Effect of Stress-Induced Damage Evolution on Long-Term Creep Behavior of Nonlinear Viscoelastic Polymer

2006 ◽  
Vol 324-325 ◽  
pp. 731-734 ◽  
Author(s):  
Rong Guo Zhao ◽  
Wen Bo Luo ◽  
Chu Hong Wang ◽  
Xin Tang
Keyword(s):  
Methyl Methacrylate ◽  
Temperature Stress ◽  
Creep Behavior ◽  
Damage Evolution ◽  
Creep Compliance ◽  
Superposition Principle ◽  
Nonlinear Viscoelastic ◽  
Compliance Curve ◽  
Term Creep

The mechanical behaviors were investigated by nonlinear creep tests of poly(methyl methacrylate) under different temperatures. The test duration was 4000 seconds. The corresponding temperature shift factors, stress shift factors and temperature-stress shift factors were obtained according to time-temperature superposition principle, the time-stress superposition principle and the time-temperature-stress superposition principle (TTSSP). The master creep compliance curve up to about 1-month at a reference temperature 22 degrees centigrade and a reference stress 14 MPa was constructed, and the effect of stress-induced damage evolution on the long-term creep behavior of polymeric material was accounted. It was shown that TTSSP provides an effective accelerated test technique in the laboratory, the results obtained from a short-term creep test of poly(methyl methacrylate) specimen at high temperature and stress level can be used to construct the master creep compliance curve for prediction of the long-term mechanical properties at relatively lower temperature and stress level, and the master creep compliance curve with damage considered can be applied to accurately characterize the long-term creep behavior of nonlinear viscoelastic polymer.

Time-Temperature-Stress Superposition Principle: Brief Description and Application to Polymer Creep Behavior

2012 ◽  
Vol 602-604 ◽  
pp. 681-684
Author(s):  
Yong Hua Li ◽  
Cheng Kai Jiang
Keyword(s):  
Temperature Stress ◽  
Stress Level ◽  
Creep Behavior ◽  
Physical Aging ◽  
Superposition Principle ◽  
Nonlinear Creep ◽  
Stress Superposition ◽  
Lower Temperature ◽  
Term Creep

A new accelerated characterization model for creep performances was briefly introduced first, which considers both the effects of temperature and stress level, named time-temperature- stress superposition principle (TTSSP). TTSSP assumes that the influence of stress level on the intrinsic time is similar to that of temperature for the creep behavior, as well as damage and physical aging. The creep curves at different state can be shifted into a master curve at reference state using TTSSP. Then the long-term creep behavior of viscoelastic materials at lower temperature and/or stress level can be predicted from the short-term ones. Finally, TTSSP was used to investigate the nonlinear creep behavior of high-density polyethylene (HDPE). It was shown that the long-term creep behavior of HDPE can be predicted successfully.

scholarly journals The influence of physical ageing on the in-plane shear creep compliance of 5HS C/PPS

2019 ◽  
Vol 24 (2) ◽  
pp. 197-220
Author(s):  
E. R. Pierik ◽  
W. J. B. Grouve ◽  
M. van Drongelen ◽  
R. Akkerman
Keyword(s):  
Creep Compliance ◽  
Superposition Principle ◽  
Woven Fabric ◽  
Tensile Creep ◽  
Physical Ageing ◽  
Creep Response ◽  
Structural Applications ◽  
Term Creep ◽  
Over Time

Abstract Thermoplastic polymer-matrix composites, such as carbon woven fabric reinforced poly(phenylene sulphide) (C/PPS), are increasingly used in the aircraft industry. Primary structural applications, however, are limited due to uncertainty concerning the long-term behaviour. Recent work indicated a progressive creep response over time, which would render these materials unusable for such applications. However, the effect of physical ageing was neglected, which is well known to alleviate the creep behaviour and hence physical ageing is rigorously included in this study on the long-term creep response of C/PPS. Short-term tensile creep tests in the bias direction were performed at temperatures of 50, 60, 65, 70, 75 and 80$^{\circ}\mbox{C}$ C ∘ to obtain a master curve using the time–temperature superposition principle. Ordinary horizontal shifting failed to produce a smooth curve and therefore three alternative approaches were used and compared. The physical ageing rate was, however, characterised with horizontal shifting only at 50$^{\circ}\mbox{C}$ C ∘ and was implemented by means of the effective time theory (Struik, 1977) to correct the momentary master curves for the influence of physical ageing. The resulting predictions are more realistic and demonstrate that the structural changes in a material reduce the creep rate over time. Hence, the long-term creep compliance tends to increase asymptotically towards a finite value, in contrast to the unbounded momentary response.

