Kinetics for the tensile strength degradation of nylon and kevlar yarns

1989 ◽  
Vol 37 (8) ◽  
pp. 2213-2227 ◽  
Author(s):  
I. Auerbach
Keyword(s):  
Tensile Strength ◽  
Strength Degradation

Enhanced Method of Predicting Tensile Strength Degradation of Steel Bridge Members Due to Corrosion

2012 ◽  
Vol 2 (1) ◽  
pp. 30-41
Author(s):  
J. M.R.S. Appuhamy ◽  
M. Ohga ◽  
T. Kaita ◽  
P. Chun ◽  
P. B.R. Dissanayake
Keyword(s):  
Tensile Strength ◽  
Strength Degradation ◽  
Steel Bridge

scholarly journals Strength Degradation in Curved FRP bars as Concrete Reinforcement

2020 ◽  
Author(s):  
Thanongsak Imjai ◽  
Reyes Garcia ◽  
Maurizio Guadagnini ◽  
Kypros Pilakoutas
Keyword(s):  
Tensile Strength ◽  
Structural Damage ◽  
Mechanical Performance ◽  
Failure Criteria ◽  
Strength Degradation ◽  
Future Research ◽  
Frp Composites ◽  
Current Design ◽  
Frp Reinforcement ◽  
Superior Corrosion Resistance

Steel reinforcement in concrete has the tendency to corrode and this process can lead to structural damage. FRP reinforcement represents a viable alternative for structures exposed to aggressive environments and has many possible applications where superior corrosion resistance properties are required. The use of FRP rebars as internal reinforcements for concrete, however, is limited to specific structural elements and does not yet extend to the whole structure. The reasons for this relate to the limited availability of curved or shaped reinforcing elements on the market and their reduced structural performance. Various studies, in fact, have shown that the mechanical performance of bent portions of composite bars is reduced significantly under a multiaxial combination of stresses and that the tensile strength can be as low as 25% of the maximum tensile strength that can be developed in the straight part. In a significant number of cases, the current design recommendations for concrete structures reinforced with FRP, however, were found to overestimate the bend capacity of FRP rebar. This paper presents the state-of-the art review of the research works on the strength degradation in curved FRP composites and highlighted the performance of exiting predictive models for the bend capacity of FRP reinforcement. Recent practical predictive model based on the Tsai-Hill failure criteria by considering the material at marcromechanical level is also discussed and highlighted. The review also identifies the challenges and highlights the future directions of research to explore the use of shaped FRP composites in civil engineering applications and the trends for future research in this area.

scholarly journals Experimental Evaluation of Strength Degradation of Orthodontic Chain Elastics Immersed in Hot Beverages

2019 ◽  
Vol 53 (4) ◽  
pp. 244-248 ◽  
Author(s):  
Emanuel Braga ◽  
Gabriella Souza ◽  
Paula Barretto ◽  
Caio Ferraz ◽  
Matheus Pithon
Keyword(s):  
Tensile Strength ◽  
Green Tea ◽  
Artificial Saliva ◽  
Testing Machine ◽  
Strength Degradation ◽  
Hot Water ◽  
Group 4 ◽  
Group 2 ◽  
Force Reduction ◽  
Elastomeric Chains

Introduction: Elastomeric chains are relevant in orthodontic mechanics due to the form memory property; however, elastomers present high force reduction in some circumstances. The objective was to evaluate the effect of hot beverages on tensile strength degradation of orthodontic elastomeric chains. Material and Methods: Four groups were tested according to different immersion liquids: artificial saliva (group 1), hot water (group 2), green tea (group 3), and coffee (group 4). The elastomeric chains of groups 2, 3, and 4 were immersed in the respective liquids, with temperature of 70 ± 1°C twice daily for 30 seconds for a period of 7, 14, or 21 days. All samples were kept in artificial saliva and stored in an incubator at controlled temperature of 37 ± 1°C. The elastomeric chains were then examined in the testing machine (AME-2kN; Filizola, São Paulo, Brazil) to measure the tensile strength degradation. Results: It was observed through intragroup comparisons that the control showed a progressive reduction of tensile strength in a statistically significant manner throughout the study period. In turn, the hot water, green tea, and coffee samples showed a statistically significant reduction from 7 to 14 days. From 14 to 21 days, the tension remained stable. When the test groups were compared with the control, it was observed that all groups presented tension reduction in a statistically significant manner at all periods, except for the coffee group at 21 days ( P < .001). Conclusions: Experimental immersion in hot water, green tea, and coffee at 70 ± 1°C contributed in a statistically significant manner to the strength degradation of orthodontic elastomeric chains in the period of 7 and 14 days.

scholarly journals Tensile strength degradation of a 2.5D-C/SiC composite under thermal cycles in air

