An improved Couette high shear viscometer

Summary The advantages of theCouette-type concentric cylinder viscometer have been cited for making viscosity measurements at high shear rates. Significant improvements in theBarber design are described which have resulted in the development of an instrument which can make measurements under laminar shear conditions at over several decades of shear rate. The range is over twice that of previous instruments demonstrating the achievement of shear rates to above 1 000 000 sec^–1, and with minimum viscous heating and over a temperature range of over 100°C.

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Zusammenfassung Nachdem auf die Vorteile desCouette-Viskosimeters für Viskositätsmessungen bei hohen Schergeschwindigkeiten hingewiesen worden ist, werden wesentliche Verbesserungen des Geräts nachBarber beschrieben, die zur Entwicklung eines Instruments geführt haben, das Messungen unter laminaren Scherbedingungen über mehrere Dekaden der Schergeschwindigkeit erlaubt. Der Bereich ist mehr als doppelt so groß wie bei früher beschriebenen Instrumenten und reicht bis über 10⁶ sec^–1. Dabei tritt nur eine geringe viskose Erwärmung auf, und es kann noch bei Temperaturen von mehr als 100°C gemessen werden.

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With 4 figures and 2 tables     

Comparison of stress-controlled and strain-controlled rheometers for large amplitude oscillatory shear

In linear viscoelastic region, it is well known that dynamic modulus and dynamic compliance can be converted to each other. However, it is questionable whether there exists an interconversion between large amplitude oscillatory shear (LAOS) data measured from different types of rheometers—stress-controlled and strain-controlled rheometers. Hence, we tried to prove the existence by use of polyethylene oxide (PEO) aqueous solutions with well-developed entanglements. From this experiment, we can conclude that a stress-controlled rheometer can simulate LAOS behavior measured from a strain-controlled rheometer under the conditions where inertia effect is not significant. Furthermore, it is investigated whether the LAOS data of the stress-controlled rheometer obey stress–frequency superposition as the strain–frequency superposition found by Cho et al. (J Rheol 54:27–63, 2010) from LAOS data measured by the strain-controlled rheometer. This scaling relation shows that the dimensionless stress amplitude is a function of zeta which is the product of the stress amplitude and linear viscoelastic function J′(ω). The plot shows that all of the data are superposed in a single curve without regard to frequency, molecular weight, and concentration of PEO aqueous solutions.     

A stress-controlled drag-reduction phenomenon

An unusual stress controlled turbulent flow phenomenon observed in aqueous solutions of some derivatives of an unsaturated 18 carbon atom fatty acidis described. Some other unusual viscometric and rheogoniometric properties of these solutions are also discussed.Presented at Soc. Petr. Engr. (AIME-USA) Symposium on Mechanics of Rheologically Complex Fluids, Houston, Texas, Dec. 15–16, 1966.     

Comparison of viscometer geometries for non-steady shear flows

Summary Suitability of cone- and-plate, parallel disk and concentric cylinder viscometric geometries for nonsteady shear flow of non-Newtonian fluids was analyzed. Both the cone- and plate and the parallel disk viscometers possess the undesirable property that the equations of motion do not permit simple solutions, i. e., solutions for which only one pair of components of the shear stress tensor is non-zero. No such difficulty appears in the analysis of the concentric cylinder viscometer, and therefore this instrument is to be preferred for this type of study.

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Zusammenfassung Die Geometrien des Kegel-Platte-, des Parallelscheiben- und des konzentrischen Zylinderviskosimeters werden auf ihre Eignung für Messungen bei nichtstationärer Scherströmung nicht-Newtonscher Flüssigkeiten untersucht. Die Kegel-Platte und die Parallelscheiben-Viskometer haben beide die unerwünschte Eigenschaft, daß die Bewegungsgleichungen keine einfachen Lösungen haben, das heißt, Lösungen für die alle außer einem einzigen Paar der Komponenten des Schubspannungstensors verschwinden. Diese Schwierigkeit erscheint nicht in den Ergebnissen für das konzentrische Zylinderviskosimeter, und damit ist dieses Gerät für diese Versuche bevorzugt.

