Nonlinear stress relaxation of an entangled linear polystyrene in single step-strain flow: A quantitative theoretical investigation

2003 ◽  
Vol 41 (12) ◽  
pp. 1281-1293 ◽  
Author(s):  
Chun Y. Chen ◽  
Seng M. Wu ◽  
Zhi R. Chen ◽  
Tien J. Huang ◽  
Chi C. Hua
Keyword(s):  
Stress Relaxation ◽  
Theoretical Investigation ◽  
Single Step ◽  
Nonlinear Stress ◽  
Step Strain

Pom-pom model predictions on nonlinear stress relaxation in single-step strain flow

2007 ◽  
Vol 15 (3) ◽  
pp. 213-224
Author(s):  
Sheng Cheng Shie ◽  
Tzy Ming Yang ◽  
Chi Chung Hua
Keyword(s):  
Stress Relaxation ◽  
Single Step ◽  
Nonlinear Stress ◽  
Model Predictions ◽  
Step Strain

Nonlinear Stress Relaxation of H-Shaped Polymer Melt Revisited Using a Stochastic Pom-Pom Model

2003 ◽  
Vol 36 (6) ◽  
pp. 2141-2148 ◽  
Author(s):  
Sheng C. Shie ◽  
Chang T. Wu ◽  
Chi C. Hua
Keyword(s):  
Stress Relaxation ◽  
Polymer Melt ◽  
Nonlinear Stress

STRESS RELAXATION OF MAGNETORHEOLOGICAL FLUIDS

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2655-2661
Author(s):  
W. H. LI ◽  
G. CHEN ◽  
S. H. YEO ◽  
H. DU
Keyword(s):  
Stress Relaxation ◽  
Viscoelastic Model ◽  
Relaxation Modulus ◽  
Damping Function ◽  
Mr Fluids ◽  
Large Step ◽  
Linear Viscoelastic ◽  
Predicted Values ◽  
Two Parameters ◽  
Step Strain

In this paper, the experimental and modeling study and analysis of the stress relaxation characteristics of magnetorheological (MR) fluids under step shear are presented. The experiments are carried out using a rheometer with parallel-plate geometry. The applied strain varies from 0.01% to 100%, covering both the pre-yield and post-yield regimes. The effects of step strain, field strength, and temperature on the stress modulus are addressed. For small step strain ranges, the stress relaxation modulus G(t,γ) is independent of step strain, where MR fluids behave as linear viscoelastic solids. For large step strain ranges, the stress relaxation modulus decreases gradually with increasing step strain. Morever, the stress relaxation modulus G(t,γ) was found to obey time-strain factorability. That is, G(t,γ) can be represented as the product of a linear stress relaxation G(t) and a strain-dependent damping function h(γ). The linear stress relaxation modulus is represented as a three-parameter solid viscoelastic model, and the damping function h(γ) has a sigmoidal form with two parameters. The comparison between the experimental results and the model-predicted values indicates that this model can accurately describe the relaxation behavior of MR fluids under step strains.

scholarly journals Nonlinear stress relaxation of transiently crosslinked biopolymer networks

2021 ◽  
Vol 104 (3) ◽  
Author(s):  
Sihan Chen ◽  
Chase P. Broedersz ◽  
Tomer Markovich ◽  
Fred C. MacKintosh
Keyword(s):  
Stress Relaxation ◽  
Nonlinear Stress

scholarly journals Fractional Stress Relaxation Model of Rock Freeze-Thaw Damage

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Q. Liu ◽  
W. Chen ◽  
J. K. Guo ◽  
R. F. Li ◽  
D. Ke ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Fatigue Loading ◽  
Element Model ◽  
Model Parameters ◽  
Rock Stress ◽  
Relaxation Equation ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Nonlinear Stress ◽  
Freeze Thaw Cycle

