Time-stress correspondence in viscoelastic materials: an equation for the stress and temperature shift factor

2000 ◽  
Vol 3 (6) ◽  
pp. 347-351 ◽  
Author(s):  
Witold Brostow
Keyword(s):  
Temperature Shift ◽  
Shift Factor ◽  
Viscoelastic Materials ◽  
Time Stress

Temperature Correction of Backcalculated Moduli and Deflections Using Linear Viscoelasticity and Time-Temperature Superposition

1997 ◽  
Vol 1570 (1) ◽  
pp. 108-117 ◽  
Author(s):  
Sun Woo Park ◽  
Y. Richard Kim
Keyword(s):  
Linear Viscoelasticity ◽  
Superposition Principle ◽  
Asphalt Mixture ◽  
Temperature Shift ◽  
Relaxation Modulus ◽  
Analytical Description ◽  
Shift Factor ◽  
Temperature Correction ◽  
Temperature Superposition ◽  
Time Temperature Superposition

New analytical procedures for temperature correction of backcalculated asphalt concrete moduli and surface deflections were developed based on the theory of linear viscoelasticity and the time-temperature superposition principle and verified using falling weight deflectometer data and field temperature measurements. The new correction procedures explicitly utilize the thermorheological properties of the asphalt mixture. The resulting temperature-modulus correction factors depend only on the relaxation modulus and time-temperature shift factor of the mixture. The temperature-deflection correction factor depends on both the material properties and the layer thicknesses of the pavement section. Emphasis has been placed on the analytical description of the mixture’s thermoviscoelasticity responsible for temperature effects on mixture modulus and pavement deflection. A mechanistic framework for dealing with temperature correction problems for asphalt pavement has been introduced.

S0406-3-4 Determination of Time-temperature Shift Factor for Accelerated Testing of CFRP

2009 ◽  
Vol 2009.1 (0) ◽  
pp. 345-346
Author(s):  
Makoto OGATA ◽  
Katsuya FUKUSHIMA ◽  
Hongneng CAI ◽  
Masayuki NAKADA ◽  
Yasushi MIYANO
Keyword(s):  
Temperature Shift ◽  
Shift Factor ◽  
Accelerated Testing

Effect of Saturation Pressure on Equivalency of Decompression Time and Foaming Temperature on Cell Density of Foamed Polystyrene

2007 ◽  
Vol 26 (5) ◽  
pp. 295-304 ◽  
Author(s):  
Susumu Nakano ◽  
Minoru Shimbo ◽  
Akihiro Misawa
Keyword(s):  
Cell Growth ◽  
Temperature Dependence ◽  
Cell Density ◽  
Saturation Pressure ◽  
Temperature Shift ◽  
Shift Factor ◽  
Saturation State ◽  
Decompression Rate ◽  
Foaming Temperature ◽  
Decompression Time

In this paper, the effect of saturation pressure on the time-temperature equivalent law of the decompression rate (decompression time) and foaming temperature of the cell density, the number of cells per unit volume remaining in foamed plastic was discussed. The foaming was carried out in the method described be by using batch foaming process. The blowing agent was soaked into the resin as a solid state at various high saturation pressures under temperatures higher than the glass transition temperature of the resin. After foaming agent reached its saturation state, cell nucleation and cell growth were accelerated by decompression. Finally, cell growth was halted by cooling. The polystyrene (PS) specimens were foamed under the various saturation pressures, foaming temperatures and decompression rates. The following results were obtained. (1) Cell density of foamed PS shows time and temperature dependence as follows. The cell density increases when the decompression rate is quick, i.e. the decompression time is shortened at the condition of low foaming temperature, and cell density decreases when the decompression rate is slow, i.e. decompression time is lengthened at the condition of high foaming temperature under various saturation pressures. (2) The time-temperature equivalent law is maintained between the time dependence and temperature dependence of the cell density of foamed PS, and it can expressed with the same time-temperature shift factor if the decompression rate is the same even if saturation pressure changes.

