The abundance of non-renewable energy resource is interlaced with frangibility of the environment... more The abundance of non-renewable energy resource is interlaced with frangibility of the environment in many areas of China. In this paper, we developed a theoretical model explaining why resources exploitation will impede economic growth mainly through the demand scale of local environment products. Moreover, we construct a standardization framework to estimate the ecological and environment external cost, which include estimating methods, estimating process and preferences, etc. we apply this standardization estimating framework to systemically and completely value the environment pollution and ecological depravation loss during non-renewable energy resource mining in northern Shaanxi. Our results confirmed that urgent requirement of sustainable development in China is to reform the extraction mode of non-renewable energy resource thoroughly in order to prolong its mining term and to sufficiently compensate the ecological and environmental loss during resource extraction.
It is frequently hypothesized that environment management systems (EMS) may improve firms' i... more It is frequently hypothesized that environment management systems (EMS) may improve firms' innovation performance. Whether this hypothesis is true based on the relevant policy incentives for income distribution and its environmental innovation. There are two channels which EMS affects technical innovation (1) rich people migrate out region cause lower demand for local environment, (2) small size of the market demand caused by inequalities barriers to technical innovation. Based on ample empirical evidence from Shaanxi province, Our theoretical and empirical results indicate through influences of greater inequalities why EMS have fewer effects on Environmental innovation in rich nature resource area.
Discrete element method (DEM) was used to simulate the dynamic process of microbond test of fiber... more Discrete element method (DEM) was used to simulate the dynamic process of microbond test of fiber reinforced composites, in which the fiber and matrix were modeled as elastic and elastic-plastic materials, respectively. The interface between fiber and matrix was represented by a bilinear contact softening model. Plastic deformation and progressive cracking of the matrix were observed in the simulation with comparable similarity to the existing experimental results. The initiation and propagation of interfacial debonding were also captured by the DEM simulations, whereas it is very difficult to achieve this by other numerical methods. Vertical and inclined vises with two different vise angles were tested in the simulations. It was found that both vise geometry and vise angle had significant effect on the damages of the material, and the inclined vise was sensitive to the vise angle in terms of large variation of cutting force. The developed DEM model can also be applied to predict material damages in other more complicated fiber reinforce composite system.
A numerical simulation has been conducted to study the solid-fluid multi-phase flow problem in co... more A numerical simulation has been conducted to study the solid-fluid multi-phase flow problem in concrete pumping process. The kinematics and trajectory of the discrete particles as well as the particle-particle interaction were predicted by DEM while the motion of the continuous fluid phase was evaluated by a Navier-Stokes solver, and a pressure gradient force model was adopted to calculate the solid-fluid interaction force. A case of pneumatic conveying was utilized to demonstrate the capability of the coupling model. The concrete pumping process was then simulated, where several flow features were observed such as roping, particle segregation and particle concentration. The frequency of the particles impacting on the bended pipe was monitored, a new time average collision intensity model based on impact force has been proposed to investigate the wear mechanism of the elbow. The location of maximum erosive wear damage in the elbow was predicted. Statistical results were in good agreement with that observed in actual pumping process. It is found that the present multi-phase coupling model can predict the wear behavior of the bended pipe accurately, and consequently provide an effective guidance for the design of concrete pumping pipe.