     

Falling coaxial cylinder viscometer with wide shear rate range

Summary A novel viscometer was devised to measure flow curves of polymer melts over a wide range of shear rates. The apparatus comprises a concentric cylinder viscometer with the inner moving piston driven axially at set speeds. Immersion depth of the moving piston increases continuously during the course of an experiment. An Instron or similar piston-operated capillary viscometer can be easily modified for this purpose.The flow analysis provides a general expression for shear rate and shear stress at the wall of the moving rod, with elimination of instrumental and end effects. No calibration is needed. True flow curves can be obtained with less experimental effort than in comparable capillary extrusion studies.

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Zusammenfassung Es wurde ein neues Viskosimeter entworfen, das die Messung von Fließkurven von Polymerschmelzen über einen weiten Schergeschwindigkeitsbereich ermöglicht. Das Gerät besteht aus zwei konzentrischen Zylindern, wobei der innere als Kolben mit vorgegebener Geschwindigkeit axial bewegt wird. Die Eintauchtiefe des bewegten Kolbens ändert sich im Lauf des Experiments kontinuierlich. Ein Kapillar-Viskosimeter mit Kolbenantrieb vom Instron- oder ähnlichen Typ kann zu diesem Zweck in einfacher Weise umgebaut werden.Die Analyse des Strömungsvorgangs liefert einen allgemeinen Ausdruck für Schergeschwindigkeit und Schubspannung an der Wand des bewegten Stabes, wobei instrumentelle und Endeffekte eliminiert werden können. Es wird keine Eichung benötigt. Wahre Fließkurven können auf diese Weise mit geringerem experimentellen Aufwand erhalten werden als bei vergleichbaren Kapillar-Extrusions-Untersuchungen.

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With 4 figures     

A simple extensional viscometer

An extensional viscometer is described in which the liquid filament leaving a capillary is subjected to a stretching deformation. In order to keep the flow rate through the capillary unaltered upon inception of stretching, the pressure head at the capillary entrance has to be reduced by an amount equal to the extensional viscoelastic stress at the capillary exit. This affords a simple means of measuring small fluid forces such as those that occur in the stretching of dilute polymer solutions. Since stretch rates can be obtained from a knowledge of the mass flow rate and the filament diameter profile, extensional viscosities can be computed. The efficacy of the technique is demonstrated by obtaining the anticipated results for Newtonian liquids.     

Extrapolation procedures for zero shear viscosity with a falling sphere viscometer

Summary Several theoretical and empirical extrapolation procedures for the determination of zero shear viscosity in a falling sphere viscometer are critically analysed. They are experimentally tested and it is concluded that the extrapolation procedure based onCaswells work appears to be the most appropriate.

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Zusammenfassung Es werden einige theoretische und empirische Extrapolationsmethoden zur Bestimmung der Anfangs-Scherviskosität in einem Kugelfallviskosimeter kritisch analysiert. Diese werden experimentell überprüft, und es wird hieraus geschlossen, daß die Extrapolationsmethode, die auf der Arbeit vonCaswell beruht, die geeignetste zu sein scheint.

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Non-Newtonian viscosity measurements in the intermediate shear rate range with the falling-ball viscometer

An attempt to use the falling-ball experiment to measure the non-Newtonian viscosity in the intermediate shear rate range was successfully accomplished by combining the direct experimental observations with a simple analytical model for the average shear and shear rate at the surface of a sphere. The viscosity data of aqueous solutions of Carbopol-960, carboxymethyl cellulose, polyethylene oxide and polyacrylamide obtained from the falling-ball viscometer gave good agreement with those from other viscometers, confirming the general applicability of the analytical approach.In the experiments with the highly viscoelastic polyacrylamide solutions the terminal velocity was observed to be dependent on the time interval between the dropping of successive balls. This time-dependent phenomenon was used to determine characteristic diffusion times of the concentrated solutions of polyacrylamide. These values were, in turn, compared with characteristics relaxation times determined by the Powell-Eyring model.The experimental program revealed that the falling-ball viscometer has very limited utility for the measurement of the steady shear viscosity of aqueous polymer solutions.     

A rotational double coaxial cylinder viscometer

Summary Design principles for a rotational coaxial cylinder viscometer which directly measures viscosity and yield stress without need for any corrections have been developed. A viscometer with a rotating external cylinder is combined with one with a rotating inner cylinder. The torque is measured on a common tube which makes the inner cylindrical surface in the first viscometer and the outer one in the second one. Two rotational double cylinder viscometers are described in detail. The determinations are illustrated by measurements onNewtonian fluids, time-dependent shear thinning fluids, and a thixotropic suspension and by determination of zero shear viscosity of polymer solutions.

