scholarly journals The elastics – viscosity propertis of printing role offset inks according to relacxation rheometry

2021 ◽  
pp. 37-48
Author(s):  
A.K. Dorosh ◽  
A.V. Shevchuk
Keyword(s):  
Shear Stress ◽  
Elastic Modulus ◽  
Shear Rate ◽  
Strain Rate ◽  
Loss Modulus ◽  
Complex Viscosity ◽  
Shear Strain Rate ◽  
Loss Angle ◽  
Flow Curves ◽  
Quantitative Measurements

Dire relacxation rheometry methods carried out quantitative measurements and established quvalitative patterns of the dependencies of the main elastic-viscous characteristics for the Cybo black ink system in the temperature range of ( 293-333)°K of its technological resistence, namely : the equilibrium elastic modulus and the angle loss modulus and loss angle tangent; complex viscosity and full reological flow curves of the first shear rate and second (viscosity) of the species; degree of destraction of elastic and viscous properties depending on the value: shear stress; shear strain rate ; relative or absolute deformation on the sample and its temperature.

scholarly journals The influence of base oil type on the rheological properties of ecological lubricating greases

Nafta-Gaz ◽  
2021 ◽  
Vol 77 (2) ◽  
pp. 127-135
Author(s):  
Rafał Kozdrach ◽  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Rheological Properties ◽  
Measurement Data ◽  
Measuring System ◽  
Rheological Parameters ◽  
Flow Curves ◽  
Lubricating Grease ◽  
Dispersion Phase ◽  
Base Oil

The article presents the results of research on the influence the type of base oil in lubricating compositions has on the rheological parameters of selected lubricants. Vegetable, mineral, and synthetic dispersion phases were used to produce lubricating greases. The modified amorphous silica was used as the dispersed phase. However, as a modifying additive was used a substance containing the antioxidants, corrosion inhibitors, and EP/AW additives. The experiments on rheological properties were carried out using a Physica MCR 101 rotational rheometer (manufactured by Anton Paar), equipped with a diffusion air bearing and connected to a pneumatic supply – an oil-free Jun-Air compressor and air drying block. The device is equipped with a Peltier system for temperature control in the range of –20°C to 200°C and an external thermostatic VISCOTHERM V2 system, working in the temperature range of –20°C to 200°C. The rheometer control and measurement data analysis were performed using Rheoplus software. The tests were carried out using a cone-plate measuring system with a shear rate range of 0.01–100 s-1 at 20°C for lubricating compositions prepared on various oil bases. To evaluate the value of rheological parameters, the results of tests of the dependence between shear stress and shear rate (flow curves) were used. For the theoretical determined on the flow curves, the following rheological models were used: Bingham, Herschel–Bulkley, Casson, and Tscheuschner. The values of the shear stress (yield point) in depending on the type of dispersion phase has changed. This proves that the use of a base oil with the appropriate functional properties does not weaken, but reinforces the spatial structure of a lubricating grease. It has an important meaning when selecting construction parameters when designing a central lubrication system with grease made from a vegetable oil base (Abyssinian oil). The rheological properties of the lubricating grease are influenced by the type of base oil and thickener, any additives in the grease, the production technology of the grease, and the conditions in which it is used. The tests revealed an important influence of the base oil on the rheological parameters that describe the behaviour of lubricating compositions subjected to stresses and strains in a lubricating system.

scholarly journals Erebus Glacier Tongue, Mcmurdo Sound, Antarctica

1974 ◽  
Vol 13 (67) ◽  
pp. 27-35 ◽  
Author(s):  
G. Holdsworth
Keyword(s):  
Shear Stress ◽  
Strain Rate ◽  
Shear Strain ◽  
Longitudinal Strain ◽  
Strain Rates ◽  
Shear Strain Rate ◽  
Mcmurdo Sound ◽  
Glacier Tongue ◽  
The Past ◽  
Image Position

