scholarly journals Experimental Investigation and Constitutive Modeling of the Uncured Rubber Compound Based on the DMA Strain Scanning Method

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2700
Author(s):  
Yong Li ◽  
Xunhua Sun ◽  
Shoudong Zhang ◽  
Yanan Miao ◽  
Shanling Han
Keyword(s):  
Tensile Deformation ◽  
Constant Strain Rate ◽  
Large Data ◽  
Thermomechanical Analysis ◽  
Elastic Stiffness ◽  
Dynamic Force ◽  
Amplitude Curve ◽  
Rubber Compound ◽  
Scanning Method ◽  
Burgers Model

Existing research tends to focus on the performance of cured rubber. This is due to a lack of suitable testing methods for the mechanical properties of uncured rubber, in particular, tensile properties. Without crosslinking by sulfur, the tensile strength of uncured rubber compounds is too low to be accurately tested by general tensile testing machines. Firstly, a new tensile stress testing method for uncured rubber was established by using dynamic thermomechanical analysis (DMA) tensile strain scanning. The strain amplitude was increased under a set frequency and constant temperature. The corresponding dynamic force needed to maintain the amplitude was then measured to obtain the dynamic force-amplitude curve observed at this temperature and frequency. Secondly, the Burgers model is usually difficult to calculate and analyze in differential form, so it was reduced to its arithmetic form under creep conditions and material relaxation. Tensile deformation at a constant strain rate was proposed, so the Burgers model could be modified to a more concise form without any strain terms, making mathematical processing and simulating much more convenient. Thirdly, the rate of the modified Burgers model under constant strain was in good agreement with the test data, demonstrating that the elastic stiffness was 1–2 orders of magnitude less than the tensile viscosity. In the end, it was concluded that large data dispersion caused by the universal tensile test can be overcome by choosing this model, and it may become an effective way to study the tensile modeling of uncured rubber compound.

The Effect of Nitrogen on High Temperature Deformation Behaviors in Type 316L Stainless Steel

2007 ◽  
Vol 345-346 ◽  
pp. 69-72 ◽  
Author(s):  
F. Liu ◽  
J.G. Jung ◽  
Soo Woo Nam
Keyword(s):  
Tensile Deformation ◽  
Low Cycle Fatigue ◽  
Cell Structure ◽  
Constant Strain Rate ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Cycle Fatigue ◽  
Nitrogen Effect ◽  
Type 316L ◽  
Deformation Behaviors

Both tensile and strain controlled low cycle fatigue (LCF) tests were conducted for 316L and 316LN at 550oC and 600oC to investigate the nitrogen effect on the deformation behavior of type 316L stainless. The waveform of LCF was a symmetrical triangle with a constant strain rate of 4×10-3/s was employed for most tests. It shows that the addition of nitrogen in the alloy results in an increase in tensile strength but a decrease in ductility. Both the alloys exhibited cell structure after severe tensile deformation. However, after low cycle fatigue, only planar slip band is observed in 316LN, whereas cell structure is still the main feather of microstructure in 316L. This is due to the strong interstitial-substitutional Mo-N pairs and various stress strain conditions.

In Situ Testing and Heterogeneity of UFG Cu at Elevated Temperatures

2015 ◽  
Vol 1127 ◽  
pp. 67-72
Author(s):  
Martin Petrenec ◽  
Petr Král ◽  
Jiří Dvořák ◽  
Milan Svoboda ◽  
Vàclav Sklenička
Keyword(s):  
Elevated Temperature ◽  
Tensile Test ◽  
Grain Growth ◽  
Elevated Temperatures ◽  
Tensile Deformation ◽  
Constant Strain Rate ◽  
Electron Back Scatter Diffraction ◽  
Coarse Grained ◽  
Ultrafine Grained

