Vane Yield Stress of Native and Cross-linked Starch Dispersions in Skimmed Milk: Effect of Starch Concentration and λ-carrageenan Addition.

2006 ◽  
Vol 12 (3) ◽  
pp. 253-260 ◽  
Author(s):  
A. Tárrega ◽  
E. Costell ◽  
M. A. Rao
Keyword(s):  
Yield Stress ◽  
Maize Starch ◽  
Starch Concentration ◽  
Native Starch ◽  
Highly Sensitive ◽  
Before And After ◽  
Static Yield ◽  
Dynamic Yield ◽  
D Values ◽  
Static Yield Stress

The effects of starch concentration and -carrageenan addition on the yield stress values of native and cross-linked waxy maize starch-milk systems were studied. Static yield stress (0-S) and dynamic yield stress (0-D) of each dispersion were measured using the vane method before and after breaking down its structure by shearing, respectively. Increases in values of 0-S with concentration of starch and -carrageenan were higher for cross-linked starch than those of native starch. 0-D values of cross-linked starch also increased with the concentration of starch and -carrageenan. In contrast, for native starch samples, 0-D values were very low and did not vary much with concentration of either starch or -carrageenan indicating that the structures responsible for the yield stresses were highly sensitive to shearing.

scholarly journals Shear Rate-Dependent Rheological Properties of Mine Tailings: Determination of Dynamic and Static Yield Stresses

2019 ◽  
Vol 9 (22) ◽  
pp. 4744
Author(s):  
Sueng-Won Jeong
Keyword(s):  
Shear Rate ◽  
Yield Stress ◽  
Stress Growth ◽  
Rate Dependent ◽  
Static Yield ◽  
Dynamic Yield ◽  
Bingham Yield Stress ◽  
Growth Methods ◽  
Static Yield Stress

In this paper, shear rate-dependent rheological properties of mine tailings taken from abandoned mine deposits prone to mass movements are examined using a commercial ball-measuring rheological system. The yield stresses (i.e., dynamic and static yield stresses) and viscosity of sand-rich materials are examined by the shear rate-controlled flow curve and time-dependent stress growth methods. Before yielding, the shear stress reaches a peak value (i.e., yield stress) observed for all flow curves. In the steady-state condition, the materials have a minimum shear stress (i.e., dynamic yield stress). The static yield stress can be determined under a constant applied shear rate with different initial values ranging from 10−4 to 10−1 s−1. As a result, the Bingham yield stress and viscosity can be used as a first approximation for estimating the debris flow mobility of post-failure materials. However, the Bingham yield stress is competitive with the static yield stress measured from stress growth methods. Upon comparison of the dynamic and static yield stresses, the static yield stress is approximately 35–45 times greater than the dynamic yield stress, and may be strongly related to microstructural changes (i.e., thixotropy). In this context, special attention must be paid to the determination of yield stresses in debris flow mitigation programs.

STATIC YIELD STRESS IN MAGNETORHEOLOGICAL FLUID

2001 ◽  
Vol 15 (06n07) ◽  
pp. 1078-1084 ◽  
Author(s):  
W. KORDONSKI ◽  
S. GORODKIN ◽  
N. ZHURAVSKI
Keyword(s):  
Experimental Data ◽  
Yield Stress ◽  
Magnetorheological Fluid ◽  
Dynamic Yield Stress ◽  
Mr Fluids ◽  
Static Yield ◽  
Dynamic Yield ◽  
Static Yield Stress

A method and a device for measuring a true static yield stress in magnetorheological (MR) fluids are proposed. The data obtained by means of this device are compared with the measured values of the dynamic yield stress for similar compositions as well as with the quantities calculated by the reported models. It is shown that the dynamic yield stress exceeds the static one. The experimental data better agree with Rosensweig's model.

scholarly journals The use of flat-ended projectiles for determining dynamic yield stress I. Theoretical considerations

1948 ◽  
Vol 194 (1038) ◽  
pp. 289-299 ◽  
Keyword(s):  
Yield Stress ◽  
High Stress ◽  
Maximum Acceleration ◽  
Static Yield ◽  
Dynamic Yield ◽  
The Difference ◽  
Actual Yield ◽  
Short Time ◽  
Theoretical Considerations ◽  
Static Yield Stress

It has long been known that metals may be subjected momentarily to stresses for exceeding their static yield stress without suffering plastic strain. One of the simplest methods for subjecting a metal to a high stress for a short time is to form it into a cylindrical specimen and fire this at a steel target. The front part of this projectile crumples up, but the rear part is left undeformed. If the target is rigid the distance which this portion travels while it is being brought to rest may be taken as the difference between the initial length and the length of the deformed specimen after impact. Knowing the velocity of impact, a minimum possible value can be assigned to the maximum acceleration of the material, and from this a minimum value for the yield stress can be calculated. The actual yield stress is considerably greater than this minimum, and methods are given for calculating a more probable value.

