bluuebunny/crossref_metadata_2025_split huggingface dataset:
On permanent capillar‐heavy waves in infinite channels
Authors: Moussa Nabil 
Published: August 2005

AbstractThis work is based on the constructive existence proof of solutions of a comprehensive class of non‐linear free boundary‐value problems of plane hydrodynamics by E. Zeidler (1971) and a general computational method for constructing the solutions numerically given by the author (1991). The case of permanent capillar‐heavy waves in infinite channels will be considered.
Quickly convergent integration methods for plane stress plasticity
Authors: Schoenfeld Scott , Benson Dave 
Published: August 2005

AbstractExplicit finite‐element programs, such as DYNA3D, are frequently used to solve large structural problems, such as automobile impacts, that involve tens of thousands of shell elements. Since the explicit finite‐element programs do not use a stiffness matrix, the major cost of the calculation is the evaluation of the force vector. A significant part of that cost is the evaluation of the constitutive models. The standard algorithm for integrating J2 plasticity at the stress points is the radial return method. An iterative variation of radial return is commonly used to impose the zero normal stress condition within the shell elements. In this paper we explore several different non‐iterative methods that impose the zero normal stress condition in an approximate manner. We show that the cost of the constitutive evaluation can be reduced by 25 per cent without introducing significant errors.
On bicubic transformation for the numerical evaluation of Cauchy principal value integrals
Authors: Chen T. Charles 
Published: August 2005

AbstractRecently a bicubic transformation was introduced to numerically compute the Cauchy principal value (CPV) integrals. Numerical results show that this new method converges faster than the conventional Gauss–Legendre quadrature rule when the integrand contains different types of singularity. Assume η is the singular point of a CPV integral. The point η divides the interval [−1, 1] into two parts: [−1, η] and [η, 1]. The bicubic transformation maps the intervals [−1, η] and [η, 1] to the interval [−1, 1] with the following constraints: it maps the point η − ϵ to μn, and η + ϵ to −μn, where μn is the largest Gaussian point of an n‐point Gauss–Legendre quadrature rule, and ϵ is a user‐supplied constant. The n‐point Gauss–Legendre quadruture rule is then applied. In contrast to ordinary expectation, further numerical experiment shows that smaller ϵ does not always produce better results. In this paper we are concerned with the selection of ϵ to yield rapid convergence of numerical integration when the bicubic transformation method is applied.
Suitability of three‐dimensional finite elements for modelling material incompressibility using exact integration
Authors: Bell R. W. , Houlsby G. T. , Burd H. J. 
Published: August 2005

AbstractThis paper examines the suitability of three‐dimensional finite elements to model accurately problems involving material incompressibility, using the displacement finite element method and exact numerical integration. The previously used method for classification of element suitability is presented and extended to the three‐dimensional case. However, an alternative approach for examining suitability, quantified in terms of free degrees of freedom (equal to the degrees of freedom minus the incompressibility constraints), is introduced. This is used to examine Lagrangian cubic, serendipity cubic and tetrahedral three‐dimensional elements configured in a regular cubic arrangement. The findings of this paper are substantiated by a number of three‐dimensional numerical experiments and comparison with a separate two‐dimensional study.All serendipity cubic elements are found to be unsuitable. The linear strain tetrahedron is on the borderline of suitability in a 6‐tetrahedra‐per‐cube arrangement, and is thought to be only suitable if the mesh boundary nodes are not over‐constrained. The same element in a 5‐tetrahedra‐per‐cube arrangement, and higher order tetrahedra (quadratic strain etc), are suitable. The Lagrangian cube elements of higher order than the 27‐node cube are suitable, but are probably not as efficient computationally as the tetrahedral elements of the same order.
Evaluation of field singularities by an iterative boundary‐element method
Authors: Heyliger P. R. , Rudolphi T. J. 
Published: August 2005