Discrete element method (DEM) was employed in the research works presented in this paper to simul... more Discrete element method (DEM) was employed in the research works presented in this paper to simulate the microscopic machining process of ceramics. A densely packed particle assembly system of the polycrystalline SiC has been generated in DEM software package PFC2D using bonded-particle model (BPM) in order to represent for the ceramic part numerically. Microscopic mechanical properties of SiC were calibrated
International Journal of Machine Tools & Manufacture, 2008
Discrete element method (DEM) was introduced to simulate crack initiation and propagation of poly... more Discrete element method (DEM) was introduced to simulate crack initiation and propagation of polycrystalline alumina during the brittle model machining process. A bonded particle model (BPM) was employed in the DEM simulations procedure to generate a particle assembly system similar to the micro-structure of the polycrystalline alumina. Particle and parallel bond properties, which were calibrated through a series of numerical tests, were subsequently used in the simulations of polycrystalline alumina cutting process and scratching tests. It is found that the cracks initiated right under or in front of the machining tool. There were many micro-cracks remained on the machined surface, some of them propagated downwards to form macro-cracks or forwards to lead material removal. Both DEM simulations and acoustic emission measure experiments have found that the fracture became acute when the normal and the tangential force changed suddenly, causing the crack number to increase. In 3D DEM scratching simulation, the surface cracks length and subsurface cracks depth linearly increased with the scratching depth, the value agreed well with the experimental results, and the surface-damage width decreased gradually with the depth to the surface, looking like half of a coin. r
Pre-stressing scratching tests have been preformed on polished surfaces of Al 2 O 3 ceramic under... more Pre-stressing scratching tests have been preformed on polished surfaces of Al 2 O 3 ceramic under a Rockwell diamond indenter which moved with uniform speed and constant normal load to investigate how the pre-stress contributes to the material removal mechanism. With the measurement of acoustic emission signals as well as indenter tangential forces, surface damages and cross-section of grooves of Al 2 O 3 ceramic were evaluated under the action of different values of pre-stress. It was found that the scratched groove width was increased with the increasing of pre-stress when same normal loads were applied. The existence of pre-stress tends to restrain the crack propagation along the direction of pre-stress, and obvious plastic deformation at the bottom of scratched groove has been observed. Moreover, the fluctuation of tangential force was obviously enhanced, and the magnitude of tangential force in the test of pre-stress was higher than that of without pre-stress. The acoustic emission signals showed that fewer damages were produced in the process of scratching with an appropriate pre-stress. However, the continuing increase of pre-stress would aggravate the machining process.
a b s t r a c t A particle discrete element method (DEM) was employed to simulate transverse crac... more a b s t r a c t A particle discrete element method (DEM) was employed to simulate transverse cracking in laminated fiber reinforced composites. The microstructure of the laminates was modeled by a DEM model using different mechanical constitutive laws and materials parameters for different constituents, i.e. fiber, matrix and fiber/matrix interface. Rectangular, hexagonal and random fiber distributions were simulated to study the effect of fiber distribution on the transverse cracking. The initiation and dynamic propagation of transverse cracking and interfacial debonding were all captured by the DEM simulation, which showed similar patterns to those observed from experiments. The effect of fiber volume fraction was also studied for laminae with randomly distributed fibers. It was found that the distribution and volume fraction of fibers affected not only the transverse cracking path, but also the behavior of matrix plastic deformation and fiber/matrix interface yielding in the material.
Discrete element method (DEM) was used to model progressive delamination of fiber reinforced comp... more Discrete element method (DEM) was used to model progressive delamination of fiber reinforced composite laminates. The anisotropic composite plies were constructed through a hexagonal packing of particle elements. Contacts between the particles were represented by parallel bonds with the verified normal and shear elastic properties. The ply interface was characterized by a contact softening model with a bilinear elastic behavior which is similar to the cohesive zone model in the continuum mechanics. DCB, ELS and FRMM tests were simulated by the DEM model to assess its capability of modeling mode I, mode II and mix mode fracture of delamination, respectively. Good agreements were observed between the DEM and existing numerical and experimental results of loading curves, which confirmed that the DEM model can be used to simulate initiation and propagation of composite delamination, with more insights into microscopic material behavior, such as damage extension and plastic zone.
A representative element of the cross-ply laminate was modeled by the discrete element method (DE... more A representative element of the cross-ply laminate was modeled by the discrete element method (DEM) to analyze the stresses distribution. The DEM modeling results were compared with those from alternative approaches to validate the DEM model. The transverse cracking and interfacial delamination in [0˚1/90˚3] s and [90˚n/0˚1] s cross-ply laminates under transverse loading were analyzed by comparing crack densities as well as stiffness reduction with those from experiments and other numerical methods. It was found that the proposed DEM model can simultaneously capture the transverse cracking and delamination phenomenon, and can predict the variation of crack density and stiffness reduction accurately.
A numerical simulation of fluid transportation process was carried out focused on the investigati... more A numerical simulation of fluid transportation process was carried out focused on the investigation into predicting the location of the puncture point location in elbow. The kinematics and trajectory of the discrete particles as well as the particle-particle interaction were described by discrete element method (DEM) while the hydrodynamic model of the fluid phase was based on the volume-averaged Navier-Stokes equations, and a fluid density-based buoyancy model was adopted to calculate the solid-fluid interaction force. In this paper, the spatial distribution of particle-wall interaction force was calculated and corresponded to the wear pattern in the elbow, the puncture point locations have been observed. In particular, the influences of slurry velocity, bend orientation and angle of elbow on the puncture point location were discussed.
