scholarly journals Experimental and Theoretical Research on the Stress-Relaxation Behaviors of PTFE Coated Fabrics under Different Temperatures

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Yingying Zhang ◽  
Shanshan Xu ◽  
Qilin Zhang ◽  
Yi Zhou
Keyword(s):  
Stress Relaxation ◽  
Process Analysis ◽  
Theoretical Research ◽  
Good Prediction ◽  
Construction Process ◽  
Membrane Structures ◽  
Coated Fabric ◽  
Different Temperatures ◽  
C 50 ◽  
Coated Fabrics

As polymer composites, the stress-relaxation behaviors of membrane materials have significant effects on the pattern cutting design, the construction process analysis, and the stiffness degradation of membrane structures in the life cycle. In this paper, PTFE coated fabric is taken as the research object. First, the stress-relaxation behaviors under different temperatures (23°C, 40°C, 50°C, 60°C, and 70°C) are studied, and the variations of main mechanical parameters are got. Then, a simple review of several current viscoelastic models is presented. Finally, several common models for the material viscoelasticity are used to compare with the test results. Results show PTFE coated fabric is typically viscoelastic. The stress relaxation is obvious in the initial phase and it decreases with time increasing. The stress decreases significantly and then tends to a stable value. With temperature increasing, the decrease rate of membrane stress decreases and the final stable value increases. This material performs obvious hardening with temperature increasing. Most of the current models can make good prediction on the stress-relaxation behaviors of PTFE coated fabrics under different temperatures. The results can be references for the determination of pattern shrinkage ratio and construction process analysis of membrane structures.

Effect of Temperature and Water Immersion on the Mechanical Properties of Coated Fabrics

2010 ◽  
Vol 129-131 ◽  
pp. 230-234
Author(s):  
Ying Ying Zhang ◽  
Qi Lin Zhang ◽  
Chuan Zhi Zhou ◽  
Ying Zhou
Keyword(s):  
Mechanical Properties ◽  
Water Immersion ◽  
Effect Of Temperature ◽  
C 23 ◽  
Different Temperatures ◽  
Temperature Induction ◽  
Effects Of Temperature ◽  
C 50 ◽  
Coated Fabrics ◽  
Increasing Temperature

As composite, the mechanical properties of coated fabrics are sensitive to environment. This paper presented mechanical properties under different environments. A list of uniaxial tests are carried out under different temperatures including -20°C, 0°C, 23°C, 50°C, and 70°C. First, the tensile behaviors at room temperature and the failure behaviors are studied. Then, the effects of temperature on mechanical properties are determined. Finally, the effects of water immersion on mechanical properties are discussed. Results show PTFE coated fabrics remained unchanged in varying temperature and humidity. The temperature has effects on the mechanical properties of PVC coated fabrics. With increasing temperature, the strength decrease and the strain at break increase. The temperature induction factors are proposed for the design and analysis. The water immersion has little effect on the mechanical properties because of the impervious coating.

Mechanical properties of PVDF-coated fabric under tensile tests

2015 ◽  
Vol 35 (4) ◽  
pp. 377-390 ◽  
Author(s):  
Andrzej Ambroziak
Keyword(s):  
Mechanical Properties ◽  
Polyvinylidene Fluoride ◽  
Cyclic Load ◽  
Tensile Tests ◽  
Woven Fabrics ◽  
Uniaxial Tensile ◽  
Cyclic Tests ◽  
Comprehensive Investigation ◽  
Coated Fabric ◽  
Coated Fabrics

Abstract This article describes the laboratory tests necessary to identify the mechanical properties of the polyvinylidene fluoride (PVDF)-coated fabrics named Precontraint 1202S and Precontraint 1302S. First, a short survey of the literature concerning the description of coated woven fabrics is presented. Second, the material parameters for PVDF-coated fabrics are specified on the basis of biaxial tensile tests. A comparison of the 1:1 biaxial and the uniaxial tensile tests results is also given. Additionally, biaxial cyclic tests were performed to observe the change of immediate mechanical properties under cyclic load. The article is aimed as an introduction to a comprehensive investigation of the mechanical properties of coated fabrics.