Examination of the past and present behaviour of the Erebus Glacier tongue over the last 60 years indicates that a major calving from the tongue appears to be imminent. Calculations of the regime of the tongue indicate that bottom melt rates may exceed 1 m a−1. By successive mapping of the ice tongue between the years 1947 and 1970, longitudinal strain-rates were determined using the change in distance between a set of 15 teeth, which are a prominent marginal feature of the tongue. Assuming a flow law for ice of the form where τ is the effective shear stress and is the effective shear strain-rate, values of the exponent n = 3 and B = 1 × 108 N m−2 are determined. These are in fair agreement with published values.

scholarly journals PROCESSING ADDITIVES AND RHEOLOGICAL PROPERTIES OF MOLDED PHENOLIC PLASTICS

2019 ◽  
Vol 14 (1) ◽  
pp. 90-96
Author(s):  
P. V. Surikov ◽  
N. L. Shembel ◽  
A. A. Yurkin ◽  
A. V. Petrogradsky ◽  
V. D. Sevruk ◽  
...  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Phenolic Resin ◽  
Volume Fraction ◽  
Slip Flow ◽  
Capillary Wall ◽  
Flow Curves ◽  
Flow Through ◽  
Capillary Viscosimetry ◽  
Stress Flow

By the method of capillary viscosimetry, the melt flow curves of the molded phenolic resin and its compositions with lubricant, plasticizer and their mixture were obtained. It was shown that the size (diameter) of the capillary channel influences the dependence of the effective shear rate on the shear stress (flow curves) of the studied compositions. Such rheological behavior of the compositions during flow is associated with the effect of sliding along the surface of the capillary wall. According to the Mooney method, the dependences of the effective shear rate at given values of shear stress on the reciprocal of the capillary radius are plotted. The function of the slip velocity on the shear stress on the capillary wall is characterized in terms of the slip coefficient, which relates the shear stress on the capillary wall to the velocity of the composition along it. For the studied compositions, the total flow through the capillary was divided into volume fractions, one of which is associated with a shear flow; the other is determined by the slip effect. It has been shown that the introduction of both a lubricant and a plasticizer into the composition leads to an increase in the fluidity of the compositions. At the same time, adding of lubricant increases the volume fraction of the slip flow. The greatest effect of increasing the fluidity of the composition gives the use of complex modifying additives containing both lubricant and plasticizer.

Yield Stress of Emulsions and Suspensions as Measured in Steady Shearing and in Oscillations

2008 ◽  
Vol 18 (4) ◽  
pp. 44790-1-44790-8 ◽  
Author(s):  
I. Masalova ◽  
A.Ya. Malkin ◽  
R. Foudazi
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Yield Stress ◽  
Flow Curves ◽  
Dynamic Yield Stress ◽  
Shear Rates ◽  
Meaningful Material ◽  
Dynamic Yield ◽  
Steady Shearing ◽  
Concentrated Emulsions

Abstract The yield stresses of five samples (two highly concentrated emulsions, two Kaolin dispersions and mayonnaise) were determined in two ways. In one case, steady shear experiments were performed over a range of incrementally decreasing shear rates. The resulting flow curves, plotted as shear stress against shear rate, clearly showed the existence of a yield stress for each sample, the Herschel-Bulkley model being fitted to obtain values. In the second case, oscillatory amplitude sweeps were performed at three frequencies, and the “dynamic yield stress” was defined as the stress at which deviation from linearity occurred; this procedure has often been used to determine the yield stress of emulsions. It was found that the dynamic yield stress is frequency dependent, and cannot therefore be thought of as physically meaningful material property. At no frequency did the dynamic yield stress correlate with the yield stress obtained from the flow curves.

