Wyniki wyszukiwania - BazTech

1

Właściwości reologiczne stopów miedzi w stanie ciekłym i stało-ciekłym

Sołek Krzysztof

Inżynieria Materiałowa

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2022

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Vol. 43, nr 5

16--22

PL

W pacy przedstawiono analizę podstawowych właściwości reologicznych wybranego stopu miedzi w stanie ciekłym oraz częściowo ciekłym, z uwagi na brak w literaturze dostatecznej liczby badań z tego zakresu oraz potencjalne możliwości wykorzystania technologii tiksotropowych do kształtowania stopów na osnowie miedzi. Przeprowadzona analiza obejmowała złożoną charakterystykę lepkości pod kątem wpływu temperatury oraz prędkości odkształcenia. Wyniki wzbogacono o modele reologiczne, które mogą być wykorzystywane w badaniach symulacyjnych.

EN

An analysis of the basic rheological properties of a selected copper alloy in a liquid and partially liquid state was presented, due to the lack of sufficient research in this field in the literature and the potential possibilities of using thixotropic technologies to shape alloys on a copper matrix. The analysis carried out a complex characteristic of viscosity in terms of the influence of temperature shear rate. The results were enriched with rheological models that can be used in simulation studies.

2

Stress relaxation phenomena in polymeric orthodontic ligatures

Milewski Grzegorz

Engineering of Biomaterials

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2021

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Vol. 24, no. 162

2--6

EN

Elastomeric products are applied in orthodontics mainly as elastic ligatures or chains and have become an alternative to wire ligation made of titanium alloy or stainless steel. Despite their popularity among the dentists and undoubtful advantages, some essential warnings are being raised regarding the degree of load loss. This relaxation phenomenon seems to be a dominant feature in the time-dependent behaviour of those elements in orthodontic procedures, such as dentition corrections or teeth extrusions. The aim of the paper was to examine and analyse the rheological properties of biocompatible orthodontic elastomeric ligatures. Five different polymeric orthodontic ligatures were examined in the following experiments: a simple relaxation test, relaxation simulating orthodontic extrusion and the two-steps relaxation process, which stands for so-called ‘secondary tightening’, resulting in the increase of the orthodontic force. The results of the relaxation experiments proved that among various descriptions of that phenomenon, the power-law descriptions fit the best time-dependent behaviour during orthodontic procedures. Power-law models give the most intensive initial relaxation, which is characteristic for elastomeric ligatures. The obtained results and analyses allow precise control of the treatment progress in the orthodontic extrusion procedure.

3

Rheology of drugs for topical and transdermal delivery

Walicka A., Falicki J., Iwanowska-Chomiak B.

International Journal of Applied Mechanics and Engineering

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2019

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Vol. 24, no. 1

179--198

EN

Skin drug delivery systems are a constant source of interest because of the benefits that they offer to overcome many drawbacks associated with other modes of drug delivery (i.e. oral, intravenous, etc.). Because of the impermeable nature of the skin, designing a suitable drug delivery vehicle that penetrates the skin barrier is challenging. Skin drug delivery can be subdivided into topical and transdermal (Fig.1). In a topical administration the drug is intended to act at skin level, this is indicated for the treatment of skin diseases. The aim of transdermal administration is getting a systemic release and in this case the skin represents a barrier not a target. The availability of drugs or other active substances through the skin depends basically on two consecutive steps: the release of these drugs or substances from vehicle or carrier and their subsequent permeation through the skin. Hence, studies on the specific properties of vehicles or carriers, such as their rheological behaviours, are of great interest in the field of pharmaceutical products. The objective of the present study is to systematically characterize a nonlinear rheological behaviour and flow properties of drugs and drug carriers into topical and transdermal administration. To this aim, one- and threedimensional rheological models are presented, which may be used to describe drug release through the skin and through the extracellular and interstitial matrix structures. Finally, the rheological measurements of some commercial creams and ointments were made.

4

Identification of the Process of Dynamic Stretching of Threads in Warp Knitting Technology Part II: Experimental Identification of the Process of Stretching Threads, with Verification of Rheological Models

Prążyńska A., Mikołajczyk Z.

