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K S Pandey - One of the best experts on this subject based on the ideXlab platform.
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some aspects on cold forging of aluminium iron powder metallurgy composite under Triaxial Stress state condition
Materials & Design, 2008Co-Authors: R Narayanasamy, T Ramesh, K S PandeyAbstract:Abstract An experimental investigation on the barreling of aluminium with various per cent additive of iron composites, namely, 2%, 4%, 6%, 8% and 10% with different iron particle sizes, namely −53 +45 μm, −75 +63 μm and −106 +90 μm under Triaxial Stress state condition has been studied in the present work. Sintered aluminium–iron composites with height to diameter ratio of 0.44 were prepared, sintered, furnace cooled and cold upset forged. A new empirical relationship for the determination of the barrel radius is proposed based on the circular radius of curvature and compared with the experimentally measured barrel radius. Various Stress ratio parameters, namely (σθ/σz), (σm/σz), (σeff/σz) and (σm/σeff), respectively, were determined and their behaviour against the relative density and barrel radius has been systematically analyzed. A straight-line relationship was observed for the measured and the calculated radius of curvature of barrel and an exponential relationship was found between the Stress ratio parameters and the relative density.
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effect of geometric work hardening and matrix work hardening on workability and densification of aluminium 3 5 alumina composite during cold upsetting
Materials & Design, 2008Co-Authors: R Narayanasamy, V Anandakrishnan, K S PandeyAbstract:Abstract The densification is a measure of deformation in upset forming of Powder Metallurgy (P/M) processes. A complete experimental investigation on the deformation behaviour of aluminium–3.5% alumina powder composite has been discussed for the case of Triaxial Stress state condition. Cold upsetting of aluminium–3.5% alumina composite with and with no annealing having different initial preform relative density and with different aspect ratio was carried out and the densification behaviour of the preform under Triaxial Stress state condition was determined. A new true strain considering the effect of bulging was taken into account for the case of determination of the hoop strain. Plots made for different preforms were analyzed for the densification behaviour of preforms considering the effect of both geometrical work-hardening (GWH) and the matrix work-hardening (MWH).
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some features on hot forging of powder metallurgy sintered high strength 4 titanium carbide composite steel preforms under different Stress state conditions
Materials & Design, 2008Co-Authors: R Narayanasamy, V Senthilkumar, K S PandeyAbstract:In this paper, the authors propose mathematical expressions for the determination of different Stress ratio parameters under plane and Triaxial Stress state conditions. Experiments were carried out to evaluate the hot forging features in the high strength sintered powder metallurgy 4%titanium carbide composite steel performs under different Stress states, namely, plane Stress and Triaxial Stress states. Cylindrical compacts with aspect ratios 0.45, 0.75 and 1.25 were prepared, sintered and forged at the temperatures of 1120 ± 10 °C. The investigation suggests that the experimentally determined relative density has a straight-line relationship with the new geometrical shape factor. The measured barrel radius of curvature is found to have a circular arc. Relationship is established between the measured barrel radius and the Stress ratio parameters under plane and Triaxial Stress state conditions. An attempt is also made to establish a relationship between the various Stress ratio parameters under plane and Triaxial Stress state conditions and the relative density.
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some aspects of workability studies on hot forging of sintered high strength 4 titanium carbide composite steel preforms
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: R Narayanasamy, V Senthilkumar, K S PandeyAbstract:Abstract The aim of the paper is the study of workability of Fe–1.0% C–4% TiC steel composite during hot upsetting. Ductile fracture is the most common failure acting in bulk forming process. The formability during hot upsetting depends on the temperature, strain and strain rate. A complete experimental investigation of the workability behaviour of Fe–1.0% C–4% TiC steel composite was performed under the Triaxial Stress state condition. Hot upsetting of Fe–1.0% C–4% TiC steel composite preforms was carried out at a temperature of 1120 °C and the formability behaviour of the same at Triaxial Stress state condition was determined. The curves plotted for different preforms were analysed and the relationship between the axial strain and the formability Stress index were obtained. A relationship between the relative density and the axial strain was also established. A particular attempt was made to relate the various Stress ratio parameters, namely, (σθ/σeff), (σm/σeff) and (σz/σeff) with the relative density.