The abundance of non-renewable energy resource is interlaced with frangibility of the environment... more The abundance of non-renewable energy resource is interlaced with frangibility of the environment in many areas of China. In this paper, we developed a theoretical model explaining why resources exploitation will impede economic growth mainly through the demand scale of local environment products. Moreover, we construct a standardization framework to estimate the ecological and environment external cost, which include estimating methods, estimating process and preferences, etc. we apply this standardization estimating framework to systemically and completely value the environment pollution and ecological depravation loss during non-renewable energy resource mining in northern Shaanxi. Our results confirmed that urgent requirement of sustainable development in China is to reform the extraction mode of non-renewable energy resource thoroughly in order to prolong its mining term and to sufficiently compensate the ecological and environmental loss during resource extraction.
It is frequently hypothesized that environment management systems (EMS) may improve firms' i... more It is frequently hypothesized that environment management systems (EMS) may improve firms' innovation performance. Whether this hypothesis is true based on the relevant policy incentives for income distribution and its environmental innovation. There are two channels which EMS affects technical innovation (1) rich people migrate out region cause lower demand for local environment, (2) small size of the market demand caused by inequalities barriers to technical innovation. Based on ample empirical evidence from Shaanxi province, Our theoretical and empirical results indicate through influences of greater inequalities why EMS have fewer effects on Environmental innovation in rich nature resource area.
Discrete element method (DEM) was used to simulate the dynamic process of microbond test of fiber... more Discrete element method (DEM) was used to simulate the dynamic process of microbond test of fiber reinforced composites, in which the fiber and matrix were modeled as elastic and elastic-plastic materials, respectively. The interface between fiber and matrix was represented by a bilinear contact softening model. Plastic deformation and progressive cracking of the matrix were observed in the simulation with comparable similarity to the existing experimental results. The initiation and propagation of interfacial debonding were also captured by the DEM simulations, whereas it is very difficult to achieve this by other numerical methods. Vertical and inclined vises with two different vise angles were tested in the simulations. It was found that both vise geometry and vise angle had significant effect on the damages of the material, and the inclined vise was sensitive to the vise angle in terms of large variation of cutting force. The developed DEM model can also be applied to predict material damages in other more complicated fiber reinforce composite system.
A numerical simulation has been conducted to study the solid-fluid multi-phase flow problem in co... more A numerical simulation has been conducted to study the solid-fluid multi-phase flow problem in concrete pumping process. The kinematics and trajectory of the discrete particles as well as the particle-particle interaction were predicted by DEM while the motion of the continuous fluid phase was evaluated by a Navier-Stokes solver, and a pressure gradient force model was adopted to calculate the solid-fluid interaction force. A case of pneumatic conveying was utilized to demonstrate the capability of the coupling model. The concrete pumping process was then simulated, where several flow features were observed such as roping, particle segregation and particle concentration. The frequency of the particles impacting on the bended pipe was monitored, a new time average collision intensity model based on impact force has been proposed to investigate the wear mechanism of the elbow. The location of maximum erosive wear damage in the elbow was predicted. Statistical results were in good agreement with that observed in actual pumping process. It is found that the present multi-phase coupling model can predict the wear behavior of the bended pipe accurately, and consequently provide an effective guidance for the design of concrete pumping pipe.