Autex Research Journal

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2018

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Vol. 18, no. 1

1--6

EN

The study is a continuation of the first part of the publication, concerning the theoretical analysis of sensitivity of rheological models of dynamically stretched thread. This part presents the experimental research on the characteristics of stretching forces as a function of time, in the context of comparing the obtained results with theoretical data. The selected research material was three types of polyester silk threads with linear densities 84, 110 and 334 dtex. During the tests, threads of 400 to 1300 mm were stretched at speeds in the range of V ∈ [0.65, 1.47] m/s, which corresponds to the knitting speed n ∈ [700, 1600] courses/min. An original measuring device for empirical identification of dynamic processes of threads stretching was used during the tests. In total, 36 tests variants were performed. The procedures of mathematical equivalence were also worked out for the rheological models of Kelvin-Voigt, Zener and the three-parameter Standard model 2, which enabled the description of threads stretching phenomena in technological processes with the help of generalized rheological model, taking into account the visco-elastic qualities of threads. Experimental results showed that for the assumed deformation speeds ε(t) ∈ [0.53, 4.00] 1/s, the open three-parameter models – Standard model 2 and Zener model most reliably describe the stretching process.

5

Analysis of Rheological Models of Modified Sewage Sludge

Wolski P.

Rocznik Ochrona Środowiska

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2017

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Tom 19

230--239

EN

This paper presents the results of examinations of sewage sludge from cellulose and paper industry. The aim of the study was to determine rheological models (the Ostwald-de Waele, Bingham and Herschel-Bulkley models) of non-conditioned sewage sludge and the sludge exposed to the effect of the ultrasound field at its different intensities and then stabilized in flasks and in the bioreactor. Evaluation of rheological properties of sewage sludge allows for a detailed characterization of their pumpability and abilities during the hydraulic transport. The examinations revealed the increase in the yield stress and consistency coefficient through application of the energy of the ultrasound field. The values of the parameters discussed were reduced on consecutive days of the stabilization process.

PL

W artykule przedstawiono wyniki badań prowadzone na osadach ściekowych z przemysłu celulozowo-papierniczego. Celem prowadzonych badań było wyznaczenie modeli reologicznych (Ostwalda-de Waele, Binghama, Herschela-Bulkley’a) dla osadów ściekowych niekondycjonowanych oraz poddanych działaniu pola ultradźwiękowego przy różnych jego natężeniach, a następnie stabilizacji w kolbach i bioreaktorze. Poznanie właściwości reologicznych osadów umożliwia dokładną charakterystykę ich pompowalności oraz zdolności podczas transportu hydraulicznego. W wyniku przeprowadzonych badań stwierdzono zwiększenie granicy płynięcia, jak również konsystencji poprzez zastosowanie energii pola ultradźwiękowego. Wartości omawianych parametrów ulegały obniżenie podczas kolejnych dni prowadzenia procesy stabilizacji.

6

Identification of the Process of Dynamic Stretching of Threads in Warp-Knitting Technology

Prążyńska A., Mikołajczyk Z.

Autex Research Journal

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2017

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Vol. 17, no. 4

334--343

EN

The publication presents a theoretical study of the susceptibility of rheological models of threads to dynamic stretching in the context of modern, highly efficient textile technologies. Input parameters of the four analyzed models, the Kelvin-Voigt model, the Maxwell model, Standard model 2, and the Zener model, corresponded to the actual values of the coefficients of viscosity, elasticity, kinematic and dynamic loading, and stretching speed for the analyzed polyester silk threads produced in a knitting process, with knitting speeds from 700 to 1,600 courses/min. The research proves that the tested thread models behave differently in the stretching process-the Kelvin-Voigt model is sensitive to both the increases in kinematic loading and viscosity coefficient, Standard model 2 is only susceptible to dynamic stiffness, and the Zener model is significantly sensitive to kinematic loading. All responses of the models increase with the increase in stretching speeds. The obtained results indicate substantial “accuracy tolerance” in setting input parameters while identifying dynamics of the knitting process on warp-knitting machines.