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Zusammenfassung Ein Viskosimeter mit einem äußeren rotierenden Zylinder ist mit einem Viskosimeter mit einem inneren rotierenden Zylinder zusammengebaut worden. Das Torsionsmoment wird an dem Hohlzylinder gemessen, der von der inneren Zylinderoberfläche des ersten Viskosimeters und von der äußeren Zylinderoberfläche des zweiten Viskosimeters abgegrenzt ist. Die Aufbauprinzipien sind entwickelt worden. Es ist möglich, die Viskosität und die Fließfestigkeit direkt als absolute Größen zu messen. Einige Messungen anNewtonschen und nicht-Newtonschen Flüssigkeiten, zeitabhängigen makromolekularen Lösungen und einer thixotropen Suspension werden mitgeteilt.

     

A microtube viscometer with a thermostat

The viscometer presented in this paper is suitable for measuring the viscosity of liquids in micro-litre quantities. It consists of a micro-flow experimental system with a thermostat. Using the measurements of the flow rates and pressure drops of a liquid passing through a microtube, the liquids viscosity can be calculated from on Hagen-Poiseuille theory. After calibration, the viscometer was used to measure viscosities of deionized water and ethyl alcohol at temperatures ranging from 0 to 40 °C. For both test liquids, the relative deviation of the measured values from those quoted in the literature (obtained using other viscometers) was less than 2.6%. The relative uncertainty of the experimental system was reduced to ±1.8% using the relative measuring method. Due to the micro-scale of the test section, only a micro-litre quantity of liquid is needed for a test; this is a potential advantage for measurement of bio-liquid viscosities.     

A laboratory viscometer—gelation timer

During the past two decades, the information explosion has led to a demand for systems of storing and retrieving information in every branch of science and technology. A number of the larger abstracting services are already experimenting with systems covering so great an area that the use of a computer is essential.Since, however, the, field of rheology is relatively small a simple classification and retrieval system is being developed, for use inRheology Abstracts, based upon ordinary 132-hole edge-punched cards. The first half of the system deals with the rheology of fluids and is already in use; it is described in detail in a recent paper (1). The second half, dealing with the rheology of solids, is still being developed.In the fluids system, holes are punched to indicate the following essential features of a paper: general nature; language; type of fluid; rheological properties; type of flow; boundary conditions; important variables and effects; theoretical treatment; type of apparatus; industrial processes involved. As a result two simple hand operations will serve to retrieve, for example, all the papers concerned with turbulent flow of suspensions, or with fracture in polymer melts. Additional operations lead to a narrower, more precise, retrieval.At present the classifying is being done by abstractors. It is hoped that authors will become familiar with the system and will make a practice of classifying their own papers; this would lead to more accurate classification and to the benefit of all concerned.Paper presented at the Conference on Experimental Rheology, University of Bradford, April 17–19, 1968.     

A slit viscometer for polymer melts

Summary The construction of a new type of viscometer is described. The essential feature of this apparatus is the use of a capillary with rectangular cross-section, one side of the rectangle being at least ten times larger than the other. Membrane pressure gauges can be mounted into the capillary wall of such an apparatus without disturbing the flow pattern inside the capillary.Thus the pressure drop is measured between two points inside the capillary without a need for end corrections.The shear rate-shear stress relationship of a molten polyethylene was studied with this apparatus. The results are compared with those obtained with cylindrical capillaries.

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Zusammenfassung Die Konstruktion eines neuen Viskosimetertyps wird beschrieben. Charakteristisch für dieses Viskosimeter ist die Verwendung einer Kapillare mit rechteckigem Querschnitt, dessen Rechteckseiten in einem Verhältnis von mindestens 101 gewählt werden. Membranmanometer können in die Kapillarwand eines derartigen Apparates eingebaut werden, ohne daß hierdurch das Strömungsprofil im Innern der Kapillare gestört wird.Auf diese Weise wird der Druckabfall zwischen zwei Stellen innerhalb der Kapillaren gemessen. Endkorrekturen werden überflüssig.Für ein geschmolzenes Polyäthylen wurde in diesem Apparat die Abhängigkeit des Geschwindigkeitsgefälles von der Schubspannung untersucht. Ein Vergleich mit den bei Verwendung zylindrischer Kapillaren erhaltenen Ergebnissen wurde angestellt.

