Relationship of mechanical properties of crushed stone source rocks to their technological-mechanical performance

2020 ◽  
Author(s):  
Richard Prikryl
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Physical Property ◽  
Evaluation Process ◽  
Source Rocks ◽  
Crushed Stone ◽  
Strength Data ◽  
Fundamental Physical Property ◽  
Relationship Of ◽  
Selection Of

<p>Decision on suitability of rocks for production of crushed stone and their use in specific constructional activities relies on series of empirically-designed tests which partly simulate certain degradation forces acting during the service of aggregates. Tests for integrity of crushed stone particles subjected to mechanical forces employ several approaches simulating abrasion, attrition, and/or crushing; these can thus be generally designated as technological-mechanical performance (TMP) tests. Design of these tests has nothing to do with testing of mechanical properties viewed as fundamental physical property. However, numerous authors attempted to correlate certain mechanical properties (specifically uniaxial compressive strength data) with TMP of crushed stone source rocks. Unfortunately, relatively low correlation has been generally achieved.</p><p>In the recent study, this approach is re-examined by using not only ultimate strength data, but also knowledge on deformational process and on its energetic parameters. The results of laboratory experiments show, that some of the obtained data exhibit much tighter correlation; however, one has be very careful in selection of proper parameters. Thorough understanding of damage mechanisms of crushed stone particles (i.e. mechanisms of their wear and breakage during service life) makes critical part of this evaluation process.</p>

Degree of size reduction of selected crushed-stone source rocks and its relationship to technological-mechanical performance parameters

2020 ◽  
Author(s):  
Kateřina Krutilová ◽  
Richard Přikryl
Keyword(s):  
Particle Size ◽  
Czech Republic ◽  
Los Angeles ◽  
Mechanical Performance ◽  
Size Reduction ◽  
Reduction Ratio ◽  
Source Rocks ◽  
Crushed Stone ◽  
Performance Parameters ◽  
Particle Size Reduction

<p>Degree of size reduction of selected crushed-stone source rocks and its relationship to technological-mechanical performance parameters</p><p> </p><p>Kateřina Krutilová (1), Richard Přikryl (2)</p><p> </p><p>(1) Stone testing laboratory Ltd., Hořice v Podkrkonoší, Czech Republic</p><p>(2) Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, 128 43, Prague 2, Czech Republic</p><p> </p><p>Particle size reduction (PSR) is one of the principal processing methods employed in extractive industry including production of crushed stone aggregates. The purpose of particle size reduction is production of certain size fractions which are directly applicable for final uses or necessary for further industrial activities. On industrial scale, crushing of rocks for crushed stone production is commonly performed in 2-3 successive steps (stages). The conditions of crushing in these individual steps is selected in order to reach lower reduction ratio, thus facilitating production of particles with favourable geometry. Conditions of crushing are influenced by numerous factors, of which only part was thoroughly investigated. In the recent study, we attempt to correlate knowledge on PSR behaviour of various petrographic types with other technological-mechanical performance parameters (e.g. Los Angeles attrition value, Nordic abrasion test, aggregate crushing value) and/or physical / mechanical properties of aggregate source rocks (specifically volcanic rocks of variable composition, ages, and properties). PSR behaviour obtained by experimental laboratory crushing (one-step process) is reported as degree of size reduction and reduction ratio. </p>

scholarly journals Effect of Al2O3–SiO2 Addition on Gehlenite Growth and the Mechanical Performance of Steel Slag

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 936
Author(s):  
Ying Xu ◽  
Pan Song ◽  
Weigang Cao ◽  
Hui Li ◽  
Jinglong Liang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Mechanical Performance ◽  
Steel Slag ◽  
Phase Changes ◽  
Morphology Evolution ◽  
Industrial Solid Waste ◽  
Increasing Temperature ◽  
Relationship Of ◽  
The Relationship

