Decellularized Plant-Based Scaffolds as a New Biomaterial

2021 ◽  
Vol 22 (22) ◽  
pp. 12347
Author(s):  
Ashlee F. Harris ◽  
Jerome Lacombe ◽  
Frederic Zenhausern
Keyword(s):  
Mechanical Properties ◽  
Fruits And Vegetables ◽  
Low Cost ◽  
Three Dimensional ◽  
Structural Features ◽  
Cellular Models ◽  
Current State ◽  
Wide Range ◽  
Future Challenges

The decellularization of plant-based biomaterials to generate tissue-engineered substitutes or in vitro cellular models has significantly increased in recent years. These vegetal tissues can be sourced from plant leaves and stems or fruits and vegetables, making them a low-cost, accessible, and sustainable resource from which to generate three-dimensional scaffolds. Each construct is distinct, representing a wide range of architectural and mechanical properties as well as innate vasculature networks. Based on the rapid rise in interest, this review aims to detail the current state of the art and presents the future challenges and perspectives of these unique biomaterials. First, we consider the different existing decellularization techniques, including chemical, detergent-free, enzymatic, and supercritical fluid approaches that are used to generate such scaffolds and examine how these protocols can be selected based on plant cellularity. We next examine strategies for cell seeding onto the plant-derived constructs and the importance of the different functionalization methods used to assist in cell adhesion and promote cell viability. Finally, we discuss how their structural features, such as inherent vasculature, porosity, morphology, and mechanical properties (i.e., stiffness, elasticity, etc.) position plant-based scaffolds as a unique biomaterial and drive their use for specific downstream applications. The main challenges in the field are presented throughout the discussion, and future directions are proposed to help improve the development and use of vegetal constructs in biomedical research.

scholarly journals Effects of pre-mature harvest and heat exposure on physical and mechanical properties of Pandanus tectorius leaves

2017 ◽  
Author(s):  
John A Toman
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Heat Exposure ◽  
Physical And Mechanical Properties ◽  
Maximum Growth ◽  
Mechanical Efficiency ◽  
French Polynesia ◽  
Plant Materials ◽  
Wide Range ◽  
Pandanus Tectorius

Plant materials have long been utilized for human use because of their wide range of physical properties and incredible mechanical efficiency as eco-friendly structures. One example of their use today is the practice of using the sturdy leaves of Pandanus tectorius for thatching purposes. An increase in modern demand for P. tectorius is pressuring farmers to deviate from traditional harvesting methods in an attempt to increase leaf yield. With little knowledge of the repercussions of their new practice, modern farmers are pre-maturely harvesting leaves through heat-induced leaf drying while the leaves remain on the tree. In this study, life-history characteristics, physical and mechanical properties of P. tectorius leaves on Mo’orea, French Polynesia are examined to determine whether or not this deviation from traditional harvest methods reduces leaf efficacy as a thatching material. Quantitative measures of P. tectorius leaves suggest that pre-mature harvest does not alter the size of collected leaves for thatch because most leaves on a tree have already reached maximum growth. Heat-induced leaf drying, however, reduces the tensile strength of P. tectorius leaves by about 25%. Further research may find that this loss in leaf tensile strength may correlate to less robust roofing structures, hindered longevity and ultimately an increase in energy cost to repair and rebuild such structures.

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