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some aspects on workability of aluminium iron powder metallurgy composite during cold upsetting
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005Co-Authors: R Narayanasamy, T Ramesh, K S PandeyAbstract:Abstract Workability is a measure of the extent of deformation that a powder metallurgy materials can withstand prior to fracture occurred in the forming or upsetting processes. Ductile fracture is the most common mode of failure in bulk forming process. The formability is a complicated phenomenon, dependent upon the process as well as the material parameters. A complete experimental investigation on the workability behaviour of Al–Fe composite was performed under the Triaxial Stress state. Upsetting of Al–Fe composite having different iron contents with different aspect ratios and iron particle sizes were carried out and the formability behaviour of the compacts at Triaxial Stress condition was determined. A new true strain considering the effect of the bulging was taken in to account. The curves plotted for different compacts were analyzed and concluded that there is a drastic changes in the formability behaviour of compacts because of different content of iron and its particle sizes and aspect ratios.
R Narayanasamy - One of the best experts on this subject based on the ideXlab platform.
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effect of various Stress ratio parameters on cold upset forging of irregular shaped billets using graphite as lubricant under plane and Triaxial Stress state conditions
Materials & Design, 2008Co-Authors: K Baskaran, R NarayanasamyAbstract:Abstract This paper examines the effect of various Stress ratio parameters on cold upset forging of commercially pure aluminium solid billets of irregular shaped billets, using graphite mixed with oil as lubricant applied on both sides under plane and Triaxial Stress state conditions. Billets with three different aspect ratios (ratio of height to diameter) namely, 0.5, 0.75 and 1.0, with different ‘b/a’ ratios (ratio of minor to major diameter) namely, 0.6 and 0.7 were prepared and cold forged. Cold deformation on samples were subjected to an incremental deformation steps of 3 metric tones load and at the end of each step, dimensions such as height, contact and bulged diameters being measured. The calculations were made with the assumption that the radius of curvature of the barrel followed the form of a circular arc. Analysis of the experimental data showed that there exist a relationship between the measured barrel radius and various Stress ratio parameters namely, (σθ/σz), (σm/σz), (σeff/σz) and (σm/σeff) developed under plane and Triaxial Stress conditions. An attempt has also been made to relate the percentage height reduction with respect to the Stress ratio parameters namely, (σθ/σz), (σm/σz), (σeff/σz) and (σm/σeff) developed under plane and Triaxial Stress conditions and found to have an increasing trend and a straight line trend with enhanced level of deformation irrespective of aspect ratios and b/a ratios tested or selected.
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effect of geometric work hardening and matrix work hardening on workability and densification of aluminium 3 5 alumina composite during cold upsetting
Materials & Design, 2008Co-Authors: R Narayanasamy, V Anandakrishnan, K S PandeyAbstract:Abstract The densification is a measure of deformation in upset forming of Powder Metallurgy (P/M) processes. A complete experimental investigation on the deformation behaviour of aluminium–3.5% alumina powder composite has been discussed for the case of Triaxial Stress state condition. Cold upsetting of aluminium–3.5% alumina composite with and with no annealing having different initial preform relative density and with different aspect ratio was carried out and the densification behaviour of the preform under Triaxial Stress state condition was determined. A new true strain considering the effect of bulging was taken into account for the case of determination of the hoop strain. Plots made for different preforms were analyzed for the densification behaviour of preforms considering the effect of both geometrical work-hardening (GWH) and the matrix work-hardening (MWH).