Discrete element method (DEM) was employed in the research works presented in this paper to simul... more Discrete element method (DEM) was employed in the research works presented in this paper to simulate the microscopic machining process of ceramics. A densely packed particle assembly system of the polycrystalline SiC has been generated in DEM software package PFC2D using bonded-particle model (BPM) in order to represent for the ceramic part numerically. Microscopic mechanical properties of SiC were calibrated
International Journal of Machine Tools & Manufacture, 2008
Discrete element method (DEM) was introduced to simulate crack initiation and propagation of poly... more Discrete element method (DEM) was introduced to simulate crack initiation and propagation of polycrystalline alumina during the brittle model machining process. A bonded particle model (BPM) was employed in the DEM simulations procedure to generate a particle assembly system similar to the micro-structure of the polycrystalline alumina. Particle and parallel bond properties, which were calibrated through a series of numerical tests, were subsequently used in the simulations of polycrystalline alumina cutting process and scratching tests. It is found that the cracks initiated right under or in front of the machining tool. There were many micro-cracks remained on the machined surface, some of them propagated downwards to form macro-cracks or forwards to lead material removal. Both DEM simulations and acoustic emission measure experiments have found that the fracture became acute when the normal and the tangential force changed suddenly, causing the crack number to increase. In 3D DEM scratching simulation, the surface cracks length and subsurface cracks depth linearly increased with the scratching depth, the value agreed well with the experimental results, and the surface-damage width decreased gradually with the depth to the surface, looking like half of a coin. r
Pre-stressing scratching tests have been preformed on polished surfaces of Al 2 O 3 ceramic under... more Pre-stressing scratching tests have been preformed on polished surfaces of Al 2 O 3 ceramic under a Rockwell diamond indenter which moved with uniform speed and constant normal load to investigate how the pre-stress contributes to the material removal mechanism. With the measurement of acoustic emission signals as well as indenter tangential forces, surface damages and cross-section of grooves of Al 2 O 3 ceramic were evaluated under the action of different values of pre-stress. It was found that the scratched groove width was increased with the increasing of pre-stress when same normal loads were applied. The existence of pre-stress tends to restrain the crack propagation along the direction of pre-stress, and obvious plastic deformation at the bottom of scratched groove has been observed. Moreover, the fluctuation of tangential force was obviously enhanced, and the magnitude of tangential force in the test of pre-stress was higher than that of without pre-stress. The acoustic emission signals showed that fewer damages were produced in the process of scratching with an appropriate pre-stress. However, the continuing increase of pre-stress would aggravate the machining process.
a b s t r a c t A particle discrete element method (DEM) was employed to simulate transverse crac... more a b s t r a c t A particle discrete element method (DEM) was employed to simulate transverse cracking in laminated fiber reinforced composites. The microstructure of the laminates was modeled by a DEM model using different mechanical constitutive laws and materials parameters for different constituents, i.e. fiber, matrix and fiber/matrix interface. Rectangular, hexagonal and random fiber distributions were simulated to study the effect of fiber distribution on the transverse cracking. The initiation and dynamic propagation of transverse cracking and interfacial debonding were all captured by the DEM simulation, which showed similar patterns to those observed from experiments. The effect of fiber volume fraction was also studied for laminae with randomly distributed fibers. It was found that the distribution and volume fraction of fibers affected not only the transverse cracking path, but also the behavior of matrix plastic deformation and fiber/matrix interface yielding in the material.
Discrete element method (DEM) was used to model progressive delamination of fiber reinforced comp... more Discrete element method (DEM) was used to model progressive delamination of fiber reinforced composite laminates. The anisotropic composite plies were constructed through a hexagonal packing of particle elements. Contacts between the particles were represented by parallel bonds with the verified normal and shear elastic properties. The ply interface was characterized by a contact softening model with a bilinear elastic behavior which is similar to the cohesive zone model in the continuum mechanics. DCB, ELS and FRMM tests were simulated by the DEM model to assess its capability of modeling mode I, mode II and mix mode fracture of delamination, respectively. Good agreements were observed between the DEM and existing numerical and experimental results of loading curves, which confirmed that the DEM model can be used to simulate initiation and propagation of composite delamination, with more insights into microscopic material behavior, such as damage extension and plastic zone.
A representative element of the cross-ply laminate was modeled by the discrete element method (DE... more A representative element of the cross-ply laminate was modeled by the discrete element method (DEM) to analyze the stresses distribution. The DEM modeling results were compared with those from alternative approaches to validate the DEM model. The transverse cracking and interfacial delamination in [0˚1/90˚3] s and [90˚n/0˚1] s cross-ply laminates under transverse loading were analyzed by comparing crack densities as well as stiffness reduction with those from experiments and other numerical methods. It was found that the proposed DEM model can simultaneously capture the transverse cracking and delamination phenomenon, and can predict the variation of crack density and stiffness reduction accurately.
A numerical simulation of fluid transportation process was carried out focused on the investigati... more A numerical simulation of fluid transportation process was carried out focused on the investigation into predicting the location of the puncture point location in elbow. The kinematics and trajectory of the discrete particles as well as the particle-particle interaction were described by discrete element method (DEM) while the hydrodynamic model of the fluid phase was based on the volume-averaged Navier-Stokes equations, and a fluid density-based buoyancy model was adopted to calculate the solid-fluid interaction force. In this paper, the spatial distribution of particle-wall interaction force was calculated and corresponded to the wear pattern in the elbow, the puncture point locations have been observed. In particular, the influences of slurry velocity, bend orientation and angle of elbow on the puncture point location were discussed.
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