Time-Temperature-Stress Equivalence Applied to Accelerated Characterization of Creep Behavior of Viscoelastic Polymer

2007 ◽  
Vol 353-358 ◽  
pp. 1386-1389 ◽  
Author(s):  
Rong Guo Zhao ◽  
Wen Bo Luo ◽  
Chu Hong Wang ◽  
Xin Tang
Keyword(s):  
Temperature Stress ◽  
Stress Level ◽  
Creep Compliance ◽  
Superposition Principle ◽  
Test Duration ◽  
Nonlinear Creep ◽  
Creep Tests ◽  
Test Technique ◽  
Compliance Curve ◽  
Stress Superposition

Temperature induced change, and stress induced change as well, in intrinsic timescale were investigated by nonlinear creep tests on poly(methyl methacrylate). With four different experimental temperatures, from 14 to 26 degrees centigrade, time-dependent axial elongations of the specimen were measured at seven different stress levels, from 14 MPa to 30 MPa, and modeled according to the concept of time-temperature-stress equivalence. The test duration was only 4000 seconds. The corresponding temperature shift factors, stress shift factors and temperature-stress shift factors were obtained according to the time-temperature superposition principle (TTSP), the time-stress superposition principle (TSSP) and the time-temperature-stress superposition principle (TTSSP). The master creep compliance curve up to about two-year at a reference temperature 14 degrees centigrade and a reference stress 14 MPa was constructed by shifting the creep curves horizontally along the logarithmic time axis using shift factors. It is shown that TTSSP provides an effective accelerated test technique in the laboratory, the results obtained from a short-term creep test of PMMA specimen at high temperature and stress level can be used to construct the master creep compliance curve for prediction of the long-term mechanical properties at relatively lower temperature and stress level.

Application of Time-Ageing Time and Time-Temperature-Stress Equivalence to Nonlinear Creep of Polymeric Materials

2008 ◽  
Vol 575-578 ◽  
pp. 1151-1156 ◽  
Author(s):  
Rong Guo Zhao ◽  
Wen Bo Luo ◽  
Qi Fu Li ◽  
Chao Zhong Chen
Keyword(s):  
Creep Rate ◽  
Temperature Stress ◽  
Ageing Time ◽  
Superposition Principle ◽  
Time Shift ◽  
Test Duration ◽  
Nonlinear Creep ◽  
Test Technique ◽  
Term Creep

Based on the observations that high temperature accelerates creep rate of polymer while physical ageing plays a reverse role, and that there is an analogy between the influences of stress and temperature on the intrinsic times of polymers, the time-ageing time superposition principle (TASP) and the time-temperature-stress superposition principle (TTSSP) are used to evaluate the long-term creep behavior of poly(methyl methacrylate) (PMMA). PMMA specimens were aged for 2 to 120 hours at identical temperature, their short-term creep strains with 2-hour test duration were measured under various stress levels ranging from 14 to 30 MPa at room temperature, and modeled by means of time-ageing time equivalence and time-stress equivalence. The results show that the creep rate increases with stress, but decreases with ageing time. The ageing time shift factors vary with the stresses at which the shifts are applied. The ageing shift rate is independent on imposed stress in linear viscoelastic region, while it decreases with increasing stress when the material behaves in a nonlinear viscoelastic manner. The master creep compliance curve up to about 1-month at reference ageing time 120 hours and stress 18 MPa, which is nearly 2.5 decades longer than the test duration, is constructed by shifting the creep curves horizontally along the logarithmic time axis. The result illustrates that TTSSP, combined with TASP, provides an effective accelerated test technique for long-term mechanical behaviors of polymers.

Physical Aging and Creep Behavior of Poly(Methyl Methacrylate)

2007 ◽  
Vol 561-565 ◽  
pp. 2041-2044 ◽  
Author(s):  
Wen Bo Luo ◽  
Xin Tang ◽  
Rong Guo Zhao ◽  
Jiang Hua Tan ◽  
Yoshihiro Tomita
Keyword(s):  
Methyl Methacrylate ◽  
Aging Time ◽  
Stress Level ◽  
Creep Behavior ◽  
Physical Aging ◽  
Superposition Principle ◽  
Test Time ◽  
Nonlinear Creep ◽  
Poly Methyl Methacrylate ◽  
Compliance Curve

In this work, the physical aging and its effect on nonlinear creep behavior of poly(methyl methacrylate) are presented. After annealing above Tg to release the previous thermal and stress history, the samples were quenched to 60oC, aged for various times, and were then tested at three different stress levels (22MPa, 26MPa and 30MPa) at room temperature of 27oC. At each stress level, the creep strain was converted to compliance and measured as a function of test time and aging time. The test results show that higher stress accelerates creep rate of the material while physical aging plays a reverse role. The time-aging time superposition is applicable to build a master creep compliance curve at each stress level, and it is demonstrated that the shift rate deceases with increasing stress. Moreover, based on the time-stress superposition principle, a unified master curve was constructed by further shifting the sub-master curves at 30MPa and 26 MPa to a reference stress level of 22MPa.

The Creep Behavior of Wood-Polymer Composites

2013 ◽  
Vol 815 ◽  
pp. 632-638
Author(s):  
Yuan Zhu ◽  
Pei Ying Liu ◽  
Zhi Hong Jiang
Keyword(s):  
Power Law ◽  
Creep Behavior ◽  
Creep Compliance ◽  
Burgers Model ◽  
Wood Polymer ◽  
Different Temperatures ◽  
Linear Viscoelastic ◽  
Term Creep ◽  
Long Term Behavior

The creep behavior of WPCs needs to be addressed when developing and using this kind of materials. In this paper, the creep behavior of WPCs under linear viscoelastic region was investigated at different temperatures and bamboo flours levels. The creep compliance increase with the rise of temperature, the addition of bamboo flour has a positive effect on the creep behavior. Burgers model, Findley power law and TTSP were used to predict the long-term behavior of this kind material. Finely power law can well describe the creep properties of WPCs while Burgers model begins to diverge from measured data at about 100min. The application of TTSP was used to create master curve covered more than 108 from 30-min short-term creep compliance curves.

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