bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the stabilization of the rectangular 4‐node quadrilateral element
Authors: Hueck U. , Reddy B. D. , Wriggers P. 
Published: August 2005

AbstractThe standard bilinear displacement field of the plane linear elastic rectangular 4‐node quadrilateral element is enhanced by incompatible modes. The resulting gradient operators are separated into constant and linear parts corresponding to underintegration and stabilization of the element stiffness matrix. Minimization of potential energy is used to generate exact analytical expressions for the hourglass stabilization of the rectangle. The stabilized element is shown to coincide with the element obtained by the mixed assumed strain method.
The unimportance of the spurious root of time integration algorithms for structural dynamics
Authors: Hulbert G. M. , Chung J. 
Published: August 2005

AbstractMost commonly used second‐order‐accurate, dissipative time integration algorithms for structural dynamics possess a spurious root. For an algorithm to be accurate, it has been suggested that the spurious root must be small and ideally be zero in the low‐frequency limit. In the paper we show that good accuracy can be achieved even if the spurious root does not tend towards zero in the low‐frequency limit. This permits more flexibility in the design of time integration algorithms. As an example, we present an algorithm that has greater accuracy than several other dissipative algorithms even though for all frequencies its spurious root is non‐zero. We also show that the degraded performance of the Bazzi‐ρ algorithm is not due to its non‐zero spurious root.
Derivation of shape functions for an exact 4‐D.O.F. Timoshenko beam element
Authors: Eisenberger Moshe 
Published: August 2005

AbstractTimoshenko beam elements have been the subject of numerous publications. The difficulty was that of arriving at a superconvergent element with four degrees of freedom, as is the case for the Bernuli‐Euler classical beam element. Two different approaches are presented here for the derivation of the shape functions. The first is based on the flexibility matrix, where utilizing the unit load method, including the term that accounts for the shear deformations in the virtual work expression, the stiffness matrix is derived. Then, a second method is presented to derive the exact shape functions, directly from the differential equations of the Timoshenko beam theory. The resulting shape functions are the same in both methods.
Convergence of stress maxima in finite element computations
Authors: Yosibash Zohar , Szabó Barna A. 
Published: August 2005

AbstractThe convergence of stress maxima, computed directly from finite element solutions, is investigated with respect to a family of exact solutions characterized by varying degrees of smoothness. The performances of h‐ and p‐extensions and the product and trunk spaces are evaluated and documented with respect to a family of benchmark problems. In uniform p‐extensions a characteristic pattern in the convergence of stress maxima was observed. There does not appear to be a clear‐cut advantage of the product space over the trunk space in this respect. The much faster convergence of stress maxima in the case of p‐extensions, as compared with h‐extensions, is evident from the results.
Enhanced 8‐node three‐dimensional solid and 4‐node shell elements with incompatible generalized displacements
Authors: Slavković Radovan , Živković Miroslav , Kojić Miloš 
Published: August 2005

AbstractEnhanced 8‐node three‐dimensional solid and 4‐node shell elements are proposed in the paper. Improvement of the response of the 3‐D solid is achieved through additional strains corresponding to generalized displacements incompatible between elements. In the case of the 4‐node shell, the membrane behaviour is improved through addition of incompatible membrane strains.Some linear and geometrically non‐linear examples demonstrate significant improvements of the elements. Results are compared with solutions obtained with the standard, displacement‐based elements and with results available in the literature.
A three‐dimensional symmetric linear equation solver
Authors: Gravvanis George A. 
Published: August 2005

AbstractFactorization procedures for the efficient solution of large sparse linear finite difference systems have been introduced recently. In these procedures the large sparse symmetric coefficient matrix of a certain structure is factorized exactly, yielding a direct solution method. Furthermore, approximate factorization procedures yeild implicit preconditioning iterative methods for the finite difference solution. The numerical implementation of these algorithms is presented and Fortran subroutines for the efficient solution of the resulting sparse symmetric linear system of algebraic equations are given.
Discretization error dominance over subgrid terms in large eddy simulation of compressible shear layers in 2D
Authors: Vreman Bert , Geurts Bernard , Kuerten Hans 
Published: August 2005

AbstractSecond‐ and fourth‐order‐accurate spatial discretization methods give rise to discretization errors which are large than the corresponding subgrid terms in large eddy simulation of compressible shear layers in 2D, if the ratio between the filter width and the grid spacing is close to one. Even if an exact representation for the subgrid‐scale contributions is assumed, large eddy simulation is accurate only if this ratio is sufficiently larger than one. In that regime fourth‐order methods are more accurate than second‐order methods. An analysis of the data obtained from two‐dimensional direct numerical simulations of compressible shear layers substantiates these assertions.
Influence of contact area on service life of gears with crack in tooth root
Authors: Flašker J. , Glodež S. , Pehan S. 
Published: August 2005