AbstractA numerical method is presented for the evaluation of field singularities of the type (1/r1‐λ) using iterative solutions of standard boundary‐element analyses in a region surrounding the origin of singularity. Results for λ are presented for both two and three‐dimensional problems, and representative asymptotic fields for these examples are discussed.
Direct method for a class of symmetric linear systems
Authors: Onana Awono , Mbala H. A. 
Published: August 2005

AbstractA direct method is proposed for the numerical solution of a wide class of symmetric block‐tridiagonal systems of linear equations resulting from a finite‐difference or finite‐element discretization of elliptic boundary‐value problems with Dirichlet boundary‐value conditions on rectangular domains. The method is based on a result which generalizes the classical Cramer rule and on extensive use of the modified Chebȳshev polynomials for the formulation of the algorithm. A numerical example is provided to illustrate the validity of the proposed approach.
Solar pressure evaluation on large reflectors for space applications
Authors: Brunello P. 
Published: August 2005

AbstractThe evaluation of solar pressure effects over the antenna reflectors for communication satellites is becoming more and more important, since the diameters of such devices tend to be increased. For this purpose, a statistical approach based on the Monte Carlo method has been developed, as described in this paper, within a research project of the European Space Agency (ESA). In this way, detailed simulations can be carried out easily, thus allowing for analysing different geometrical and technological solutions and for defining an adequate compromise between antenna gain and pointing control capability of the satellite.
Application of augmented Lagrangian techniques for non‐linear constitutive laws in contact interfaces
Authors: Wriggers P. , Zavarise G. 
Published: August 2005

AbstractThe use of micromechanically based constitutive equations for contact interfaces leads to technically relevant parameters to ill‐conditioned finite‐element equations. In the paper an augmented Lagrangian technique is employed to overcome this difficulty and to provide a good converging algorithm.
Comparison of the BEM and FEM approach for the electromagnetic field analysis in a zoned medium
Authors: Krajewski Wojciech , Salon Sheppard J. 
Published: August 2005

AbstractIn the paper the BEM and FEM results have been compared in the context of 2D electromagnetic field analysis in a zoned medium with eddy current subregions. The practical problem concerning the turbogenerator end region has been discussed. The magnetic flux density over the surface of the end package and the current density in the non‐magnetic pressure plate have been analysed.
Finite‐element analysis of elastic contact between a shell of revolution and a rigid plate
Authors: Gautham B. P. , Ganesan N. 
Published: August 2005

AbstractElastic contact between a thick shell of revolution and a rigid plate in the case when the plate is brought into contact with the shell by giving a finite displacement to the plate is analysed by the finite‐element method. Field‐consistent higher‐order strain‐displacement relations with vanishing shear stresses on the surfaces are used. A finite element based on these relations is developed and used for the analysis. The contact conditions are imposed by use of the Lagrangian multipliers method, and the resulting minimization problem is solved iteratively. This procedure will lead to reduced memory requirements and computation time.
Comparison of strain recovery techniques for the mixed iterative method
Authors: Červenka Jan , Keating Scott C. , Felippa Carlos A. 
Published: August 2005

AbstractThree strain recovery techniques are investigated in the framework of the mixed iterative method. The need for appropriate strain recovery for low‐order elements is shown. The three techniques compared are: C‐lumping, strain‐smoothing and a new technique called C‐splitting. It is shown that the use of C‐lumping has negative effects on the convergence of the mixed iterative method. Both strain‐smoothing and C‐splitting deliver convergent results, but the new technique converges faster.
Optimization analysis of the three‐level time schemes
Authors: Shayya Walid H. , Segerlind Larry J. , Bralts Vincent F. 
Published: August 2005

AbstractA procedure was implemented to determine the optimum values for the two parameters of the Zienkiewicz three‐level time schemes which could be utilized for the numerical solution of a system of ordinary differential equations. A multivariable search method was implemented to estimate optimum values for these parameters. The resultant optimum three‐level time scheme produced very accurate results, satisfied physical reality, and did not produce any oscillations for the various problems that were investigated. The optimum values for the two parameters β and γ in the three‐level scheme were β = 0·50005 and γ = 1·0007. A comparison was made between this optimum scheme and other existing three‐level time schemes. The optimum scheme demonstrated superior results for all the problems that were analysed. However, the results of the optimization analysis produced a set of optimum parameters that were identical to the values that would reduce the general three‐level time scheme into a central‐difference two‐level time scheme, i.e. β = 1/2 and γ = 1.
Arbitrary Lagrangian‐Eulerian thermomechanical finite‐element model of material cutting
Authors: Rakotomalala R. , Joyot P. , Touratier M. 
Published: August 2005