Thermal Decomposition of Vulcanized Structures of Deformed Vulcanizates Containing Various Accelerators

1953 ◽  
Vol 26 (4) ◽  
pp. 759-763 ◽  
Author(s):  
B. Dogadkin ◽  
Z. Tarasova
Keyword(s):  
Stress Relaxation ◽  
Physical And Mechanical Properties ◽  
Heat Stability ◽  
Chemical Bonds ◽  
Structural Elements ◽  
Specific Chemical ◽  
Vulcanized Rubber ◽  
Different Temperatures ◽  
Chemical Groups ◽  
The Given

Abstract According to the hypotheses developed by the authors, vulcanized rubber is a system in which the molecular chains are united by local molecular and chemical bonds of varying intensity. The concentration, distribution, and strength of these bonds determine the principal physical and mechanical properties of the vulcanizates. Consequently the study of the structure of the vulcanizate is of primary practical value. The explanation of the nature of the bonds in a vulcanizate by chemical methods is very difficult, mainly because of the impossibility of distinguishing the specific chemical groups which enter into the composition of the different molecular chains from those bonds between the chains which are responsible for the development of spatial structures. From this view point, the thermo-mechanical method described below, which is based on the study of stress relaxation at different temperatures, is of great significance. As was shown by Dogadkin and Reznikovskii˘, the delayed stress relaxation in a vulcanizate at temperatures up to 70° C is caused by rupture of the local intermolecular bonds and the regrouping of the structural elements of the polymeric chains without destruction of the chemical bonds between them. Accordingly, after some time at these temperatures, a practically balanced stress is established, which depends on the number of the stronger bonds remaining. At temperatures above 70° C, rupture of the chemical bonds between the chains takes place; its speed increases with decrease of the energy activating the rupture of the given type of bond. Particularly in the case of sulfur vulcanizates, we can assume that the following types of bonds exist between the chains of the rubber: (1) —C—C—, which develop as a result of the polymerizationprocesses; (2) —C—S—C— monosulfide; (3) —C—S—S—C— disulfide, and (4) —C—Sn—C— polysulfide, formed as a result of the direct participation of the vulcanizing agent, sulfur, in the process of joining of the molecular chains. The energy of these chains can be estimated as 62.7 kcal, per mole for C—C, 54.5 kcal. per mole for C—S, and 27.5 kcal. per mole for the —S—S bond. Naturally, the heat stability of a vulcanizate will depend on which of the indicated types of bonds predominates.

Construction process analysis of Lianyungang gymnasium suspen dome

2010 ◽  
Vol 97 (19) ◽  
pp. 9-13
Author(s):  
Yingying Zhang ◽  
Qilin Zhang ◽  
Lu Chen
Keyword(s):  
Process Analysis ◽  
Construction Process

Effects of the Potassium Titanate Functional Filler Types on the Thermal Protection Performance of Heat Resistant Ablative Coated Fabrics

NANO ◽  
2018 ◽  
Vol 13 (02) ◽  
pp. 1850014 ◽  
Author(s):  
Guoyi Liu ◽  
Yuanjun Liu ◽  
Xiaoming Zhao
Keyword(s):  
Thermal Stability ◽  
Thermal Protection ◽  
High Strength ◽  
Radiant Heat ◽  
Insulation Property ◽  
Minimum Diameter ◽  
Potassium Titanate ◽  
Heat Resistant ◽  
Coated Fabric ◽  
Coated Fabrics

Considering sub-micron potassium titanate whiskers (BX-101), nanoscale potassium titanate whiskers (AX-301), sub-micron potassium titanate whiskers (AX-316) and high strength potassium titanate crystal (AX-319) as functional fillers, heat resistant ablative coated fabrics which have high radiant heat reflectivity were prepared. The effect of the type of functional filler on the thermal protection performance of heat resistant ablative coated fabrics was mainly discussed. Research showed that the microstructure of potassium titanate functional filler had a significant impact on the radiant heat reflectivity and thermal insulation performance of the prepared coated fabric. The coated fabric which took nanoscale potassium titanate whiskers (AX-301) with a minimum diameter and greater length-diameter ratio as functional filler has the highest thermal reflectivity and the best insulation property. Heat ray reflectivity of potassium titanate coated fabrics had positive correlation with their crystallinities. The higher the coated fabric crystallinity was, the greater the heat ray reflectivity. Thermogravimetric analysis results showed that after adding four kinds of potassium titanate fillers, the thermal stability of the prepared coated fabrics was enhanced, and the nanoscale potassium titanate whiskers (AX-301) coated fabrics had the best thermal stability.