     

A note on capillary viscometer theory: Start-up flow contribution

In gravity flow type capillary viscometer, the non-linear relationship between kinematic viscosity and efflux time can be due to two factors — the well known kinetic energy correction and the start-up flow during which the flow within the capillary attains its Poiseuillean character. The start-up contribution, however, appears to be an order of magnitude lower than that introduced by the kinetic energy correction for commonly used low-viscosity liquids encountered in practice.     

基于DIHPB技术的高应变率剪切测试方法

在测试材料动态力学性能时,直接撞击式霍布金森压杆（direct impact Hopkinson pressure bar,DIHPB）实验系统相对于分离式霍布金森压杆（split Hopkinson pressure bar,SHPB）,往往能获得更高的应变率。本文中采用一种新型双剪切试样,在DIHPB系统下对603钢进行了动态剪切测试。获得了603钢在应变率1 500～33 000 s⁻¹的剪应力-剪应变曲线,并与SHPB系统下的测试结果进行了对比。结果表明,由两种测试方法获得的流动应力具有较好的一致性,但曲线的上升沿存在明显区别。采用数值模拟对DIHPB方法的准确性进行了验证,并对该实验方法的适用条件进行了分析。采用DIHPB方法,可以观察到603钢的流动应力存在明显的应变率效应,但在较高的加载速度下材料的失效应力随着加载速度的增加而呈降低趋势。

     

Interaction between gravitational sedimentation and shear diffusion in a suspension moving in a rotational viscometer gap

The start up behavior of a concentrated suspension of nonaggregating settling particles in a rotational viscometer is examined. The results of one of the experiments are presented.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 44–51, September–October, 1990.     

A small scale capillary viscometer for polymer melts

Summary A small scale capillary viscometer that is capable of measuring the flow curves of 2–3 gms of molten polymer over the shear rate range 0.4 sec^–1 to 20,000 sec^–1 is described. A piezo electric crystal pressure transducer is used to measure the pressure directly above the capillary. Flow curves are given for anionic polystyrenes and polyethylene fractions, and it is shown that the viscosities measured agree with determinations in a cone and plate viscometer.

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Zusammenfassung Es wird ein maßstäblich kleines Kapillarviskosimeter für 2–3 g geschmolzener Polymere beschrieben, das die Durchfiußkurve in Abhängigkeit vom Scherkoeffizienten im Bereich von 0,4 sec^–1 bis 20000 sec^–1 bestimmt. Verwendet wird ein piezoelektrischer Kristall-Druckaufnehmer, der den Druck genau über der Kapillare mißt. Angeführt werden Durchflußkurven für anionische Polystyrole und Polyäthylenanteile. Es wird gezeigt, daß die gemessenen Zähigkeiten mit denen von Kegel- und Plattendichtemessern übereinstimmen.

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Paper presented at the Conference on Experimental Rheology, University of Bradford, April 17–19, 1968.     

基于手机惯性传感器与多特征CNN的驾驶行为识别算法

不良驾驶行为识别对于减少交通事故的发生及实现智能交通具有重要意义。针对目前驾驶行为识别精度不高及系统稳定性不好问题,提出了一种基于多特征卷积神经网络和智能手机惯性传感器的新型驾驶行为识别方法。通过获取手机惯性传感器数据,利用多特征卷积神经网络对数据集进行特征提取和分析,来实现对多种驾驶行为的识别。最后,利用实际采集的车载数据进行不同方法试验对比,该算法对驾驶行为的分类精度达到97.14%,在识别精度上有一定优势。此外,MFCNN测试结果的方差仅为0.014 391,小于其它3种网络模型,可见所研究的网络模型及方法更加稳定可靠。     

A contribution to the theory of the capillary viscometer

Summary A general arrangement of a capillary viscometer is examined with a non-steady flow of aNewtonian liquid. The flow is determined by a pressure dependent upon the time. The velocity is found as a function of the pressure gradient or the length coordinate and the time. The result can serve for the determination of the viscosity.Three illustrative examples are given.

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Zusammenfassung Der allgemeine Aufbau eines Kapillar-Viskosimeters wird an Hand des nichtstationären Fließens einer Newtonschen Flüssigkeit überprüft. Das Fließen wird durch einen zeitabhängigen Druck bestimmt. Die Geschwindigkeit ergibt sich danach als Funktion des Druckgradienten oder der Längen-Koordinate und der Zeit. Das Ergebnis kann zur Bestimmung der Viskosität dienen. Drei Beispiele dienen der Erläuterung.

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