AbstractAn arbitrary Lagrangian‐Eulerian model is described for the prediction of metal flow in a steady‐state forming process. The formulation is shown to be capable of dealing with free surface and boundary friction; the coupling with thermal effects is also considered. The numerical techniques are based on the finite elements for spatial discretization of the momentum equation and on an explicit integration scheme for discretization relative to time. The mass and energy equations are integrated by a finite‐volume method. Details on the application to an orthogonal cutting process are given in the final Section of the paper.
Eigensolution reanalysis of modified structures using perturbations and Rayleigh quotients
Authors: Chen Su‐Huan , Song Da‐Tong , Ma Ai‐Jun 
Published: August 2005

AbstractA new eigensolution reanalysis method for modified structures is developed and presented based on the usual first‐order perturbation scheme and the Rayleigh quotients. By this method, the accuracies of the eigensolutions of the modified structures computed by perturbation methods are improved. A numerical example is presented and the accuracies of the usual first‐order perturbation method, second‐order perturbation method, William B. Bickford method and the proposed method are compared.
Truncated envelope peconditioning technique
Authors: Júdice J. J. , Patrício J. M. 
Published: August 2005

AbstractIn the paper the use of a truncated envelope technique is discussed as a preconditioning for the conjugate gradient method for solving large linear systems of equations with symmetric positive‐definite matrices. An algorithm to generate a truncated envelope is introduced. Computational experience with systems of linear equations from the Harwell‐Boeing collection is presented to highlight the efficiency of this approach.
Accurate finite element method for steady and quasisteady lifting aerofoil
Authors: Shi Jun , Hitchings D. 
Published: August 2005

AbstractA finite element formulation based on superposition is proposed for a lifting aerofoil in incompressible potential flow. An accuracy improvement technique for the singularity at the aerofoil trailing edge is discussed. It is shown that the quarter‐node quadrilateral element can be readily employed to simulate this singularity. It is also demonstrated that the circulation in the flow field can be easily represented by a single constraint equation rather than introducing an artificial cut line in the mesh. The influence of finite‐element mesh size on solution accuracy and the correct form of the boundary condition have been investigated as well. Numerical examples are given for both steady and quasisteady Joukowski aerofoils of various thicknesses and at a range of incidences. In all test cases, good agreement is observed between the analytical solution and the numerical result.
Explicit variable time‐step method for implicit moving boundary problems
Authors: Zerroukat M. , Chatwin C. R. 
Published: August 2005

AbstractThe diffusion of oxygen into an absorbing medium as an example of an implicit moving boundary problem has been dealt with by a number of authors using various numerical techniques, and, where appropriate, approximate analytical expressions. To evaluate the time for complete absorption, extrapolation is usually employed. An unconditionally stable explicit numerical scheme that avoids the limitations of such methods is presented and tested herein. Unlike existing schemes this method is fully numerical; it avoids the large array size, generally required for existing methods, by using a variable‐length time step. The time for complete absorption emerges from the final step in the normal computing procedure with no recourse to extrapolation. Furthermore, owing to the implicit condition prevailing at the moving boundary, no iterations are needed to evaluate the time step required for the moving boundary to move a single space increment. The numerical results obtained compare very favourably with those due to earlier authors.
Boundary‐element solution of some structural‐acoustic coupling problems using the multiple reciprocity method
Authors: Sladek V. , Sladek J. , Tanaka M. 
Published: August 2005

