Experimental Investigations on the Influence of Temperature on the Behavior of Steel Reinforcement (Strands and Rebars)

2016 ◽  
Vol 711 ◽  
pp. 908-915
Author(s):  
Wiem Toumi Ajimi ◽  
Sylvain Chataigner ◽  
Yannick Falaise ◽  
Laurent Gaillet
Keyword(s):  
Prestressed Concrete ◽  
Temperature Increase ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
Steel Reinforcement ◽  
Experimental Investigations ◽  
Tensile Behaviour ◽  
Nuclear Containment ◽  
Different Temperatures ◽  
The Impact

In the case of exceptional accidents, nuclear containment structures may be submitted to an internal temperature increase. This may have an influence on the prestressed concrete structures behavior regarding both its mechanical performance and its porosity. The presented study got interested on the impact that a temperature increase may have on the mechanical behavior of the steel reinforcement for both prestressing strands and rebars. In order to remain in realistic situations, it was chosen to study temperatures between 20°C and 140°C. Some experimental investigations regarding the tensile behaviour of steel rebars and their adherence within concrete will first be presented. Then, some investigations on steel strands will be described: some tensile tests at different temperatures, and some relaxation tests to check how the level of prestress loss may be affected by the temperature. This experimental study is part of a national French project (MACENA) aiming at assessing the impact of an accident on the behavior of nuclear containment structures. The gathered experimental data will be used for their damage assessment.

scholarly journals Low-carbon cast microalloyed steel intercritically heat-treated at different temperatures: microstructure and mechanical properties

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
Hadi Torkamani ◽  
Shahram Raygan ◽  
Carlos Garcia Mateo ◽  
Yahya Palizdar ◽  
Jafar Rassizadehghani ◽  
...  
Keyword(s):  
Carbon Content ◽  
Volume Fraction ◽  
Block Size ◽  
Tensile Tests ◽  
Total Elongation ◽  
Martensite Phase ◽  
Low Carbon ◽  
Steel Increase ◽  
Different Temperatures ◽  
The Impact

AbstractIn this study, dual-phase (DP, ferrite + martensite) microstructures were obtained by performing intercritical heat treatments (IHT) at 750 and 800 °C followed by quenching. Decreasing the IHT temperature from 800 to 750 °C leads to: (i) a decrease in the volume fraction of austenite (martensite after quenching) from 0.68 to 0.36; (ii) ~ 100 °C decrease in martensite start temperature (Ms), mainly due to the higher carbon content of austenite and its smaller grains at 750 °C; (iii) a reduction in the block size of martensite from 1.9 to 1.2 μm as measured by EBSD. Having a higher carbon content and a finer block size, the localized microhardness of martensite islands increases from 380 HV (800 °C) to 504 HV (750 °C). Moreover, despite the different volume fractions of martensite obtained in DP microstructures, the hardness of the steels remained unchanged by changing the IHT temperature (~ 234 to 238 HV). Applying lower IHT temperature (lower fraction of martensite), the impact energy even decreased from 12 to 9 J due to the brittleness of the martensite phase. The results of the tensile tests indicate that by increasing the IHT temperature, the yield and ultimate tensile strengths of the DP steel increase from 493 to 770 MPa, and from 908 to 1080 MPa, respectively, while the total elongation decreases from 9.8 to 4.5%. In contrast to the normalized sample, formation of martensite in the DP steels could eliminate the yield point phenomenon in the tensile curves, as it generates free dislocations in adjacent ferrite.

Tensile Testing of Ti-6Al-4V Alloy Superplasticity

2013 ◽  
Vol 762 ◽  
pp. 392-397 ◽  
Author(s):  
Sergey A. Aksenov ◽  
Eugene N. Chumachenko ◽  
Irina V. Logashina
Keyword(s):  
Strain Rate ◽  
Material Flow ◽  
Flow Characteristics ◽  
Tensile Tests ◽  
Processing Maps ◽  
Dynamic Materials ◽  
Different Temperatures ◽  
Stress And Strain Rate ◽  
The Impact ◽  
Dynamic Materials Model