AbstractThe paper describes the influence of contact area on the service life of dynamically loaded gears with a crack in a tooth root. Numerical results obtained with the finite element method using the program package BERSAFE are compared with the experimental results obtained on the universal testing machine INSTRON 1255. Numerical and experimental results are in good agreement. The analysis shows that the contact area directly influences the speed and direction of the crack propagation and the service life of the gear with a crack in a tooth root.
A numerical solution for dynamic interaction between rigid wheel and flexible beam
Authors: Lee Kisu 
Published: August 2005

AbstractA numerical method is presented for the analysis of dynamic interaction between rigid wheel and flexible beam. In contrast to traditional approaches, the wheel nominal motion as well as the contact force are considered here as unknowns. The correct contact force between the wheel and the beam is computed by iteratively reducing the constraint error towards zero, and a simple time integration is employed for the solution of equations of motion. Convergence of the iterative scheme is analysed, and numerical simulations are conducted to demonstrate the accuracy of the solution.
On the eigenvalues basic to the analytical solution of convective heat transfer with axial diffusion effects
Authors: Oliveira M. C. , Ramos R. , Cotta R. M. 
Published: August 2005

AbstractThe integral transform method is employed in the analytical solution of the non‐classical eigenvalue problem that appears in connection with the analysis of forced convection in ducts, including the effect of fluid heat diffusion in the axial direction. The related eigenfunctions are expanded in terms of eigenfunctions from a simpler auxiliary eigenvalue problem, and the original eigenvalues are determined from the associated matrix eigensystem analysis. Convergence rates of the proposed solutions are illustrated and reference results established for different values of the governing parameters.
Permanent heavy waves in circular‐shaped channels
Authors: Moussa Nabil 
Published: August 2005

AbstractBecause of the earth's curvature, all existing channels have a curvature. E. Zeidler gave an existence and uniqueness proof for permanent heavy and capillar‐heavy waves in such circular shaped channels. Based on this proof and on a general computational method for constructing the solutions numerically, the case of permanent heavy waves in circular‐shaped channels is considered in this work.
On a novel mesh for the regular boundary layers arising in advection‐dominated transport in two dimensions
Authors: Hegarty Alan F. , Miller John J. H. , O'riordan Eugene , Shishkin G. I. 
Published: August 2005

AbstractUpwind finite difference operators on uniform meshes are well known to be unsuitable for the numerical solution of singularly perturbed partial differential equations, in the sense that, in the neighbourhood of the boundary layers, the error in the numerical approximation may increase as the mesh is refined. Recently, on the other hand, it has been predicted theoretically that the use of upwind finite difference operators on specially designed piecewise uniform meshes guarantees the decrease of the nodal error to zero as the number of mesh elements increases. In the paper the general theorem is quoted and its prediction is validated by numerical experiment for a specific linear advection‐dominated transport equation in two dimensions. Experimental values of the convergence rate are obtained, which also agree with the theoretical estimates.
Similarity of stiffness and mass matrices in plate bending elements
Authors: Krishnan A. , Krishnadasan C. K. 
Published: August 2005

AbstractIt has been noticed that the stiffness and mass matrices of a triangular plate bending element can be generated from the known stiffness and mass matrices of a similar triangular element making use of scaling matrices. This could be used to advantage in solving problems involving large degrees of freedom if the structure could be discretized into similar triangles. The idea is extended to study the free vibration of a square plate clamped on all edges with a square central cutout.
Dynamic stiffness matrix for variable cross‐section Timoshenko beams
Authors: Eisenberger Moshe 
Published: August 2005

AbstractThe Timoshenko beam model incorporates the effect of shear deformations and rotary inertia in the vibration response of beams. For constant cross‐section beams it was shown that the effect is dependent on the aspect ratio of the beams, and for beams with large ratio the effect is small. In this work exact vibration frequencies for variable cross‐section beams are found using the dynamic stiffness matrix approach. An example is given and compared with known results of beams with various taper ratios.
Non‐linear Wilson's brick element for finite elastic deformations of three‐dimensional solids
Authors: Ibrahimbegović Adnan , Kožar Ivica 
Published: August 2005

AbstractA geometrically non‐linear version of the well known 8‐node Wilson brick element is presented. The element is based on a sound variational formulation and the modified method of incompatible modes, which are shown to render quite a satisfying, locking‐free performance in some challenging large displacement problems.
The new variational problem in three‐dimensional eddy‐current field computation
Authors: Jian Huang , Bangding Tan , Jihui Yu , Mingzhong Rao 
Published: August 2005

