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Triangular Differential Quadrature for Bending Analysis of Reissner Plates with Curved Boundaries

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Tsinghua Science and Technology 2003年第2期8卷 206-214页

作者： HUA Yongxia(华永霞) ZHONG Hongzhi(钟宏志) Department of Civil Engineering Tsinghua University Beijing 100084 China Department of Civil Engineering Tsinghua University Beijing 100084 China

The recently proposed concept of the triangular differential quadrature method (TDQM) is applied to the bending analysis of Reissner plates with various curvilinear geometries subjected to various combinations of boundary conditions. An unit isosceles right triangle is used as the standard triangle for all the derivatives expressed using the triangular differential quadrature rule. Geometric transformations are introduced using basis functions to determine the weighting coefficients for the triangular differential quadrature to map an arbitrary curvilinear triangle into the standard triangle. The triangular differential quadrature method provides good accuracy and rapid convergence relative to other available exact and numerical results.

关键词： boundary conditions Mathematical techniques

Dynamic Response Analysis of Towed Cable During Deployment/Retrieval

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Journal of Shanghai Jiaotong university(Science) 2008年第2期13卷 245-251页

作者：王飞黄国樑邓德衡 Merchant Marine College Shanghai Maritime University State Key Laboratory of Ocean Engineering Shanghai Jiaotong UniversityShanghai 200240China State Key Laboratory of Ocean Engineering Shanghai Jiaotong University

A numerical approach was developed to analyze the transient behavior of towed cable during ac- tively controlled deployment/retrieval (DR).The cable motion is described by the lumped parameter method, its corresponding boundary conditions are *** view of its varying length during DR,two auxiliary arguments are introduced to describe its continuous varying length and discrete number of nodes(equations), the length is determined by the pay out(or reel-in) rate,which is then used to determine the node number by a logic *** the discrete mathematical model of towed cable,an algorithm was developed to deal with the discrete governing *** simulation results indicate that the cable experiences more com- plex motions due to its varying length,and tension fluctuates seriously in the startup and ending stage of deployment/*** effect of towing ship's motion in waves on cable during deployment/retrieval is also considered via numerical simulation.

关键词： towed cable boundary conditions deployment/retrieval numerical simulation

Calculation of Strain Amplification Matrix for Strain Invariant Failure Theory Based on Representative Volume Element Models with Periodical boundary Condition

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Journal of Shanghai Jiaotong university(Science) 2017年第5期22卷 523-529页

作者：赵剑汪海吕新颖谢宗蕻 School of Aeronautics and Astronautics Shanghai Jiao Tong University School of Astronautics Northwestern Polytechnical University

Strain invariant failure theory (SIFT) is a micro-mechanics-based failure theory for multi-scale failure analysis of composite materials originally proposed by Gosse and Christensen. In this paper, the approach for obtaining strain amplification matrix which is a key step for the execution of SIFT is improved by adopting representative volume element (RVE) finite element models considering periodical boundary condition, based on which more actual deformation mode is reflected. The deformation modes and strain data at the characteristic points of the centroid cell of multi-cell RVE model are analyzed and taken as a reference. It can be concluded that more reasonable deformation mode and relationship between the micro-mechanical and macro-mechanical strain states are obtained by employing the new model. Finally, numerical examples are provided to illustrate the determination of strain amplification factors within the RVEs considering periodical boundary condition at the characteristic points. © 2017, Shanghai Jiaotong University and Springer-Verlag GmbH Germany.

关键词： boundary conditions Deformation Finite element method Strain Volume measurement

Computational Methods for Electromechanical Fields in Self-Assembled Quantum Dots

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Communications in Computational Physics 2012年第3期11卷 797-830页

作者： D.Barettin S.Madsen B.Lassen M.Willatzen Alsion 2 Mads Clausen InstituteUniversity of Southern DenmarkDK-6400 SønderborgDenmark

A detailed comparison of continuum and valence force field strain calculations in quantum-dot structures is presented with particular emphasis to boundary conditions,their implementation in the finite-elementmethod,and associated implications for electronic *** first part of this work provides the equation framework for the elastic continuum model including piezoelectric effects in crystal structures as well as detailing the Keating model equations used in the atomistic valence force field *** the variety of possible structure shapes,a choice of pyramidal,spherical and cubic-dot shapes is made having in mind their pronounced shape differences and practical *** this part boundary conditions are also considered;in particular the relevance of imposing different types of boundary conditions is highlighted and *** the final part,quantum dots with inhomogeneous indium concentration profiles are studied in order to highlight the importance of taking into account the exact In concentration profile for real quantum *** influence of strain,electric-field distributions,and material inhomogeneity of spherical quantum dots on electronic wavefunctions is briefly discussed.

关键词： Quantum dots electromechanical fields continuum model valence force field boundary conditions

FORCED　OSCILLATIONS　OF　HYPERBOLIC　DIFFERENTIAL　EQUATIONS　WITH　DEVIATING　ARGUMENTS

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Acta Mathematicae Applicatae Sinica 1995年第4期11卷 369-377页

作者：崔宝同俞元洪 Binzhou Normal College Binzhou China Department of Mathematics University of Saskatchewan Saskatoon Canada Institute of Applied Mathematics the Chinese Academy of Sciences Beijing China

Sufficient conditions are established for the oscillation of some hyperbolic equations with deviating arguments under various boundary conditions.