A Rheological Study of Lemon Curd Made of Frozen-thawed Liquid Egg Yolk

2021 ◽  
pp. 7-11
Author(s):  
Karina I. Hidas ◽  
◽  
Anna Visy ◽  
Ildikó Cs. Nyulas-Zeke ◽  
László Friedrich ◽  
...  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Frozen Storage ◽  
Egg Yolk ◽  
Egg White ◽  
Lemon Juice ◽  
Hot Water ◽  
Rheological Parameters ◽  
Flow Curves ◽  
Rheological Study

In this study, we examined the industrial usability of frozen and thawed liquid egg yolk (LEY) by preparing lemon curd samples. Therefore, LEY frozen at-18°C was used to make lemon curd samples. LEY was stored for 90 days at -18°C and it was thawed with two different methods (in 2 hours, 35°C and in 24 hours, 5°C) on measurement days (day 1, 7, 14, 30, 60 and 90). After thawing of LEY samples, lemon curd samples were made by adding liquid egg white, butter, lemon juice and sugar. Ingredients were mixed by constant whisking over the steam of hot water. After that, butter was also added to the cream and it was cooled to 20°C. Rheological parameters of the lemon curd samples were examined with rotational rheometer. Shear stress data were recorded by increasing, than by decreasing shear rate values in the range of 10-1000 1/s. Herschel-Bulkley model was fitted to the flow curves of decreasing shear rate. Based on our measurements, we found that the thawing method of frozen liquid egg yolk does not affect the rheological properties of lemon curd made of them, but the length of the frozen storage does.

Application and Prospect of the Non-Newtonian Fluid in Industrial Field

2013 ◽  
Vol 770 ◽  
pp. 396-401 ◽  
Author(s):  
Yan Peng ◽  
Bing Hai Lv ◽  
Ju Long Yuan ◽  
Hong Bo Ji ◽  
Lei Sun ◽  
...  
Keyword(s):  
Shear Stress ◽  
Strain Rate ◽  
Shear Strain ◽  
Linear Relationship ◽  
Rheological Properties ◽  
Newtonian Fluid ◽  
Shear Strain Rate ◽  
Mechanical Processing ◽  
Different Types ◽  
Individual Protection

Non-Newtonian fluid is a kind of fluid that its shear stress is not always keeps a linear relationship with the shear strain rate. An overview of its applications was made here. Based on the special rheological properties, non-Newtonian fluids are divided into different types and used as additives, mediums and protective materials in many fields. The paper focuses on its applications in fluid rheological properties improving, damping devices, individual protection equipments and mechanical processing. The main achievements in application of the non-Newtonian fluid were introduced and a further prospect was also summarized.

scholarly journals Rheological and Prediction of melt viscosity flow curves for blend of Polycarbonate (PC) and Polyacrylonitrile butadiene styrene (ABS)

2019 ◽  
Vol 12 (6) ◽  
pp. 33-40
Author(s):  
Alsaeed Douaa ◽  
Deri Fawaz
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Temperature Dependence ◽  
Melt Viscosity ◽  
Flow Curves ◽  
Actual Measurement ◽  
Shear Rates ◽  
Different Temperatures ◽  
Experimental Validity ◽  
Butadiene Styrene

A knowledge of the variation of melt viscosity of thermoplastic polymers with both shear rate and temperature is of considerable importance to plastics engineers as well as to polymer rheologists. The Actual measurement of melt viscosity at large number of temperatures and shear rates is frequently a tedious and time-consuming task. The experimental validity for superimposing Log shear stress – Log shear rate curves at different temperatures along the log shear rate axis has been established for the mixture of (polycarbonate and polyacrylonitrile butadiene styrene). The temperature dependence of the resultant shift factors has been determined to predict viscosities as a function of temperature and shear rate is discussed

Non-axisymmetric Homann stagnation-point flows

2012 ◽  
Vol 702 ◽  
pp. 460-469 ◽  
Author(s):  
P. D. Weidman
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Strain Rate ◽  
Stagnation Point ◽  
Rate Ratio ◽  
Numerical Solutions ◽  
New Family ◽  
Outer Potential ◽  
Asymptotic Behaviours ◽  
Stress Parameters

