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1
Optymalizacja procesu wywozu węgla poprzez przebudowę urządzeń sterowania ruchem kolejowym – studium przypadku
Łukaszczyk Zygmunt, Granieczny Przemysław
Rynek Energii
|
2023
|
Nr 4
52--57
PL
Przebudowa urządzeń sterowania ruchem kolejowym doprowadziła do optymalizacji procesu wywozu węgla poprzez ograniczenie ilości błędów generowanych przez pracowników. Nastąpiła znaczna poprawa bezpieczeństwa oraz zmniejszenie kosztów prowadzenia ruchu oraz utrzymania infrastruktury kolejowej. Zmiana urządzeń sterowania ruchem kolejowym z przekaźnikowych na komputerowe przyczyniła się do kontroli nad stanem urządzeń srk, stanami awaryjnymi poprzez pozyskiwanie informacji w stanie rzeczywistym. System umożliwia wprowadzanie poleceń do systemu i równocześnie kontroluje czy owe polecenia są prawidłowe pod względem formalnym.
EN
The reconstruction of the railway traffic control devices led to the optimization of the coal removal process by reducing the number of errors generated by employees. There has been a considerable improvement in safety and a reducing the costs of traffic management and maintenance of railway infrastructure. The change of railway traffic control devices from relay to computer ones contributed toward improving control over the status of railway traffic devices and emergency states by obtaining information in the real state. The system enables the entering commands into the system and controls whether these commands are formally correct at the same time.
2
Content available remote Effect of silane coating surface treatment on friction and wear properties of carbon fiber/PI composites
Liu Yang, Li Bin, He Yichuan, Dong Yuncheng, Wang Shiguo
Materials Science Poland
|
2022
|
Vol. 40, No. 2
214--222
EN
PAN-based carbon fiber was surface-modified with silane coating, and a composite material was prepared using a PI resin as a matrix. The structure and surface properties of carbon fibers were studied by means of X-ray photoelectron spectroscopy (XPS) and SEM. The tensile strength of the composite was measured by a tensile tester, and the friction properties of the composite were measured by a micro-nano mechanics comprehensive test system. The results show that treatment with silane coating can improve the surface roughness and chemical activity of carbon fiber, improve the interface between carbon fiber and PI resin matrix, and improve the tensile strength and wear rate of the composite.
3
Content available Influence of Carbon Particle in Polymer Matrix Composite over Mechanical Properties and Tribology Behavior
Sravanthi K., Mahesh V., Nageswara Rao Boggarapu
Archives of Metallurgy and Materials
|
2021
|
Vol. 66, iss. 4
1171--1178
EN
In this research, the carbon particle dispersions are made in two different levels as carbon nano tube (CNT) and carbon particle in microns range. The mechanical strength is evaluated for the composites developed by axial loading and bending test analysis. In addition, the air jet abrasive particle erosion study is performed for different angle of impingement. The dispersion of carbon particle in the matrix material has reduced the mechanical strength. The sample with 4% of CNT dispersion in the composite has a maximum strength of 143 MPa and a minimum strength of 112 MPa. For the same combination (4% of CNT composite), the maximum flexural strength is 116 MPa. It is clear to infer that the strength of CNT in matrix materials is superior to the increase in length of carbon particle. The dispersion of carbon particle in the matrix material increases the brittleness and the strength is diminished. During the flexural bending, the fiber delamination occurred with severe deformation in the plain composite. When the materials are subjected to impingement of solid particle, the attrition effect on the exposed surfaces is vulnerable towards erosive mechanism. The presence of carbon in the matrix material has significantly increased the surface property. The results are appreciable for 4% of CNT composite. Especially at 30º, the minimum erosive wear 0.0033 g/g has been recorded. Erosive wear is less at minimum impingement angle and the wear is found increasing at higher impingement angle. Therefore, it is recommended not to add carbon particle to a higher weight percentage, since it leads to brittleness.
4
Content available remote Sensitivity of composite structure with directional properties of annular three-layered plate mechanically and thermally loaded
Pawlus D.