Dynamic and Static Yield Stress of Metallic Suspensions

2006 ◽  
Vol 116-117 ◽  
pp. 587-590 ◽  
Author(s):  
Michael Modigell ◽  
M. Hufschmidt
Keyword(s):  
Shear Stress ◽  
Yield Stress ◽  
Internal Structure ◽  
Time Dependency ◽  
Creep Tests ◽  
Structural Dynamic ◽  
Maximum Value ◽  
Static Yield ◽  
Dynamic Yield ◽  
Static Yield Stress

Oscillation experiments, creep tests and shear stress ramps have been performed to analyze the yield stress and its time dependency. It has to be distinguished between iso-structural, dynamic and static yield stress. The iso-structural yield stress occurs immediately after shearing. Since the slurry structure remains unchanged, it is equivalent to the structure during shearing. At rest an internal structure builds up, this leads to an increase of the yield stress, which is referred to as the dynamic yield stress. It increases until its maximum value, the static yield stress, is reached.

LANTHANUM TITANATE NANOPARTICLES ER FLUIDS WITH HIGH PERFORMANCE

2012 ◽  
Vol 26 (13) ◽  
pp. 1250079 ◽  
Author(s):  
DE WANG ◽  
RONG SHEN ◽  
SHIQIANG WEI ◽  
KUNQUAN LU
Keyword(s):  
Yield Stress ◽  
Silicone Oil ◽  
Heating Temperature ◽  
Hydroxyl Group ◽  
Lanthanum Titanate ◽  
Different Temperatures ◽  
Static Yield ◽  
Er Fluids ◽  
Er Fluid ◽  
Static Yield Stress

A new type of electrorheological (ER) fluid consisting of lanthanum titanate (LTO) nanoparticles is developed. The ER fluids were prepared by suspending LTO powder in silicone oil and the particles were fabricated by wet chemical method. This ER fluid shows excellent ER properties: The static yield stress reaches over 150 kPa under 5 kV/mm with linear dependence on the applied DC electric field, and the current density is below 10 μA/cm2. In order to investigate the affect factor on the ER behavior, the LTO powder were heated under different temperatures. The ER performances of two particles treated under different temperatures were compared and the composition changes for those particles were analyzed with TG-FTIR technique. It was found that the static yield stress of the suspensions fell from over 150 kPa to about 40 kPa and the current densities decreased prominently as the rise of the heating temperature. TG-FTIR analysis indicated that polar groups remained in the particles such as alkyl group, hydroxyl group and carbonyl group etc., contribute to the ER effect significantly. The experimental results are helpful to understand the mechanism of the high ER effect and to synthesize better ER materials.

Influence of Fructose and Sucrose on Small and Large Deformation Rheological Behaviour of Heated Amioca Starch Dispersions

2004 ◽  
Vol 10 (1) ◽  
pp. 51-57 ◽  
Author(s):  
D. B. Genovese ◽  
V. M. Acquarone ◽  
K. -S. Youn ◽  
M. A. Rao
Keyword(s):  
Yield Stress ◽  
Large Deformation ◽  
Heating Temperature ◽  
Ageing Time ◽  
Rheological Behaviour ◽  
Angular Frequency ◽  
Rheological Parameters ◽  
Static Yield ◽  
Pasting Temperature ◽  
Dynamic Yield

Effect of sucrose or fructose on the rheological behaviour of gelatinized 5% w/w amioca starch dispersions (GSDs), was studied by small and large deformation rheological techniques. Storage (G0) and loss (G00) moduli as a function of angular frequency (o), and shear stress (s) as a function of shear rate (_) data were obtained on GSDs with: 0, 30 and 60% w/w sugars. Magnitudes of Herschel–Bulkley yield stress (0-HB) were determined from – _ data. Using the vane method, the static yield stress (0s), the dynamic yield stress (0d) and the shear modulus (G) were determined. Effect of pasting temperature and ageing time were also studied by the vane method. Addition of sugars produced an increase in all rheological parameters except 0d, suggesting that sugars increased the strength of the internal bonds or cohesiveness of the GSDs; in general, fructose was slightly more effective than sucrose. Equivalent parameters: G0 and G, and 0-HB and 0s showed good agreement. Decreasing the heating temperature increased G. GSDs with fructose showed a clear increase in 0s and G with ageing time.

scholarly journals A study of the static yield stress in a binary Lennard-Jones glass

2004 ◽  
Vol 120 (6) ◽  
pp. 2788-2801 ◽  
Author(s):  
F. Varnik ◽  
L. Bocquet ◽  
J.-L. Barrat
Keyword(s):  
Yield Stress ◽  
Lennard Jones ◽  
Static Yield ◽  
Static Yield Stress
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