bluuebunny/crossref_metadata_2025_split huggingface dataset:
Arch dam–fluid interactions: By fem–bem and substructure concept
Authors: Tsai Chong‐Shien , Lee George C. 
Published: August 2005

AbstractArch dams can be conveniently analysed by the finite element method. For dam–fluid interaction problems, the fluid domain may be more conveniently handled by the boundary element method as a substructure first before connecting to the dam substructure. The added‐mass matrix calculated from the fluid domain is symmetrized and lumped first so that the banded and symmetrical characteristics of the finite element method are retained. In the boundary element formulation, a mirror image method and quadratic elements are used for computational efficiency and accuracy. The strong singular terms are handled by using a solution which satisfies the governing equation and the free surface boundary condition. Infinite boundary conditions at the upstream of the reservoir can be reasonably approximated from the fundamental solution with accurate results, if the interior pressure distribution in the fluid domain is neglected. Numerical solutions on hydrodynamic pressure distribution and the natural frequencies of the dam–reservoir system with various water levels are obtained and compared with available analytical and experiment results.
Generalized hybrid‐combined methods for the singularity problems of homogeneous elliptic equations
Authors: Li Z. C. , Bui T. D. 
Published: August 2005

AbstractCombinations of the Ritz–Galerkin and finite element methods are applied to solving singularity problems of homogeneous, elliptic equations. The Ritz‐Galerkin method is used in the subdomains where there exist singular points; and the finite element method is still used in the rest of the solution domains. More general coupling techniques than those of Reference 6 along the common boundary of subdomains are discussed. Numerical experiments using these kinds of coupling techniques are provided for the first time. It is interesting that the calculated results of Motz's problem have shown the simplified hybrid strategy in Reference 6 to be optimal for both error bounds and stability of numerical solutions, among all general coupling techniques.
Spectral collocation methods for the primary two‐point boundary value problem in modelling viscoelastic flows
Authors: Karageorghis A. , Phillips T. N. , Davies A. R. 
Published: August 2005

AbstractExpansions in terms of beam functions and Chebyshev polynomials are used to compute solutions to the primary two‐point boundary value problem within a spectral collocation formulation. The performance of the methods is analysed in terms of accuracy and robustness relative to the level of non‐linearity. Accurate results are obtained with Chebyshev polynomials and the performance of these trial functions is insensitive to the level of non‐linearity whereas the behaviour of the beam functions shows great sensitivity to the level of non‐linearity. The use of Newton's method to solve the mixed linear‐non‐linear system for the Chebyshev coefficients is successful for highly non‐linear problems without the need for parameter continuation.
Monte Carlo structural optimization in discrete variables with annealing algorithm
Authors: Elperin T. 
Published: August 2005

AbstractThe paper describes the basic ideas of Monte Carlo annealing algorithms for structural optimization with discrete design parameters. The algorithm generates randomly a set of design parameters, with probability depending on the objective function and given by the Boltzmann–Gibbs distribution. In this model the search for the global minimum is simulated by a relaxation process of the statistical mechanical system with the Hamiltonian proportional to the objective function. The rate of the convergence of the method and its dependence upon the annealing probability are discussed. Numerical implementation of the method for the weight optimization of the ten‐bar planar cantilever truss is presented. The results of numerical simulation are compared with those obtained by the dual methods. The principal conjecture is that the method is fairly efficient and has great potential for applicaton in engineering design.
Multi‐domain BEM for two‐dimensional problems of elastodynamics
Authors: Ahmad Shahid , Banerjee Prasanta K. 
Published: August 2005

AbstractAn advanced implementation of the boundary element technique for the periodic and transient dynamic analyses of two‐dimensional elastic or visco elastic solids of arbitrary shape and connectivity is presented. For transient dynamic analysis the problem is first solved in the Laplace transform space and then the time domain solutions are obtained by numerical inversion of transformed domain solutions.The present analysis is capable of treating very large, multi‐domain problems by substructuring and satisfying the equilibrium and compatibilities at the interfaces. With the help of this substructuring capability, problems related to the layered media and soil–structure interaction can all be analysed. This paper also introduces a new type of element called ‘Enclosing Element’, which has been developed and used to model the infinitely extending boundaries of a half‐space or a layered medium. A number of numerical examples are presented, and through comparisons with available analytical and numerical results, the accuracy, stability and efficiency of the present analysis are established.
Thin plate elements with relaxed Kirchhoff constraints
Authors: Stolarski Henryk K. , Chiang Martin Y. M. 
Published: August 2005

AbstractAn analysis of thin plates by C0 elements is presented. The fundamental part of it is the formulation of a set of constraints that relate the rotational degrees of freedom to the translational degrees of freedom and which are weaker than the usual Kirchhoff constraints. A penalty term associated with these constraints is then introduced instead of the usual expression for the shear strain energy. It is shown that the approach is effective for both quadrilateral and triangular elements.
A full range analysis of reinforced concrete slabs using finite elements
Authors: May I. M. , Ganaba T. H. 
Published: August 2005

