Stress Relaxation of a Twaron®/Natural Rubber Composite

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
N. V. David ◽  
X.-L. Gao ◽  
J. Q. Zheng
Keyword(s):  
Stress Relaxation ◽  
Natural Rubber ◽  
Rheological Model ◽  
Maxwell Model ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
Generalized Maxwell Model ◽  
Rubber Composite ◽  
Long Time ◽  
Different Levels

The stress relaxation behavior of a Twaron CT709® fabric/natural rubber composite under a uniaxial constant strain is studied using three viscoelasticity models with different levels of complexity and a newly developed para-rheological model. The three viscoelasticity models employed are a one-term generalized Maxwell model (comprising one Maxwell element and an additional spring in parallel), a two-term generalized Maxwell model (including two Maxwell elements and an additional spring in parallel), and a four-parameter Burgers model. The values of the parameters involved in each model are extracted from the experimental data obtained in this study. The stress relaxation tests reveal that the stress starts to decay exponentially for a short duration and then continues to decrease linearly with time. It is found that the initial relaxation response of the composite is predicted fairly well by all of the four models, while the long-time stress relaxation behavior is more accurately predicted by the para-rheological model. The accuracy of each model in describing the stress relaxation behavior of the composite is quantitatively compared.

Effects of accelerator type on stress relaxation behavior and network structure of aged natural rubber/chloroprene rubber vulcanizates

2016 ◽  
Vol 49 (5) ◽  
pp. 381-396 ◽  
Author(s):  
Farzad A Nobari Azar ◽  
Murat Şen
Keyword(s):  
Stress Relaxation ◽  
Natural Rubber ◽  
Network Structure ◽  
Structural Changes ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
Rubber Blends ◽  
Chloroprene Rubber ◽  
Weather Changes ◽  
Behavior Network

Natural rubber/chloroprene rubber (NR/CR) blends are among the commonly used rubber blends in industry and continuously are exposed to severe weather changes. To investigate the effects of accelerator type on the network structure and stress relaxation of unaged and aged NR/CE vulcanizates, tetramethyl thiuram disulfide, 2-mercaptobenzothiazole, and diphenyl guanidine accelerators have been chosen to represent fast, moderate, and slow accelerator groups, respectively. Three batches have been prepared with exactly the same components and mixing conditions differing only in accelerator type. Temperatures scanning stress relaxation and pulse nuclear magnetic resonance techniques have been used to reveal the structural changes of differently accelerated rubber blends before and after weathering. Nonoxidative thermal decomposition analyses have been carried out using a thermogravimetric analyzer. Results indicate that there is a strong interdependence between accelerator type and stress relaxation behavior, network structure, cross-linking density, and aging behavior of the blends. Accelerator type also affects decomposition energy of the blends.

The Effect of Aging Conditions on the Stress Relaxation Behavior of 17-7PH Stainless Steel

2021 ◽  
Vol 1016 ◽  
pp. 1664-1669
Author(s):  
Shota Yamasaki ◽  
K. Takano
Keyword(s):  
Stainless Steel ◽  
Stress Relaxation ◽  
Dislocation Density ◽  
Cold Working ◽  
Relaxation Behavior ◽  
Age Hardening ◽  
Stress Relaxation Behavior ◽  
Long Time ◽  
Aging Conditions ◽  
High Age

17-7PH stainless steel is high age-hardening property due to precipitate NiAl intermetallics by aging heat treatment after the deformation induced martensitic transformation by cold working. In this study, the effect of aging conditions on stress relaxation behavior of 17-7PH stainless steel was investigated, and the mechanism of the stress relaxation was discussed. The 0.2% proof stress after aging at 753K for 180s-18ks is about 450MPa, and then decreases after 18ks. On the other hand, the stress relaxation ratio decreases by long time aging at 753K. The dislocation density of 17-7PH decreases by long time aging at 753K. The formation of NiAl clusters around 5nm by 3D-AP analysis is observed in 17-7PH aged at 753K for 1.8ks. It is suggested that the reduction of the stress relaxation ratio after long time aging at 753K is caused by NiAl clusters and decreasing mobile dislocation density.

The Stress-Relaxation Behavior of Rice as a Function of Time, Moisture and Temperature

2017 ◽  
Vol 13 (2) ◽  
Author(s):  
Pan Wang ◽  
Li-jun Wang ◽  
Dong Li ◽  
Zhi-gang Huang ◽  
Benu Adhikari ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Moisture Content ◽  
Master Curve ◽  
Superposition Principle ◽  
Relaxation Modulus ◽  
Maxwell Model ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
Linear Viscoelastic ◽  
Single Rice

Abstract: Stress-relaxation behavior of single rice kernel was studied using a dynamic mechanical analyzer (DMA) in compression mode. The relaxation modulus was measured in a moisture content range of 12–30 % on dry basis (d.b.) and a temperature range of 25–80°C. A constant stain value of 1 % (within the linear viscoelastic range) was selected during the stress-relaxation tests. The relaxation modulus was found to decrease as the temperature and moisture increased. A master curve of relaxation modulus as a function of temperature and moisture content was generated using the time–moisture–temperature superposition principle. Results showed that the generalized Maxwell model satisfactorily fitted the experimental data of the stress-relaxation behavior and the master curve of relaxation modulus (R2> 0.997). By shifting the temperature curves horizontally, the activation energy of the stress relaxation was obtained which significantly decreased with increase in the moisture content.