Mechanics and Mechanical Engineering
|
2018
|
Vol. 22, nr 3
691--702
EN
Paper presents the sensitivity of the three-layered plate structure on the acting of mechanical and thermal loads. The cases of the annular plates, whose individual layers: facings and core have homogeneous building and/or heterogeneous one expressed by the variable material properties in radial direction have been examined. Numerical investigations have been carried out modelling the select examples of plate structure with the use of the finite element method. Plate is loaded in the plane of facings or is subjected to the flat temperature field. The evaluation of the structure sensitivity has been carried out analysing the values of critical loads or critical temperatures and corresponding with them buckling modes. Numerous results presented in diagrams create the image of plate behaviours, show responses of plate structure and indicate on the means of structure designs, which can fulfil the expected conditions of plate work.
5
Content available remote The Tensile Strength of Hot-Dip Galvanized HC260LA and DD11 Steels
Jastrzębski M., Misztela A., Gołoś K.
Machine Dynamics Research
|
2017
|
Vol. 41, No. 2
109--118
EN
The study aims to examine the impact of hot-dip galvanizing technology on mechanical properties (Re - yield strength, Rm - ultimate tensile strength and percent elongation - A) of carbon steels HC260LA and DD11 (StW22). These steels are commonly used to manufacture components of building scaffoldings, guardrails, pipes etc. Obtained results showed the effect of galvanization parameters on mechanical properties. The yield stress (Re) increased by 24.49% for HC260LA and by 9.98% for DD11 (StW22). The decrease of the ultimate tensile strength (Rm) was: 2.07%, and 0.29% respectively. Moreover, the average percent elongation (A) dropped comparing to ungalvanized samples for HC260LA steel by 19.96%, and increased for DD11 (StW22) steel by 4.59%. This may be important information for many constructional applications.
6
Content available remote Powierzchniowe umocnienie brązu aluminiowego poprzez obróbkę cieplną
Lipiński T.
Mechanik
|
2015
|
R. 88 nr 4CD
38--42
PL
Badania przeprowadzono na brązie aluminiowym stosowanym na silnie obciążone części maszyn i aparatury narażone na korozję i ścieranie oraz porównawczo na miedzi. Obróbkę powierzchniową prowadzono wykorzystując skupione źródło ciepła. Zastosowano hel, jako gaz osłonowy. Analizowano mikrostrukturę, parametry geometryczne ściegu, rozkład mikrotwardości. Stosowano parametry pozwalające na uzyskanie przetopu lub przetopu z nadmiarem energii pozwalającej na odparowanie metalu.
EN
The study was conducted on aluminum bronze used for highly stressed parts of machinery and equipment subject to corrosion and abrasion wear and cooper for comparison. The surface treatment is carried out using a concentrated heat source. Helium was used as the shielding gas. The microstructure, the parameters geometric stitching, the distribution of microhardness were analyzed. The parameters for penetration or penetration with an excess of energy allowing for evaporation of the metal were used.
7
Content available remote The influence of the distribution of nonmetalic inclusion on the fatigue strength coefficient of high purity steels
Lipiński T.
Journal of Achievements in Materials and Manufacturing Engineering
|
2015
|
Vol. 69, nr 1
18--25
EN
Purpose: In this study, attempts were made to analyze the impact of impurities with various diameters and spacing between non-metalic inclusion λ on fatigue strength coefficient k determined under rotary bending fatigue conditions zgo of high purity steels produced in an industrial plant. Design/methodology/approach: The study was performed on 21 heats produced in an industrial plant. Fourteen heats were produced in 140 ton electric furnaces, and 7 heats were performed in a 100 ton oxygen converter. The experimental variants were compared in view of the applied melting technology and heat treatment options. The results were presented to account for the correlations between the fatigue strength coefficient during rotary bending, the diameter of and spacing between submicroscopic impurities. Findings: Equations for calculating the fatigue strength coefficient at each tempering temperature and a general equation for all tempering temperatures were proposed. Equations for estimating the fatigue strength coefficient based on the relative volume of submicroscopic non-metallic inclusions were also presented. The relationship between the fatigue strength and hardness of high-grade steel vs. the quotient of the diameter of impurities and the spacing between impurities, and the fatigue strength and hardness of steel vs. the relative volume of non-metallic impurities were determined. Practical implications: The proposed linear regression equations supported the determination of fatigue strength coefficient k and bending fatigue strength as a function of hardness taking into account impurities. Originality/value: The proposed equations contributes to the existing knowledge base of practices impact of impurities with various diameters and spacing between non-metalic inclusion on fatigue strength.