AbstractIn the paper we have developed a new formulation for solution of structural‐acoustic coupling problems by boundary elements using the multiple reciprocity method. It is assumed that the structure is composed of plate components and is excited by the external or the internal noise source. The efficiency of the proposed formulation becomes especially remarkable if the boundary‐value problem is to be solved repeatedly for different values of frequency. The accuracy of the numerical computations has been compared with the analytical solution in a test example.
Lagrange multiplier approach for evaluation of friction in explicit finite‐element analysis
Authors: Zhong Zhi‐Hua , Nilsson Larsgunnar 
Published: August 2005

AbstractAn algorithm for evaluation of friction in general contact‐impact interfaces is described. The algorithm is based on an explicit finite‐element method. Coulomb's friction law is assumed. The defence node algorithm is used such that the sticking condition can be imposed with the Lagrange multiplier method even in explicit dynamic analysis. The algorithm is supposed to be applicable in general situations, including large deformations of the contact‐impact bodies and large relative sliding between the contact‐impact boundaries. Numerical results are presented to demonstrate the performance of the algorithm.
Homogenization and effective elastoplasticity models for periodic composites
Authors: Swan Colby C. , Cakmak Ahmet S. 
Published: August 2005

AbstractTechniques for stress‐ and strain‐controlled in situ homogenization of inelastic periodic composites are presented. The results of homogenization computations on a specific elastoplastic composite solid are then employed to validate the form of an orthotropic elastoplasticity model with a tensorial kinematic hardening law.
General forming of transition elements
Authors: Horváth Ágnes 
Published: August 2005

AbstractA generalization of the r(1−m)/m strain singularity of higher‐order isoparametric elements is presented. It is shown that, by variable placement of the side nodes between their original and singular positions, the point of singularity sensed by the element can be controlled. The transition elements have a strain singularity outside their domain. The singular and non‐singular elements are elements are special cases of the general mapping. The transition elements, together with the singular isoparametric elements, can be used for solving crack problems.
Fourth‐order difference method for quasilinear Poisson equation in cylindrical symmetry
Authors: Jain M. K. , Jain R. K. , Krishna Meera 
Published: August 2005

AbstractWe propose in this paper a nine‐point, fourth‐order difference method for the numerical solution of the quasilinear Poisson equation

with appropriate boundary conditions. The method is based on five evaluations of f. The numerical results of four problems obtained using this method are listed. The results demonstrate the fourth‐order accuracy of the method.
Accelerated modified Newton‐Raphson iteration‐based finite‐element solution of structural problems involving non‐linear deformation behaviour
Authors: Chen Chang‐New 
Published: August 2005

AbstractA new global secant relaxation (GSR)‐method‐based improvement procedure is used to improve the overall convergency performance of the modified Newton‐Raphson iteration in carrying out the solution of discrete systems resulting from the finite‐element discretization of a certain class of structural problems involving non‐linear deformation behaviour.
Addressing the corner problem in BEM solution of heat conduction problems
Authors: Kassab Alain J. , Nordlund R. S. 
Published: August 2005

AbstractA numerical problem which features prominently in the implementation of the boundary‐element method (BEM) for the solution of heat‐conduction problems arises from double‐valued heat fluxes at boundary corners. This problem is readily dealt with by explicitly treating nodal heat fluxes as double‐valued prior to assembly of the nodal equations. This formulation is very flexible as it also permits imposing discontinuous thermal conditions at any boundary node. However, at corner nodes where temperature only is prescribed, the scheme leads to two unknowns, while only one nodal BEM equation is available there. An additional equation which closely follows the previous work of Walker and Fenner is derived for these nodes, and this provides sufficient information to resolve the upstream and downstream values of the heat flux at the temperature node. The additional equation is general, is free of heuristic constraints, and is applicable through the wide range of acute, shallow, obtuse and re‐entrant angles encountered in practice. Numerical examples are used to compare the present method with the Walker and Fenner approach and with analytical solutions. Results indicate both improved accuracy and generality, thus validating the present method.
Variational formulation for Timoshenko beam element by separation of deformation mode
Authors: Lee Seok‐Soon , Koo Jeong‐Seo , Choi Jin‐Min 
Published: August 2005

