Determination of the Long-Term Properties in Laminate-Thickness Direction of Textile-Reinforced Thermoplastic Composites under Compression Using Time-Temperature Superposition

2015 ◽  
Vol 18 (3) ◽  
pp. 369-375 ◽  
Author(s):  
Martin Pohl ◽  
Robert Kupfer ◽  
Ilja Koch ◽  
Niels Modler ◽  
Werner A. Hufenbach
Keyword(s):  
Thermoplastic Composites ◽  
Thickness Direction ◽  
Temperature Superposition ◽  
Time Temperature Superposition ◽  
Laminate Thickness

Time and temperature effects on geomembrane strain from a gravel particle subjected to sustained vertical force

2012 ◽  
Vol 49 (3) ◽  
pp. 249-263 ◽  
Author(s):  
A. Sabir ◽  
R.W.I. Brachman
Keyword(s):  
Experimental Data ◽  
Temperature Effects ◽  
High Density Polyethylene ◽  
Measured Data ◽  
Vertical Force ◽  
Temperature Superposition ◽  
Measured Strain ◽  
Time Temperature Superposition ◽  
Tensile Strains

Experimental data is reported that quantifies how time (up to 10 000 h) and temperature (from 22 to 85 °C) impact tensile strains in a 1.5 mm thick high-density polyethylene geomembrane — with a compressible clay liner beneath it — that are induced by an overlying gravel particle when subjected to a sustained vertical force. At an average applied stress of 250 kPa and clay water content of 16%, tensile strains were found to increase by 1.25 times as the temperature was increased from 22 to 55 °C after 1000 h. Similarly, strains were found to increase by factors between 1.2 to 1.3 as time was increased from 10 to 1000 h. Based on the measured data, time–temperature superposition (tTS) was then used to develop an approach to predict long-term geomembrane strains from gravel indentations. The tTS approach was validated against independent experiments conducted for 10 000 h (1.14 years) as it was found that the predicted strain of 19% was very close to the measured strain of 18%. Provided that the physical properties of the geomembrane do not decrease abruptly, the results suggest that the tTS approach developed can be used to provide estimates of long-term geomembrane strains.

Prediction of fiber-directional flexural strength of carbon fiber-reinforced polypropylene based on time–temperature superposition principle

2017 ◽  
Vol 52 (6) ◽  
pp. 793-805 ◽  
Author(s):  
Tsuyoshi Matsuo ◽  
Masayuki Nakada ◽  
Kazuro Kageyama
Keyword(s):  
Carbon Fiber ◽  
Flexural Strength ◽  
Master Curve ◽  
Superposition Principle ◽  
Bending Test ◽  
Thermoplastic Composites ◽  
Fiber Reinforced ◽  
Temperature Superposition ◽  
Time Temperature Superposition ◽  
Time Temperature Superposition Principle

This study verified that the time–temperature superposition principle for fiber-directional flexural strength can be applied to thermoplastic composites undergoing instantaneous fast phenomena such as impact failure and long-term phenomena such as creep failure, by constructing the time- and temperature-dependent master curve of relaxation modulus of thermoplastic resin. The master curve could be transformed to another master curve that predicts fiber-directional flexural strength of carbon fiber-reinforced thermoplastic composites based on the micro-buckling failure theory expressed mainly by the resin’s elastic modulus. The experimental results obtained from high-speed bending test, static bending test at various temperatures, and creep bending test demonstrated that kink band failure occurred on the compressive surface of the specimen at every test condition. This validation and verification related to thermoplastic composites made it possible to predict static and dynamic flexural strengths at arbitrary temperature and creep flexural strength.

scholarly journals Residual stresses developed in thermoplastic composites during laser-assisted tape laying

2021 ◽  
Author(s):  
Anna Maria El Bayssari ◽  
Frédéric Jacquemin ◽  
Mael Péron ◽  
Anaïs Barasinski ◽  
Fédérica Daghia ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Filament Winding ◽  
Thermoplastic Composites ◽  
Whole Process ◽  
Curvature Variation ◽  
Laminate Theory ◽  
Winding Machine ◽  
Laminate Thickness

The main focus of the study is the determination of residual stresses developed in thermoplastic composites during tape placement. An experimental characterization of the residual stresses is carried out and based on the measurement of the curvature variation with temperature for unsymmetrical laminates. The tested plates are made of APC-2 and processed on the SPIDE-TP, a filament winding machine based in Cetim, France. A thermo-mechanical model based on the modified laminate theory is used in this work. Heat transfer and crystallization are taken into account in the model, allowing the description of the evolution of the mechanical properties of the composite during the whole process. The model is able to predict the residual stresses present at the end of the process. The results showed stress gradients through the thickness of the laminates where the transverse residual stresses can reach up to 20 MPa. In addition, the results showed that increasing the mandrel temperature reduces the crystallization and thermal gradients in the laminate thickness.

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