This paper presents the research on the flow characteristics of the Ti-6V-4Al alloy in wide ranges of temperature (725 ‑ 950 °C) and strain rate (10-5 ‑ 10-2 s-1). The material processing maps were constructed based on the basis of dynamic materials model (DMM) developed by Prassad and modified by Narayana Murty. For the construction of such maps the data of the material flow stress at different temperatures and strain rates is necessary. To obtain such data the stepped tensile tests which allow obtaining the stress - strain rate dependence at a given temperature are ideal. The experiments conducted consist of the tensile test series at various temperatures with stepped change of the deformation rate. By the results of these tests the constitutive equations, which describe relationship between stress and strain rate for each temperature, were obtained. The data was analyzed in terms of the two different approaches proposed by Prassad and Narayana Murty to assess the impact of deformation conditions on the formability and flow stability of the material. Based on these approaches, the processing maps, which enable identifying the conditions of the Ti-6V-4Al alloy superplasticity, were constructed.

A Study on Optical Fiber Damage Due to Optoelectronic Assembly Processes

2005 ◽  
Author(s):  
Kaustubh R. Nagarkar ◽  
Peter Borgesen ◽  
Krishnaswami Srihari
Keyword(s):  
Optical Fibers ◽  
Fiber Optic ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
Sem Analysis ◽  
Primary Sources ◽  
Mechanical Degradation ◽  
Fiber Damage ◽  
The Individual ◽  
The Impact

Optoelectronic assembly processes, such as laser and photodiode packaging, connector assembly, and splicing, tend to involve extensive handling of optical fibers. These processes offer considerable likelihood of inducing severe damage to the fibers. Such damage degrades the strength of optical fibers and could result in lower than expected lifetimes in service. The objective of this research was to investigate the impact of fiber-optic assembly processes on the mechanical performance of optical fibers. Certain applications such as fiber-optic splices, connectors, and optoelectronic packages require that the protective coating of the fibers be removed through a process called ‘fiber-stripping’. The process of ‘fiber-stripping’ was characterized to identify the primary sources of mechanical degradation. The related handling and cleaning steps were also evaluated. Further, the process steps in the assembly of fiber optic connectors were closely examined and the impact of assembling fibers into adhesives was tested. Qualitative and quantitative tools have been used to investigate the problems and have been discussed in this paper. Tensile tests were used to compare the mechanical performance of the fibers. Special fixtures and test set-ups were created that enabled the testing of the fibers. Characterization techniques, such as Scanning Electron Microscopy (SEM) analysis and optical microscopy, were also used. The results have enabled to identify the contributions of the individual assembly steps that impair the strength of optical fibers. This paper provides an understanding of the potential sources and mechanisms of degradation due to such processes.

Evaluation of the Mechanical Behavior of Bisphenol-A Polycarbonate after Thermal Degradation

2020 ◽  
Vol 1012 ◽  
pp. 51-56
Author(s):  
Foluke Salgado de Assis ◽  
Sergio Neves Monteiro ◽  
Anderson Oliveira da Silva ◽  
Ricardo Pondé Weber ◽  
Artur Camposo Pereira ◽  
...  
Keyword(s):  
Thermal Degradation ◽  
Bisphenol A ◽  
Mechanical Behavior ◽  
High Temperatures ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
Bisphenol A Polycarbonate ◽  
Different Temperatures

This work investigates the mechanical behavior of a PCLIGHT type of polycarbonate (PC). PC samples display interesting results after thermal degradation at different temperatures. Samples of PC in sheet form were exposed for a period of 5 hours at temperatures of 50, 100, 150 e 200°C. After, thermogravimetric test, flexural, impact and tensile tests were performed. The results show that the samples treated at 200oC have their mechanical performance affected. This indicates that the temperature acts on the PC embrittlement behavior. Thus, it can be inferred that temperatures above 150oC can negatively influence the mechanical behavior of the polycarbonate indicating that this material should not be used in association with high temperatures.