2016 ◽  
Vol 36 (12) ◽  
pp. 3011-3019 ◽  
Author(s):  
Chengyu Zhang ◽  
Mengmeng Zhao ◽  
Yongsheng Liu ◽  
Bo Wang ◽  
Xuanwei Wang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Strength Degradation ◽  
Thermal Cycles

Processing of SiC-Based Fibres from Polycarbosilane

1992 ◽  
Vol 271 ◽  
Author(s):  
Vasilios Kalyvas ◽  
J. C. Ko ◽  
G. C. East ◽  
J. E. Mcintyre ◽  
B. Rand ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
Thermolysis Product ◽  
Strength Degradation ◽  
The Self ◽  
Thermal Curing ◽  
Oxidative Reactions ◽  
High Yields

ABSTRACTA commercial polycarbosilane, thermolysis product of polysilastyrene, was spun into fibres. The self-curing character of the polymer permitted both oxidative and thermal curing of the precursor fibres. Pyrolysis of the latter produced ceramic fibres in high yields, which were fully characterised. Optimum tensile strength was attained after heat treatment at 1100°C. Oxidative reactions and crystallisation caused strength degradation above this temperature.

scholarly journals Artificial Weathering Mechanisms of Uncoated Structural Polyethylene Terephthalate Fabrics with Focus on Tensile Strength Degradation

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 618
Author(s):  
Hastia Asadi ◽  
Joerg Uhlemann ◽  
Natalie Stranghoener ◽  
Mathias Ulbricht
Keyword(s):  
Tensile Strength ◽  
Polyethylene Terephthalate ◽  
Building Materials ◽  
Structural Changes ◽  
Degradation Pathway ◽  
Strength Degradation ◽  
Uniaxial Tensile ◽  
Accelerated Weathering ◽  
Degradation Mechanisms ◽  
Pet Fabric

In the past five decades, reinforced coated textile membranes have been used increasingly as building materials, which are environmentally exposed. Thus, their weathering degradation over the service life must be taken into account in design, fabrication, and construction. Regarding such structural membranes, PVC (polyvinylchloride)-coated PET (polyethylene terephthalate) fabric is one of the most common commercially available types. This paper focuses on the backbone of it, i.e., the woven PET fabric. Herein, weathering of uncoated PET, as the load-bearing component of the composite PET-PVC, was studied. This study assessed the uniaxial tensile strength degradation mechanisms of uncoated PET fabric during artificial accelerated weathering tests. For this purpose, exploratory data analysis was carried out to analyze the chemical and physical changes which were traced by Fourier transform infrared spectroscopy and molecular weight measurements. Finally, with the help of degradation mechanisms determined from the aforementioned evaluations, a degradation pathway network model was constructed. With that, the relationship between applied stress, mechanistic variables, structural changes, and performance level responses (tensile strength degradation) was assessed.

Enhanced Method of Predicting Tensile Strength Degradation of Steel Bridge Members Due to Corrosion

2012 ◽  
Vol 2 (1) ◽  
pp. 30-41
Author(s):  
J.M.R.S. Appuhamy ◽  
M. Ohga ◽  
T. Kaita ◽  
P. Chun ◽  
P.B.R. Dissanayake
Keyword(s):  
Tensile Strength ◽  
Strength Degradation ◽  
Steel Bridge

scholarly journals Tensile Strength and Degradation of GFRP Bars under Combined Effects of Mechanical Load and Alkaline Solution

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3533 ◽  
Author(s):  
Qingping Jin ◽  
Peixia Chen ◽  
Yonghong Gao ◽  
Aihua Du ◽  
Dongxu Liu ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Alkaline Solution ◽  
Mechanical Load ◽  
Three Dimensional ◽  
Strength Degradation ◽  
Combined Effects ◽  
Gfrp Bars ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Stress Levels

Mechanical properties of glass fiber reinforced polymer (GFRP) composites degrade under the combined effects of mechanical load and alkaline solution, affecting the service ability and safety of GFRP reinforced structures. In this study, GFRP bars were loaded with cyclic tension at different stress levels and immersed in alkaline solution for days to investigate the tensile properties and degradation law of GFRP bars. The degradation mechanisms were studied at micro-, meso- and macro-scales with scanning electron microscopy (SEM) and three-dimensional X-ray microscopy, respectively. The results show that tensile strength and degradation rate of GFRP bars are mainly dependent on the different stress levels and alkaline solution. When stress level is higher, the tensile strength degrades more quickly, especially in the early stages of soaking. With the loading and immersion time, the elastic modulus and Poisson’s ratio increase at first and then decrease. The ultimate tensile strain is relatively stable, whereas the ultimate elongation is significantly reduced. A strength-degradation model was proposed and fit well with experimental data, demonstrating that the model can be applied to predict tensile strength degradation under combined effects of the load and alkaline solution.

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