Experiments were conducted to investigate deformation-induced processes during in-situ tensile test at elevated temperature. Consequently the microstructure after creep loading was examined by 3D Electron Back Scatter Diffraction (EBSD) technique. The billets of coarse-grained copper were processed by equal-channel angular pressing (ECAP) at room temperature using a die that had an internal angle of 90° between the two parts of the channel and an outer arc of curvature of ~ 20°, where these two parts intersect. The pressing speed was 10 mm/min. To obtain an ultrafine-grained (UFG) material, the billets were subsequently pressed by route Bc by 8 ECAP passes to give the mean grain size ~ 0.7 μm. The constant strain-rate test in tension was performed at 473 K using testing GATAN stage Microtest 2000EW with EH 2000 heated grips which is configured for in-situ electron back scatter diffraction (EBSD) observations. Microstructure was examined by FEG-SEM TESCAN MIRA 3 XM equipped by EBSD detector HKL NordlysMax from OXFORD INSTRUMENT. The tensile test was interrupted by fast stress reductions after different deformation step and observation of microstructure changes was performed. Despite of a considerable interest in ECAP processing method, there are not many works documenting microstructure evolution and changes during creep testing and determining creep mechanisms of ultrafine-grained materials processed by ECAP. It was found that creep resistance of UFG pure Al and Cu is considerably improved after one ECAP pass in comparison with coarse grained material, however, further repetitive pressing leads to a noticeable deterioration in creep properties of ECAP material. Recently it was observed the coarsening of the grains in microstructure of ECAP copper during creep at elevated temperature. It was suggested that creep behaviour is controlled by storage and dynamic recovery of dislocations at high-angle boundaries. In the present work was found that ultrafine-grained microstructure is instable and significant grain growth has already occurred during heating to the testing temperature. Static recrystallization during heating led to the formation of high fraction of special boundaries Σ3 and Σ9. The tensile deformation at 473 K led to the additional grain growth and formation of new grains. Microstructure was investigated also by 3D EBSD.

scholarly journals Effects of strain rate on tensile deformation behaviour in Ti-6Al-4V at cryogenic temperature

2020 ◽  
Vol 321 ◽  
pp. 06010
Author(s):  
Min-Ki Ji ◽  
Min-Su Lee ◽  
Yong-Taek Hyun ◽  
Tea-Sung Jun
Keyword(s):  
Strain Rate ◽  
Liquid Nitrogen ◽  
Cryogenic Temperature ◽  
Tensile Deformation ◽  
Electron Backscatter Diffraction ◽  
Deformation Behaviour ◽  
Constant Strain Rate ◽  
Tensile Tests ◽  
Local Deformation ◽  
Deformation Twinning

In this study, we investigated the effects of strain rate on tensile deformation behaviour in Ti-6Al-4V sheet at cryogenic temperature. X-ray diffraction (XRD) was used to identify the crystallographic orientation of rolled Ti-6Al-4V. A series of tensile tests were performed by constant strain rate method (CRS) with variable strain rates (i.e., on the order of 1x10-2 to 10-4•s-1). Liquid nitrogen (LN2) was used to mimic cryogenic environment, and for the thermal equilibrium the specimens were immersed in the vessel containing liquid nitrogen for ~10 minutes before tensile testing, and the temperature condition was continuously maintained during the testing. Microstructure and fracture surface was analysed by polarised light microscopy and scanning electron microscope (SEM). Electron backscatter diffraction (EBSD) was further used to characterise local deformation behaviour. Deformation twinning is occurred at cryogenic tempearture, which is rather different to the deformation at room temperature. It is thought that the twinning induced deformation behaviour may lead to a strength enhancement and a rate dependent ductility improvement. Key words: Ti-6Al-4V, cryogenic, microstructure, deformation twinning, EBSD

Chemisorptive electron emission as a probe of plastic deformation in reactive metals

1994 ◽  
Vol 9 (5) ◽  
pp. 1156-1165 ◽  
Author(s):  
J.T. Dickinson ◽  
L.C. Jensen ◽  
S.C. Langford ◽  
R.G. Hoagland
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Surface Area ◽  
Electron Emission ◽  
Tensile Deformation ◽  
Constant Strain Rate ◽  
Total Surface Area ◽  
Unit Surface Area ◽  
Deformation And Fracture ◽  
Reactive Metals

The surface area created during tensile deformation and fracture of the reactive metals Ti, Zr, Mg, and Al is probed by real-time measurements of chemisorptive electron emission (CSE) due to oxygen adsorption. CSE is sensitive to the number of fresh metal atoms exposed at the surface as a consequence of plastic deformation. At constant strain rate, Ti, Zr, and Mg all display exponential increases in CSE intensities during loading, reflecting exponential increases in surface area prior to fracture. In Ti and Zr, CSE begins at the onset of unstable necking. In contrast, CSE intensities from Al reflect a nearly constant rate of surface area production during deformation at constant strain rate. Calibration of the Ti CSE intensities per unit surface area allowed determination of the total surface area produced during deformation and fracture. Atomic force microscopy of the necked region in strained Ti samples shows dramatic increases in surface roughness, in near agreement with the CSE results. A model is presented to account for these observations. The utility of CSE measurements as a probe of deformation and ductile fracture is discussed.