7

The influence of anti-sedimentation agents on the technological parameters of cement slurry

Kremieniewski M., Rzepka M., Stryczek S., Wiśniowski R.

AGH Drilling, Oil, Gas

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2017

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Vol. 34, no. 4

945--957

EN

Recently, the intensifying development of shale drilling has contributed to the more numerous realization of directional and horizontal boreholes. Moreover, such boreholes are more advantageous as they provide about 4 times higher production than in their vertical counterparts, give access to poorly drained areas, or production of already developed reservoir, where only a new borehole has to be introduced to the network. It should be stressed that the sealing of the casing columns is a challenge because of the restrictions set before drilling fluids used for sealing horizontal boreholes. Slurries play a special role while sealing horizontal boreholes and therefore their technological parameters and density should be adjusted to the geological-reservoir conditions. At the stage of designing slurries for sealing horizontal boreholes, the most important parameters are: sedimentation stability, zero water settling water settling and low filtration. Meeting these requirements was possible by selecting proper admixtures and additives, which in turn, is a guarantee of the uniform and homogeneous structure of fresh and hardened cement slurry. Thus formed cement sheath of bounded slurry should be impervious to gas and have good mechanical properties over the length of the sealing without any trends of anisotropy of the medium in particular points. Modification and designing specialist recipes for definite technological conditions lie, among others, in choosing proper slurry additives and admixtures. However, obtaining appropriate parameters for given conditions may be connected with a change of other parameters deciding about the efficiency of the sealing of a given horizon. Therefore while working out a new recipe for a slurry, the designer should account for the analytical results and influence of the applied agents on all of the parameters of slurry. This is the subject matter of the paper.

8

The rheological properties of redcurrant and highbush blueberry berries

Bohdziewicz J., Czachor G.

Agricultural Engineering

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2016

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Vol. 20, No. 2

15--22

EN

The load values corresponding to the compressive strength of high-bush blueberry and redcurrant fruits during the compression test between two rigid plates were measured. The changes of coefficient of elasticity and coefficient of viscosity values during the creep and the relaxation tests were studied in the selected interval of time, also direction of load application in relation to the longitudinal axis of fruit was considered. The creep and relaxation tests were carried out with the load of 40% of determined compressive strength of berries. To describe behavior of testing the material rheological standard, Maxwell and Kelvin models as well as experimental models were used. Comparatively small changes of parameter values of assumed empirical models were reported in the course of tests. It may be recognized as characteristic for the investigated material.

PL

Wyznaczano wartości obciążenia odpowiadające wytrzymałości doraźnej podczas testu ściskania pomiędzy dwiema sztywnymi płytami owoców borówki wysokiej i porzeczki czerwonej. Badano zmiany wartości współczynnika sprężystości i współczynnika lepkości w wybranych przedziałach czasowych podczas testu pełzania i relaksacji naprężeń, uwzględniono kierunek przyłożenia obciążenia w stosunku do osi podłużnej owocu. Testy pełzania i relaksacji naprężeń realizowano przy obciążeniu odpowiadającym wartości 40% wyznaczonej wytrzymałości doraźnej. Wykorzystano standardowe oraz eksperymentalne modele reologiczne. Stwierdzono stosunkowo niewielkie zmiany wartości parametrów przyjętych modeli empirycznych z upływem czasu realizacji testu. Na tej podstawie można uznać je jako charakterystyczne dla badanego materiału.

9

Nowe modele opisu krzywych lepkości ścinania ustalonego cieczy nienewtonowskich

Steller R.

Polimery

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2015

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T. 60, nr 10

636--643

PL

Przedstawiono wybrane nowe modele oraz metody opisu krzywych lepkości w ustalonych przepływach ścinających cieczy nienewtonowskich. Omówiono modele wynikające z teorii objętości swobodnej, modele będące uogólnieniem równania Carreau oraz tzw. modele wielomodowe, umożliwiające opis lepkości układów reologicznie złożonych. Podano szereg praktycznych przykładów opisu krzywych lepkości różnorodnych kompozycji ciekłych za pomocą omawianych modeli.