关键词： Hyperbolic oscillations boundary conditions cylindrical domain

Finite element implementation of poroelasticity theory for swelling dynamics of hydrogels

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Theoretical & Applied Mechanics Letters 2013年第5期3卷 42-44页

作者： Meie Li Chao Jin Jinxiong Zhou State Key Laboratory of Mechanical Behaviors of Metal Materials School of Material Sciences and Engineering Xi'an Jiaotong University State Key Laboratory for Strength and Vibration of Mechanical Structures and School of Aerospace Xi'an Jiaotong University

Abstract Hydrogel can swell to many times of its dry volume, resulting in large deformation which is vital for its function. The swelling process is regulated by many physical and chemical mechanisms, and can, to some extent, be fairly described by the poroelasticity theory. Implementation of the poroelastieity theory in the framework of finite element method would aid the design and optimization of hydrogel-based soft devices. Choosing chemical potential and displacement as two field variables, we present the implementation of poroelastieity tailored for hydrogel swelling dynamics, detail the normalization of physical parameters and the treatment of boundary conditions. Several examples are presented to demonstrate the feasibility and correctness of the proposed strategy.

关键词： finite element poroelasticity theory normalization boundary conditions

AN　IMPROVEMENT　FOR　LOWER－ORDER　PANEL　METHOD　BASED　ON　THE　DIRICHLET　boundary　CONDITION

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Chinese Journal of Aeronautics 1994年第4期7卷 241-248页

作者： Xu Mingchu Gu Wenying(Northwestern Polytechnical University, Xi’an, China, 710072)

An improved algorithm for velocity field of general configurations ispresentd for low-order panel method based on the internal Dirichlet boundary condi-tion. A direct calculating method for the velocity distribution by means of a limit pro-cess combining with analytic evaluation of higher-order singular integrals instead of theconventional method of doublet strength gradient is devised in order to avoid the diffi-culty of edge extrapolation of doublet strength. The problem of substantialunderpredictions of the induced drag coefficient obtained from the VSAERO analysisdisappears for the present improved algorithm. Illustrative calculations for several testcases such as swept back wing, swept forward wing and wing-body combination showthat the accuracy of results may be improved and is competitive with high-order panelmethod. In addition, the present direct integral method can be used to evaluate the ve-locity distribution for external flow field correctly, where the method of gradient cannot be used at all.

关键词： Dirichlet problem boundary conditions panel method (fluid dynamics),velocity distribution

LYAPUNOV-TYPE STABILIZATION FOR NONLINEAR UNCERTAIN SYSTEMS AND NONLINEAR H~∞ CONTROL

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Chinese Journal of Aeronautics 1997年第4期10卷 58-63页

作者： Fei Shumin (Research Institute of Automation, Southeast University, Nanjing, 210018, China) Wang Liangui (Department of Electronics, Zhongshan College, Zhongshan, 528403, China)

The local robust stabilization for a class of nonlinear uncertain systems is studied. The robustness concept of Lyapunov type stabilizability for nonlinear uncertain systems is defined. Under the norm bounded structured condition, two cases for uncertainty in control matrix are taken to discuss Lyapunov type stabilizability of systems. The sufficient conditions of Lyapunov type stabilization are given from differential geometry and nonlinear H ∞ control of view, respectively.

关键词： nonlinear systems norms boundary conditions robustness uncertainty Lyapunov type stabilization

Effect of geometry simplification and boundary condition specification on flow field and aerodynamic noise in the train head and bogie region of high-speed trains

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第9期25卷 716-731页

作者： Jiawei SHI Yuan HE Jiye ZHANG Tian LI State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong UniversityChengdu 610031China Institute of Sound and Vibration Research Faculty of Engineering and Physical SciencesUniversity of SouthamptonSouthampton SO171BJUK

The purpose of this study is to determine a suitable modeling method to make computational fluid dynamics(CFD)simulation more efficient for aeroacoustics optimization of the bogie region of high-speed *** this end,four modeling methods are considered,which involve different geometry simplifications and boundary condition *** corresponding models are named the three-car marshalling model,computational domain shortening model,carbody shortening model,and sub-domain *** the detached eddy simulation(DES)model and Ffowcs Williams-Hawkings(FW-H)equation,the unsteady flow field and far-field noise of the four models are *** evaluate the effect of the different modeling methods,the time-averaged flow field,fluctuating flow field,and far-field noise results of the four models are compared and analyzed in detail with the results of the three-car marshalling model used as basis for *** results show that the flow field results of the bogie region predicted by the four models have relatively high ***,the usage of the non-time varying outlet boundary conditions in the computational domain shortening model and sub-domain model could affect the pressure fluctuation on the upstream carbody *** only the bogie region is used as the source surface,the differences between the far-field noise results of the three simplified models and the three-car marshalling model are all within 1 dB;when the train head is used as the source surface,the results of the carbody shortening model and the three-car marshalling model are more consistent.

关键词： Bogie region Train head Flow field Aerodynamic noise Geometry simplification boundary conditions