scholarly journals In Situ WAXD and SAXS during Tensile Deformation Of Moulded and Sintered Polyamide 12

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1001 ◽  
Author(s):  
Fabio Paolucci ◽  
Leon Govaert ◽  
Gerrit Peters
Keyword(s):  
Mechanical Response ◽  
Mechanical Performance ◽  
Tensile Deformation ◽  
Constant Strain Rate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Polyamide 12 ◽  
X Ray Scattering ◽  
The Difference

To provide knowledge to improve the mechanical performance of Polyamide 12 (PA12) sintered products, we have studied experimentally the mechanical response and structure development under constant strain rate of compression moulded and laser sintered PA12 by means of in situ small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) experiments. It is found that at low temperatures, i.e., below the glass transition temperature, the brittle failure of laser sintered samples is determined by the fast formation of voids that originate at the beginning of the macroscopic plastic deformation. This effect appears to be faster at temperatures below room temperature and it is less effective at higher temperatures. When tested at 120 ∘ C, sintered PA12 shows a better mechanical response in terms of yield stress and a comparable strain at break with respect to moulded PA12. This can be explained by considering that sintered samples have slightly thicker crystals that can sustain higher stress at high temperature. However, this also leads to the formation of a larger number of voids at low testing temperatures. This work does not attempt to quantify the micromechanics behind crystals deformation and disruption, but it provides a deeper insight in the difference between the mechanical response of moulded and sintered PA12.

Deformation Behavior of Nitrogen Bearing Austenitic Steels with Various Nitrogen Contents

2007 ◽  
Vol 345-346 ◽  
pp. 117-120 ◽  
Author(s):  
Yong Suk Kim ◽  
Seung Man Nam ◽  
Sung Joon Kim
Keyword(s):  
Nitrogen Content ◽  
Deformation Behavior ◽  
Tensile Deformation ◽  
Constant Strain Rate ◽  
Tensile Tests ◽  
Austenitic Steels ◽  
High Nitrogen ◽  
Tensile Deformation Behavior ◽  
Nitrogen Steel ◽  
Nitrogen Contents

Tensile deformation behavior of the high-nitrogen austenitic Fe-18Cr-14Mn-4Ni-3MoxN steel with various nitrogen contents has been studied. The nitrogen content of the steel varied from 0.28 to 0.88 wt. %. Nitrogen atoms in high nitrogen steel (HNS) make an interstitial solid solution by being scattered in the steel constituting a short-range order. They strengthen the austenite matrix without deteriorating ductility of the steel. The present investigation was carried out to elucidate the hardening and plasticizing role of the nitrogen in the HNS by analyzing tensile deformation behavior of the steel containing various nitrogen contents. Tensile tests of the steel specimens were performed at room temperature with a constant strain rate of 5x10-5/sec. Microstructure of the tested specimens was analyzed to explore the deformation mechanism of the HNS as a function of nitrogen contents. The flow stress of the steel increased with the increase of the nitrogen content; however, the specimen with the highest nitrogen content (0.88 wt. %) showed saturated strength and reduced ductility. The superior mechanical property of the HNS was explained by the low stacking fault energy and the twin-induced plasticity provoked by the nitrogen.

Microstructure of TC21 Titanium Alloy after Superplastic Deformation and Heat Treatment

2013 ◽  
Vol 275-277 ◽  
pp. 1855-1858
Author(s):  
Zhi Wei Ling ◽  
Hong Bo Dong
Keyword(s):  
Heat Treatment ◽  
Titanium Alloy ◽  
Superplastic Deformation ◽  
Tensile Deformation ◽  
Testing Machine ◽  
Constant Strain Rate ◽  
Tensile Tests ◽  
Tensile Testing Machine ◽  
Α Phase ◽  
Annealing Heat Treatment

The isothermal constant strain rate tensile tests of the TC21 titanium alloy were conducted by SSAN-CMT4104 electronic tensile testing machine at different temperature. After superplastic deformation, the alloy was treated with double annealing heat treatment, and microstructure of the alloy was analyzed. The results show that dynamically recrystallization occurs during the superplastic tensile deformation. The primary α-grains aggregated and merged to form new crystal grains with irregular grain boundaries. The amount and morphology of primary α phase change gradually with the increasing of temperature. The alloy has duplex microstructure composed of primary α phase and different forms of β-transformed structure after superplastic deformation and double annealing. At deformation temperature of 930°C, the basket weave structure with equiaxed α phase appears.