AbstractA variational formulation for a Timoshenko beam element is derived by the separation of the deformation mode into the bending deflection and shear deflection. Shear deflection is projected into bending deflection and the projection matrix is constructed by using the equilibrium equation and the relation of force and displacement. The exact stiffness matrix of the Timoshenko beam element can be obtained by the present method. Examples are solved in order to show the effectiveness of the beam element in comparison with other elements.
Approximate solution of the Fokker‐Planck‐Kolmogorov equation by finite elements
Authors: El‐Gebeily Mohamed A. , Shabaik Hosam E. Emara 
Published: August 2005

AbstractThe paper considers the solution of the Fokker‐Planck‐Kolmogorov equation by the finite element method (FEM). The problem is set in a variational formulation suitable for the FEM. Some theoretical aspects related to applying the method are discussed. Discretization of the problem is carried out and questions of convergence and order of the method are also addressed. A numerical example is given to verify the validity of the approach.
Application of direct boundary integration method to wave diffraction by submerged bodies
Authors: Shankar N. Jothi , Cheong Hin‐Fatt , Nallayarasu S. 
Published: August 2005

AbstractThe diffraction of waves due to the presence of submerged objects in the ocean environment is solved by a relatively novel approach involving the direct boundary integration method (DBIM). Firstly, the method is tested for the case of a submerged circular cylinder and compared with the conventional boundary element method (BEM) results. The agreement between the results using this method and the BEM is good. Further, the DBIM has been applied to the case of a submerged horizontal plate for which the horizontal and vertical force coefficients are computed and compared with a semi‐analytical solution using the matched eigenfunction expansion method (EFEM). It is found that the computed results using DBIM are in good agreement with those of EFEM and BEM. Further, the DBIM is found to be computationally more efficient than the BEM for the water wave diffraction problems presented in this paper.
Statistical analysis for static responses of structures with stochastic shape
Authors: Liu Hanbing , Chen Su‐Huan 
Published: August 2005

AbstractThe paper presents a probabilistic boundary element method for analysis of structural responses to static loading, when the shape parameters of structures are considered as random variables. We can use this method to evaluate the mean values and standard deviations of the responses, and estimate the stochastic errors of structural character resulting from manufacturing errors.
Finite element solution of steady natural convection equations by a false diffusion method
Authors: Sen Swarnendu , Sarkar A. 
Published: August 2005

AbstractUse of upwind finite element methods was so far confined to forced convection problems. The present work is devoted to the application of false diffusion techniques to phenomena involving natural convection. A range of Rayleigh numbers in which the discretization by the conventional Galerkin scheme fails is considered. A false diffusion method similar to the Streamline upwind technique has been employed to avoid cross‐wind diffusion. The upwind parameter is changed continually until a true solution is obtained. The present scheme provides convenient means for obtaining gradually improved guesses from which a more accurate solution can be obtained using the conventional Galerkin method. The criterion for the determination of a true solution is established, and hot‐wall Nusselt number values are documented in tabular form.
Incompressibility and axisymmetry: A modified B method
Authors: Jinka Ashoka G. K. , Lewis Roland W. 
Published: August 2005

AbstractThe paper deals with a B‐type strain projection method with specific reference to axisymmetric incompressible solids. Essentially the \documentclass{article}\pagestyle{empty}\begin{document}$ \overline{\overline {\rm{B}}} $\end{document} (B double bar) method, which is reported in the present study, is based on Hughes' B‐bar approach utilizing modified shape functions to represent the radial displacement and geometry. As a consequence of adopting these procedures the \documentclass{article}\pagestyle{empty}\begin{document}$ \overline{\overline {\rm{B}}} $\end{document} method results in an exact satisfaction of incompressibility constraints. The rationale of the \documentclass{article}\pagestyle{empty}\begin{document}$ \overline{\overline {\rm{B}}} $\end{document} method leads to the modified mean‐dilatation approach for the case of an axisymmetric incompressible problem. It is interesting to note in the present work that the explicit influence of enhanced hoop strain is eliminated from the discrete divergence condition.