Method of determining rheological parameters for linear viscoelastic medium under four kinds of uniform loading

1990 ◽  
pp. 103-112
Keyword(s):  
Viscoelastic Medium ◽  
Rheological Parameters ◽  
Uniform Loading ◽  
Linear Viscoelastic

SYNTHESIS AND VISCOELASTIC BEHAVIORS OF POLY(ANILINE-CO-O-ETHOXYANILINE) PARTICLES SUSPENDED ELECTRORHEOLOGICAL FLUID

2001 ◽  
Vol 15 (06n07) ◽  
pp. 649-656 ◽  
Author(s):  
H. J. CHOI ◽  
J. W. KIM ◽  
M. S. SUH ◽  
M. J. SHIN ◽  
K. TO
Keyword(s):  
Particle Size ◽  
Silicone Oil ◽  
Loss Modulus ◽  
Chemical Oxidation ◽  
Steady Shear ◽  
Rheological Parameters ◽  
Linear Viscoelastic Region ◽  
Linear Viscoelastic ◽  
Er Fluids ◽  
Poly Aniline

Copolyanilines are synthesized by a chemical oxidation of aniline and o-ethoxyaniline with various molar ratios in an acidic media, and then characteristics of these polymers such as chemical structure, particle size and the particle size distribution were examined by using FT-IR, SEM and particle size analyzer, respectively. Suspensions of copolyaniline containing ethoxy group, namely poly(aniline-co-o-ethoxyaniline), in silicone oil have been investigated as one of many potential candidates for dry-base electrorheological (ER) fluid systems. Rotational rheometer (Physica) equipped with a high voltage generator was used to characterize the rheological properties of ER fluids from both steady shear and dynamic tests. From the steady shear experiment, we obtained flow properties and found that ER fluids exhibited the yield phenomenon. On the other hand, viscoelastic property was also obtained from the dynamic experiment. Since viscoelastic properties for ER fluids are mainly dominated by the particle chain structure, the state at different time scale was analyzed from the rheological parameters such as storage modulus (G'), loss modulus (G'') and tan δ. We conducted a strain amplitude sweep at 1 Hz under an applied electric field to determine a linear viscoelastic region first. The G' and G'' were then measured by a frequency sweep from 0.1 to 100 Hz in the linear viscoelastic region.

The Fractional derivative rheological model and the linear viscoelastic behavior of hydrocolloids

2012 ◽  
Vol 33 (1) ◽  
pp. 141-151 ◽  
Author(s):  
Magdalena Orczykowska ◽  
Marek Dziubiński
Keyword(s):  
Fractional Derivative ◽  
Viscoelastic Properties ◽  
Rheological Model ◽  
Xanthan Gum ◽  
Viscoelastic Behavior ◽  
Rheological Parameters ◽  
Rice Starch ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic ◽  
The Impact

The Fractional derivative rheological model and the linear viscoelastic behavior of hydrocolloids This study was aimed at evaluating the possibility to use the Friedrich-Braun fractional derivative rheological model to assess the viscoelastic properties of xanthan gum with rice starch and sweet potato starch. The Friedrich-Braun fractional derivative rheological model allows to describe viscoelastic properties comprehensively, starting from the behaviour characteristic of purely viscous fluids to the behaviour corresponding to elastic solids. The Friedrich-Braun fractional derivative rheological model has one more virtue which distinguishes it from other models, it allows to determine the relationship between stress and strain and the impact of each of them on viscoelastic properties on the tested material. An analysis of the data described using the Friedrich-Braun fractional derivative rheological model allows to state that all the tested mixtures of starch with xanthan gum form macromolecular gels exhibiting behaviour typical of viscoelastic quasi-solid bodies. The Friedrich-Braun fractional derivative rheological model and 8 rheological parameters of this model allow to determine changes in the structure of the examined starch - xanthan gum mixtures. Similarly important is the possibility to find out the trend and changes going on in this structure as well as their causes.

scholarly journals Creep in oak material from the Vasa ship: verification of linear viscoelasticity and identification of stress thresholds

2020 ◽  
Vol 78 (6) ◽  
pp. 1095-1103
Author(s):  
R. Afshar ◽  
M. Cheylan ◽  
G. Almkvist ◽  
A. Ahlgren ◽  
E. K. Gamstedt
Keyword(s):  
Rheological Parameters ◽  
Stress Strain ◽  
Compressive Stresses ◽  
Linear Viscoelastic ◽  
Standard Linear Solid ◽  
Standard Linear ◽  
Linear Viscoelastic Behaviour ◽  
Creep Deformations ◽  
High Degree ◽  
Wooden Structures