8
Content available Comparison of Properties of Polymer Composite Materials Reinforced with Carbon Nanotubes
Zygoń P., Gwoździk M., Peszke J., Nitkiewicz Z.
Archives of Metallurgy and Materials
|
2015
|
Vol. 60, iss. 1
193--198
EN
Carbon nanotubes because of their high mechanical, optical or electrical properties, have found use as semiconducting materials constituting the reinforcing phase in composite materials. The paper presents the results of the studies on the mechanical properties of polymer composites reinforced with carbon nanotubes (CNT). Three-point bending tests were carried out on the composites. The density of each obtained composite was determined as well as the surface roughness and the resistivity at room temperature. Moreover the surface studies on an atomic forces microscope (AFM) and X-ray studies (phase composition analysis, crystallite sizes determination) were carried out on such composites. Measurements of the surface topography using the Tapping Mode method were performed, acquiring the data on the height and on the phase imaging. The change of intensity, of crystallite size and of half-value width of main reflections originating from carbon for composites have been determined using the X-ray analysis. Carbon nanotubes constituting the reinforcement for a polymer composite improve the mechanical properties and con-ductivity of the composite.
PL
Nanorurki węglowe ze względu na wysokie właściwości mechaniczne, optyczne czy elektryczne znalazły zastosowanie jako faza wzmacniająca materiałów kompozytowych. W pracy przedstawiono wyniki badań właściwości mechanicznych kompozytów polimerowych wzmacnianych nanorurkami węglowymi (CNT). Na kompozytach została przeprowadzona próba trójpunktowego zginania. Określono gęstość każdego z otrzymanych kompozytów, wyznaczono chropowatość powierzchni na profilometrze oraz rezystywność w temperaturze pokojowej. Dla każdego z kompozytów przeprowadzono również badania powierzchni na mikroskopie sił atomowych (AFM), badania rentgenograficzne (analiza składu fazowego, określenie wielkości krystalitów). Przeprowadzono pomiary topografii powierzchni metodą Tapping Mode zbierając dane z wysokości i obrazowania fazowego. Za pomocą analizy rentgenograficznej określono zmianę intensywności, wielkości krystalitów oraz szerokości połówkowej refleksów głównych pochodzących od węgla dla nanorurek różnie modyfikowanych. Nanorurki węglowe stanowiące zbrojenie dla kompozytów polimerowych poprawiają właściwości mechaniczne oraz przewodność kompozytu.
9
Content available remote Cybernetyczny model strat mechanicznych silnika spalinowego
Wrona Jan, Wrona Rafał
Zeszyty Naukowe WSEI. Seria Transport i Informatyka
|
2013
|
T. 3, nr 1
59--66
PL
W opracowaniu sformułowano matematyczny model oporów mechanicznych tłokowego silnika spalinowego, który uwzględnia parametry konstrukcyjne i eksploatacyjne silnika wraz z osprzętem. Wstępna weryfikacja opracowanego modelu wskazuje na poprawność przyjętych zależności, zaś uzyskane wyniki zachęcają do analizy strat mechanicznych zwłaszcza w zakresie częściowych obciążeń silnika i sugerują możliwość poprawy sprawności ogólnej silnika spalinowego poprzez zmniejszenie oporów mechanicznych.
EN
The paper presents effects of the exploitation I. C. engine wear on its internal mechanical losses balance. The influence of geometric modifications in the frictional associations as well as assembly plays of the chosen kinematic pairs which strongly affect mechanical losses was analyzed. Specific elements of the losses and total values were shown as functions of the variable parameters. Results complemented by some experimental data create useful background for designers and users of the I. C. engines.