EN

Selected novel models and methods of describing viscosity curves in steady shear flows of non-Newtonian liquids are presented. The models resulting from free volume theory, those being a generalization of the Carreau equation and so called multi-mode models, which make it possible to describe the viscosity of rheologically complex systems, are discussed. A few practical examples for describing the viscosity curves of various liquid compositions using these models are given.

10

Zaczyny cementowe jako ciecze reoniestabilne

Pikłowska A., Stryczek S., Gonet A., Formela M.

Nafta-Gaz

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2015

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R. 71, nr 10

747--753

PL

Proces cementowania kolumn rur okładzinowych w głębokich otworach wiertniczych wymaga, aby zaczyny cementowe były przetłaczalne w dłuższym okresie czasu, a zatem celowym jest wykonywanie badań właściwości reologicznych w funkcji czasu, jaki upływa od sporządzenia zaczynu do górnej granicy jego przetłaczalności. Dzięki badaniom stwierdzono, że zaczyny te mogą wykazywać zjawisko tiksotropii. Polega ono na tym, że na skutek niszczenia wewnętrznej struktury zaczynu (forma żelu) następuje izotermiczne zmniejszenie się tarcia wewnętrznego z upływem czasu ścinania (rozpad ziaren cementu), jak również dający się zmierzyć w czasie powolny powrót do pierwotnej konsystencji w czasie spoczynku. Zmiana lepkości pozornej układu tiksotropowego w funkcji czasu powoduje powstanie pętli histerezy naprężeń przy określaniu krzywej płynięcia, tj. wyznaczeniu naprężeń ścinających przy wzrastających i malejących szybkościach ścinania. Z kolei wielkość pętli histerezy naprężeń określa wielkość tiksotropii układu. Pętla histerezy może mieć różny kształt, w zależności od warunków przebiegu badań laboratoryjnych. Zmiana szybkości ścinania oraz krzywe (pętle) przecinające się przy pośrednich szybkościach ścinania mogą utrudniać interpretację tiksotropii, ponieważ w takich przypadkach powierzchnia pola pętli nie jest równoznaczna z wielkością tiksotropii. W artykule przedstawiono wyniki badań laboratoryjnych określających wpływ funkcji czasu na zmiany właściwości reologicznych świeżych zaczynów cementowych sporządzanych na osnowie cementu wiertniczego marki Dyckerhoff (API Class G HSR – Black Label, produkt importowany z Niemiec). W przeprowadzanych badaniach zmiennymi były: współczynnik wodno-cementowy, czas pomiaru (liczony od zarobienia zaczynu). Współczynniki wodno-cementowe dla badanych zaczynów cementowych były zmienne i wynosiły odpowiednio: 0,45; 0,55 i 0,65.

EN

The process of cementing casing columns in deep boreholes requires that the cement slurries were pumped over a longer period of time, so by all means it is advisable to perform studies of rheological properties as a function of time that elapses from the preparation to the upper limit of the possibility of its circulation. Studies show that the slurries may exhibit the phenomenon of thixotropy. This phenomenon consists in the fact, that due to the destruction of the internal structure of the slurry (gel form), followed by the isothermal reduction of internal friction with the passage of coagulation time (decay of particles of cement), as well as a measurable during the time slow return to its original consistency at rest. Changing the apparent viscosity of the thixotropic system in a function of time creates a strain hysteresis loop when determining the flow curve, i.e. designation stress at increasing and decreasing coagulation rates. The size of strain hysteresis loop determines the size of the system thixotropy. The hysteresis loop can have different shapes depending on the course of laboratory tests. Changing the coagulation rate and the curves (loops) intersecting at intermediate coagulation rates may hinder interpretation of thixotropy, because in such cases the surface of the loop field is not equivalent to the size of thixotropy. The article presents results of laboratory tests defining the influence of the function of time on changes in the rheological properties of fresh cement slurries prepared on the base of the drill Class G cement, grade HSR (cement imported from Germany). In the study performed the variables were: the ratio of w/c, the measurement time(counted from mixing the slurry). Water-cement ratios for the tested cement slurries were variable and amounted to 0.45; 0.55 and 0.65.