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some aspects on cold forging of aluminium iron powder metallurgy composite under Triaxial Stress state condition
Materials & Design, 2008Co-Authors: R Narayanasamy, T Ramesh, K S PandeyAbstract:Abstract An experimental investigation on the barreling of aluminium with various per cent additive of iron composites, namely, 2%, 4%, 6%, 8% and 10% with different iron particle sizes, namely −53 +45 μm, −75 +63 μm and −106 +90 μm under Triaxial Stress state condition has been studied in the present work. Sintered aluminium–iron composites with height to diameter ratio of 0.44 were prepared, sintered, furnace cooled and cold upset forged. A new empirical relationship for the determination of the barrel radius is proposed based on the circular radius of curvature and compared with the experimentally measured barrel radius. Various Stress ratio parameters, namely (σθ/σz), (σm/σz), (σeff/σz) and (σm/σeff), respectively, were determined and their behaviour against the relative density and barrel radius has been systematically analyzed. A straight-line relationship was observed for the measured and the calculated radius of curvature of barrel and an exponential relationship was found between the Stress ratio parameters and the relative density.
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some features on hot forging of powder metallurgy sintered high strength 4 titanium carbide composite steel preforms under different Stress state conditions
Materials & Design, 2008Co-Authors: R Narayanasamy, V Senthilkumar, K S PandeyAbstract:In this paper, the authors propose mathematical expressions for the determination of different Stress ratio parameters under plane and Triaxial Stress state conditions. Experiments were carried out to evaluate the hot forging features in the high strength sintered powder metallurgy 4%titanium carbide composite steel performs under different Stress states, namely, plane Stress and Triaxial Stress states. Cylindrical compacts with aspect ratios 0.45, 0.75 and 1.25 were prepared, sintered and forged at the temperatures of 1120 ± 10 °C. The investigation suggests that the experimentally determined relative density has a straight-line relationship with the new geometrical shape factor. The measured barrel radius of curvature is found to have a circular arc. Relationship is established between the measured barrel radius and the Stress ratio parameters under plane and Triaxial Stress state conditions. An attempt is also made to establish a relationship between the various Stress ratio parameters under plane and Triaxial Stress state conditions and the relative density.
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some aspects of workability studies on hot forging of sintered high strength 4 titanium carbide composite steel preforms
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: R Narayanasamy, V Senthilkumar, K S PandeyAbstract:Abstract The aim of the paper is the study of workability of Fe–1.0% C–4% TiC steel composite during hot upsetting. Ductile fracture is the most common failure acting in bulk forming process. The formability during hot upsetting depends on the temperature, strain and strain rate. A complete experimental investigation of the workability behaviour of Fe–1.0% C–4% TiC steel composite was performed under the Triaxial Stress state condition. Hot upsetting of Fe–1.0% C–4% TiC steel composite preforms was carried out at a temperature of 1120 °C and the formability behaviour of the same at Triaxial Stress state condition was determined. The curves plotted for different preforms were analysed and the relationship between the axial strain and the formability Stress index were obtained. A relationship between the relative density and the axial strain was also established. A particular attempt was made to relate the various Stress ratio parameters, namely, (σθ/σeff), (σm/σeff) and (σz/σeff) with the relative density.
Yubing Liu - One of the best experts on this subject based on the ideXlab platform.
