scholarly journals The effect of loading frequency on the cyclic mechanical behavior of polyethylene

2015 ◽  
Vol 18 (4) ◽  
pp. 162-169
Author(s):  
Thao Song Thanh Nguyen ◽  
Nhung Thi Tuyet Le
Keyword(s):  
Experimental Investigation ◽  
Mechanical Behavior ◽  
Hysteresis Loop ◽  
Room Temperature ◽  
Tensile Tests ◽  
Loading Frequency ◽  
Ratcheting Strain ◽  
Accumulated Strain ◽  
Long Time ◽  
Kinetics Of

An experimental investigation into ratcheting strain and stress-strain hysteresis loop in stress-controlled cyclic tensile tests at room temperature was performed to determine the effect of loading frequency on the cyclic mechanical behavior of highdensity polyethylene (HDPE). It was found that frequencies ranging from 0.01 Hz up to 1 Hz mostly affects the accumulated strain over related time scales (i.e that of the cycle itself) and not over long time scale (i.e. during the full test). In addition, the higher the frequency is, the more closed and vertical the loops are. Furthermore, the frequency affects only on the kinetics of stabilization of ratcheting strain but not on one of hysteresis loop.

Effect of Intercritical Annealing Time on Microstructure and Mechanical Behavior of Advanced Medium Mn Steels

2012 ◽  
Vol 706-709 ◽  
pp. 2693-2698 ◽  
Author(s):  
A. Arlazarov ◽  
M. Gouné ◽  
O. Bouaziz ◽  
A. Hazotte ◽  
F. Kegel
Keyword(s):  
Mechanical Behavior ◽  
Annealing Time ◽  
Room Temperature ◽  
Intercritical Annealing ◽  
Tensile Tests ◽  
The Other ◽  
Metastable Austenite ◽  
High Fraction ◽  
Cold Rolled ◽  
Strength And Ductility

The study about the influence of intercritical annealing time on a cold rolled 0.1%C – 4.6%Mn (wt.%) steel was performed. The tensile tests show an interesting balance between strength and ductility especially after 7 hours annealing at 670°C. A part of this good result can be explained by the presence of rather high fraction of metastable austenite at room temperature. On the other hand a very complex microstructure combining lath-like and polygonal features was observed making the interpretation complicated.

scholarly journals Effect of Aerogel Particle Concentration on Mechanical Behavior of Impregnated RTV 655 Compound Material for Aerospace Applications

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Firouzeh Sabri ◽  
Jeffrey G. Marchetta ◽  
K. M. Rifat Faysal ◽  
Andrew Brock ◽  
Esra Roan
Keyword(s):  
Mechanical Behavior ◽  
Room Temperature ◽  
Particle Concentration ◽  
Tensile Tests ◽  
Limiting Factor ◽  
Thermal And Mechanical Properties ◽  
Aerospace Applications ◽  
Elastomeric Matrix ◽  
Compound Material ◽  
And Behavior

Aerogels are a unique class of materials with superior thermal and mechanical properties particularly suitable for insulating and cryogenic storage applications. It is possible to overcome geometrical restrictions imposed by the rigidity of monolithic polyurea cross-linked silica aerogels by encapsulating micrometer-sized particles in a chemically resistant thermally insulating elastomeric “sleeve.” The ultimate limiting factor for the compound material’s performance is the effect of aerogel particles on the mechanical behavior of the compound material which needs to be fully characterized. The effect of size and concentration of aerogel microparticles on the tensile behavior of aerogel impregnated RTV655 samples was explored both at room temperature and at 77 K. Aerogel microparticles were created using a step-pulse pulverizing technique resulting in particle diameters between 425 μm and 90 μm and subsequently embedded in an RTV 655 elastomeric matrix. Aerogel particle concentrations of 25, 50, and 75 wt% were subjected to tensile tests and behavior of the compound material was investigated. Room temperature and cryogenic temperature studies revealed a compound material with rupture load values dependent on (1) microparticle size and (2) microparticle concentration. Results presented show how the stress elongation behavior depends on each parameter.

Microstructural Evolution and Mechanical Behavior of AZ31 Magnesium Alloy Sheets with Li Addition

2015 ◽  
Vol 816 ◽  
pp. 399-403
Author(s):  
Qing Shan Yang ◽  
Bin Jiang ◽  
Wei Jiang ◽  
Bo Song ◽  
Su Qing Luo ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Mechanical Behavior ◽  
Room Temperature ◽  
Mechanical Performance ◽  
Texture Evolution ◽  
Tensile Tests ◽  
Az31 Alloy ◽  
Az31 Magnesium Alloy ◽  
Basal Texture ◽  
X Ray Diffraction

AZ31 magnesium alloy and its alloy with 5% lithium were extruded to 1mm in thickness sheets at 380 oC with extrusion ratio of 101. Microstructure evolution and mechanical behavior of the extruded Mg alloy sheets were examined. The microstructure and texture evolution were investigate by electronic backscattered diffraction (EBSD) and X-ray diffraction (XRD). Mechanical performance was carried out by tensile tests at room temperature. In addition, the evolution of neutral layer and microstructure was also examined by V-bending. It was found that Li addition resulted in the strong divergence of the grain orientation. (0002) basal texture of AZ31 alloy sheets with 5% lithium has been weakened. The room temperature ductility of these textural sheets was enhanced owing to the tilted weak basal texture. Moreover, it exhibits superior ductility during V-bending process at room temperature.

scholarly journals High temperature oxidation and mechanical behavior of β21s and Ti6242S Ti-based alloys