Study of Mechanical Behavior of Polycarbonate after Thermal Degradation

2020 ◽  
Vol 1012 ◽  
pp. 94-99
Author(s):  
Cleyson Santos de Paiva ◽  
Foluke Salgado de Assis ◽  
Sergio Neves Monteiro ◽  
Verônica Scarpini Candido ◽  
Carlos Alberto Martins Ferreira ◽  
...  
Keyword(s):  
Thermal Degradation ◽  
Mechanical Behavior ◽  
High Temperatures ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
Different Temperatures

This work investigates the mechanical behavior of a PCLIGHT type of polycarbonate (PC). PC samples display interesting results after thermal degradation at different temperatures. Samples of PC in sheet form were exposed for a period of 5 hours at temperatures of 50, 100, 150 e 200°C. After, thermogravimetric test, flexural, impact and tensile tests were performed. The results show that the samples treated at 200oC has their mechanical performance affected this indicates that the temperature acts on the PC embrittlement behavior. Thus, it can be inferred that temperatures above 150oC can negatively influence the mechanical behavior of the polycarbonate indicating that this material should not be used in association with high temperatures.

scholarly journals Poly(ε-Caprolactone)/Brewers’ Spent Grain Composites—The Impact of Filler Treatment on the Mechanical Performance

2020 ◽  
Vol 4 (4) ◽  
pp. 167
Author(s):  
Aleksander Hejna
Keyword(s):  
Chemical Structure ◽  
Mechanical Performance ◽  
Natural Fiber ◽  
Reactive Extrusion ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Mechanical Tests ◽  
Interface Surface ◽  
Spent Grain ◽  
The Impact

Waste lignocellulose materials, such as brewers’ spent grain, can be considered very promising sources of fillers for the manufacturing of natural fiber composites. Nevertheless, due to the chemical structure differences between polymer matrices and brewers’ spent grain, filler treatment should be included. The presented work aimed to investigate the impact of fillers’ reactive extrusion on the chemical structure and the poly(ε-caprolactone)/brewers’ spent grain composites’ mechanical performance. The chemical structure was analyzed by Fourier-transform infrared spectroscopy, while the mechanical performance of composites was assessed by static tensile tests and dynamic mechanical analysis. Depending on the filler pretreatment, composites with different mechanical properties were obtained. Nevertheless, the increase in pretreatment temperature resulted in the increased interface surface area of filler, which enhanced composites’ toughness. As a result, composites were able to withstand a higher amount of stress before failure. The mechanical tests also indicated a drop in the adhesion factor, pointing to enhanced interfacial interactions for higher pretreatment temperatures. The presented work showed that reactive extrusion could be considered an auspicious method for lignocellulose filler modification, which could be tailored to obtain composites with desired properties.

Microstructural and Mechanical Behaviour Evaluation of Mg-Al-Zn Alloy Friction Stir Welded Joint

2020 ◽  
Vol 17 (3) ◽  
pp. 8150-8159
Author(s):  
Kulwant Singh ◽  
Gurbhinder Singh ◽  
Harmeet Singh
Keyword(s):  
Heat Treatment ◽  
Friction Stir Welding ◽  
Magnesium Alloys ◽  
Mechanical Performance ◽  
Fuel Efficiency ◽  
Research Work ◽  
Grain Structure ◽  
Tensile Fracture ◽  
Friction Stir ◽  
The Impact

The weight reduction concept is most effective to reduce the emissions of greenhouse gases from vehicles, which also improves fuel efficiency. Amongst lightweight materials, magnesium alloys are attractive to the automotive sector as a structural material. Welding feasibility of magnesium alloys acts as an influential role in its usage for lightweight prospects. Friction stir welding (FSW) is an appropriate technique as compared to other welding techniques to join magnesium alloys. Field of friction stir welding is emerging in the current scenario. The friction stir welding technique has been selected to weld AZ91 magnesium alloys in the current research work. The microstructure and mechanical characteristics of the produced FSW butt joints have been investigated. Further, the influence of post welding heat treatment (at 260 °C for 1 h) on these properties has also been examined. Post welding heat treatment (PWHT) resulted in the improvement of the grain structure of weld zones which affected the mechanical performance of the joints. After heat treatment, the tensile strength and elongation of the joint increased by 12.6 % and 31.9 % respectively. It is proven that after PWHT, the microhardness of the stir zone reduced and a comparatively smoothened microhardness profile of the FSW joint obtained. No considerable variation in the location of the tensile fracture was witnessed after PWHT. The results show that the impact toughness of the weld joints further decreases after post welding heat treatment.