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anisotropic mechanical properties and the permeability evolution of cubic coal under true Triaxial Stress paths
Rock Mechanics and Rock Engineering, 2019Co-Authors: Guangzhi Yin, Yubing Liu, Dongming Zhang, Bozhi Deng, Chao LiuAbstract:The geological sequestration of CO2, underground coal mining, and coalbed methane production in deep coal reservoirs is executed under high levels of 3-D geo-Stress, and it is accompanied by significant variations in both vertical and horizontal Stresses. In addition, coal is a highly fractured porous medium characterized by complex natural fracture systems. This exterior and interior anisotropy complicates the replication of in situ conditions in the laboratory. In this study, we divided pre-existing fracture systems of cubic coal into three flow planes: a bedding plane, face cleat plane, and butt cleat plane. Gas flowed through cubic coal samples along each flow plane under differently designed true Triaxial Stress paths. We then further analyzed anisotropic mechanical and flow property responses of cubic coal after failure by model fitting, CT scan reconstruction, and fractal representation. The experimental results indicate that pre-existing flow planes play significant roles in the strength levels, failure modes, and permeability levels. Low strength levels, typical shear failure patterns, and low initial permeability levels were observed in the butt cleat plane direction. Anisotropic strength data can be effectively fit by applying a linear relationship between octahedral shear Stress and mean effective normal Stress. After coal failure, the peak permeability observed in the face and butt cleat plane directions also presents a strong linear relationship with the fractal dimension. An anisotropic conceptual failure process model was established for the description of internal fracture development during Stress loading. Horizontal Stress unloading decreased the strength and formed a more complex fracture system in cubic coal regardless of the different flow planes involved, producing the increments of associated peak permeability.
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directional permeability evolution in intact and fractured coal subjected to true Triaxial Stresses under dry and water saturated conditions
International Journal of Rock Mechanics and Mining Sciences, 2019Co-Authors: Guangzhi Yin, Yubing Liu, Dongming Zhang, Bozhi Deng, Chao Liu, Honggang Zhao, Siyu YinAbstract:Abstract Investigations of the directional permeability evolution of intact and fractured coal are conducted under different simulated geological conditions. The effects of fracture geometry, water adsorption and Stress conditions on the permeability evolution of coal as a function of Stress are systematically studied. The results indicate that permeability anisotropy is more pronounced in fractured coal than in intact coal. The permeability order, i.e., the kfa > kbu > kbe relationship, is maintained following the introduction of macrofractures into coal. The fracture compressibility in the butt cleat plane flow direction is higher than that in the other two flow directions for both intact and fractured coal. The presence of water in coal can reduce the permeability by up to one order of magnitude, and a more significant permeability decrease is observed in coal specimens containing rough macrofractures. Permeability hysteresis for both intact and fractured coal is somewhat dependent on the Stress condition. The hysteresis effect of coal is more significant under Triaxial Stress conditions and less pronounced under true-Triaxial Stress conditions.
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permeability characteristics of layered composite coal rock under true Triaxial Stress conditions
Journal of Natural Gas Science and Engineering, 2019Co-Authors: Guangzhi Yin, Bozhi Deng, Chao Liu, Weizhong Zhang, Xiuwei Chai, Yubing LiuAbstract:Abstract It is important to understand the gas flow properties in coal and sandstone under different Stress conditions for underground carbon dioxide storage and coal bed gas drainage in underground engineering. In an actual project, the rock layers are complex and varied, and the in situ Stress presents a significant three-dimensional anisotropy (σ1 > σ2 ≠ σ3). Although a large amount of data on the permeability of coal have been reported previously, studies on the permeability of layered composite coal rock under true Triaxial Stress conditions are lacking. In this study, the permeability of layered composite coal rock under true Triaxial Stress conditions was measured by using a true Triaxial apparatus. Under experimental Stress conditions, the permeability always decreased as the principal Stress increased. The thickness changes in coal seams and sandstone formations have major influences on the evolution of composite coal rock permeability. Furthermore, the normalized permeability increases with the thickness ratio of sandstone to coal. We analyzed the Stress state of layered composite coal rock by considering the interaction of coal and sandstone under true Triaxial Stress conditions. Based on the anisotropy consideration of coal rock and the Stress difference of composite coal rock masses, a permeability model for layered composite coal rock under true Triaxial Stress condition was proposed (TCP model: layered composite coal rock permeability model). It was found that this model can well reflect the permeability characteristics of composite coal rock under true Triaxial Stress conditions while simultaneously considering the effect of the three principal Stresses and the mutual strain restraint effects of coal and sandstone.