TEM examination of 2014-SiC metal matrix composite

1988 ◽  
Vol 46 ◽  
pp. 726-727
Author(s):  
M. G. Burke ◽  
M. N. Gungor ◽  
P. K. Liaw
Keyword(s):  
Metal Matrix Composite ◽  
Metal Matrix Composites ◽  
Matrix Composite ◽  
Metal Matrix ◽  
Tensile Deformation ◽  
Microstructural Characterization ◽  
Thin Foil ◽  
Matrix Alloy ◽  
Matrix Composites ◽  
Ion Milling

Aluminum-based metal matrix composites offer unique combinations of high specific strength and high stiffness. The improvement in strength and stiffness is related to the particulate reinforcement and the particular matrix alloy chosen. In this way, the metal matrix composite can be tailored for specific materials applications. The microstructural characterization of metal matrix composites is thus important in the development of these materials. In this study, the structure of a p/m 2014-SiC particulate metal matrix composite has been examined after extrusion and tensile deformation.Thin-foil specimens of the 2014-20 vol.% SiCp metal matrix composite were prepared by dimpling to approximately 35 μm prior to ion-milling using a Gatan Dual Ion Mill equipped with a cold stage. These samples were then examined in a Philips 400T TEM/STEM operated at 120 kV. Two material conditions were evaluated: after extrusion (80:1); and after tensile deformation at 250°C.

An example of spectrum imaging used for comparison of EELS quantitative analysis techniques on Al-Li

1991 ◽  
Vol 49 ◽  
pp. 726-727
Author(s):  
John A. Hunt
Keyword(s):  
Quantitative Analysis ◽  
Large Data ◽  
Difference Spectrum ◽  
Large Data Sets ◽  
Foil Thickness ◽  
Data Sets ◽  
Analysis Techniques ◽  
Spectrum Imaging ◽  
Normal Spectrum ◽  
Electron Energy Loss

Spectrum-imaging is a useful technique for comparing different processing methods on very large data sets which are identical for each method. This paper is concerned with comparing methods of electron energy-loss spectroscopy (EELS) quantitative analysis on the Al-Li system. The spectrum-image analyzed here was obtained from an Al-10at%Li foil aged to produce δ' precipitates that can span the foil thickness. Two 1024 channel EELS spectra offset in energy by 1 eV were recorded and stored at each pixel in the 80x80 spectrum-image (25 Mbytes). An energy range of 39-89eV (20 channels/eV) are represented. During processing the spectra are either subtracted to create an artifact corrected difference spectrum, or the energy offset is numerically removed and the spectra are added to create a normal spectrum. The spectrum-images are processed into 2D floating-point images using methods and software described in [1].

Scanning ion microscopy images

1987 ◽  
Vol 45 ◽  
pp. 180-181
Author(s):  
R. Levi-Setti ◽  
J.M. Chabala ◽  
Y.L. Wang
Keyword(s):  
Metal Ion ◽  
Secondary Emission ◽  
Scanning Method ◽  
Ion Channeling ◽  
Secondary Ions ◽  
High Resolution Images ◽  
Ion Microscopy ◽  
Z Contrast ◽  
Focused Beams ◽  
Microscopy Images

Finely focused beams extracted from liquid metal ion sources (LMIS) provide a wealth of secondary signals which can be exploited to create high resolution images by the scanning method. The images of scanning ion microscopy (SIM) encompass a variety of contrast mechanisms which we classify into two broad categories: a) Emission contrast and b) Analytical contrast.Emission contrast refers to those mechanisms inherent to the emission of secondaries by solids under ion bombardment. The contrast-carrying signals consist of ion-induced secondary electrons (ISE) and secondary ions (ISI). Both signals exhibit i) topographic emission contrast due to the existence of differential geometric emission and collection effects, ii) crystallographic emission contrast, due to primary ion channeling phenomena and differential oxidation of crystalline surfaces, iii) chemical emission or Z-contrast, related to the dependence of the secondary emission yields on the Z and surface chemical state of the target.

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