Steel slag, as industrial solid waste, is difficult to recycle owing to its complex components and poor mechanical properties. However, steel slag can be modified by adding Al2O3–SiO2 through high temperature sintering, which would improve the mechanical properties and expand the scope of its application. The phase changing, morphology evolution and the mechanical properties of the modified steel slag were investigated. The results indicate that the main phase changes to gehlenite occur with increasing temperature. The compressive strength increases to 115 MPa at 1350 °C. The relationship of the quantity of gehlenite and the compressive strength were explored.

scholarly journals Kenaf Composites for Automotive Components: Enhancement in Machinability and Moldability

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1707 ◽  
Author(s):  
Nabilah Afiqah Mohd Radzuan ◽  
Nur Farhani Ismail ◽  
Mohd Khairul Fadzly Md Radzi ◽  
Zakaria Bin Razak ◽  
Izdihar Binti Tharizi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
High Tensile Strength ◽  
Compression Moulding ◽  
Moulding Process ◽  
Automotive Components ◽  
Polymer Resin ◽  
Kenaf Fibre ◽  
Kenaf Composites ◽  
Selection Of

To date, the mechanical performance of kenaf composites is still unsatisfied in term of its mechanical performance. Therefore, research focuses on kenaf composites fabrication through the selection of polymer resin, including epoxy, polypropylene, and polylactic acid. The incorporated kenaf fibre at 10 wt % to 40 wt % loadings was conducted using injection and a compression moulding process. The compressed materials indicated high tensile strength at 240 MPa compared to inject materials (60 MPa). Significant improvement on impact strength (9 kJ/m2) was due to the unpulled-out fibre that dispersed homogenously and hence minimize the microcrack acquire. Meanwhile, high flexural strength (180 MPa) obtained by kenaf/epoxy composites due to the fibre orientate perpendicular to the loading directions, which improve its mechanical properties. The findings indicate that the kenaf fibre reinforced thermoset materials exhibit better mechanical properties as a function to the battery tray applications.

Цифровая морфометрия разнокачественности семян овощных культур

2018 ◽  
Author(s):  
F.B. Musaev ◽  
N.S. Priyatkin ◽  
M.V. Arkhipov ◽  
P.A. Shchukina ◽  
A.F. Bukharov ◽  
...  
Keyword(s):  
Seed Quality ◽  
Image Analysis System ◽  
Flatbed Scanner ◽  
The Future ◽  
Scanned Images ◽  
Computer Morphometry ◽  
Analysis System ◽  
Matrix Heterogeneity ◽  
Relationship Of ◽  
Selection Of

