The concept of a space solar power station(SSPS)was proposed in 1968 as a potential approach for solving the energy crisis.In the past 50 years,several structural concepts have been proposed,but none have been sent in...The concept of a space solar power station(SSPS)was proposed in 1968 as a potential approach for solving the energy crisis.In the past 50 years,several structural concepts have been proposed,but none have been sent into orbit.One of the main challenges of the SSPS is dynamic behavior prediction,which can supply the necessary information for control strategy design.The ultra-large size of the SSPS causes difficulties in its dynamic analysis,such as the ultra-low vibration frequency and large fexibility.In this paper,four approaches for the numerical analysis of the dynamic problems associated with the SSPS are reviewed:the finite element,absolute nodal coordinate,foating frame formulation,and structure-preserving methods.Both the merits and shortcomings of the above four approaches are introduced when they are employed in dynamic problems associated with the SSPS.Synthesizing the merits of the aforementioned four approaches,we believe that embedding the structure-preserving method into finite element software may be an effective way to perform a numerical analysis of the dynamic problems associated with the SSPS.展开更多
This investigation is intended to develop a computer procedure for the integration of NURBS geometry and the rational absolute nodal coordinate formulation （RANCF） finite element analysis. A linear transformation is...This investigation is intended to develop a computer procedure for the integration of NURBS geometry and the rational absolute nodal coordinate formulation （RANCF） finite element analysis. A linear transformation is given that can be used to convert the NURBS curve to RANCF cable element mesh retaining the same geometry and the same degree of continuity, including the discussion of continuity control and mesh refinement. The green strain tensor is used to establish the nonlinear dynamic equations with numerical examples to demonstrate the use of the procedure in the dynamic analysis of flexible bodies.展开更多
A new term involving the rate of pressure change is introduced into the continuity equation of an existing biphasic mixture model. Based on this new continuity equation, a penalized numerical formulation of finite ele...A new term involving the rate of pressure change is introduced into the continuity equation of an existing biphasic mixture model. Based on this new continuity equation, a penalized numerical formulation of finite element method is given. Computational result shows that this new biphasic mixture model can provide better description of the transient response of biological media such as articular cartilage, muscle, and soft tissue. 展开更多
A finite volume method is applied to simulate a closed die hot forging process of a cylinder billet. Since variation and distribution of temperature play very important role in hot forging, the code involves a methodo...A finite volume method is applied to simulate a closed die hot forging process of a cylinder billet. Since variation and distribution of temperature play very important role in hot forging, the code involves a methodology of a coupled system of mechanical and thermal equations. The simulated results are compared with the experimental ones. The distribution of temperature in the billet obtained from the simulation is also discussed.展开更多
Based on flux-based formulation, a nodeless variable element method is developed to analyze two-dimensional steady-state and transient heat transfer problems. The nodeless variable element employs quadratic interpolat...Based on flux-based formulation, a nodeless variable element method is developed to analyze two-dimensional steady-state and transient heat transfer problems. The nodeless variable element employs quadratic interpolation functions to provide higher solution accuracy without necessity to actually generate additional nodes. The flux-based formulation is applied to reduce the complexity in deriving the finite element equations as compared to the conventional finite element method, The solution accuracy is further improved by implementing an adaptive meshing technique to generaie finite element mesh that can adapt and move along corresponding to the solution behavior. The technique generates small elements in the regions of steep solution gradients to provide accurate solution, and meanwhile it generates larger elements in the other regions where the solution gradients are slight to reduce the computational time and the computer memory. The effectiveness of the combined procedure is demonstrated by heat transfer problems that have exact solutions. These problems tire： （a） a steady-state heat conduction analysis in a square plate subjected to a highly localized surface heating, and （b） a transient heat conduction analysis in a long plate subjected to moving heat source.展开更多
The vapor deposition chemical reaction processes, which are of extremely extensive applications, can be classified as a mathematical model by the following governing nonlinear partial differential equations containing...The vapor deposition chemical reaction processes, which are of extremely extensive applications, can be classified as a mathematical model by the following governing nonlinear partial differential equations containing velocity vector, temperature field, pressure field, and gas mass field. The mixed finite element （MFE） method is employed to study the system of equations for the vapor deposition chemical reaction processes. The semidiscrete and fully discrete MFE formulations are derived. And the existence and convergence （error estimate） of the semidiscrete and fully discrete MFE solutions are demonstrated. By employing MFE method to treat the system of equations for the vapor deposition chemical reaction processes, the numerical solutions of the velocity vector, the temperature field, the pressure field, and the gas mass field can be found out simultaneously. Thus, these researches are not only of important theoretical means, but also of extremely extensive applied vistas.展开更多
In this paper, we extend the applications of proper orthogonal decomposition （POD） method, i.e., apply POD method to a mixed finite element （MFE） formulation naturally satisfied Brezz-Babu^ka for parabolic equatio...In this paper, we extend the applications of proper orthogonal decomposition （POD） method, i.e., apply POD method to a mixed finite element （MFE） formulation naturally satisfied Brezz-Babu^ka for parabolic equations, establish a reduced-order MFE formulation with lower dimensions and sufficiently high accuracy, and provide the error estimates between the reduced-order POD MFE solutions and the classical MFE solutions and the implementation of algorithm for solving reduced-order MFE formulation. Some numerical examples illustrate the fact that the results of numerical computation are consis- tent with theoretical conclusions. Moreover, it is shown that the new reduced-order MFE formulation based on POD method is feasible and efficient for solving MFE formulation for parabolic equations.展开更多
基金supported by the National Natural Science Foundation of China(12172281,11972284,11672241,11432010,and 11872303)Fund for Distinguished Young Scholars of Shaanxi Province(2019JC-29)+2 种基金Foundation Strengthening Program Technical Area Fund(2021-JCJQ-JJ-0565)Fund of the Science and Technology Innovation Team of Shaanxi(2022TD-61)Fund of the Youth Innovation Team of Shaanxi Universities.