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permeability evolution of anthracite coal considering true Triaxial Stress conditions and structural anisotropy
Journal of Natural Gas Science and Engineering, 2018Co-Authors: Yubing Liu, Dongming Zhang, Ozhi DengAbstract:Abstract It is critical to understand the gas flow behavior in coal under a reservoir Stress condition for coal bed methane production, underground coal mining, and CO2-sequestration in deep coal seams. With respect to coal seams, the in-situ Stress is anisotropic and generally exists under true Triaxial Stress (σ1 > σ2 > σ3) conditions. Additionally, the flow channels determining the permeability of coal are also anisotropic. This dual anisotropy produces difficulties in replicating the gas transport characteristics of coal at the laboratory scale, and there is a paucity of relevant studies. In this study, we performed a series of permeability measurements using cubic anthracite coal samples and changing the principal Stresses and flow directions under various true Triaxial Stress conditions. The coal permeability exhibited greater anisotropy in the vertical direction as a result of the presence of minerals in cleats across the bedding plane. After each principal Stress compression at a differential Stress of 20 MPa, the permeability in each direction decreased by an order of magnitude. With an increase in the intermediate Stress parameter, the permeability values of two horizontal cleats experienced higher decreasing rates compared with the vertical bedding permeability. This increased the significance of the horizontal permeability anisotropy. With respect to the true Triaxial Stress condition with a higher horizontal principal Stress (σH > σh > σv), a higher permeability reduction was observed during the principal Stress loading period. The butt cleat plane was more sensitive to changes in the principal Stress because of the lower connectivity of the flow channels induced by the closure of the face cleat that acted as a cross-linked pathway. The anisotropic permeability data measured under true Triaxial Stress conditions were well expressed by an exponential equation containing different mean cleat compressibility and Stress terms. The cleat compressibility values in different directions were obtained by data fitting.
Guangzhi Yin - One of the best experts on this subject based on the ideXlab platform.
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mechanical properties of layered composite coal rock subjected to true Triaxial Stress
Rock Mechanics and Rock Engineering, 2020Co-Authors: Gun Huang, Dongming Zhang, Heng Gao, Guangzhi YinAbstract:Underground mining or tunnelling activity is always associated with the composite geological formations. The mechanical properties of layered composite coal–rock subjected to true Triaxial Stress conditions are significantly different from those under conventional Triaxial or uniaxial Stress conditions. In this work, we conducted a series of true Triaxial tests using the self-developed true-Triaxial apparatus to investigate the mechanical response (e.g., deformation, strength, and failure characteristics) of the layered composite coal–rock (CCR). The results show that the uniaxial strength of CCR lies between the strength of pure sandstone and coal, and the direction of the bedding affects the overall strength of the samples. The true Triaxial strength of both the pure rock and CCR increases first and then decreases with the increase of the intermediate principal Stress. Moreover, for a given loading direction, as the thickness of the sandstone layer increased, the strength of the CCR increases. The deformation of the CCR shows more obvious plasticity than that of the pure sandstone due to the coordinated deformation of the coal and sandstone layers. In addition, a new true Triaxial strength criterion expressed by the first and third equivalent principal Stress invariants was proposed, which can well describe the strength characteristics of different coal rocks. The Stress states, weak structural planes, and localized Stress have a great influence on the failure modes of CCR. The local Stress concentration near the contact surface promotes the development of the secondary failure fractures. These findings are of great significance in stability designing in deep underground engineering.
