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.

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.

Effect of Long-Term Aging and Creep Exposure on the Microstructure of TiAl-Based Alloy for Industrial Applications

2004 ◽  
Vol 842 ◽  
Author(s):  
Juraj Lapin ◽  
Mohamed Nazmy ◽  
Marc Staubli
Keyword(s):  
Chemical Composition ◽  
Constant Load ◽  
Industrial Applications ◽  
Tensile Creep ◽  
Creep Tests ◽  
Fine Needle ◽  
Term Creep ◽  
Applied Stresses ◽  
Creep Exposure

ABSTRACTThe effect of long-term aging and creep exposure on the microstructure of a cast TiAl-based alloy with nominal chemical composition Ti-46Al-2W-0.5Si (at.%) was studied. The aging experiments were performed at temperatures between 973 and 1073 K for various times ranging from 10 to 14000 h in air. Constant load tensile creep tests were performed at applied stresses ranging from 150 to 400 MPa and at temperatures between 973 and 1123 K up to 25677 h. During aging and creep testing the α2(Ti3Al)-phase in the lamellar and feathery regions transforms to the γ(TiAl)-phase and fine needle-like B2 precipitates. Microstructural instabilities lead to a softening of the alloy. The effect of this softening on long-term creep resistance is negligible at temperatures of 973 and 1023 K.

Creep Compliance of Polymer-Modified Asphalt, Asphalt Mastic, and Hot-Mix Asphalt

2003 ◽  
Vol 1829 (1) ◽  
pp. 33-38 ◽  
Author(s):  
Ota Vacin ◽  
Jiri Stastna ◽  
Ludo Zanzotto
Keyword(s):  
Creep Compliance ◽  
Superposition Principle ◽  
Asphalt Binder ◽  
Tensile Creep ◽  
Asphalt Binders ◽  
Simple Relationship ◽  
Modified Asphalt ◽  
Asphalt Mastic ◽  
Polymer Modified Asphalt ◽  
Time Temperature Superposition Principle

The possibility of using commercial rheometers for comprehensive testing of asphalt binders, asphalt mastics, and hot-mix asphalts (HMA) is explored. Samples of one polymer-modified asphalt, its mix with fine mineral filler (mastic), and one HMA prepared with the same modified asphalt as binders were tested in the dynamic shear rheometer (DSR) and the bending beam rheometer (BBR). All tested materials can be characterized by their discrete relaxation and retardation spectra (under the condition of small deformations). DSR testing was performed in the plate–plate and the torsion bar geometry. From the obtained relaxation and retardation spectra, the shear compliance, J(t), was calculated and compared with the tensile creep compliance, D(t), measured in BBR (both creep and recovery experiments were run). A simple relationship between J(t) and D(t) was found for the asphalt binder and the asphalt mastic. In the case of HMA, the bulk compliance, B(t), contributes to D(t) at short and long times. Both the Boltzmann superposition principle and the time–temperature superposition principle hold very well for all tested materials at low temperatures. There are qualitative differences, in the rheological behavior, of the asphalt binder and asphalt mastic on one side and the HMA on the other. These differences can be seen in dynamic (DSR) as well as in transient (BBR) experiments.

scholarly journals Long-Term Creep and Shrinkage Behavior of Concrete-Filled Steel Tube

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 295
Author(s):  
Doan-Binh Nguyen ◽  
Wei-Sheng Lin ◽  
Wen-Cheng Liao
Keyword(s):  
Stress Transfer ◽  
Shrinkage Strain ◽  
Steel Tube ◽  
Vertical Stress ◽  
Concrete Core ◽  
Concrete Filled Steel Tube ◽  
Structural Applications ◽  
Term Creep ◽  
Creep And Shrinkage

A concrete-filled steel tube (CFT) combines the advantages of concrete and steel in construction and structural applications. However, research on the time-dependent deformation of the CFT under long-term sustained loading are still limited, particularly for stress transfer between the steel tube and concrete due to creep. This study investigated the creep behavior of CFT over a long period of 400 days. The creep and shrinkage strain of CFT was significantly lower than those of concrete that was not confined within a steel tube. The vertical strains of the steel tube and concrete core were almost identical, and it was shown that they were well bonded and acted as a composite. The vertical stress of steel increased by 32.7%, whereas the vertical stress of concrete decreased by 15.8% at 375 days. The stress transfer is notable and cannot be neglected in CFT design. Moreover, the results of creep and shrinkage were compared to prediction values of the B4 model and B4-TW model to verify their validity.

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