Equivalent Time Temperature Model for Physical Aging and Temperature Effects on Polymer Creep and Relaxation

2004 ◽  
Vol 126 (4) ◽  
pp. 413-419 ◽  
Author(s):  
Ever J. Barbero ◽  
Kevin J. Ford
Keyword(s):  
Physical Aging ◽  
Temperature Shift ◽  
Shift Factor ◽  
Master Curves ◽  
Nonuniform Temperature ◽  
Equivalent Time ◽  
Temperature Method ◽  
Temperature Superposition ◽  
Term Data

The equivalent time temperature method (ETT) is a novel extension of the equivalent time method. ETT is developed in this work to deal with time-temperature shifting of long-term polymer and polymer composite creep data, including the effects of physical aging at nonuniform temperature. Modifications to classical testing methods and protocols are presented to obtain accurate and repeatable data that can support long-term predictions with nonuniform temperature conditions through time. These techniques are used to generate momentary Time temperature superposition (TTSP) master curves, temperature shift factor rates, and aging shift factor rates. Novel interpretation and techniques are presented to deal with the coupled age-temperature behavior over long times. Validation of predictions against over 20,000 Hr of long-term data in field conditions is presented.

Stress Relaxation Behavior of Ethylene Propylene-Hexadiene Terpolymers

1971 ◽  
Vol 44 (4) ◽  
pp. 1057-1064
Author(s):  
C. K. Shih
Keyword(s):  
Stress Relaxation ◽  
Abrupt Change ◽  
Temperature Shift ◽  
Shift Factor ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
Ethylene Propylene ◽  
Wlf Equation ◽  
Ethylene Content ◽  
Higher Temperature

Abstract 1. The stress relaxation behavior of E/P/hexadiene polymer over wide temperature [Tg to (Tg+140°C)] and composition (molar E/P = 1.7 to 4.4) ranges is described. 2. Although Tg of the polymers is essentially constant (− 60° C), the onset temperature for rubbery flow characterized by an abrupt change in the rate of stress relaxation is highly dependent upon composition. It increases to a higher temperature as the ethylene content is increased. It is also affected by the catalysts used for polymer synthesis. 3. The time-temperature shift factor for one sample was found to follow the WLF equation over the temperature range from − 50° C to 0° C.

Optimal Cooling Paths for a Class of Thermorheologically Complex Viscoelastic Materials

1985 ◽  
Vol 52 (3) ◽  
pp. 634-638 ◽  
Author(s):  
B. D. Harper
Keyword(s):  
Residual Stress ◽  
Thermal Stresses ◽  
Optimal Path ◽  
Shift Factor ◽  
Plate Material ◽  
Viscoelastic Materials ◽  
Vertical Shift ◽  
Jump Discontinuities ◽  
Cooling Path ◽  
Thermorheological Behavior

This paper concerns the optimal cooling of thin viscoelastic plates so as to minimize the residual thermal stresses upon completion of the cool-down process. The thermorheological behavior of the plate material is assumed complex in the sense that both horizontal and vertical shift factors are employed. The optimal path is shown to possess initial and final jump discontinuities and to depend on only one of the two components of the vertical shift factor. It is further demonstrated that significant reductions in the level of residual stress may be attained by following the optimal cooling path.

Automated system for investigating the short-time stress relaxation of viscoelastic materials

1977 ◽  
Vol 12 (1) ◽  
pp. 126-130
Author(s):  
M. R. Kilevits ◽  
Ya. Ya. Indulevich ◽  
P. N. Adavich
Keyword(s):  
Stress Relaxation ◽  
Automated System ◽  
Viscoelastic Materials ◽  
Time Stress ◽  
Short Time

Time–Temperature Superposition for Asphalt Mixtures with Growing Damage and Permanent Deformation in Compression

2003 ◽  
Vol 1832 (1) ◽  
pp. 161-172 ◽  
Author(s):  
Yanqing Zhao ◽  
Y. Richard Kim
Keyword(s):  
Permanent Deformation ◽  
Superposition Principle ◽  
Asphalt Mixture ◽  
Temperature Shift ◽  
Shift Factor ◽  
Compression Tests ◽  
Loading Test ◽  
Temperature Superposition ◽  
Time Temperature Superposition ◽  
Time Temperature Superposition Principle

The objective in this study was to check the validity of the time–temperature superposition principle for hot-mix asphalt (HMA) with growing damage and viscoplastic strain in the compression state, which is essential for the permanent deformation characterization of HMA. Constant crosshead rate compression tests were conducted at temperatures between 25°C and 55°C, and data were analyzed to construct the stresslog reduced-time master curves for various strain levels. Research results indicate that HMA with growing damage remains thermorheologically simple in the temperature range used in this study and that the time–temperature shift factor is only a function of temperature and is independent of the strain level. Two types of tests, the repeated creep and recovery test and the cyclic sinusoidal loading test, were performed in this study to validate the time–temperature superposition in loading histories commonly used in asphalt mixture testing. The results further confirm that the time–temperature superposition is valid for HMA with growing damage and permanent deformation and that the response of HMA depends only on the reduced loading history.

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