Static and Dynamic Studies of Gasoline in View of its Octane Number and its Toxic Effect

2013 ◽  
Vol 12 (7) ◽  
pp. 451-459
Author(s):  
Ashraf Yehia El-Naggar ◽  
Mohamed A. Ebiad
Keyword(s):  
Toxic Effect ◽  
Aromatic Hydrocarbons ◽  
Octane Number ◽  
Liquid Fuel ◽  
Positive Impact ◽  
Hydrocarbon Composition ◽  
Different Temperatures ◽  
Different Seasons ◽  
The One ◽  
The Impact

Gasoline come primarily from petroleum cuts, it is the preferred liquid fuel in our lives. Two gasoline samples of octane numbers 91 and 95 from Saudi Arabia petrol stations were studied. This study was achieved at three different temperatures 20oC, 30oC and 50oC representing the change in temperatures of the different seasons of the year. Both the evaporated gases of light aromatic hydrocarbons (BTEX) of gasoline samples inside the tank were subjected to analyze qualitatively and quantitatively via capillary gas chromatography. The detailed hydrocarbon composition and the octane number of the studied gasoline samples were determined using detailed hydrocarbon analyzer. The idea of research is indicating the impact of light aromatic compounds in gasoline on the toxic effect of human and environment on the one hand, and on octane number of gasoline on the other hand. Although the value of octane number will be reduced but this will have a positive impact on the environment as a way to produce clean fuel.

scholarly journals Wastes from Agricultural Silage Film Recycling Line as a Potential Polymer Materials

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1383
Author(s):  
Jerzy Korol ◽  
Aleksander Hejna ◽  
Klaudiusz Wypiór ◽  
Krzysztof Mijalski ◽  
Ewelina Chmielnicka
Keyword(s):  
Vinyl Acetate ◽  
Thermal Performance ◽  
Mechanical Performance ◽  
Ethylene Vinyl Acetate ◽  
Tensile Tests ◽  
Solid Particles ◽  
Polymer Materials ◽  
Slight Reduction ◽  
Scanning Calorimetry ◽  
Crystallinity Degree

The recycling of plastics is currently one of the most significant industrial challenges. Due to the enormous amounts of plastic wastes generated by various industry branches, it is essential to look for potential methods for their utilization. In the presented work, we investigated the recycling potential of wastes originated from the agricultural films recycling line. Their structure and properties were analyzed, and they were modified with 2.5 wt % of commercially available compatibilizers. The mechanical and thermal performance of modified wastes were evaluated by tensile tests, thermogravimetric analysis, and differential scanning calorimetry. It was found that incorporation of such a small amount of modifiers may overcome the drawbacks caused by the presence of impurities. The incorporation of maleic anhydride-grafted compounds enhanced the tensile strength of wastes by 13–25%. The use of more ductile compatibilizers—ethylene-vinyl acetate and paraffin increased the elongation at break by 55–64%. The presence of compatibilizers also reduced the stiffness of materials resulting from the presence of solid particles. It was particularly emphasized for styrene-ethylene-butadiene-styrene and ethylene-vinyl acetate copolymers, which caused up to a 20% drop of Young’s modulus. Such effects may facilitate the further applications of analyzed wastes, e.g., in polymer film production. Thermal performance was only slightly affected by compatibilization. It caused a slight reduction in polyethylene melting temperatures (up to 2.8 °C) and crystallinity degree (up to 16%). For more contaminated materials, the addition of compatibilizers caused a minor reduction in the decomposition onset (up to 6 °C). At the same time, for the waste after three washing cycles, thermal stability was improved. Moreover, depending on the desired properties and application, materials do not have to go through the whole recycling line, simplifying the process, reducing energy and water consumption. The presented results indicate that it is possible to efficiently use the materials, which do not have to undergo the whole recycling process. Despite the presence of impurities, they could be applied in the manufacturing of products which do not require exceptional mechanical performance.

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