11

Wpływ współczynnika wodno-cementowego na rodzaj modelu reologicznego zaczynu cementowego

Skrzypaszek K., Stryczek S., Wiśniowski R.

Nafta-Gaz

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2015

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R. 71, nr 1

18--23

PL

Zaczyny uszczelniające, a zwłaszcza typu cementowego, są skoncentrowanymi układami dyspersyjnymi zawierającymi cząstki stałe o znacznie rozwiniętej powierzchni właściwej. Układy takie pod względem reologicznym należą do niezwykle złożonych. Wynika to między innymi z faktu, że na właściwości reologiczne w sposób istotny wpływają: dodatki i domieszki modyfikujące właściwości technologiczne świeżych i stwardniałych zaczynów, złożony chemicznie mechanizm reakcji hydratacji zachodzącej w zaczynie w funkcji czasu. Szczególną uwagę, ze względu na zapewnienie skuteczności uszczelniania kolumn rur okładzinowych w otworach wiertniczych, należy zwrócić na właściwości reologiczne zatłaczanych zaczynów cementowych. W artykule przedstawiono wyniki badań wpływu współczynnika wodno-cementowego na parametry reologiczne zaczynu sporządzanego na osnowie cementu wiertniczego klasy G.

EN

Sealing slurries, especially cement slurries, are concentrated dispersive systems containing solids of a considerably developed specific surface. Rheologically, such systems are very complex which stems from the fact that certain factors significantly influence rheology, i.e.: additives and admixtures modifying technological properties of fresh and set slurries, chemically complex hydration reaction mechanism occurring in the slurry in a function of time. Special attention should be paid to providing efficient sealing conditions in the wellbore, i.e. rheological properties of injected cement slurries. The influence of water/cement ratio on the rheological parameters of sealing slurries based on drilling cement class G was analyzed and the results presented in the paper.

12

Assessment of impact of the rheological parameters change on sensitivity of the asphalt strain based on the test results

Kurpiel A., Wysokowski A.

Civil and Environmental Engineering Reports

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2015

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No. 16

105--117

EN

The creep test under the static loading, that allows to determine rheological properties of asphalt based on the creep curve, is the most effective test nowadays. Applied loads are non-destructive and allow to observe the course of the strain after the test load. The test can be carried out on compressing, shearing, bending as well as on triaxial test, that depends on the applied apparatus implementing different intensity [1, 2, 3, 4, 5, 6]. Based on the creep test, the stress of different properties can be specified. Among them there are valuable rheological properties based on selected viscoelascity models [1]. The properties of the viscoelascity models are relevant indexes depicting resistance to deformation. They can be used to forecast the wheel-truck in the accepted rheological model [1]. In this article it is shown the impact of different rheological properties of the viscoelacity model on the wheel-truck as well as the impact of different properties on shape and the course of the creep curve. The asphalt mixtures presented in this article are characterized by variable rheological properties. It is therefore difficult to determine which property mostly affects the size of the strain. However, the authors of this article attempted to analyse the change of the asphalt strain value of the different variables in particular rheological model, called Bürgers’s model.