2020 ◽  
Vol 321 ◽  
pp. 04011
Author(s):  
Aurelie Vande Put ◽  
Carole Thouron ◽  
Philippe Emile ◽  
Raphaëlle Peraldi ◽  
Benjamin Dod ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Room Temperature ◽  
Tensile Tests ◽  
Lower Amount ◽  
Aircraft Industry ◽  
Micro Hardness ◽  
Temperature Oxidation ◽  
Specific Strength ◽  
High Specific Strength

Aircraft industry always looks for higher in-service temperatures and lighter structures. With a high specific strength, Ti-based alloys are good candidates for such applications. However, when exposed to oxidizing environments at high temperatures, they undergo large oxygen dissolution while forming an oxide scale, which can greatly affect their mechanical properties. Then, evaluating the oxidation resistance and mechanical behavior of such alloys is essential. In this aim, long term oxidation tests were performed under laboratory air between 500 °C and 625 °C on two Ti-based alloys: β21s, exhibiting a fully β microstructure supposed to dissolve lower amount of oxygen and nitrogen, and Ti6242S, with an α/β microstructure. The oxidized samples were characterized using XRD, Raman spectroscopy, SEM-EDS and micro-durometer. As for the mechanical behavior, tensile tests were performed at room temperature on not aged and on oxidized samples. While larger mass variations were obtained at 500 and 560 °C and up to 997 h at 625 °C for β21s, its mass variations became lower than those of Ti6242S for longer durations at 625 °C. Nevertheless, β21s exhibited thicker micro-hardness affected depths and underwent larger mechanical property modifications compared to Ti6242S.

Mechanical Behavior of 980MPa NANOHITENTM at Elevated Temperatures and its Effect on Springback in Warm Forming

2014 ◽  
Vol 611-612 ◽  
pp. 11-18 ◽  
Author(s):  
Toru Minote ◽  
Yoshimasa Funakawa ◽  
Naoko Saito ◽  
Mitsugi Fukahori ◽  
Hiroshi Hamasaki ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Stress Relaxation ◽  
Mechanical Behavior ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Warm Forming ◽  
Bending Test ◽  
Uniaxial Tensile ◽  
High Tensile Strength

High tensile strength steel sheets have large springback after being formend at room temperature. Warm forming can be a solution to reduce springback of high tensile strength steel parts. NANOHITENTM is a high strength ferritic steel precipitation-strengthened by nanometer-sized carbides developed by JFE Steel Corporation. Tensile strength of the steel at room temperature does not change before and after deformation at elevated temperatures up to 873K since the carbides in the steel are stable at high temperatures less than 973K. Therefore, the steel is suitable for warm forming. Springback of 980MPa NANOHITENTM parts warm formed at 873K is the same level of that of cold formed conventional 590MPa steel parts. In this study, two kinds of material testing at room temperature and at elevated temperatures between 573K and 937K were performed to understand the mechanical behavior of 980MPa NANOHITENTM: uniaxial tensile tests and bending tests. The steels flow stress depends on not only material temperature but also strain rate in uniaxial tensile tests. After a bending test, the specimen shows springback measured by the change of an angle between the two sides. Stress relaxation happens while a test specimen is held at the bottom dead point after bending. And the stress relaxation could be used to reduce springback of warm formed parts.

Investigation of irradiation-induced nucleation processes in silicon and germanium

1995 ◽  
Vol 53 ◽  
pp. 224-225
Author(s):  
Harry A. Atwater ◽  
C.M. Yang ◽  
K.V. Shcheglov
Keyword(s):  
Room Temperature ◽  
Crystal Size ◽  
Initial Distribution ◽  
Engineering Control ◽  
Size Evolution ◽  
Silicon And Germanium ◽  
Ge Quantum Dot ◽  
And Control ◽  
Germanium Quantum Dots ◽  
Kinetics Of

Studies of the initial stages of nucleation of silicon and germanium have yielded insights that point the way to achievement of engineering control over crystal size evolution at the nanometer scale. In addition to their importance in understanding fundamental issues in nucleation, these studies are relevant to efforts to (i) control the size distributions of silicon and germanium “quantum dots𠇍, which will in turn enable control of the optical properties of these materials, (ii) and control the kinetics of crystallization of amorphous silicon and germanium films on amorphous insulating substrates so as to, e.g., produce crystalline grains of essentially arbitrary size.Ge quantum dot nanocrystals with average sizes between 2 nm and 9 nm were formed by room temperature ion implantation into SiO2, followed by precipitation during thermal anneals at temperatures between 30°C and 1200°C[1]. Surprisingly, it was found that Ge nanocrystal nucleation occurs at room temperature as shown in Fig. 1, and that subsequent microstructural evolution occurred via coarsening of the initial distribution.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Kinetics of the Thermal Disappearance of Radicals Formed During the Radiolysis of Aspartic Acid

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Mihai Contineanu ◽  
iulia Contineanu ◽  
Ana Neacsu ◽  
Stefan Perisanu
Keyword(s):  
Thermal Resistance ◽  
Aspartic Acid ◽  
Room Temperature ◽  
Esr Spectra ◽  
Complex Mechanism ◽  
Radical Species ◽  
Mechanisms Of Formation ◽  
Kinetics Of

The radiolysis of the isomers L-, D- and DL- of the aspartic acid, in solid polycrystalline state, was investigated at room temperature. The analysis of their ESR spectra indicated the formation of at least two radicalic entities. The radical, identified as R3, resulting from the deamination of the acid, exhibits the highest concentration and thermal resistance. Possible mechanisms of formation of three radical species are suggested, based also on literature data. The kinetics of the disappearance of radical R3 indicated a complex mechanism. Three possible variants were suggested for this mechanism.

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