AbstractThis paper describes a full range analysis of reinforced concrete slabs, which includes the effects of both geometric and material non‐linearities, using the finite element method. A computer program is described which has been used to analyse slabs previously tested by a number of investigators. The comparisons between the test results and the computer program are considered to be good.
A mixed formulation of C0‐linear triangular plate/shell element—the role of edge shear constraints
Authors: Saleeb A. F. , Chang T. Y. , Yingyeunyong S. 
Published: August 2005

AbstractA simple and effective linear C0‐triangular element for plates and shells is developed on the basis of the Hellinger‐Reissner mixed variational principle with independently assumed stress and displacement fields. Two main features are emphasized in this development concerning the assumed transverse shear stress field. Firstly, this assumption results in edge‐type penalty constraints in the thin plate/shell regimes. Secondly, the element is used in the form of a four‐triangle, cross‐diagonal macroelement mesh. As a result, the element is shown to be free from shear locking in thin plate/shell applications, and it satisfied all the appropriate patch tests required for Kirchhoff plate models. In addition, the element exhibits good overall convergence properties in a variety of test problems for plates and shells. Finally, from the computational standpoint, the element is very efficient since all stiffness component matrices are derived in explicit forms.
Sensitivity analysis with plate and shell finite elements
Authors: Brockman R. A. , Lung F. Y. 
Published: August 2005

AbstractThis paper addresses the problem of calculating sensitivity data by direct methods for isoparametric plate or shell elements. Sensitivity parameters of interest include intrinsic properties such as material modulus and plate thickness, as well as geometry variables which influence the size and shape of a structure. The sensitivity calculation therefore must consider the parametric mapping within an element, as well as the influence of geometric variables on the orientation of an element in space. The methods presented specialize directly to continuum elements, in which the co‐ordinate transformation is omitted, or to simple structural members situated arbitrarily in space. Numerical examples are presented which illustrate the accuracy of the proposed techniques, and the effect of discretization error on computed sensitivities.
A robust triangular plate bending element of the Reissner–Mindlin type
Authors: Zienkiewicz O. C. , Lefebvre D. 
Published: August 2005

AbstractA new triangular plate element is presented. This new element is based on independent interpolations for slopes, displacement and shear forces, and it is shown that it does not suffer from any defect common to other Mindlin plate elements. Several examples are presented to illustrate the behaviour of this new element.
A new method for derivation of locking‐free plate bending finite elements via mixed/hybrid formulation
Authors: Gellert M. 
Published: August 2005

AbstractThe shear‐locking phenomenon in discrete bending analysis of Mindlin/Reissner plates is investigated. Mixed/hybrid variational principles are introduced which, unlike the rigorous displacement model, allow systematic derivation of locking‐free finite elements. This is achieved by satisfaction of an auxiliary condition, having the clear physical interpretation of shear‐force elimination on account of equilibrium. An example, using competitive techniques, demonstrates the applicability of the idea.
Curved composite boundary elements for Kirchhoff plate‐bending problems
Authors: Silva Paul J. , Mote C. D. 
Published: August 2005

AbstractComposite boundary elements are formed for plate‐bending problems by attaching a circular sector to a triangle. Elements utilizing cubic and quintic interpolation are developed for convex and concave boundaries.Smaller error and less numerical effort result when triangular elements are replaced by the composite boundary elements on clamped and most simply supported convex, boundaries. For domains with concave boundaries, greater accuracy is obtained when the quintic composite boundary element replaces the triangular element in fine mesh configurations.
A new finite‐volume approach with adaptive upwind convection
Authors: Kinney Robert B. , Mahdi Hashim S. 
Published: August 2005

AbstractA new finite‐volume approach is developed and applied to the two‐dimensional continuity and convective‐diffusive energy equations. The variation of the field variables is approximated by bi‐quadratic interpolation formulae over the space occupied by the finite volume and the region surrounding it. These are used in the integral conservation laws for energy and mass. The convective transport is modelled using a new upstream‐weighting approach which uses volume averages for the energy transported across the boundaries of the finite volume. The weighting is dependent on the skewness of the velocity field to the surfaces of the finite volume as well as its strength. It is adaptive to local flow conditions. Two test cases are treated which have exact solutions. The first is not new and involves a rotating shaft. The errors are less than 0.06 per cent for this case. The second case is new and involves convection past a source and sink. In contrast to the first case, the global Peclet number is a strong parameter, and cell Peclet numbers (Peh) range from 0 to 20. The maximum error is 2.3 per cent for Peh = 4, and there is no evidence of numerical diffusion for even the largest value of Peh. For both test cases, the maximum error occurs at moderate values of Peh and diminishes at the extreme low and high values.
Buckling of multi‐lamellae compression flanges of welded I‐beams: A unilateral elasto‐plastic plate‐stability problem
Authors: Chen Zhen‐Sheng , Mang Herbert A. 
Published: August 2005

