scholarly journals Mechanical Properties of a Typical Jurassic Shaximiao Sandstone Under Subzero and Deep in situ Temperature Conditions

2021 ◽  
Vol 9 ◽  
Author(s):  
R. He ◽  
L. He ◽  
B. Guan ◽  
C. M. Yuan ◽  
J. Xie ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Crack Front ◽  
Image Correlation ◽  
Correlation Technique ◽  
Direct Tension ◽  
Reservoir Stimulation ◽  
The Difference ◽  
Lower Temperature ◽  
Highly Strained

Insight into the difference between the mechanical properties of rocks at low and in situ deep reservoir temperatures is vital for achieving a better understanding of fracking technologies with supercritical CO2 and liquid nitrogen. To address this issue, the fracking-related mechanical properties of the Shaximiao Formation sandstone (SS) were investigated through direct tension, uniaxial compression, and three-point bending fracture tests at a typical low temperature (Tlow) of −10°C and a reservoir temperature (Tin situ) of 70°C. The results showed that the tensile strength σt, compressive strength σc, and fracture toughness KIC of the SS were all higher at Tlow than at Tin situ, although to different extents. The KIC of the SS increased slightly more than σt at the lower temperature, while both σt and KIC of the SS increased significantly more than σc at the lower temperature. In addition to the strength, the stiffness (particularly the tensile stiffness) and the brittleness indices of SS were similarly higher at Tlow than at Tin situ. In situ monitoring using the digital image correlation technique revealed that a highly strained band (HSB) always appeared at the crack front. However, because of the inhomogeneous microstructure of the SS, the HSB did not always develop along the line connecting the notch tip to the loading point. This was a possible cause of the highly dispersed KIC values of the SS. The HSB at the crack front was notably narrower at Tlow than at Tin situ, suggesting that low temperatures suppress the plastic deformation of rocks and are therefore beneficial to reservoir stimulation.

Corrosion Rates and Changes in Mechanical Properties of Copper Alloys due to Seawater Exposure

2012 ◽  
Author(s):  
Andrew Drach ◽  
Igor Tsukrov ◽  
Todd Gross ◽  
Uwe Hofmann ◽  
Jochen Aufrecht ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Prolonged Exposure ◽  
North Atlantic Ocean ◽  
Copper Alloys ◽  
Image Correlation ◽  
Correlation Technique ◽  
Rectangular Plates ◽  
Material Loss ◽  
The North ◽  
The Difference

A field study on corrosion was conducted on several copper alloys subjected to prolonged exposure in seawater. Rectangular plates made of nine alloys were deployed for a year in the North Atlantic Ocean. Material loss rates were quantified by measuring the difference in weight between the initial virgin specimens and the cleaned specimens after recovery. Changes in mechanical properties due to the seawater exposure were quantified by performing standard uniaxial tension tests. Stress-strain dependence was obtained for each of the tested materials using the digital image correlation technique. Some degradation of tensile strength was observed in all alloys, but for most of them it was not substantial.

scholarly journals Local Mechanical Properties and Microstructure of EN AW 6082 Aluminium Alloy Processed via ECAP–Conform Technique

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2572 ◽  
Author(s):  
Radek Procházka ◽  
Peter Sláma ◽  
Jaromír Dlouhý ◽  
Pavel Konopík ◽  
Zuzanka Trojanová
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Tensile Testing ◽  
Electron Backscatter Diffraction ◽  
Extrusion Direction ◽  
Strain Differences ◽  
Image Correlation ◽  
Correlation Technique ◽  
Plastic Properties ◽  
2D Digital Image Correlation

An ultrafine-grained EN AW 6082 aluminum alloy was prepared by continuous serve plastic deformation (i.e., thermo-mechanical equal channel angular pressing (ECAP)–Conform process). A miniaturized tensile testing technique was used for estimating local mechanical properties with the aim to reveal the inhomogeneity of elastic and plastic properties in a workpiece volume. These inhomogeneities may appear due to the irregular shear strain distribution in a Conformed wire. Miniaturized samples for tensile testing were cut from the Conformed workpiece. Elongation of miniaturized samples was measured with a 2D digital image correlation technique as the optical extensometer. Tensile test characteristics, such as the yield strength and ultimate tensile strength, were consequently compared with results of conventional and hardness tests. The microstructure of Conformed bars was studied in the cross-section perpendicular and parallel to the extrusion direction using scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) analysis. The microstructure of samples exhibits pronounced inhomogeneity, which is reflected by the hardness and tensile test results. Estimated distinctions between peripheral and central parts of the Conformed wires are probably a consequence of the significant strain differences realized in the upper and bottom wire parts.

Fabrication of Ti2AlC/TiAl Composites with the Addition of Niobium by Spark Plasma Sintering

2008 ◽  
Vol 368-372 ◽  
pp. 1004-1006 ◽  
Author(s):  
Yun Long Yue ◽  
H.T. Wu
Keyword(s):  
Mechanical Properties ◽  
Spark Plasma Sintering ◽  
Bending Strength ◽  
Three Point Bending ◽  
Plasma Sintering ◽  
Titanium Aluminum ◽  
Spark Plasma ◽  
The Difference ◽  
The Relationship

Ti2AlC/TiAl composites with the addition of niobium were prepared by spark plasma sintering using titanium, aluminum, niobium elemental powers and TiC particles as reactants. The experimental and analytical studies on this kind of material concentrated on the relationship between reinforcement phase and mechanical properties. The Ti2AlC/TiAl composites with 5% niobium exhibit high mechanical properties. The three-point bending strength and fracture toughness reaches as high as 915MPa and 23 MPa·m1/2, respectively. It is found that the in-situ reaction occurs at 1100°C with the addition of niobium at the interface between the TiAl matrix and original reinforcement TiC. Further XRD results indicate that the difference in the reinforcement phase from TiC to Ti2AlC is one of the most important origins to the variation in mechanical properties.

Mechanical characterization of tetraxial textiles

2017 ◽  
Vol 48 (1) ◽  
pp. 3-24 ◽  
Author(s):  
Mehdi Ghazimoradi ◽  
Valter Carvelli ◽  
Maria Chiara Marchesi ◽  
Roberto Frassine
Keyword(s):  
Mechanical Properties ◽  
Strain Field ◽  
Mechanical Characterization ◽  
Tensile Tests ◽  
Image Correlation ◽  
Correlation Technique ◽  
Digital Image Correlation Technique ◽  
Experimental Campaign ◽  
Out Of Plane

In this paper, the mechanical properties of different tetraxial fabrics are investigated. Fabrics were produced using an innovative loom capable of weaving four threads at the same time with complete discretion of yarn type and count. The experimental investigation deals with in-plane and out-of-plane mechanical testing of tetraxial fabrics, as well as yarns made of four different materials (polyethylene terephthalate, glass, aramid, and basalt). The digital image correlation technique was used to measure the in-plane strain field for both uniaxial and biaxial tensile tests. The extensive experimental campaign allowed for a complete mechanical characterization of this novel fabric architecture including interlacement of different yarns.

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