PL

Badanie pełzania pod obciążeniem statycznym jest obecnie najbardziej efektywnym badaniem pozwalającym na określenie reologicznych parametrów mieszanek mineralno - asfaltowych na podstawie krzywej pełzania. Stosowane obciążenia mają poziom nieniszczący i pozwalają na obserwację przebiegu odkształceń w czasie również po odciążeniu. Badanie może być realizowane przy ściskaniu, ścinaniu, rozciąganiu i zginaniu, a także w zakresie trójosiowym, w zależności od stosowanego aparatu realizującego zadany schemat naprężeń [1, 2, 3, 4, 5, 6]. Na podstawie badania pełzania można określić parametry oparte o różne teorie pełzania a szczególnie cenne parametry reologiczne w oparciu o wybrane modele lepkosprężyste [1]. Parametry z modeli lepkosprężystych są miarodajnymi wskaźnikami obrazującymi odporność mieszanek na deformacje. Można za ich pomocą prognozować głębokości koleiny w przyjętym modelu reologicznym [1]. W niniejszym artykule przedstawiono jaki wpływ na głębokość koleiny mają różne wartości parametrów reologicznych z analizowanego modelu lepkosprężystego oraz wpływ parametrów na kształt i przebieg krzywej pełzania. Przedstawione w artykule mieszanki mineralno - asfaltowe charakteryzują się zmiennymi parametrami reologicznymi, zatem trudno jest określić, który parametr decyduje o wielkości odkształcenia danej mieszanki. Mając na uwadze powyższe, w artykule podjęto próbę analizy zmiany wartości odkształcenia mieszanki mineralno – asfaltowej przy zmianie jednego oraz dwóch parametrów w danym modelu reologicznym – w tym przypadku - Bürgersa.

13

Dynamic analysis of a soft-contact problem using viscoelastic and fractional-elastic rheological models

Zbiciak A., Kozyra Z.

Archives of Civil and Mechanical Engineering

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2015

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Vol. 15, no. 1

286--291

EN

The paper presents mathematical formulation of a dynamic soft-contact problem consisting of a material point impacting rheological structures. Two different models were analyzed. The first model concerns a viscoelastic structure while the second one applies to the so-called fractional-elastic scheme. In both cases the formulation of the problem needs the notion of variational inequalities describing unilateral constraints. Moreover, the fractional-elastic model contains an element defined via fractional derivatives (spring-pot) that complicates the numerical solution. Thanks to the methods used in this paper, both problems were described mathematically applying appropriate systems of algebraic-differential equations. The solution of the fractional-elastic problem involving a fractional-differential equation (FDE) was obtained with the use of time-discretization schemes proposed in the literature. Selected numerical results of the initial-value problem solution, modelling a material point falling freely and impacting the rheological structures were presented.

14

Numerical simulation of drilling fluid flow in annular the space of the borehole

Kowalska-Kubsik I.

AGH Drilling, Oil, Gas

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2015

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Vol. 32, no. 4

775--783

EN

This paper presents the numerical results of a numerical analysis of drilling fluid flow through annular space in the borehole. The analysis used the Herschel–Bulkley rheological fluid model. The obtained results of the analysis for three cases with variable geometry. Variable geometry is associated with a larger diameter drill in the joints of drill pipes, and consequently, with reduced flow cross-section. A comparison of pressure values at the end of the analyzed examples showed that in the example of a simple drill pipe without joints, pressure values were 30% higher than in the case, which takes into account changes in the geometry of the joints.

15

The influence of time of rheological parameters of fresh cement slurries

Stryczek St., Wiśniowski R., Gonet A., Złotkowski A.

AGH Drilling, Oil, Gas

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2014

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Vol. 31, no. 1

123--133

EN

The rheological properties of sealing slurries are very important at the stage of designing and realization of works related to the sealing and reinforcement of the ground rock mass with the use of drilling technologies. For providing high efficiency of the works related to the sealing of casing pipes in deep wells and the rock mass with borehole injection methods, the rheological parameters of sealing slurries should be selected depending on [1,2]: - reservoir conditions of ground and rocks to be sealed, — geometry of borehole and circulation system, — interactions between the stream of injected slurry and the resulting flow resistance, especially in the sealed medium. The results of laboratory experiments focusing on the influence of time on the rheological parameters of fresh sealing slurries based on API Class G HSR - Black Label drilling cement (Dyckerhoff) for various water to cement ratios are presented in the paper

16

The influence of ash from fluidized-bed combustion of lignite on rheological properties of cement slurries

Skrzypaszek K., Stryczek S., Wiśniowski R.

