Electropulse stimulation provides an energy-efficient means of excavating hard rocks through repeated application of high voltage pulses to the rock surface.As such,it has the potential to confer significant advantage...Electropulse stimulation provides an energy-efficient means of excavating hard rocks through repeated application of high voltage pulses to the rock surface.As such,it has the potential to confer significant advantages to mining and drilling operations for mineral and energy resources.Nevertheless,before these benefits can be realized,a better understanding of these processes is required to improve their deployment in the field.In this paper,we employ a recently developed model of the grain-scale processes involved in electropulse stimulation to examine excavation of hard rock under realistic operating conditions.To that end,we investigate the maximum applied voltage within ranges of 120e600 kV,to observe the onset of rock fragmentation.We further study the effect of grain size on rock breakage,by comparing fine(granodiorite)and coarse grained(granite)rocks.Lastly,the pore fluid salinity is investigated,since the electric conductivity of the pore fluid is shown to be a governing factor for the electrical conductivity of the modeled system.This study demonstrates that all investigated factors are crucial to the efficiency of rock fragmentation by electropulsing.展开更多
Naturally deposited soils are always found in the complex three-dimensional stress state.Constitutive models developed for modeling the three-dimensional mechanical behavior of soils should obey the basic laws of ther...Naturally deposited soils are always found in the complex three-dimensional stress state.Constitutive models developed for modeling the three-dimensional mechanical behavior of soils should obey the basic laws of thermo-mechanical principles.Based on the incremental dissipation function,a new deviatoric shift stress is derived and then introduced into the existing constitutive models to describe the yield behavior in the deviatoric plane for geomaterials.By adopting the proposed shift stress,the relationship between dissipative stress tensors and true stress tensors can be established.Therefore,the threedimensional plastic strain can be calculated reasonably through the associated flow rule in the three-dimensional dissipative stress space.At the same time,three methods that are conventionally adopted for generalizing constitutive models to model the three-dimensional stress-strain relationships are examined under the thermo-mechanical framework.The TS(transformed stress)method is shown to obey the thermo-mechanical rules and the TS space adopted in TS method is actually a translational three-dimensional dissipative stress space.However,it is illustrated that the other two approaches,the method of using failure criterion directly and the method of using g()function,violate the basic rules of thermo-mechanical theories although they may bring convenience and simplicity to numerical analysis for geotechnical engineering.Comparison between model predictions and experimental data confirms the validity of the proposed three-dimensional dissipative stress space.展开更多
A framework of continuum breakage mechanics was used to investigate the dependence of compressibility on grain size distribution(GSD)as well as relative density of sand.Compressibility dependence on GSD was considered...A framework of continuum breakage mechanics was used to investigate the dependence of compressibility on grain size distribution(GSD)as well as relative density of sand.Compressibility dependence on GSD was considered by employing a GSD index and relative density dependence was reflected by varying the plastic-breakage coupling angle.Simulations of the experimental results including isotropic compression and one-dimensional compression of sands with different relative densities and GSDs revealed that sand compressibility increased with the increasing GSD index and plastic-breakage coupling angle.The coupling angle decreased with increasing relative density,indicating that grains would break more in sand with comparatively high relative density.展开更多
Heat Treating is a critical manufacturing technology. This is particularly true in countries with large manufacturing industry including:; automotive, construction, transportation, and aerospace sectors. Technical adv...Heat Treating is a critical manufacturing technology. This is particularly true in countries with large manufacturing industry including:; automotive, construction, transportation, and aerospace sectors. Technical advancement of the heat treating industry will be a critical component of the increasing need to remain competitive in this manufacturing sector on a global scale. ASM International has identified the development of process modeling and numerical simulation as a critical technology for the advancement of the heat treating process industry. In this paper, a selective overview of the current accomplishments and future needs of process modeling technologies in heat treatment will be provided.展开更多
基金supported by Innosuisse-Swiss Innovation Agency-under grant number 28305.1 PFIW-IWsupport from SwissGeoPower。
文摘Electropulse stimulation provides an energy-efficient means of excavating hard rocks through repeated application of high voltage pulses to the rock surface.As such,it has the potential to confer significant advantages to mining and drilling operations for mineral and energy resources.Nevertheless,before these benefits can be realized,a better understanding of these processes is required to improve their deployment in the field.In this paper,we employ a recently developed model of the grain-scale processes involved in electropulse stimulation to examine excavation of hard rock under realistic operating conditions.To that end,we investigate the maximum applied voltage within ranges of 120e600 kV,to observe the onset of rock fragmentation.We further study the effect of grain size on rock breakage,by comparing fine(granodiorite)and coarse grained(granite)rocks.Lastly,the pore fluid salinity is investigated,since the electric conductivity of the pore fluid is shown to be a governing factor for the electrical conductivity of the modeled system.This study demonstrates that all investigated factors are crucial to the efficiency of rock fragmentation by electropulsing.
基金supported by the National Natural Science Foundation of China (Grants Nos. 11072016,51179003,11272031,51209002)
文摘Naturally deposited soils are always found in the complex three-dimensional stress state.Constitutive models developed for modeling the three-dimensional mechanical behavior of soils should obey the basic laws of thermo-mechanical principles.Based on the incremental dissipation function,a new deviatoric shift stress is derived and then introduced into the existing constitutive models to describe the yield behavior in the deviatoric plane for geomaterials.By adopting the proposed shift stress,the relationship between dissipative stress tensors and true stress tensors can be established.Therefore,the threedimensional plastic strain can be calculated reasonably through the associated flow rule in the three-dimensional dissipative stress space.At the same time,three methods that are conventionally adopted for generalizing constitutive models to model the three-dimensional stress-strain relationships are examined under the thermo-mechanical framework.The TS(transformed stress)method is shown to obey the thermo-mechanical rules and the TS space adopted in TS method is actually a translational three-dimensional dissipative stress space.However,it is illustrated that the other two approaches,the method of using failure criterion directly and the method of using g()function,violate the basic rules of thermo-mechanical theories although they may bring convenience and simplicity to numerical analysis for geotechnical engineering.Comparison between model predictions and experimental data confirms the validity of the proposed three-dimensional dissipative stress space.
基金supported by China Scholarship Council(Grant No.201306710022)
文摘A framework of continuum breakage mechanics was used to investigate the dependence of compressibility on grain size distribution(GSD)as well as relative density of sand.Compressibility dependence on GSD was considered by employing a GSD index and relative density dependence was reflected by varying the plastic-breakage coupling angle.Simulations of the experimental results including isotropic compression and one-dimensional compression of sands with different relative densities and GSDs revealed that sand compressibility increased with the increasing GSD index and plastic-breakage coupling angle.The coupling angle decreased with increasing relative density,indicating that grains would break more in sand with comparatively high relative density.
文摘Heat Treating is a critical manufacturing technology. This is particularly true in countries with large manufacturing industry including:; automotive, construction, transportation, and aerospace sectors. Technical advancement of the heat treating industry will be a critical component of the increasing need to remain competitive in this manufacturing sector on a global scale. ASM International has identified the development of process modeling and numerical simulation as a critical technology for the advancement of the heat treating process industry. In this paper, a selective overview of the current accomplishments and future needs of process modeling technologies in heat treatment will be provided.