Influence of service ageing on polyester-reinforced polyvinyl chloride-coated fabrics reported through mathematical material models

2018 ◽  
Vol 89 (8) ◽  
pp. 1472-1487
Author(s):  
Krzysztof Zerdzicki ◽  
Pawel Klosowski ◽  
Krzysztof Woznica
Keyword(s):  
Polyvinyl Chloride ◽  
Constitutive Models ◽  
Uniaxial Tensile ◽  
Creep Tests ◽  
Material Models ◽  
Material Parameters ◽  
Coated Fabric ◽  
Coated Fabrics ◽  
Term Creep

In this paper the coupled service (constructional tension) and environmental (sunlight, rainfalls, temperature variations) ageing influence on the polyester-reinforced polyvinyl chloride (PVC)-coated fabric VALMEX is studied. Two cases of the same fabric have been analyzed: one USED for 20 years on the real construction of the Forest Opera in Sopot (Poland), and one kept as a spare material (NOT USED). The following tests have been conducted: uniaxial tensile, biaxial tensile and long-term creep tests. The obtained results have been used for the parameter identification of the piecewise non-linear, Burgers and Bodner–Partom models. Next, the analysis of the influence of environmental conditions on the parameters of these models has been made. It has been concluded that some parameters are more and the others are less sensitive to the exposure to environmental and mechanical conditions. The change of material parameters for fill threads (due to larger deformation) is higher. The obtained results may be useful in the durability evaluation of the textile membranes reinforced with polyester threads and PVC coated. All the constitutive models with the identified parameters may be used for the numerical analysis of structures made of fabrics at the service beginning and after long-term usage.

scholarly journals Effect of Ti3C2Tx MXenes etched at elevated temperatures using concentrated acid on binder-free supercapacitors

RSC Advances ◽  
2020 ◽  
Vol 10 (68) ◽  
pp. 41837-41845
Author(s):  
Sunil Kumar ◽  
Dongwoon Kang ◽  
Hyeryeon Hong ◽  
Malik Abdul Rehman ◽  
Yeon-jae Lee ◽  
...  
Keyword(s):  
Carbon Black ◽  
Elevated Temperatures ◽  
Different Temperatures ◽  
Binder Free ◽  
C 50

The effect of Ti3C2Tx MXene etched at different temperatures (25 °C, 50 °C, and 80 °C) on the capacitance of supercapacitors without the use of conducting carbon-black or a binder was studied.

scholarly journals Stress Relaxation Aging Behavior and Constitutive Modelling of AA7150-T7751 under Different Temperatures, Initial Stress Levels and Pre-Strains

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1215 ◽  
Author(s):  
Yixian Cai ◽  
Lihua Zhan ◽  
Yongqian Xu ◽  
Chunhui Liu ◽  
Jianguang Wang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Stress Relaxation ◽  
Initial Stress ◽  
Stress Level ◽  
Relaxation Behavior ◽  
Average Error ◽  
Aging Behavior ◽  
Stress Relaxation Behavior ◽  
Stress Levels ◽  
Different Temperatures

Age forming is an advanced manufacture technology for forming large aluminum panels. Temperature, initial stress level and pre-strains have a great effect on the formability and performance. The stress relaxation aging behavior of AA7150-T7751 under different temperatures, initial stress levels and pre-strains was studied through stress relaxation tests, tensile tests and TEM observations. The results show that the formability can be improved with the increase of temperature, initial stress levels and pre-strains. Deformation mechanisms during stress relaxation of the material were analyzed on the basis of creep stress exponent and apparent activation energy. The aging precipitates of the studied alloy were not sensitive to the age forming conditions, but drastically coarsened at over aging temperature, which decreased the mechanical properties. In addition, the relationship between stress relaxation behavior and aging strengthening is discussed. Based on the dislocation theory and the modified Arrhenius equation, a stress relaxation constitutive equation considering the initial mobile dislocation density and temperature dependent activation energy was established. This model can predict very well the stress relaxation behavior under various temperature, stress level and pre-strain conditions, with an average error of 2%.

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