AGH Drilling, Oil, Gas

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2014

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Vol. 31, no. 3

403--412

EN

Cementing jobs are a very important element of drilling technology considering the completion of a given field. The selection of an appropriate recipe for sealing slurry is a challenge for the cementing services and research units. Both fresh and set slurry should meet a number of technological requirements. Various chemical, physical and mechanical properties of the ground and rock mass media to a different degree influence the technological parameters of the injected fluid. The sealing slurries have to meet certain criteria if the high efficiency of works is to be provided. The first of them is the criterion of physicochemical congruence with the environment. The second condition stems from the criterion of pumping the slurry. It is realized by selecting an appropriate rheological model and rheological parameters of the sealing slurry. The third requirement is connected with the need of providing suitable strength and durability of hardened sealing slurries as a result of the physicochemical processes. The fourth condition should account for the economy and ecology factors. The selection of recipes for sealing slurries should not be accidental or an output of unfmished laboratory tests. The correct sealing and reinforcing of the rock mass are prerequisites of further engineering works performed in the wellbore. The results of laboratory experiments on the concentration of ash from the fluidized-bed combustion of lignites on rheological parameters of fresh sealing slurries based on drilling cement class G (HSR) Dyckerhoff (API Class G HSR - Black Label) for various water/cement ratios are presented in this paper.

17

Nowe modele cieczy lepkich oparte na równaniu Carreau

Steller R.

Polimery

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2013

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T. 58, nr 11-12

913--919

PL

Przedstawiono kilka nowych modeli cieczy lepkich, stanowiących modyfikacje lub rozszerzenia modelu Carreau, opisujących krzywe lepkości jako funkcje szybkości ścinania w obszarze przejściowym między zakresem newtonowskim i potęgowym. Modele dopasowano do opisu lepkości jako funkcji naprężenia ścinającego i uogólniono do opisu bardziej złożonego zachowania, np. pseudoplastyczno-dylatantnego.

EN

Several novel models of viscous liquids, which can be regarded as modifications or extensions of the Carreau model, are presented. These models describe the viscosity curves as functions of shear rate in the transition region between Newtonian and power law flow. Models were adapted for the description of viscosity as a function of shear stress and generalized to describe more complex behaviour, e.g. pseudoplastic-dilatant.

18

Mathematical description of rheological properties of asphalt-aggregate mixes

Zbiciak A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2013

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Vol. 61, nr 1

65-72

EN

The procedure of the formulation of constitutive equations for asphalt-aggregate mixes is based very often on rheological schemes composed of classical elastic, plastic and viscous elements. The parameters of these schemes can be obtained based on laboratory experiments. In order to obtain better curve fitting results one can use non-classical viscoelastic elements described by fractional derivatives. In this paper we present the characteristics of the fractional viscoelastic Huet-Sayegh model as well as the characteristics of an original simplified fractional model. The results have been obtained using algorithms of numerical calculation of inverse Laplace transforms. Then the proposal of an original rheological model including plasticity has been given. The non-linear differential constitutive relationships of such a model are presented in the paper. The results of computer simulations are also visualized. Finally, 3D viscoelasticplastic models of asphalt aggregatemixes are proposed. The models are based on a generalized macroscopic theory taking into account the effect of pressure-dependency on yielding.

19

Influence of polycarboxylate superplasticizers on rheological properties of cement slurries used in drilling technologies

Stryczek S., Wiśniowski R., Gonet A., Złotkowski A., Ziaja J.

Archives of Mining Sciences

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2013

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Vol. 58, no. 3

719--728

EN

Sealing slurries, mainly the cement-based ones, are concentrated dispersive systems, containing solid particles of considerably developed specific surface. Rheologically, such systems are very complex. This also stems from the fact that the rheological properties have a significant effect on: additives and admixtures modifying technological properties of fresh and set slurries, chemically complex mechanism of hydration in a slurry in a function of time. Special attention should paid to plasticizing (plasticizers PL) and liquefying (traditional and new- -generation superplasticizers SP) admixtures affecting the modification and optimization of rheological properties of fresh cement slurries as far as providing efficiency of sealing of casing pipes is concerned. Laboratory analyses were focused on proving the following thesis: properly selected type of superplasticizer [by BASF Polska Sp.z o.o. (The Chemical Company) - Admixtures for Concrete Division] advantageously affects the rheological parameters of sealing slurry based on metallurgical cement CEM III /A 32,5. The following variables were used in the analyses: type of superplasticizer, type of batch fluid. The laboratory experiments were made on superplasticizers produced by BASF: SKY 501, SKY 503, SKY 591, ACE 430, Glenium 115. The superplasticizer concentration in the slurry was 0.5 wt% (as compared with mass of dry cement). Water to cement ratio for the analyzed sealing slurries was equal to 0.5. The sealing slurries were made of metallurgical cement CEM III/A 32,5 N-LH/HSR/N Lafarge Cement S.A. in Małogoszcz.