Приведено описание разработанной авторами методики цифровой компьютерной морфометрии семян овощных культур на основе системы анализа изображений, состоящей из планшетного сканера и программного обеспечения для автоматических измерений. В основу метода положено представление о разнокачественности семян, обусловленной генетической неоднородностью самих семенных растений, используемых в промышленном семеноводстве. Физические свойства семян (их форма и линейные размеры) – основные параметры при определении их качества. Цифровые изображения семян получены при помощи планшетного сканера HP Sсanjet 200 на базе Агрофизического НИИ с использованием серийного программного обеспечения «Argus-BIO», производства ООО «АргусСофт» (г. Санкт-Петербург). Метод состоит из подбора контрастной подложки (фона) для сканирования семян с минимальными теневыми эффектами, калибровку программного обеспечения для привязки к истинным размерным величинам, подбор параметров измерений и автоматическое распознавание цифровых сканированных изображений семян. Представлены экспериментальные данные по морфометрии экологически разнокачественных семян фасоли овощной, матрикально разнокачественных семян укропа, пастернака и лука Кристофа. Семена укропа и пастернака, собранные из разных порядков ветвления семенного растения, значительно различались по величине линейных параметров. Наиболее показательный линейный параметр семян – площадь проекции. Предложенная авторами методика цифровой морфометрии, уже использована на практике и в перспективе может быть задействована в исследованиях экологической и матрикальной разнокачественности семян овощных культур. Так, она прошла апробацию на разнокачественных семенах пяти сортов фасоли овощной (Настена, Магура, Миробела, Морена, Бажена) полученных в пяти контрастных эколого-географических условиях среды (Москва, Белгород, Ставрополь, Омск, Горки) в 2011–2012 годах. В дальнейшем методика может быть использована для улучшения качества цифровых изображений семян, изучения разнокачественности семян в том числе и для совершенствования контроля за селекционным процессом. Кроме того, она применима для изучения взаимосвязи совокупности морфометрических характеристик семян и их посевных качеств.The description of the method of digital computer morphometry of vegetable seeds developed by the authors on the basis of the image analysis system consisting of a flatbed scanner and software for automatic measurements is given. The method is based on the idea of seed quality, due to the genetic heterogeneity of the seed plants used in industrial seed production. Physical properties of seeds (their shape and linear dimensions) are the main parameters in determining their quality. Digital image of the seed obtained using the flatbed scanner, HP Sсanjet 200 on the basis of the Agrophysical research Institute with serial software “Argus-BIO”, produced by LLC “Argussoft” (Saint-Petersburg). The method consists of selection of a contrast substrate (background) for scanning seeds with minimal shadow effects, calibration of software for binding to true size values, selection of measurement parameters and automatic recognition of digital scanned images of seeds. Experimental data on the morphometry of ecologically different-quality seeds of vegetable beans, matrix seeds of dill, Pasternak and Christoph onion are presented. Seeds of dill and parsnip, collected from different orders of branching of the seed plant, significantly differed in size of linear parameters. The most revealing linear parameter seed – area projection. The method of digital morphometry proposed by the authors has already been used in practice and in the future can be used in studies of ecological and matrix heterogeneity of vegetable seeds. So, it was tested on different quality seeds of five varieties of vegetable beans (Nastena, Magura, Mirobelа, Morena, Bazhenf) obtained in five contrasting environmental and geographical conditions (Moscow, Belgorod, Stavropol, Omsk, Gorki) in 2011-2012. In the future, the technique can be used to improve the quality of digital images of seeds, study of seed diversity, including to improve the control of the breeding process. In addition, it is applicable to study the relationship of the set of morphometric characteristics of seeds and their sowing qualities.

The Challenge of Evaluating Virtual Communities of Practice: A Systematic Mapping Study

10.28945/4505 ◽  
2020 ◽  
Vol 15 ◽  
pp. 039-064
Author(s):  
Rogerio Ferreira da Silva ◽  
Itana Maria de Souza Gimenes ◽  
José Carlos Maldonado
Keyword(s):  
Communities Of Practice ◽  
Virtual Communities ◽  
Evaluation Process ◽  
Evaluation Methods ◽  
Systematic Mapping Study ◽  
Research Gaps ◽  
Systematic Mapping ◽  
Research Questions ◽  
Virtual Communities Of Practice ◽  
Selection Of

Aim/Purpose: This paper presents a study of Virtual Communities of Practice (VCoP) evaluation methods that aims to identify their current status and impact on knowledge sharing. The purposes of the study are as follows: (i) to identify trends and research gaps in VCoP evaluation methods; and, (ii) to assist researchers to position new research activities in this domain. Background: VCoP have become a popular knowledge sharing mechanism for both individuals and organizations. Their evaluation process is complex; however, it is recognized as an essential means to provide evidences of community effectiveness. Moreover, VCoP have introduced additional features to face to face Communities of Practice (CoP) that need to be taken into account in evaluation processes, such as geographical dispersion. The fact that VCoP rely on Information and Communication Technologies (ICT) to execute their practices as well as storing artifacts virtually makes more consistent data analysis possible; thus, the evaluation process can apply automatic data gathering and analysis. Methodology: A systematic mapping study, based on five research questions, was carried out in order to analyze existing studies about VCoP evaluation methods and frameworks. The mapping included searching five research databases resulting in the selection of 1,417 papers over which a formal analysis process was applied. This process led to the preliminary selection of 39 primary studies for complete reading. After reading them, we select 28 relevant primary studies from which data was extracted and synthesized to answer the proposed research questions. Contribution: The authors of the primary studies analyzed along this systematic mapping propose a set of methods and strategies for evaluating VCoP, such as frameworks, processes and maturity models. Our main contribution is the identification of some research gaps present in the body of studies, in order to stimulate projects that can improve VCoP evaluation methods and support its important role in social learning. Findings: The systematic mapping led to the conclusion that most of the approaches for VCoP evaluation do not consider the combination of data structured and unstructured metrics. In addition, there is a lack of guidelines to support community operators’ actions based on evaluation metrics.