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anisotropic mechanical properties and the permeability evolution of cubic coal under true Triaxial Stress paths
Rock Mechanics and Rock Engineering, 2019Co-Authors: Guangzhi Yin, Yubing Liu, Dongming Zhang, Bozhi Deng, Chao LiuAbstract:The geological sequestration of CO2, underground coal mining, and coalbed methane production in deep coal reservoirs is executed under high levels of 3-D geo-Stress, and it is accompanied by significant variations in both vertical and horizontal Stresses. In addition, coal is a highly fractured porous medium characterized by complex natural fracture systems. This exterior and interior anisotropy complicates the replication of in situ conditions in the laboratory. In this study, we divided pre-existing fracture systems of cubic coal into three flow planes: a bedding plane, face cleat plane, and butt cleat plane. Gas flowed through cubic coal samples along each flow plane under differently designed true Triaxial Stress paths. We then further analyzed anisotropic mechanical and flow property responses of cubic coal after failure by model fitting, CT scan reconstruction, and fractal representation. The experimental results indicate that pre-existing flow planes play significant roles in the strength levels, failure modes, and permeability levels. Low strength levels, typical shear failure patterns, and low initial permeability levels were observed in the butt cleat plane direction. Anisotropic strength data can be effectively fit by applying a linear relationship between octahedral shear Stress and mean effective normal Stress. After coal failure, the peak permeability observed in the face and butt cleat plane directions also presents a strong linear relationship with the fractal dimension. An anisotropic conceptual failure process model was established for the description of internal fracture development during Stress loading. Horizontal Stress unloading decreased the strength and formed a more complex fracture system in cubic coal regardless of the different flow planes involved, producing the increments of associated peak permeability.
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directional permeability evolution in intact and fractured coal subjected to true Triaxial Stresses under dry and water saturated conditions
International Journal of Rock Mechanics and Mining Sciences, 2019Co-Authors: Guangzhi Yin, Yubing Liu, Dongming Zhang, Bozhi Deng, Chao Liu, Honggang Zhao, Siyu YinAbstract:Abstract Investigations of the directional permeability evolution of intact and fractured coal are conducted under different simulated geological conditions. The effects of fracture geometry, water adsorption and Stress conditions on the permeability evolution of coal as a function of Stress are systematically studied. The results indicate that permeability anisotropy is more pronounced in fractured coal than in intact coal. The permeability order, i.e., the kfa > kbu > kbe relationship, is maintained following the introduction of macrofractures into coal. The fracture compressibility in the butt cleat plane flow direction is higher than that in the other two flow directions for both intact and fractured coal. The presence of water in coal can reduce the permeability by up to one order of magnitude, and a more significant permeability decrease is observed in coal specimens containing rough macrofractures. Permeability hysteresis for both intact and fractured coal is somewhat dependent on the Stress condition. The hysteresis effect of coal is more significant under Triaxial Stress conditions and less pronounced under true-Triaxial Stress conditions.
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permeability characteristics of layered composite coal rock under true Triaxial Stress conditions
Journal of Natural Gas Science and Engineering, 2019Co-Authors: Guangzhi Yin, Bozhi Deng, Chao Liu, Weizhong Zhang, Xiuwei Chai, Yubing LiuAbstract:Abstract It is important to understand the gas flow properties in coal and sandstone under different Stress conditions for underground carbon dioxide storage and coal bed gas drainage in underground engineering. In an actual project, the rock layers are complex and varied, and the in situ Stress presents a significant three-dimensional anisotropy (σ1 > σ2 ≠ σ3). Although a large amount of data on the permeability of coal have been reported previously, studies on the permeability of layered composite coal rock under true Triaxial Stress conditions are lacking. In this study, the permeability of layered composite coal rock under true Triaxial Stress conditions was measured by using a true Triaxial apparatus. Under experimental Stress conditions, the permeability always decreased as the principal Stress increased. The thickness changes in coal seams and sandstone formations have major influences on the evolution of composite coal rock permeability. Furthermore, the normalized permeability increases with the thickness ratio of sandstone to coal. We analyzed the Stress state of layered composite coal rock by considering the interaction of coal and sandstone under true Triaxial Stress conditions. Based on the anisotropy consideration of coal rock and the Stress difference of composite coal rock masses, a permeability model for layered composite coal rock under true Triaxial Stress condition was proposed (TCP model: layered composite coal rock permeability model). It was found that this model can well reflect the permeability characteristics of composite coal rock under true Triaxial Stress conditions while simultaneously considering the effect of the three principal Stresses and the mutual strain restraint effects of coal and sandstone.
