A non-local dislocation density based crystal plasticity model, which takes account of the microstrncture inhomogeneity, was used to investigate the micro-bending of metallic crystalline foils. In this model, both sta...A non-local dislocation density based crystal plasticity model, which takes account of the microstrncture inhomogeneity, was used to investigate the micro-bending of metallic crystalline foils. In this model, both statistically stored dislocations （SSDs） and geometrically necessary dislocations （GNDs） are taken as the internal state variables. The strain gradient hardening in micro-bending of single-grained metal foils was predicted by evolution of GNDs. The predicted results were compared with the micro-hardness distribution of the previous micro-bending experiments of CuZn37 a-brass foils with coarse grains and fine grains. Comparison of the simulated dislocation densities distribution of SSDs and GNDs with the experimental results shows that different micro-hardness distribution patterns of the coarse and fine grain foils can be attributed to the corresponding SSDs and GNDs distributions. The present model provides a physical insight into the deformation mechanism and dislocation densities evolution of the micro-bending process.展开更多
Towards the objective of improving the gas dispersion performance, the dislocated-blade Rushton impeller was applied to the gas-liquid mixing in a baffled stirred vessel. The flow field, gas hold-up, dissolved oxygen,...Towards the objective of improving the gas dispersion performance, the dislocated-blade Rushton impeller was applied to the gas-liquid mixing in a baffled stirred vessel. The flow field, gas hold-up, dissolved oxygen, power consumption before and after gassing were studied using the computational fluid dynamics （CFD） technique. Dispersion of gas in the liquid was modelled using the Eulerian-Eulerian approach along with the dispersed k-e turbulent model. Rotation of the impeller was simulated with the multiple reference frame method. A modified drag coefficient which includes the effect of turbulence was used to account for the momentum exchange. The predictions were compared with their counterparts of the standard Rushton impeller and were validated with the experimental results. It is concluded that the dislocated-blade Rushton impeller is superior to the standard Rushton impeller in the gas-liquid mixing operation, and the findings obtained here lay the basis of its application in process industries.展开更多
By using the Yoshimitsu Okada and Steketee fault dislocation model,we calculated the vertical and horizontal displacements along the Yingxiu-Beichuan inverse fault and Guanxian-Anxian inverse fault along which the Wen...By using the Yoshimitsu Okada and Steketee fault dislocation model,we calculated the vertical and horizontal displacements along the Yingxiu-Beichuan inverse fault and Guanxian-Anxian inverse fault along which the Wenchuan MS8. 0 earthquake occurred in 2008. Compared to the achievements of field surveying along the surface rupture zone,we found that our computational results are comparable to the real displacement variation trend. Furthermore,the computational results indicated that the surface displacement fields vary with the distance from the fault,and the vertical displacement fields show strong inhomogeneity,in which larger displacement is focused on the ends of the fault. However, in contrast to the vertical displacement,the horizontal displacement shows relative uniformity in space.展开更多
Flexible skew thin plate is widely used in mechanical engineering,architectural engineering and structural engineering.High-precision analysis is very important for structural design and improvement.In this paper,the ...Flexible skew thin plate is widely used in mechanical engineering,architectural engineering and structural engineering.High-precision analysis is very important for structural design and improvement.In this paper,the multivariable wavelet finite element(MWFE)based on B-spline wavelet on the interval(BSWI)is constructed for flexible skew thin plate analysis.First,the finite element formulation is derived from multivariable generalized potential energy function.Then the generalized field variables are interpolated and calculated by BSWI.Different from the traditional wavelet finite element,the analysis precision can be improved because the generalized displacement and stress field variables are interpolated and calculated independently,the secondary calculation and the computational error are avoided.In order to verify the effectiveness of the constructed MWFE,several numerical examples are given in the end.展开更多
基金Projects(50835002,50821003,50975174,51275297)supported by the National Natural Science Foundation of ChinaProjects(200802480053,20100073110044)supported by the PhD Programs Foundation of Ministry of Education of China
文摘A non-local dislocation density based crystal plasticity model, which takes account of the microstrncture inhomogeneity, was used to investigate the micro-bending of metallic crystalline foils. In this model, both statistically stored dislocations （SSDs） and geometrically necessary dislocations （GNDs） are taken as the internal state variables. The strain gradient hardening in micro-bending of single-grained metal foils was predicted by evolution of GNDs. The predicted results were compared with the micro-hardness distribution of the previous micro-bending experiments of CuZn37 a-brass foils with coarse grains and fine grains. Comparison of the simulated dislocation densities distribution of SSDs and GNDs with the experimental results shows that different micro-hardness distribution patterns of the coarse and fine grain foils can be attributed to the corresponding SSDs and GNDs distributions. The present model provides a physical insight into the deformation mechanism and dislocation densities evolution of the micro-bending process.
基金Supported by the National Natural Science Foundation of China(21306105)
文摘Towards the objective of improving the gas dispersion performance, the dislocated-blade Rushton impeller was applied to the gas-liquid mixing in a baffled stirred vessel. The flow field, gas hold-up, dissolved oxygen, power consumption before and after gassing were studied using the computational fluid dynamics （CFD） technique. Dispersion of gas in the liquid was modelled using the Eulerian-Eulerian approach along with the dispersed k-e turbulent model. Rotation of the impeller was simulated with the multiple reference frame method. A modified drag coefficient which includes the effect of turbulence was used to account for the momentum exchange. The predictions were compared with their counterparts of the standard Rushton impeller and were validated with the experimental results. It is concluded that the dislocated-blade Rushton impeller is superior to the standard Rushton impeller in the gas-liquid mixing operation, and the findings obtained here lay the basis of its application in process industries.
基金sponsored by the Foundation Funds of Institute of Geology,CEA,China (IGCEA0912)
文摘By using the Yoshimitsu Okada and Steketee fault dislocation model,we calculated the vertical and horizontal displacements along the Yingxiu-Beichuan inverse fault and Guanxian-Anxian inverse fault along which the Wenchuan MS8. 0 earthquake occurred in 2008. Compared to the achievements of field surveying along the surface rupture zone,we found that our computational results are comparable to the real displacement variation trend. Furthermore,the computational results indicated that the surface displacement fields vary with the distance from the fault,and the vertical displacement fields show strong inhomogeneity,in which larger displacement is focused on the ends of the fault. However, in contrast to the vertical displacement,the horizontal displacement shows relative uniformity in space.
基金supported by the National Natural Science Foundation of China(Grant No.51225501)the Fundamental Research Funds for the Central Universities+2 种基金the Project funded by China Postdoctoral Science Foundation(Grant No.2014M552432)the National Science and Technology Major Project of China(Grant No.2012ZX04002071)the Program for Changjiang Scholars and Innovative Research Team in University
文摘Flexible skew thin plate is widely used in mechanical engineering,architectural engineering and structural engineering.High-precision analysis is very important for structural design and improvement.In this paper,the multivariable wavelet finite element(MWFE)based on B-spline wavelet on the interval(BSWI)is constructed for flexible skew thin plate analysis.First,the finite element formulation is derived from multivariable generalized potential energy function.Then the generalized field variables are interpolated and calculated by BSWI.Different from the traditional wavelet finite element,the analysis precision can be improved because the generalized displacement and stress field variables are interpolated and calculated independently,the secondary calculation and the computational error are avoided.In order to verify the effectiveness of the constructed MWFE,several numerical examples are given in the end.