Weldability - Behavior of Welded Reinforcement

2019 ◽  
Vol 70 (10) ◽  
pp. 3469-3472
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Mechanical Characteristics ◽  
Mechanical Performance ◽  
Current Work ◽  
Carbon Equivalent ◽  
Work Process ◽  
Ultimate Limit

Weldability involves two aspects: welding behavior of components and safety in operation. The two aspects will be reduced to the mechanical characteristics of the elements and to the chemical composition. In the case of steel reinforcing rebar’s, it is reduces to the percentage of Cech(carbon equivalent) and to the mechanical characteristics: the yielding limit, the ultimate limit, and the elongations which after that represent the ductility class in which the re-bars is framed. The paper will present some types of steel reinforcing rebar’s with its mechanical characteristics and the welding behavior of those elements. In the current work, process-related behavior of welded reinforcement, joint local and global mechanical properties, and their correlation with behavior of normal reinforcement and also the mechanical performance resulted in this type of joints. Keywords: welding behavior, ultimate limit, reinforcing rebar’s

Elaboration and Characterization of the Properties of Refractory Cr Base Alloys

2010 ◽  
Vol 72 ◽  
pp. 46-52 ◽  
Author(s):  
Laurent Royer ◽  
Stéphane Mathieu ◽  
Christophe Liebaut ◽  
Pierre Steinmetz
Keyword(s):  
Mechanical Properties ◽  
Melting Point ◽  
Molten Glass ◽  
Energy Production ◽  
Creep Properties ◽  
Refractory Alloys ◽  
Industrial Use ◽  
Kinetics Of ◽  
Selection Of

For energy production and also for the glass industry, finding new refractory alloys which could permit to increase the process temperatures to 1200°C or more is a permanent challenge. Chromium base alloys can be good candidates, considering the melting point of Cr itself, and also its low corrosion rate in molten glass. Two families of alloys have been studied for this purpose, Cr-Mo-W and Cr-Ta-X alloys (X= Mo, Si..). A finer selection of compositions has been done, to optimize their chemical and mechanical properties. Kinetics of HT oxidation by air, of corrosion by molten glass and also creep properties of several alloys have been measured up to 1250°C. The results obtained with the best alloys (Cr-Ta base) give positive indications as regards the possibility of their industrial use.

scholarly journals Preparation of Long Sisal Fiber-Reinforced Polylactic Acid Biocomposites with Highly Improved Mechanical Performance

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1124
Author(s):  
Zhifang Liang ◽  
Hongwu Wu ◽  
Ruipu Liu ◽  
Caiquan Wu
Keyword(s):  
Mechanical Properties ◽  
Polylactic Acid ◽  
Mechanical Performance ◽  
Tensile Elongation ◽  
Sisal Fiber ◽  
Fiber Reinforced ◽  
Impact Performance ◽  
The Matrix ◽  
Blending Process ◽  
Extension Direction

Green biodegradable plastics have come into focus as an alternative to restricted plastic products. In this paper, continuous long sisal fiber (SF)/polylactic acid (PLA) premixes were prepared by an extrusion-rolling blending process, and then unidirectional continuous long sisal fiber-reinforced PLA composites (LSFCs) were prepared by compression molding to explore the effect of long fiber on the mechanical properties of sisal fiber-reinforced composites. As a comparison, random short sisal fiber-reinforced PLA composites (SSFCs) were prepared by open milling and molding. The experimental results show that continuous long sisal fiber/PLA premixes could be successfully obtained from this pre-blending process. It was found that the presence of long sisal fibers could greatly improve the tensile strength of LSFC material along the fiber extension direction and slightly increase its tensile elongation. Continuous long fibers in LSFCs could greatly participate in supporting the load applied to the composite material. However, when comparing the mechanical properties of the two composite materials, the poor compatibility between the fiber and the matrix made fiber’s reinforcement effect not well reflected in SSFCs. Similarly, the flexural performance and impact performance of LSFCs had been improved considerably versus SSFCs.