10
Content available remote Skeleton castings dynamic load resistance
Cholewa M., Szajnar J., Szuter T.
Journal of Achievements in Materials and Manufacturing Engineering
|
2013
|
Vol. 58, nr 2
94--98
EN
Purpose: The article is to show selected results of research in a field of new type of cast spatial composite reinforcements. This article shows skeleton casting case as a particular approach to continuous, spatial composite reinforcement. Design/methodology/approach: The research is concerning properties of cast spatial microlattice structures called skeleton castings. In this paper results of impact test of skeleton casting with octahedron elementary cell were shown. The selection of internal topology of skeleton casting was based on numerical simulations of stress distribution. Findings: The possibility of manufacturing of geometrically complex skeleton castings without use of advanced techniques was confirmed. Research limitations/implications: With use of computer tomography, analysis of deformation mechanisms was carried out. Different levels of impact energies were used. Practical implications: Spatial skeleton casting with octahedron elementary cell confirmed their usefulness as impact energy absorbers. Originality/value: The overall aim of presented research was to determine the mechanisms of skeleton castings deformation processes. Thanks to CT data next step will be to create accurate numerical model for further simulation and design optimization.
11
Content available Effect of synergic controlled pulsed and manual gas metal ARC welding processes on mechanical and metallurgical properties of AISI 430 ferritic stainless steel
Teker T
Archives of Metallurgy and Materials
|
2013
|
Vol. 58, iss. 4
1029--1035
EN
The gas metal arc is widely used in manufacturing industries because of the high metal deposition rate and ease of automation with better weld quality at permissible cost than other welding processes in joining similar and dissimilar metals. AISI 430 steel is normally difficult to weld by melting methods, due to the associated problems such as grain growth. For this purpose, AISI 430 ferritic stainless steel couples of 10 mm thick were welded by the synergic controlled pulsed (GMAW-P) and manual gas metal arc (GMAW) welding techniques. The interface appearances of the welded specimens were examined by scanning electron microscopy (SEM). Structural changes in the weld zone were analysed by energy dispersive spectrometry (EDS) and X-ray diffraction (X-RD). Microhardness, notch charpy and tensile tests were conducted to determine the mechanical properties of specimens. Accordingly, the best result was obtained from the GMAW-P technique.
PL
Spawanie elektrodą topliwą w osłonie gazów aktywnych jest szeroko stosowane w przemyśle wytwórczym, ze względu na wysokie tempo osadzania metalu i łatwość automatyzacji oraz lepszą jakości spoiny przy dopuszczalnych kosztach niż w wypadku innych procesów spawania podobnych i różnych metali. Stal AISI 430 jest trudna do spawania metodami nadtapiania (z elektrodą nietopliwą), ze względu na związane z nimi problemy takie jak wzrost ziarna. Elementy ze stali ferrytycznej AISI 430 o grubości 10 mm zostały zespawane techniką GMAW-P i GMAW. Do badania morfologii spawanych próbek wykorzystano metodę skaningowej mikroskopii elektronowej (SEM). Zmiany strukturalne w strefie spoiny analizowano metodą spektrometrii z dyspersją energii (EDS) i dyfrakcji rentgenowskiej (X-RD). Pomiary mikrotwardości, udamości i próby rozciągania przeprowadzono w celu określenia właściwości mechanicznych próbek. Stwierdzono, że najlepszy wynik uzyskano dla spoin wytworzonych techniką GMAW-P.
12
Content available remote Investigations of nanocrystalline and gradient coatings produced by cathodic arc evaporation technology
Lukaszkowicz K.