Stress-relaxation behavior of natural rubber/polystyrene and natural rubber/polystyrene/natural rubber-graft-polystyrene blends

2008 ◽  
Vol 108 (2) ◽  
pp. 904-913 ◽  
Author(s):  
R. Asaletha ◽  
P. Bindu ◽  
Indose Aravind ◽  
A. P. Meera ◽  
S. V. Valsaraj ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Natural Rubber ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior

The Stress Relaxation of Sulfur Vulcanizates of Natural Rubber

1957 ◽  
Vol 30 (1) ◽  
pp. 42-53
Author(s):  
J. P. Berry
Keyword(s):  
Experimental Study ◽  
Stress Relaxation ◽  
Natural Rubber ◽  
Oxygen Pressure ◽  
Relaxation Behavior ◽  
Two Stage ◽  
Stress Relaxation Behavior ◽  
Stage Process ◽  
Force Time ◽  
Effect Of Oxygen

Abstract An experimental study is reported of the stress relaxation behavior of sulfur vulcanizates of natural rubber maintained at constant extension. Of particular interest is the effect of oxygen pressure on the shape of the force-time curves, and the relaxation proceeding in absence of oxygen. The results are interpreted according to a two-stage process: (1) oxidation at the crosslinks and (2) scission of oxidized crosslinks.

Stress Relaxation Measurement of Agar Using a Polymer-Based Microfluidic Device

2013 ◽  
Author(s):  
Jiayue Shen ◽  
Peng Cheng ◽  
Wenting Gu ◽  
Michael Stacey ◽  
Zhili Hao
Keyword(s):  
Stress Relaxation ◽  
Microfluidic Device ◽  
Series Representation ◽  
Relaxation Modulus ◽  
Soft Materials ◽  
Maxwell Model ◽  
Relaxation Behavior ◽  
Relaxation Measurement ◽  
Stress Relaxation Behavior ◽  
Prony Series Representation

In light of the significance of the viscoelastic property of agar to cell-based tissue engineering, this paper presents the stress relaxation measurement of agar using a polymer-based microfluidic device. Comprised of a single polymer rectangular microstructure and a set of electrolyte-enabled distributed transducers, this device is capable of detecting continuous distributed static and dynamic loads. In the measurement, an agar specimen is placed on the device and a rigid probe is utilized to press the specimen against the device with a step displacement input. Consequently, the stress relaxation behavior of the specimen translates to time-dependent continuous distributed loads acting on the device and is further registered as discrete resistance changes by the device. Two agar specimens of 1% and 3% in concentration, respectively, are measured using this device; and the data analysis is conducted on the measured results to extract Young’s relaxation modulus, which is further expressed by a Prony-series representation of the Maxwell model with two exponential terms. The results demonstrate the feasibility of using this device to measure the stress relaxation behavior of soft materials.

Creep Behavior of a TWARON®/Natural Rubber Composite

2010 ◽  
Author(s):  
N. V. David ◽  
X.-L. Gao ◽  
J. Q. Zheng
Keyword(s):  
Natural Rubber ◽  
Creep Behavior ◽  
Rheological Model ◽  
Axial Strain ◽  
Time Spectrum ◽  
Secondary Creep ◽  
Creep Tests ◽  
Creep Response ◽  
Rubber Composite ◽  
Different Levels

The creep behavior of a Twaron CT709® fabric/natural rubber composite under a uniaxial constant stress is studied using three viscoelasticity models with different levels of complexity and a newly developed para-rheological model. The three models employed are a one-term generalized Maxwell (GMn = 1) model (consisting of one Maxwell element and an additional spring in parallel), a two-term generalized Maxwell (GMn = 2) model (including two parallel Maxwell elements and an additional spring in parallel), and a four-parameter Burgers model. The values of the parameters involved in each model are extracted from the experimental data obtained in this study. The creep tests reveal that the axial strain starts to increase exponentially during the primary stage and then continues to equilibrate linearly with time. The results show that the initial creep response of the composite is predicted fairly well by the GMn = 2 model, while the secondary creep is more accurately described by the GMn = 1 model. An implicit solution, together with a characteristic retardation time spectrum, obtained using the para-rheological model is found to provide more accurate predictions of the composite creep response than the three viscoelasticity models at both the primary and secondary stages.

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