The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Saburo Matsuoka - One of the best experts on this subject based on the ideXlab platform.
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effects of hydrogen on tensile properties and Fracture Surface morphologies of type 316l stainless steel
International Journal of Hydrogen Energy, 2014Co-Authors: Takashi Matsuo, Junichiro Yamabe, Saburo MatsuokaAbstract:Abstract The effects of hydrogen on the tensile properties and Fracture Surface morphologies of Type 316L stainless steel were investigated using virgin and prestrained specimens. Hydrogen gas exposure at 10 MPa and 250 °C for 192 h resulted in its uniform distribution in the specimens. Such internal hydrogen degraded the tensile ductility of the specimens. Cup–cone Fracture occurred in the non-, Ar-, and H-exposed specimens. The Fracture Surfaces were covered with large and small dimples. The H-exposed specimens exhibited larger small-dimple areas than the non- and Ar-exposed ones. The diameter of the large dimples decreased with increasing small-dimple area. Three-dimensional analysis of the dimples showed that the small-dimple regions were void sheets produced by local shear strain. Hydrogen accelerated nucleation of voids and formation of the void sheets by enhancing localization of shear deformation, thereby reducing the average size of the dimples.
Y Q Weng - One of the best experts on this subject based on the ideXlab platform.
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estimation of the size of gbf area on Fracture Surface for high strength steels in very high cycle fatigue regime
International Journal of Fatigue, 2008Co-Authors: Zhaoxiang Yang, S X Li, Y D Li, G Y Li, Y Q WengAbstract:The sizes of the "granular bright facet' (GBF) areas on Fracture Surfaces of specimens subjected to very high cycle fatigue for two high strength spring steels were measured in a field emission scanning electron microscope (FESEM) and compared with the estimated values, and a good agreement was found between the two sets of data. A criterion was proposed to estimate the sizes of GBF areas. It was assumed that when the increment of crack length in one applied stress cycle (numerically equal to crack growth rate, da/dN) is just equal to the plastic zone size in front of crack tip, r(p), the GBF stops developing. It means that hydrogen accumulating in the plastic zone under applied stress influences mostly on the fatigue behaviors which results in the morphology of GBF area quite different from the conventional fatigue Fracture Surface. The estimated sizes of GBF areas were also in accordance with the sizes measured from Fracture Surfaces of other high strength steels provided that the hydrogen concentration in those steels was not much higher than that in present spring steels. (c) 2007 Elsevier Ltd. All rights reserved.
Junichiro Yamabe - One of the best experts on this subject based on the ideXlab platform.
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effects of hydrogen on tensile properties and Fracture Surface morphologies of type 316l stainless steel
International Journal of Hydrogen Energy, 2014Co-Authors: Takashi Matsuo, Junichiro Yamabe, Saburo MatsuokaAbstract:Abstract The effects of hydrogen on the tensile properties and Fracture Surface morphologies of Type 316L stainless steel were investigated using virgin and prestrained specimens. Hydrogen gas exposure at 10 MPa and 250 °C for 192 h resulted in its uniform distribution in the specimens. Such internal hydrogen degraded the tensile ductility of the specimens. Cup–cone Fracture occurred in the non-, Ar-, and H-exposed specimens. The Fracture Surfaces were covered with large and small dimples. The H-exposed specimens exhibited larger small-dimple areas than the non- and Ar-exposed ones. The diameter of the large dimples decreased with increasing small-dimple area. Three-dimensional analysis of the dimples showed that the small-dimple regions were void sheets produced by local shear strain. Hydrogen accelerated nucleation of voids and formation of the void sheets by enhancing localization of shear deformation, thereby reducing the average size of the dimples.
Kai Zhang - One of the best experts on this subject based on the ideXlab platform.
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Strain Rate Effect on the Mechanical Properties and Fracture Surface Roughness of Sandstone Subjected to Dynamic Direct Tension
IEEE Access, 2020Co-Authors: Yanlong Chen, Ming Li, Kai ZhangAbstract:Dynamic properties of rocks are extremely important in a variety of rock mechanics and rock engineering problems. The split Hopkinson tensile bar (SHTB) system is used in this paper to measure the mechanical properties of sandstone specimens under dynamic direct tension, and the full stress-strain curves of the specimens at different strain rates is obtained. The experimental results indicate that the tensile strength, the tensile modulus and the peak strain of the specimen increase almost linearly with the strain rate. The increases in the tensile strength, the tensile modulus and the peak strain reach 125 %, 37 % and 98 % respectively as the strain rate increases by 252 %. The microscopic structure characteristics of the Fracture Surfaces after the tensile failure of the specimens are investigated by three-dimensional scanning. The results suggest that the Fracture Surface roughness of the sandstone under direct tension is significantly sensitive to the strain rate. Both the roughness coefficient and the fractal dimension of the specimen increase with the strain rate. The Fracture Surface of the specimen changes from a relatively flat two-dimensional state to a three-dimensional state, and its relative area gradually increases. Finally, it is manifested from the aspect of energy consumption that both the energy consumed in the Fracture process and the dynamic direct tensile strength enhance with the Fracture Surface roughness. It is believed that the investigation results can provide an important reference for the research on dynamic properties of rocks involved in experimental research and engineering practice.
Anna Suzuki - One of the best experts on this subject based on the ideXlab platform.
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use of tracers and temperature to estimate Fracture Surface area for egs reservoirs
Geothermics, 2017Co-Authors: Michael G Shook, Anna SuzukiAbstract:Abstract A key uncertainty in the design and long-time behavior of EGS reservoirs, and their management, is the Fracture Surface area that controls the rate of heat transfer between the host rock and the circulating injected water. A workflow is developed that uses analytic solutions to estimate this Surface area. We first analyze a tracer test to estimate the Fracture pore volume swept, the flow geometry, and the presence of multiple Fractures (or damage zones around the primary Fracture). Using this information about Fracture properties, an analytic solution describing produced temperature vs. time can be solving iteratively to estimate Surface area. In the case of multiple Fractures, we show that the equation governing the produced fluids’ temperature is superposed to estimate the Surface area. The workflow is shown to be robust, even in the presence of heterogeneity. The workflow is then used to make design decisions and predictions about the sustainably of a reservoir. Also shown is the use of the workflow to estimate power generation as a function of Fracture properties (measured) and flow rates (controlled), and show how to scale up to multiple production wells and Fracture packs. Assumptions used, and limitations of the method are discussed.