Journal of Achievements in Materials and Manufacturing Engineering
|
2012
|
Vol. 52, nr 2
75--82
EN
Purpose: The main aim of the this research was the investigation of the microstructure, corrosion resistance and the mechanical properties of the nanocrystalline TiAlSiN, CrAlSiN, AlTiCrN and the gradient TiAlN, TiCN, AlSiCrN coatings deposited by cathodic arc evaporation technology onto the X40CrMoV5-1 hot work tool steel substrate. Design/methodology/approach: The surfaces’ topography and the microstructure of the investigated coatings were observed on the scanning electron microscopy. Diffraction and thin film structure were tested with the use of the transmission electron microscopy. The microhardness tests were made on the dynamic ultra-microhardness tester. Tests of the coatings’ adhesion to the substrate material were made using the scratch test. Findings: It was found that the microstructure of the nanocrystalline coatings consisted of fine crystallites, while their average size fitted within the range of 11-25 nm, depending on the coating type. The critical load LC2 lies within the range of 46-54 N. In case of the gradient coatings it was found that the microstructure consisted of crystallites while their average size fitted within the range of 25-50 nm, depending on the coating type. The coatings demonstrated columnar structure as well as good adhesion to the substrate. The critical load LC2 lies within the range 46-59 N. The coatings demonstrate a high hardness (40 GPa) and corrosion resistance. Practical implications: In order to evaluate with more detail the possibility of applying these surface layers in tools, further investigations should be concentrated on the determination of the thermal fatigue resistance of the coatings. The very good mechanical properties of the nanocrystalline and gradient coatings make them suitable in industrial applications. Originality/value: The investigation results will provide useful information to applying the nanocrystalline and gradient coatings for the improvement of mechanical properties of the hot work tool steels.
13
Content available Studies of properties of polypropylene/halloysite composites
Szczygielska A., Kijeński J.
Polish Journal of Chemical Technology
|
2011
|
Vol. 13, nr 3
61-65
EN
The results of the studies on the synthesis, mechanical and thermal properties of polypropylene composites with various amount of halloysite filler are presented. Halloysite (HNT) belongs to the silica type characterized by a two-layer 1:1 structure. This work was aimed to develop a method for the modification of halloysite in its prime use as a filler for polypropylene by extrusion. The composites contain 1, 3, 5 and 7 wt.% of HNT. The degree of crystallinity of the composites decrease with increasing halloysite content. The results confirm the expectations that composites of interesting physicochemical, mechanical and thermal properties can be obtained. The mechanical properties studied show that the filler modification method used leads to the synthesis of polymer composites of improved thermal and mechanical properties.
14
Analiza eksperymentalna zachowań pokrytycznych na przykładzie ściskanych kolumn metalowych
Imiełowski S., Ajdukiewicz C., Glinicka A.
Logistyka
|
2011
|
nr 3
PL
Przedmiotem opracowania jest analiza eksperymentalna zachowania się ściskanych słupów w fazie dokrytycznej i w fazie pokrytycznej. Zachowanie się tych słupów zbadano w procesie obciążenia wzrastającego i obciążenia malejącego. Badano słupy stalowe i słupy ze stopu aluminium o kształcie prostokątnym, teowym i ceowym w przekroju poprzecznym. Badania eksperymentalne przeprowadzono wykorzystując maszynę wytrzymałościową INSTRON 8802, z której oprogramowania zastosowano proces obciążenia i odciążenia. W trakcie testów rejestrowano siłę P, zmianę odległości między uchwytami próbki - u i strzałkę ugięcia w połowie rozpiętości próbki - f. W efekcie końcowym przedstawiono eksperymentalny model zachowania się słupa w procesie obciążenia i w fazie pokrytycznej.
EN
The subject of the study is an experimental analysis of behavior of compressed columns in the pre and post- critical phase. The behavior of compressed columns were investigated in the loading and unloading process. There were studied steel and aluminum columns of rectangular, T and C shapes. The experimental study was conducted in testing machine INSTRON 8802 runs in a programmed loading and unloading processes. During the tests there were recorded the load - P, the change of distance between the jaws - u and the deflection in the middle of the span of the compressed rod - f. There was made an attempt to model the behavior of the compressed rod in the loading and unloading process.
15
Content available remote Experimental study of influence factors on compression stress relaxation of ACM
Santos dos D J, Tavares L B, Batalha G. F.