AbstractBuckling of compression flanges of welded I‐beams consisting of more than one lamella is characterized by partial loss of contact between the lamella welded to the web and the neighbouring lamella. The boundaries of the contact regions of the buckling modes of the two lamellae are originally unknown. Thus, the present elasto‐plastic plate‐stability problem is coupled with a contact problem. It represents a unilateral problem because eigenforms with penetrations of lamellae are physically impossible. This problem is solved first for the elastic material domain. The Rayleigh‐Ritz method is used for determining symmetric eigenforms. A finite‐strip technique is employed for determining unsymmetric eigenforms. The solution of the unilateral elastic plate‐buckling problems serves as the starting point for the iterative solution of the corresponding elasto‐plastic plate‐stability problem. The buckling pressures obtained are compared with corresponding buckling stresses resulting from a classical design procedure disregarding the interaction of the lamellae at buckling.
A numerical study of holonomic approximations to problems in plasticity
Authors: Griffin T. B. , Reddy B. D. , Martin J. B. 
Published: August 2005

AbstractThe incremental holonomic boundary‐value problem in elastoplasticity has been shown to be characterized by a variational inequality. The problem may be approximated, however, by a perturbed minimization problem, characterized by a variational equality. This formulation is used as the basis for constructing finite element approximations of the original boundary‐value problem, leading to a system of non‐linear algebraic equations. Procedures for solving these equations are described and numerical results are presented and compared with those obtained using a conventional approach.
A parallel element‐by‐element solution scheme
Authors: Barragy E. , Carey Graham F. 
Published: August 2005

AbstractA parallel element‐by‐element scheme is developed for finite‐element solution of elliptic boundary‐value problems. It is shown that, for a broad class of computational grids, the solution algorithm is totally parallelizable. Moreover, the conversion of an existing serial EBE code to a parallel code is seen to be quite simple. The method is implemented on the Alliant FX/8 and Sequent Balance parallel computers and ‘speedup’ performance studies are conducted for a representative elliptic PDE in two dimensions. The present procedure can be applied quite generally to other finite‐element applications, and the associated programs can be modified in a straightforward way to implement the method.
Geometry‐based fully automatic mesh generation and the delaunay triangulation
Authors: Schroeder W. J. , Shephard M. S. 
Published: August 2005

AbstractOne approach to fully automatic mesh generation in two and three dimensions is to generate and triangulate a set of points within and on the boundary of a geometry using the properties of the Delaunay triangulation. Because the point data generate mesh topology of greater dimension, it is necessary to insure topological compatibility and perform classification of the resulting mesh with respect to the original geometry. Necessary and sufficient conditions for classification of mesh topology on three‐dimensional planar geometry are given, as well as a discussion of the more complex case of curved geometry. This paper also presents conditions to insure topological compatibility along with techniques for identifying and resolving cases of incompatibility.
Description of some numerical tools for solving incompressible turbulent and free surface flows
Authors: Daubert O. , Hervouet J. M. , Jami A. 
Published: August 2005

AbstractDuring the past ten years various methods have been devised to deal with the solution of the Navier–Stokes equations. In the meantime, different models have been worked out to represent turbulent incompressible flows. At LNH, deep participation in this enthusiastic research is still going on, together with a closely related development of physical modelling and metrology. In this paper, we will give an insight into a set of numerical codes which are now currently in use at our laboratory and some of their main applications to coastal engineering. This will include thermohydraulic internal flows and free surface flows. For each code a short presentation of the algorithm of solution is described.
Wind waves evaluation in the Adriatic and Mediterranean seas
Authors: Cavaleri Luigi , Bertotti Luciana , Lionello Piero 
Published: August 2005

AbstractWe present the results of the implementation of an advanced wave model in the Adriatic and in the Mediterranean Sea. With respect to the first and second generation models, the new approach does not accept any a priori assumption on the spectral shape of the wind waves, this being determined uniquely by the dynamical equilibrium of the various source functions. These include the generation by wind, non‐linear interactions and the dissipation due to whitecapping and to bottom friction.The Adriatic is characterized by highly variable wind regimes. Several storms have been hindcasted, testing the model in the various possible meteorological conditions. In this paper we focus our attention on a particular storm that allowed us to verify the shallow water behaviour of the model. For the Mediterranean we concentrate on a heavy storm that occurred in February‐March 1986 in the Sicily Channel. The very good results obtained in these two highly different conditions prove the effectiveness of the physical approach to the numerical description of the wind waves evolution.
Wave plan computation method in study of the Calvi Bay erosion in Corsica, France
Authors: Lejeune A. , Lejeune M. , Sahloul M. 
Published: August 2005