PL

Zaczyny uszczelniające, a zwłaszcza typu cementowego, są skoncentrowanymi układami dyspersyjnymi, zawierającymi cząstki stałe o znacznie rozwiniętej powierzchni właściwej. Układy takie pod względem reologicznym należą do niezwykle złożonych. Wynika to między innymi z faktu, że na właściwości reologiczne w sposób istotny wpływają: dodatki i domieszki modyfikujące właściwości technologiczne świeżych i stwardniałych zaczynów, złożony chemicznie mechanizm reakcje hydratacji zachodzące w zaczynie w funkcji czasu. Na szczególną uwagę ze względu na zapewnienie skuteczność uszczelniania kolumn rur okładzinowych w otworach wiertniczych zasługują domieszki uplastyczniające (plastyfikatory PL) i upłynniające (superplastyfikatory SP typu tradycyjnego oraz nowej generacji) wpływające na modyfikację oraz optymalizację cech reologicznych świeżych zaczynów uszczelniających. Przeprowadzone badania laboratoryjne miały na celu udowodnianie następującej tezy: odpowiednio dobrany rodzaj superplastyfikatorów [firmy BASF Polska Sp.z o.o. ( The Chemical Company) - Dział Domieszek do Betonu], wpływa korzystnie na parametry reologiczne zaczynu uszczelniającego sporządzanego na osnowie cementu hutniczego CEM III /A 32,5. W przeprowadzanych badaniach zmiennymi były: rodzaj superplastyfikatora, rodzaj cieczy zarobowej. W badaniach laboratoryjnych zastosowano następujące superplastyfikatory firmy BASF: SKY 501, SKY 503, SKY 591, ACE 430, Glenium 115. Koncentracja superplastyfikatora w zaczynie wynosiła: 0,5% wagowo (w stosunku do masy suchego cementu). Współczynnik wodno-cementowy dla badanych zaczynów uszczelniających wynosił: 0,5. Do sporządzania zaczynów uszczelniających stosowano cement hutniczy klasy CEM III/A 32,5 N-LH/ HSR/NA - Cementownia Małogoszcz, Grupa Lafarge Cement S.A. w Małogoszczy.

20

Possibilities of applying rheological measurements in metallurgy

Korolczuk-Hejnak M.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 55, nr 2

541--546

EN

Purpose: The purpose of this paper is to analyse from the literature point of view the issues concerning modern methods of measuring the viscosity of liquid steel and solid-liquid steel in the course of rheological research with the use of a high temperature rheometer. The paper reviews the subject of measuring and modelling the viscosity value of steel with the use of equations and data available in the literature. It also presents the difficulties connected to rheological measurements of liquid steel and metallurgical slag. Design/methodology/approach: The main purpose of this paper is to present the issues relating to rheological measurements and the possibilities of their application in metallurgy. Findings: The paper describes the issues pertaining to the viscosity measurements of liquid and metallurgical slag. Research limitations/implications: In the future the authors are planning to develop an empirical model which would include rheological parameters and would be used to calculate the viscosity of liquid iron solutions on the basis of conducted rheological measurements of liquid steel. Practical implications: The results of investigation might be used in the future in semi-solid metal (SSM) forming. A fundamental and detailed understanding of the steel rheology is crucial for industrialization. Originality/value: The paper presents the issues connected to the subject of and difficulties encountered in the course of rheological measurements of liquid ferroalloys and metallurgical slag.