牙颌面的变化主要是通过正畸医师对牙齿、牙周组织和骨骼施加力来实现的。掌握正畸治疗中的生物力学,可以帮助正畸医师对患者做出正确的治疗。随着电子计算机的迅速发展及各种分析软件的推广和应用,有限元分析法(finite element method,...牙颌面的变化主要是通过正畸医师对牙齿、牙周组织和骨骼施加力来实现的。掌握正畸治疗中的生物力学,可以帮助正畸医师对患者做出正确的治疗。随着电子计算机的迅速发展及各种分析软件的推广和应用,有限元分析法(finite element method,FEM)逐渐成为口腔正畸学中生物力学研究的常用工具,为口腔临床工作提供了理论依据,对正畸学科研和临床事业的发展有重要意义。本文主要对近年来有限元法在口腔正畸学中横向、水平向、矢状向问题的研究做一综述,并对三维有限元技术的未来发展做出展望。展开更多
Cold rotary forging is an advanced and complex metal forming technology with continuous local plastic deformation.Investigating the contact force between the dies and the workpiece has a great significance to improve ...Cold rotary forging is an advanced and complex metal forming technology with continuous local plastic deformation.Investigating the contact force between the dies and the workpiece has a great significance to improve the life of the dies in cold rotary forging.The purpose of this work is to reveal the contact force responses in cold rotary forging through the modelling and simulation.For this purpose,a 3D elastic-plastic dynamic explicit FE model of cold rotary forging is developed using the FE code ABAQUS/Explicit.Through the modelling and simulation,the distribution and evolution of the contact force in cold rotary forging is investigated in detail.The experiment has been conducted and the validity of the 3D FE model of cold rotary forging has been verified.The results show that: 1) The contact force distribution is complex and exhibits an obvious non-uniform characteristic in the radial and circumferential directions; 2) The maximum contact force between the upper die and the workpiece is much larger than that between the lower die and the workpiece; 3) The contact force evolution history is periodic and every period experiences three different stages; 4) The total normal contact force is much larger than the total shear contact force at any given time.展开更多
The strategies that minimize the overall solution time of multiple linear systems in 3D finite element method (FEM) modeling of direct current (DC) resistivity were discussed. A global stiff matrix is assembled and st...The strategies that minimize the overall solution time of multiple linear systems in 3D finite element method (FEM) modeling of direct current (DC) resistivity were discussed. A global stiff matrix is assembled and stored in two parts separately. One part is associated with the volume integral and the other is associated with the subsurface boundary integral. The equivalent multiple linear systems with closer right-hand sides than the original systems were constructed. A recycling Krylov subspace technique was employed to solve the multiple linear systems. The solution of the seed system was used as an initial guess for the subsequent systems. The results of two numerical experiments show that the improved algorithm reduces the iterations and CPU time by almost 50%, compared with the classical preconditioned conjugate gradient method.展开更多
文摘牙颌面的变化主要是通过正畸医师对牙齿、牙周组织和骨骼施加力来实现的。掌握正畸治疗中的生物力学,可以帮助正畸医师对患者做出正确的治疗。随着电子计算机的迅速发展及各种分析软件的推广和应用,有限元分析法(finite element method,FEM)逐渐成为口腔正畸学中生物力学研究的常用工具,为口腔临床工作提供了理论依据,对正畸学科研和临床事业的发展有重要意义。本文主要对近年来有限元法在口腔正畸学中横向、水平向、矢状向问题的研究做一综述,并对三维有限元技术的未来发展做出展望。
基金Project(51105287)supported by the National Natural Science Foundation of ChinaProject(2012BAA08003)supported by the Key Research and Development Project of New Products and New Technologies of Hubei Province,ChinaProject(2013M531750)supported by China Postdoctoral Science Foundation
文摘Cold rotary forging is an advanced and complex metal forming technology with continuous local plastic deformation.Investigating the contact force between the dies and the workpiece has a great significance to improve the life of the dies in cold rotary forging.The purpose of this work is to reveal the contact force responses in cold rotary forging through the modelling and simulation.For this purpose,a 3D elastic-plastic dynamic explicit FE model of cold rotary forging is developed using the FE code ABAQUS/Explicit.Through the modelling and simulation,the distribution and evolution of the contact force in cold rotary forging is investigated in detail.The experiment has been conducted and the validity of the 3D FE model of cold rotary forging has been verified.The results show that: 1) The contact force distribution is complex and exhibits an obvious non-uniform characteristic in the radial and circumferential directions; 2) The maximum contact force between the upper die and the workpiece is much larger than that between the lower die and the workpiece; 3) The contact force evolution history is periodic and every period experiences three different stages; 4) The total normal contact force is much larger than the total shear contact force at any given time.
基金Projects(40974077,41164004)supported by the National Natural Science Foundation of ChinaProject(2007AA06Z134)supported by the National High Technology Research and Development Program of China+2 种基金Projects(2011GXNSFA018003,0832263)supported by the Natural Science Foundation of Guangxi Province,ChinaProject supported by Program for Excellent Talents in Guangxi Higher Education Institution,ChinaProject supported by the Foundation of Guilin University of Technology,China
文摘The strategies that minimize the overall solution time of multiple linear systems in 3D finite element method (FEM) modeling of direct current (DC) resistivity were discussed. A global stiff matrix is assembled and stored in two parts separately. One part is associated with the volume integral and the other is associated with the subsurface boundary integral. The equivalent multiple linear systems with closer right-hand sides than the original systems were constructed. A recycling Krylov subspace technique was employed to solve the multiple linear systems. The solution of the seed system was used as an initial guess for the subsequent systems. The results of two numerical experiments show that the improved algorithm reduces the iterations and CPU time by almost 50%, compared with the classical preconditioned conjugate gradient method.