AbstractA study of linear monochromatic wave propagation is presented, based on a theory of potentials. The usual Berkhoff equation has been extended by the addition of partially pervious solid boundary effects and the bed friction.The problem has been solved by a hybrid finite element method including the effect of singular local elements such as the end of breakwaters or wharfs. This numerical method confirms the interest in quadratic Lagrangian finite elements.The comparisons with analytical solutions and existing numerical results show the validity of the method. Some original examples also prove the good performance of the proposed computation method.As an example, the study of the erosion of the beach of Calvi Bay in Corsica, France is presented. The phenomenon had started already in 1960, but the problem began to be very severe four years ago, after the implementation of a new harbour in 1982 and buildings, hotels, restaurants, and a main sewer on the beach. To consider the impact of these constructions and other factors like waves, currents and geomorphological aspects, the studies were divided into four parts: sedimentological, currents, wave propagation and geomorphological.This paper will describe the results of a complete two years study on the site, from February 1986 to December 1987.Findings show that the erosion process is due to the rise of the relative sea level with, as a catalyst, tourist behaviour and the implementation of the new constructions.
Modelling coastal/shelf systems with emphasis on long term trends
Authors: Nihoul Jacques C. J. , Djenidi S. , Hecq J. H. 
Published: August 2005

AbstractHydrodynamic studies of continental seas have been primarily concerned with tides and storm surges and the associated currents which can have velocities as high as several metres per second.However, the period of the dominant tide is only about half a day and the characteristic life time of a synoptic weather pattern is of the order of a few days. The very strong currents which are produced by the tides and the atmospheric forcing are thus relatively transitory and, over time scales of biological interest, they change and reverse so many times that they more or less cancel out, leaving only a small residual contribution to the net water circulation.Mathematical modelling appears at present as the most reliable approach to the determination of the residual circulation and of the long term transport of nutrients and pollutants in the sea.The residual circulation model developed at the GeoHydrodynamics and Environment Research Laboratory of Liège University (GHER) is described and illustrated by its application to the West‐European Continetal Shelf.Residual flow patterns on the shelf, and in particular in the Irish Sea and the North Sea, are presented and shown to be in excellent agreement with the observations.The results are exploited to estimate the typical routes and times of residence of nutrients and pollutants and the subsequent long term changes in shelf ecosystems and in the Belgian coastal zone.
Calculation of the force coefficients of a tubular jacket structural member with an appurtenance by the discrete vortex method
Authors: Downie M. J. , Murray B. A. , Bettess P. 
Published: August 2005

AbstractJacket structures have many sub‐sea appurtenances attached to them. For example, a typical jacket structure has hundreds of sacrificial anodes attached to its members. The fluid loading of these structures is calculated using Morison's formula. The force coefficients used in the equation are based on experiments carried out, for the most part, on single cylinders in laboratories in ideal flow. There are very few experimental data available for the fluid loading of cylinders with appurtenances. Moreover, it is not possible to calculate theoretically the loading on such configurations in flows of practical interest using approaches such as the finite element method. However, appurtenances can contribute significantly to the overall loading on a structure. This paper presents the preliminary theoretical work that has been carried out as part of a programme to establish a rational method for estimating the fluid loading on tubular members with appurtenances.
Application of soil–structure interaction to off‐shore foundations with specific reference to consolidation analysis
Authors: Lewis R. W. , Tran D. V. 
Published: August 2005

AbstractConsolidation problems associated with foundations for off‐shore structures are described and analysed using the finite element method. The structure itself and the soft underlying soil are modelled by finite elements with different constitutive relationships for each. Interfacial behaviour between the two is simulated by six‐noded elements, with a hyperbolic stress–strain relationship.Having modelled the soil–structure system behaviour during the consolidation stage, a soil–structure interaction analysis is then carried out for both shallow and deep foundations. Other important factors, such as the redistribution of stresses in the structure itself which have resulted from differential settlements, will also be investigated.
F.E. solution of a vertically averaged model for regional land subsidence
Authors: Simoni L. , Schrefler B. A. 
Published: August 2005

AbstractIn this paper a mathematical model is presented, based on the application of an averaging technique, in which the equations governing the behaviour of saturated porous media are integrated (averaged) over the smallest dimension of the domain of the problem (thickness). This results in a two dimensional model, in which the three dimensional nature of the problem is accounted for. In fact, the solution is sought in terms of the mean values over the thickness of the field variables and of the transverse displacement components. For the solution of the resulting governing equations a partitioned procedure is employed, which improves the efficiency of the method. The proposed model is very useful in solving problems in which the spatial nature prevents the applications of two dimensional models.Examples are presented, which illustrate the validity of this approach.