AbstractA modification of Homann’s axisymmetric outer potential stagnation-point flow of strain rate $a$ is obtained by adding periodic radial and azimuthal velocities of the form $b\hspace{0.167em} r\sin 2\theta $ and $b\hspace{0.167em} r\cos 2\theta $, respectively, where $b$ is a shear rate. This leads to the discovery of a new family of asymmetric viscous stagnation-point flows depending on the shear-to-strain-rate ratio $\gamma = b/ a$ that exist over the range $\ensuremath{-} \infty \lt \gamma \lt \infty $. Numerical solutions for the wall shear stress parameters and the displacement thicknesses are given and compared with their large-$\gamma $ asymptotic behaviours. Sample similarity velocity profiles are also presented.

Based on Rheological to Calculate Anchor Parameter for Foundation Pit

2012 ◽  
Vol 538-541 ◽  
pp. 665-668
Author(s):  
Xin Wen Suo ◽  
Chen Min Gu
Keyword(s):  
Shear Stress ◽  
Numerical Calculation ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Strain Rate ◽  
Difference Method ◽  
Rheological Model ◽  
Shear Strain Rate ◽  
Axial Distribution ◽  
Foundation Pit

Pointed to character of rheological mechanics and limited equilibrium method, a new viso-elasto-plastic rheological model is builded with minimum locked load formula abtained.The finite difference method with C++ and inline FISH program ,is applied to analyze engineering instance. Based on calculated results and testing on spot, plentiful key parameters on whole bonged and prestressed bolt is studied.Lastly,the conclusions are open out ,including minimum locked loading,stress and maximal axial distribution of prestressed steal, hump distribution of shear stress on grount,shear strain rate of surface and displacement of reinforced foundation pit and so on.The numerical calculation is coincident with testing factors.

scholarly journals Deformation rates in combined compression and shear for ice which is initially isotropic and after the development of strong anisotropy

1996 ◽  
Vol 23 ◽  
pp. 247-252 ◽  
Author(s):  
Li Jun ◽  
T.H Jacka ◽  
W.F. Budd
Keyword(s):  
Shear Stress ◽  
Steady State ◽  
Stress State ◽  
Strain Rate ◽  
Shear Strain ◽  
Uniaxial Compression ◽  
Simple Shear ◽  
Strain Rates ◽  
Shear Strain Rate ◽  
State Dependent

Laboratory-prepared fine-grained, initially isotropic polycrystalline ice samples were deformed under conditions of simple shear with simultaneous uniaxial compression at a constant temperature of −2.0°C. The aim was to investigate the effects of stress configuration on the flow rate of initially isotropic ice and on ice with subsequent stress and strain-induced anisotropy. Experiments were carried out for various combinations of shear and compression with shear stress ranging from 0 to 0.49 MPa and compressive stress ranging from 0 to 0.98 MPa, but such that for every experiment the octahedral shear stress was 0.4 MPa.The strain curves resulting from the experiments clearly exhibit minimum strain rates while the ice is still isotropic, and steady-state tertiary strain rates along with the development of steady-state anisotropic fabric patterns. With constant octahedral stress (root-mean-square of the principal stress deviators), the minimum octahedral shear-strain rate has no dependence on stress configuration. This result supports the hypothesis that the flow of isotropic ice is dependent only on the second invariant of the stress tensor. This fundamental assumption has been used to provide a general description of ice-flow behaviour independent of the stress configuration (e.g. Nye, 1953; Glen, 1958; Budd, 1969).For the tertiary flow of anisotropic ice, the octahedral strain rate is stress-state dependent as a consequence of the developed crystal-orientation fabric, which is also stress-state dependent, and which develops with strain and rotation. The present tests indicate that the enhancement factor for steady-state tertiary octahedral shear-strain rate depends on the shear or compression fraction and varies from about 10 for simple shear (with zero compression) to about 3 for uniaxial compression (with zero shear).

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