Journal of Achievements in Materials and Manufacturing Engineering
|
2011
|
Vol. 46, nr 1
33--39
EN
Purpose: Purpose: of this paper is to investigate the influence of electron beam (EB) radiation, temperature and deformation on the compression stress relaxation behavior of UV curing polyacrylate rubber (ACM). Design/methodology/approach: ACM plugs were obtained by UV radiation curing. Some samples were post cured by EB dose of 250 kGy, providing two material conditions. The plugs were submitted to compression stress relaxation experiments (CSR) for 5.000 min on two temperature levels, 23°C and 90°C, and deformation levels of 10% and 15%. Results were analyzed using 2k Factorial Design, quantifying the influence of these factors on the maintained compression force. Findings: The results have shown an increase in the maintained compression force, respectively a decrease in the compression stress relaxation, for all EB irradiated ACM specimens along the entire measured period of time. The increase of the three analyzed factors has caused an increase of the maintained compression force. Through the 2k Factorial Design was possible to find out the deformation as the most relevant influence factor, followed by irradiation, as second influence factor and temperature. Research limitations/implications: ACM molecular structures were not physical-chemically investigated. Therefore, possible molecular structural changes, caused by EB radiation, were not described. Practical implications: Decreasing of compression stress relaxation implicates on increasing working life of sealing components made from the studied material, besides the improvement of sealing capacity of these components, even under reduced deformation conditions. Originality/value: The use of EB radiation as successful method to decrease compression stress relaxation of UV curing ACM rubber, has opened opportunities to industrial applications. Thus, provide knowledge about influence factors on ACM relaxation behavior.
16
Content available Prediction of mechanical properties of cast A356 alloy as a function of microstructure and cooling rate
Shabani M. O., Mazahery A.
Archives of Metallurgy and Materials
|
2011
|
Vol. 56, iss. 3
671-675
EN
In order to predict the mechanical properties of A356, a relatively new approach is presented in this paper using finite element technique which combines mechanical properties data in the form of experimental and simulated microstructures. In this work, the comparison of this model's predictions with the ones in the literature is presented. It is revealed that predictions of this study are consistent with the other works and experimental measurements for A356 alloy. The results of this research were also used in order to form an analytical equations followed with solidification codes for SUT (Sharif University Technology) software.
PL
W celu prognozowania właściwości mechanicznych stopów A356, w pracy przedstawiono stosunkowo nowe podejście przy użyciu metody elementów skończonych, które łączy w sobie dane właściwości mechanicznych w formie badań eksperymentalnych i symulacji mikrostruktur. W pracy przedstawiono porównanie przewidywań tego modelu z danymi literaturowymi i stwierdzono, że są one zgodne z innymi pracami i danymi eksperymentalnymi dla stopu A356. Wyniki tej pracy zostały również wykorzystywane do sformułowania równań analitycznych następnie użytych do programowania krzepnięcia w oprogramowaniu SUT (Sharif University of Technology).
17
Content available remote Entrainment of particles in the Mechanobr laboratory flotation machine
Drzymała J., Hrycyna E.
Prace Naukowe Instytutu Górnictwa Politechniki Wrocławskiej. Studia i Materiały
|
2004
|
Vol. 106, nr 30
21-29
EN
Entrainment of hydrophilic particles during flotation is usually characterized by a function or parameter related to the recovery of water. In this work another approach for characterizing entrainment of hydrophilic particles was presented. It was adopted from a procedure developed for Hallimond tube micro-flotation and called the flotometry. It relies on performing batch-type mechanical carryover tests in the presence of a frother and different size fractions of various solids for several minutes until there is no more recovery of solids in the froth or a plateau on the recovery versus time curves is reached. This procedure allows elimination of time in the formulas characterizing entrainment of particles. The entrainment tests provided data on the mechanical carryover of each studied material in the form of separation curves (recovery of particles versus their size) having a characteristic point of d50. The d50 parameter is the size of particles for which the recovery due to entrainment after a long time of foam collection is 50%. The performed tests with solids of different densities p allowed to find an equation which describes the entrainment of the hydrophilic particles in the 200 cm3 cell of the Mechanobr laboratory flotation machine in the presence of 12.5 mg/dm3 of alfa-terpineol as a frother. The equation is: d50 (p'/p)1,65 = L, where L is a constant equal to 90 plus minus 9 (mm), when diameter of particles d is expressed in mm and their density in water p in g/cm3 while p is density of water (1 g/cm3). The proposed flotometric equation is useful for characterization and prediction of entrainment of different materials in the 200 cm3 cell of Mechanobr laboratory flotation machine.