Freeze-thaw cycle is a type of fatigue loading, and rock stress relaxation under freeze-thaw cycles takes into account the influence of the freeze-thaw cycle damage and deterioration. Rock stress relaxation under freeze-thaw cycles is one of the paramount issues in tunnel and slope stability research. To accurately describe the mechanical behaviour of stress relaxation of rocks under freeze-thaw, the software element is constructed based on the theory of fractional calculus to replace the ideal viscous element in the traditional element model. The freeze-thaw damage degradation of viscosity coefficient is considered. A new three-element model is established to better reflect the nonlinear stress relaxation behavior of rocks under freeze-thaw. The freeze-thaw and stress relaxation of rock are simulated by ABAQUS, the relevant model parameters are determined, and the stress relaxation equation of rock under freeze-thaw cycle is obtained based on numerical simulation results. The research shows that the test results are consistent with the calculated results, indicating that the constitutive equation can better describe the stress relaxation characteristics of rocks under freeze-thaw and provide theoretical basis for surrounding rock support in cold region.

Nonlinear Stress Relaxation of Polyisobutylene in Simple Extension

1976 ◽  
Vol 20 (1) ◽  
pp. 141-152 ◽  
Author(s):  
Carl R. Taylor ◽  
Roberto Greco ◽  
Ole Kramer ◽  
John D. Ferry
Keyword(s):  
Stress Relaxation ◽  
Simple Extension ◽  
Nonlinear Stress

Differential Dynamic Shear Moduli of Carbon Black-Filled Styrene-Butadiene Rubber Subjected to Large Shear Strain Histories

1986 ◽  
Vol 59 (2) ◽  
pp. 241-254 ◽  
Author(s):  
Koichi Arai ◽  
John D. Ferry
Keyword(s):  
Stress Relaxation ◽  
Carbon Black ◽  
Shear Strain ◽  
Single Step ◽  
Fourth Power ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Initial Value ◽  
Shear Moduli ◽  
Styrene Butadiene

Abstract Combined measurements of shear-stress relaxation and differential dynamic storage and loss shear moduli G′ and G″ following a single-step shear strain of 0.4, as well as measurements of dynamic moduli in on-off strain and stress histories, have been made on styrene-butadiene rubber (type 1502) filled with carbon black (N299) at loadings of 40, 50, 60, and 70 phr, with 10 phr Sundex 790 oil. Both cured and uncured compounds were studied at temperatures of 25.0° and −0.5°C respectively. The maximum oscillatory shear strain was 0.005, and the frequency was from 0.4 to 1.8 Hz. The storage shear modulus G′(ω, 0) measured without imposition of static strain was approximately proportional to the fourth power of the volume fraction of black. With imposition of single-step strain, the differential storage modulus G′(ω, γ; t) fell 25% to 35% but slowly recovered somewhat while the strain was maintained for 4 to 5 h. During this period, the static stress relaxed continuously. At the highest content of black, the drop in log G′ was the least, and the final recovery was closest to the initial value of G′(ω, 0). In on-off experiments on uncured compounds, when the strain was “on” for 250 s and then “off” (either stress or strain returned to zero), G′ decreased when the strain was imposed as before and decreased further when it was removed. In the “off” state, G′ recovered partially but did not attain the initial value of G′(ω, 0) even after 7 d. In on-off experiments on cured compounds, removal of stress caused G′ to either increase or decrease depending on the content of black; in any case, in the “off” state, G′ recovered completely to its initial value. Other strain histories involved on-off sequences with different “on” periods and multiple on-off sequences with different “on” periods and multiple on-off sequences. The results are interpreted in terms of a network of black particle aggregates whose contacts can slowly rearrange even in the absence of stress as shown by stress relaxation at very small strains in earlier studies. In large strains, it is postulated that some contacts are broken but can partially reform, especially in the stress-free state; the rate of reformation is similar to that of small-strain stress relaxation. Only in cured compounds is the network fully recovered, presumably because in these the particles are imbedded in a crosslinked matrix and have crosslinked bridges that facilitate reestablishment of interparticle contacts, whereas in uncured compounds the matrix has no crosslinks and the bound rubber on adjacent particles may be merely entangled.

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