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deformation and co2 gas permeability response of sandstone to mean and deviatoric Stress variations under true Triaxial Stress conditions
Tunnelling and Underground Space Technology, 2019Co-Authors: Guangzhi Yin, Dongming Zhang, Weizhong Zhang, Qinrong KangAbstract:Abstract The magnitude and direction of geo-Stress undergoes complex changes following disturbance by artificial excavation in underground engineering. Tests were conducted using the self-made multi-functional true Triaxial geophysical apparatus to investigate the influence of Stress Lode angle on deformation, deformation modulus, and permeability of sandstone under true Triaxial Stress conditions (σ1> σ2 > σ3). The results indicate that principal, volumetric, and deviatoric strains, as well as permeability varied with the Stress Lode angle, and eventually increased/decreased at different levels. For constant deviatoric Stress and variable mean Stress, the plastic strain decreased with increasing M (ratio of deviatoric Stress q to mean Stress p), whereas the permeability increased. For constant mean Stress and variable deviatoric Stress, the principal, volumetric, and deviatoric strains, as well as the permeability decreased first and then increased with the increase in M; the rock generated fracture surface when M was relatively large. The gas flow and Stress axis directions significantly influence the value and changing trend of the permeability. With increasing Stress Lode angle, the permeability increased first and then decreased. In our Stress condition testing, the permeability value and variation range were maximum when the gas flow direction was parallel to σ1; when it was parallel to σ3, the permeability demonstrated an upward trend, but with a smaller increase range. Conversely, when it was parallel to σ2, the permeability decreased and the variation range was minimized. Finally, based on the analysis of the experimental results, we developed a permeability model that is expressed by both volumetric and deviatoric strains.
V Senthilkumar - One of the best experts on this subject based on the ideXlab platform.
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some features on hot forging of powder metallurgy sintered high strength 4 titanium carbide composite steel preforms under different Stress state conditions
Materials & Design, 2008Co-Authors: R Narayanasamy, V Senthilkumar, K S PandeyAbstract:In this paper, the authors propose mathematical expressions for the determination of different Stress ratio parameters under plane and Triaxial Stress state conditions. Experiments were carried out to evaluate the hot forging features in the high strength sintered powder metallurgy 4%titanium carbide composite steel performs under different Stress states, namely, plane Stress and Triaxial Stress states. Cylindrical compacts with aspect ratios 0.45, 0.75 and 1.25 were prepared, sintered and forged at the temperatures of 1120 ± 10 °C. The investigation suggests that the experimentally determined relative density has a straight-line relationship with the new geometrical shape factor. The measured barrel radius of curvature is found to have a circular arc. Relationship is established between the measured barrel radius and the Stress ratio parameters under plane and Triaxial Stress state conditions. An attempt is also made to establish a relationship between the various Stress ratio parameters under plane and Triaxial Stress state conditions and the relative density.
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some aspects of workability studies on hot forging of sintered high strength 4 titanium carbide composite steel preforms
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: R Narayanasamy, V Senthilkumar, K S PandeyAbstract:Abstract The aim of the paper is the study of workability of Fe–1.0% C–4% TiC steel composite during hot upsetting. Ductile fracture is the most common failure acting in bulk forming process. The formability during hot upsetting depends on the temperature, strain and strain rate. A complete experimental investigation of the workability behaviour of Fe–1.0% C–4% TiC steel composite was performed under the Triaxial Stress state condition. Hot upsetting of Fe–1.0% C–4% TiC steel composite preforms was carried out at a temperature of 1120 °C and the formability behaviour of the same at Triaxial Stress state condition was determined. The curves plotted for different preforms were analysed and the relationship between the axial strain and the formability Stress index were obtained. A relationship between the relative density and the axial strain was also established. A particular attempt was made to relate the various Stress ratio parameters, namely, (σθ/σeff), (σm/σeff) and (σz/σeff) with the relative density.