PL
Wyniesienie mechaniczne ziaren hydrofilnych w czasie flotacji ziaren hydrofobowych jest zwykle charakteryzowane za pomocą funkcji lub parametru odniesionego do ilości odzyskanej z pianą wody. W tej pracy opisano inne podejście do charakteryzowania wyniesienia mechanicznego ziaren hydrofilnych. Zaadoptowano procedurę zwaną flotometrią, stosowaną przy opisie wyniesienia mechanicznego ziaren w mikroflotowniku Hallimonda. Polegała ona na przeprowadzeniu pomiarów wyniesienia mechanicznego ziaren w obecności spieniacza dla różnych klas ziarnowych różnych substancji tak długo, aż uzysk ziaren osiąga plateau. Procedura ta pozwalała na wyeliminowanie czasu w równaniach na wyniesienie mechaniczne ziaren. Przeprowadzone badania wyniesienia mechanicznego dostarczyły danych o wyniesieniu mechanicznym badanych materiałów w postaci krzywej rozdziału tj. uzysku jako funkcji wielkości ziaren, posiadającej charakterystyczny punkt d50- Parametr d50 odpowiada rozmiarowi ziarna, dla którego uzysk, powodowany wyniesieniem mechanicznym po długim czasie przepuszczania pęcherzyków przez flotownik, wynosi 50%. Przeprowadzone testy z substancjami o różnej gęstości pozwoliły na wyprowadzenie równania, które opisuje wyniesienie mechaniczne ziaren hydrofilowych w laboratoryjnej maszynce flotacyjnej typu Mechanobr o pojemności komory flotacyjnej 200 cm3 w obecności 12,5 mg/dm3 alfa-terpineolu jako spieniacza. Uzyskano równanie: d50(p'/p)1,65 = L, gdzie Z. jest stalą wynoszącą 90 plus minus 9 (im, d50 jest charakterystycznym rozmiarem ziaren, p jego gęstością w wodzie, zaś p- gęstością wody wynoszącą 1 g/cm3.
18
Content available remote Computational challenges in MEMS
Furuberg L.
International Journal of Applied Mechanics and Engineering
|
2002
|
Vol. 7, no 1
173-185
EN
Small sensors and actuators made from materials like silicon, quartz or plastic are already parts of our everyday life. In cars there are often silicon sensors measuring acceleration, tyre pressure and car roll-over. There may be microfabricated mechanical components inside your light projector or in your ink-jet printer. In the future, microsystems are believed to be widespread, being used for environment monitoring, safety systems, medical care and biochemical analyses. The small mechanical elements are easily integrated in electrical circuits that control their behaviour, process their output signals or interconnect several active and passive elements in a control system. Behaviour of the mechanical elements is often governed by interacting elastic forces, electromagnetic forces and forces due to surrounding fluids. Computation of the behaviour is therefore complicated. Engineers working with macroscopic constructions like oil-platforms, where mechanical and fluid forces interact, face similar challenges. Experiences and research results from the macroscopic world are therefore of great importance for the design of microsystems. Microsystem elements usually involve micrometer sized features. The small scale introduces effects that are negligible on larger scales, such as strong surface forces. In addition, the continuum hypothesis may break down in some problems, excluding the use of partial differential equations describing the behaviour. There are also fundamental physical effects occurring on small scales that are not yet understood. An important task in microsystems design is to develop reduced-order macromodels that capture the essential behaviour of a mechanical microelement. The complicated electrical circuits controlling the mechanical elements need to be optimised, and this will be too time-consuming without simplified descriptions. We present examples of microsystems, outline current computational technology and some remaining challenges in these fields.
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