文摘The concept of a space solar power station(SSPS)was proposed in 1968 as a potential approach for solving the energy crisis.In the past 50 years,several structural concepts have been proposed,but none have been sent into orbit.One of the main challenges of the SSPS is dynamic behavior prediction,which can supply the necessary information for control strategy design.The ultra-large size of the SSPS causes difficulties in its dynamic analysis,such as the ultra-low vibration frequency and large fexibility.In this paper,four approaches for the numerical analysis of the dynamic problems associated with the SSPS are reviewed:the finite element,absolute nodal coordinate,foating frame formulation,and structure-preserving methods.Both the merits and shortcomings of the above four approaches are introduced when they are employed in dynamic problems associated with the SSPS.Synthesizing the merits of the aforementioned four approaches,we believe that embedding the structure-preserving method into finite element software may be an effective way to perform a numerical analysis of the dynamic problems associated with the SSPS.
基金supported by the National Natural Science Foundation of China(No.11172076)the Science and Technology Innovation Talent Foundation of Harbin(No.2012RFLXG020)
文摘This investigation is intended to develop a computer procedure for the integration of NURBS geometry and the rational absolute nodal coordinate formulation （RANCF） finite element analysis. A linear transformation is given that can be used to convert the NURBS curve to RANCF cable element mesh retaining the same geometry and the same degree of continuity, including the discussion of continuity control and mesh refinement. The green strain tensor is used to establish the nonlinear dynamic equations with numerical examples to demonstrate the use of the procedure in the dynamic analysis of flexible bodies.
文摘A new term involving the rate of pressure change is introduced into the continuity equation of an existing biphasic mixture model. Based on this new continuity equation, a penalized numerical formulation of finite element method is given. Computational result shows that this new biphasic mixture model can provide better description of the transient response of biological media such as articular cartilage, muscle, and soft tissue.
文摘A finite volume method is applied to simulate a closed die hot forging process of a cylinder billet. Since variation and distribution of temperature play very important role in hot forging, the code involves a methodology of a coupled system of mechanical and thermal equations. The simulated results are compared with the experimental ones. The distribution of temperature in the billet obtained from the simulation is also discussed.
文摘Based on flux-based formulation, a nodeless variable element method is developed to analyze two-dimensional steady-state and transient heat transfer problems. The nodeless variable element employs quadratic interpolation functions to provide higher solution accuracy without necessity to actually generate additional nodes. The flux-based formulation is applied to reduce the complexity in deriving the finite element equations as compared to the conventional finite element method, The solution accuracy is further improved by implementing an adaptive meshing technique to generaie finite element mesh that can adapt and move along corresponding to the solution behavior. The technique generates small elements in the regions of steep solution gradients to provide accurate solution, and meanwhile it generates larger elements in the other regions where the solution gradients are slight to reduce the computational time and the computer memory. The effectiveness of the combined procedure is demonstrated by heat transfer problems that have exact solutions. These problems tire： （a） a steady-state heat conduction analysis in a square plate subjected to a highly localized surface heating, and （b） a transient heat conduction analysis in a long plate subjected to moving heat source.
基金Project supported by the National Natural Science Foundation of China (Nos.10471100 and 40437017)the Science and Technology Foundation of Beijing Jiaotong University
文摘The vapor deposition chemical reaction processes, which are of extremely extensive applications, can be classified as a mathematical model by the following governing nonlinear partial differential equations containing velocity vector, temperature field, pressure field, and gas mass field. The mixed finite element （MFE） method is employed to study the system of equations for the vapor deposition chemical reaction processes. The semidiscrete and fully discrete MFE formulations are derived. And the existence and convergence （error estimate） of the semidiscrete and fully discrete MFE solutions are demonstrated. By employing MFE method to treat the system of equations for the vapor deposition chemical reaction processes, the numerical solutions of the velocity vector, the temperature field, the pressure field, and the gas mass field can be found out simultaneously. Thus, these researches are not only of important theoretical means, but also of extremely extensive applied vistas.
基金supported by the National Science Foundation of China(11271127 and 11061009)Science Research Program of Guizhou(GJ[2011]2367)the Co-Construction Project of Beijing Municipal Commission of Education
文摘In this paper, we extend the applications of proper orthogonal decomposition （POD） method, i.e., apply POD method to a mixed finite element （MFE） formulation naturally satisfied Brezz-Babu^ka for parabolic equations, establish a reduced-order MFE formulation with lower dimensions and sufficiently high accuracy, and provide the error estimates between the reduced-order POD MFE solutions and the classical MFE solutions and the implementation of algorithm for solving reduced-order MFE formulation. Some numerical examples illustrate the fact that the results of numerical computation are consis- tent with theoretical conclusions. Moreover, it is shown that the new reduced-order MFE formulation based on POD method is feasible and efficient for solving MFE formulation for parabolic equations.