scholarly journals Tribological and Mechanical Properties of Multicomponent CrVTiNbZr(N) Coatings

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 41
Author(s):  
Yin-Yu Chang ◽  
Cheng-Hsi Chung
Keyword(s):  
Mechanical Properties ◽  
Nitrogen Content ◽  
Adhesion Strength ◽  
Mechanical Performance ◽  
Bulk Material ◽  
High Entropy Alloy ◽  
Composition Gradient ◽  
Multilayered Structures ◽  
High Entropy ◽  
Alloy Target

Multi-element material coating systems have received much attention for improving the mechanical performance in industry. However, they are still focused on ternary systems and seldom beyond quaternary ones. High entropy alloy (HEA) bulk material and thin films are systems that are each comprised of at least five principal metal elements in equally matched proportions, and some of them are found possessing much higher strength than traditional alloys. In this study, CrVTiNbZr high entropy alloy and nitrogen contained CrVTiNbZr(N) nitride coatings were synthesized using high ionization cathodic-arc deposition. A chromium-vanadium alloy target, a titanium-niobium alloy target and a pure zirconium target were used for the deposition. By controlling the nitrogen content and cathode current, the CrNbTiVZr(N) coating with gradient or multilayered composition control possessed different microstructures and mechanical properties. The effect of the nitrogen content on the chemical composition, microstructure and mechanical properties of the CrVTiNbZr(N) coatings was investigated. Compact columnar microstructure was obtained for the synthesized CrVTiNbZr(N) coatings. The CrVTiNbZrN coating (HEAN-N165), which was deposited with nitrogen flow rate of 165 standard cubic centimeters per minute (sccm), exhibited slightly blurred columnar and multilayered structures containing CrVN, TiNbN and ZrN. The design of multilayered CrVTiNbZrN coatings showed good adhesion strength. Improvement of adhesion strength was obtained with composition-gradient interlayers. The CrVTiNbZrN coating with nitrogen content higher than 50 at.% possessed the highest hardness (25.2 GPa) and the resistance to plastic deformation H3/E*2 (0.2 GPa) value, and therefore the lowest wear rate was obtained because of high abrasion wear resistance.

Experimental investigation of the mechanical behavior of glass fiber/high fluidity polyamide-based composites for automotive market

2021 ◽  
pp. 073168442110140
Author(s):  
Hossein Ramezani-Dana ◽  
Moussa Gomina ◽  
Joël Bréard ◽  
Gilles Orange
Keyword(s):  
Mechanical Properties ◽  
Glass Fiber ◽  
Mechanical Performance ◽  
Physical And Mechanical Properties ◽  
Ultimate Strain ◽  
Uniaxial Tensile ◽  
Compression Tests ◽  
Automotive Market ◽  
Glass Fiber Reinforced ◽  
Glass Fiber Reinforcement

In this work, we examine the relationships between the microstructure and the mechanical properties of glass fiber–reinforced polyamide 6,6 composite materials ( V f = 54%). These materials made by thermocompression incorporate different grades of high fluidity polyamide-based polymers and two types of quasi-UD glass fiber reinforcement. One is a classic commercial fabric, while the other specially designed and manufactured incorporates weaker tex glass yarns (the spacer) to increase the planar permeability of the preform. The effects of the viscosity of the polymers and their composition on the wettability of the reinforcements were analyzed by scanning electron microscopy observations of the microstructure. The respective influences of the polymers and the spacer on the mechanical performance were determined by uniaxial tensile and compression tests in the directions parallel and transverse to the warp yarns. Not only does the spacer enhance permeability but it also improves physical and mechanical properties: tensile longitudinal Young’s modulus increased from 38.2 GPa to 42.9 GPa (13% growth), tensile strength increased from 618.9 MPa to 697 MPa (3% growth), and decrease in ultimate strain from 1.8% to 1.7% (5% reduction). The correlation of these results with the damage observed post mortem confirms those acquired from analyses of the microstructure of composites and the rheological behaviors of polymers.

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