A recently proposed model coupling with the solid-fluid of the saturated sand was utilized to study the deformation band. Based on the critical state plasticity model by Borja and Andrade, the hydraulic conductivity t...A recently proposed model coupling with the solid-fluid of the saturated sand was utilized to study the deformation band. Based on the critical state plasticity model by Borja and Andrade, the hydraulic conductivity tensor was naturally treated as a function of the spatial discretization matrix about the displacement and the stress field, allowing a more realistic representation of the physical phenomenon. The fully Lagrangian form of the Darcy law was resolved by Piola algorithm, and then the flow law was gained, leading to the implementation of a modified model of the saturated sand. Then the criterion for the onset of localization was derived and utilized to detect instability. The constitutive model was implemented in a finite element program coded by FORTRAN, which was used to predict the formation and development of shear bands in plane strain compression of saturated sand. At last, the formation mechanism of the shear band was discussed. It is shown that the model works well, and the simulation sample bifurcates at 1.18% axial strain, which is in a good qualitative agreement with the experiment. The pore pressure greatly affects the onset and development of the deformation band, and it obviously increases around the localization-prone regions with the direction toward the outer side of the normal of the shear band, while the pore stress flows nearly horizontally and is distributed equally far away the shear band region.展开更多
This paper presents the Approximate Incrtial Manifold ∑ and its successive approximate incrtial manifold ∑i and ∑ij . We give the estimates of thickness of neighborhood of ∑, ∑j, Ejt respectively in which the eve...This paper presents the Approximate Incrtial Manifold ∑ and its successive approximate incrtial manifold ∑i and ∑ij . We give the estimates of thickness of neighborhood of ∑, ∑j, Ejt respectively in which the every solution of Navier-Stokcs equation enters.Another part of this paper presents construction method for A.I.M. by multilevel finite clement method and give error estimates of the approximate solution of incrtial form.展开更多
A new finite element model for single-layered strand was investigated for accurate and efficient mechanical behavior analysis.Mathematical model was created by sectional path-nodes sweeping and dynamic node-beam mappi...A new finite element model for single-layered strand was investigated for accurate and efficient mechanical behavior analysis.Mathematical model was created by sectional path-nodes sweeping and dynamic node-beam mapping.Geometric relations between nodes in center core wire and helical wires were deduced in tension and bending incorporating material elasticity theory and deformation geometrical compatibility.Based on Timoshenko beam theory,strand of a pitch length was modeled with specific material,geometric parameters and synthesized constraint equations defined in ANSYS software,and predetermined load cases were performed.The obtained results show that discrepancies between suggested method and Costello theory do not exceed 1.51% in tension and 6.21% in bending,which verifies the correctness and accuracy of the suggested finite element model in predicting mechanical behavior of single-layered wire strand.展开更多
基金Project(2006G007-C) supported by the Foundation of the Science and Technology Section of Ministry of Railway of ChinaProject(77206) supported by the Excellent PhD Thesis Innovation Foundation of Central South University,China
文摘A recently proposed model coupling with the solid-fluid of the saturated sand was utilized to study the deformation band. Based on the critical state plasticity model by Borja and Andrade, the hydraulic conductivity tensor was naturally treated as a function of the spatial discretization matrix about the displacement and the stress field, allowing a more realistic representation of the physical phenomenon. The fully Lagrangian form of the Darcy law was resolved by Piola algorithm, and then the flow law was gained, leading to the implementation of a modified model of the saturated sand. Then the criterion for the onset of localization was derived and utilized to detect instability. The constitutive model was implemented in a finite element program coded by FORTRAN, which was used to predict the formation and development of shear bands in plane strain compression of saturated sand. At last, the formation mechanism of the shear band was discussed. It is shown that the model works well, and the simulation sample bifurcates at 1.18% axial strain, which is in a good qualitative agreement with the experiment. The pore pressure greatly affects the onset and development of the deformation band, and it obviously increases around the localization-prone regions with the direction toward the outer side of the normal of the shear band, while the pore stress flows nearly horizontally and is distributed equally far away the shear band region.
文摘This paper presents the Approximate Incrtial Manifold ∑ and its successive approximate incrtial manifold ∑i and ∑ij . We give the estimates of thickness of neighborhood of ∑, ∑j, Ejt respectively in which the every solution of Navier-Stokcs equation enters.Another part of this paper presents construction method for A.I.M. by multilevel finite clement method and give error estimates of the approximate solution of incrtial form.
基金Project(2009J007)supported by Science and Technology Department of Railway Ministry of ChinaProject(U1134203)supported by Joint Fund of High-speed Railway Fundamental Research,China
文摘A new finite element model for single-layered strand was investigated for accurate and efficient mechanical behavior analysis.Mathematical model was created by sectional path-nodes sweeping and dynamic node-beam mapping.Geometric relations between nodes in center core wire and helical wires were deduced in tension and bending incorporating material elasticity theory and deformation geometrical compatibility.Based on Timoshenko beam theory,strand of a pitch length was modeled with specific material,geometric parameters and synthesized constraint equations defined in ANSYS software,and predetermined load cases were performed.The obtained results show that discrepancies between suggested method and Costello theory do not exceed 1.51% in tension and 6.21% in bending,which verifies the correctness and accuracy of the suggested finite element model in predicting mechanical behavior of single-layered wire strand.