Abstract Creep deformation is a general problem for large wooden structures, and in particular for shipwrecks in museums. In this study, experimental creep data on the wooden cubic samples from the Vasa ship have been analysed to confirm the linearity of the viscoelastic response in the directions where creep was detectable (T and R directions). Isochronous stress–strain curves were derived for relevant uniaxial compressive stresses within reasonable time spans. These curves and the associated creep compliance values justify that it is reasonable to assume a linear viscoelastic behaviour within the tested ranges, given the high degree of general variability. Furthermore, the creep curves were fitted with a one-dimensional standard linear solid model, and although the rheological parameters show a fair amount of scatter, they are candidates as input parameters in a numerical model to predict creep deformations. The isochronous stress–strain relationships were used to define a creep threshold stress below which only negligible creep is expected. These thresholds ranges were 0.3–0.5 MPa in the R direction and 0.05–0.2 MPa in the T direction.

Non-linear Rheological Properties of Soy Protein Isolate Dispersions and Acid-Induced Gels

2017 ◽  
Vol 13 (5) ◽  
Author(s):  
Chong-hao Bi ◽  
Li-jun Wang ◽  
Dong Li ◽  
Zhi-gang Huang ◽  
Benu Adhikari ◽  
...  
Keyword(s):  
Strain Amplitude ◽  
Soy Protein ◽  
Soy Protein Isolate ◽  
Protein Isolate ◽  
Rheological Parameters ◽  
Type I ◽  
Type Iv ◽  
Non Linear ◽  
Linear Viscoelastic ◽  
Rheological Experiments

Abstract This study presents the non-linear viscoelastic properties of soy protein isolate (SPI) dispersions and acid-induced gels to considerable detail. The storage (G′) and loss (G′′) moduli of SPI dispersions showed Type III (week strain overshoot) and Type IV (strong strain overshoot) networks when the strain amplitudes varied between 0.01 and 1.00 and 1.00 to 100.00, respectively. In the case of acid-induced SPI gels the rheological parameters showed the characteristics of Type I (strain thinning) network. Fourier transform rheological experiments showed that the higher harmonic curves obtained u strain sweep test showed quite different shapes for SPI dispersions and gels. In the case of dispersions, the highest I3/1 (0.101) occurred at the strain amplitude of 0.40 and then decreased to below 0.02. In the case of acid-induced SPI gels, the I3/1 value began to be appreciable at the strain amplitude of 0.1 increased rapidly to its highest value (I3/1=0.05).

Toward efficient sludge processing using novel rheological parameters: dynamic rheological testing

2006 ◽  
Vol 54 (5) ◽  
pp. 17-22 ◽  
Author(s):  
A. Ayol ◽  
S.K. Dentel ◽  
A. Filibeli
Keyword(s):  
Transport Processes ◽  
Rheological Parameters ◽  
Test Results ◽  
Linear Viscoelastic ◽  
Strain Sweep ◽  
Liquid States ◽  
Time Frames ◽  
Rheological Test ◽  
The Relationship ◽  
Slight Deformation

Materials known as complex fluids exhibit a transitional behaviour between their solid and liquid states. Sludges produced at different treatment stages of wastewater treatment are examples of these materials, since they exhibit solid behaviour within shorter time frames and liquid behaviour over longer durations. These sludges can also change from solid-like to liquid-like, or vice versa, when subjected to even a slight deformation; this stems from their complex makeup, which includes both particulate materials and polymeric gels, including both biopolymers and the synthetic polymers used in conditioning them. This paper focuses on two means of quantifying dynamic rheological test results: (1) the linear viscoelastic behaviour (LVE) of sludge samples, as measured by the strain sweep analysis storage (G′) and loss moduli (G″); and (2) the flow curve, which presents the relationship between the shear viscosity and shear rate and determines the yield stress values of samples using the strain sweep test mode. With these methods, sludges can be more accurately characterised, allowing better prediction of their behaviour in treatment and transport processes.

Nonlinear Dynamics of a Slender Axially Graded Beam Embedded in a Viscoelastic Medium

2017 ◽  
Author(s):  
Enrico Babilio
Keyword(s):  
Nonlinear Dynamics ◽  
Material Properties ◽  
Viscoelastic Medium ◽  
Motion Equation ◽  
Time Dependent ◽  
Large Deflections ◽  
Present Contribution ◽  
Transversal Motion ◽  
Linear Viscoelastic

In the present contribution the nonlinear dynamics of beams under axial time-dependent excitation is studied. The beams, which are embedded in a linear viscoelastic medium, are assumed as axially graded in terms of material properties. The transversal motion equation is derived under two main hypotheses, namely the beams satisfy the requirements of Euler-Bernoulli theory and undergo moderately large deflections.

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