AbstractA new variational problem corresponding to a three‐dimensional eddy‐current boundary‐value problem is treated in the paper. The equivalence between the variational problem and the boundary‐value problem is proved, and so is the uniqueness of the solution. These form the foundation of the H ‐ Ψ method.
Closed‐form derivation of an 8‐node hexahedral element stiffness matrix by the hybrid stress method
Authors: Saether Erik 
Published: August 2005

AbstractA general methodology for deriving explicit element stiffness matrices in hybrid stress formulations has recently been developed by the author. The technique utilizes special stress field transformations to eliminate the complementary energy matrix inherent to hybrid formulations, thus simplifying the stiffness definition such that an explicit evaluation can be accomplished. The elimination of numerical integration and matrix inversion results in a substantial decrease in computational cost. The methodology is applied to derive explicit algebraic expressions for the Pian‐Tong hexahedral element stiffness matrix.
A statistical mechanical model of solidification
Authors: Yang Y. S. , Blake N. , Abbott T. B. , McCarthy J. F. 
Published: August 2005

AbstractA model of solidification is developed from a statistical mechanics basis that incorporates nucleation of columnar and equiaxed grains, thermal and solute diffusion, and latent heat of the phase change. The model is applied to the solidification of austenitic steel. The dendritic growth of columnar and equiaxed grains is simulated, including the segregation of solute ahead of the solid‐liquid interface. The irregular branched morphology of the solid forms in a manner analogous to dendritic morphologies that arise from constitutional undercooling in real materials. There is competition between columnar and equiaxed growth. When growing grains approach, the solute layer and the thermal field act to prevent them overlapping.
Plotting of fringe contours from finite element results
Authors: Ramesh K. , Yadav A. K. , Pankhawalla Vijay A. 
Published: August 2005

AbstractA novel and simple approach to plot fringe contours from finite element results that simulates the fringe thickness variation as observed in experiments is presented. The procedure does not require solution of any non‐linear equation. Shape functions are used as interpolation functions to plot fringe contours from the nodal values of fringe orders. The various fringe contours one usually comes across in stress analysis are also reviewed. The program code in Turbo‐Pascal employing the new algorithm is given. Stress and displacement contours at the tip of a crack in an SEN (single‐edge‐notched) specimen are plotted using the code developed. The fringe contours plotted correspond to those observed in experiments such as photoelasticity, holography and Moire.
An assumed strain approach avoiding artificial thickness straining for a non‐linear 4‐node shell element
Authors: Betsch P. , Stein E. 
Published: August 2005

AbstractA quadrilateral degenerated C0 shell element is presented which relies on extensible director kinematics and which incorporates unmodified three‐dimensional constitutive models. It is shown that the direct interpolation of the extensible director field causes severe locking behaviour in the case of thin shell structures. An assumed strain interpolation is proposed to overcome the thin‐shell defect. Due to this modification the shell element is able to accommodate large rotations without a rotation tensor, even for very thin shells. Several large deformation examples confirm that the developed shell element is competitive with more elaborate formulations which use rotational degrees of freedom.
Boundary element technique for geotechnical problems of incompressible soils
Authors: Bu S. , Davies T. G. 
Published: August 2005

AbstractNovel fundamental solutions for elastodynamics of fully incompressible media are derived, by reason of their many applications to engineering and physical problems. It is demonstrated that, when Poisson's ratio equals 1/2, the frequency domain fundamental solutions (Stokes's solutions) are independent of the dilatational wave velocity, which tends to infinity. Consequently, dynamic problems involving incompressible materials can be rigorously analysed by the boundary element method without special difficulty. Numerical solutions to geotechnical problems of incompressible half‐spaces are presented to demonstrate the applicability and accuracy of the formulations.
Remarks on the stability of enhanced strain elements in finite elasticity and elastoplasticity
Authors: de Souza Neto E. A. , Perić Djordje , Huang G. C. , Owen D. R. J. 
Published: August 2005

AbstractThe stability of a class of geometrically non‐linear assumed enhanced strain elements is addressed. By means of an eigenvalue analysis of element tangent stiffnesses at finitely deformed configurations, circumstances under which enhanced elements become unstable, with possible development of non‐physical hourglass patterns, are identified. Insight into the influence of spurious eigenvalues on the stability of solution of finite elasticity and elastoplasticity problems is provided by simple numerical tests with a patch of elements. Results of simulations of some practical engineering problems are presented and limitations on the applicability of enhanced strain elements in the finite strain regime are discussed.
A mass conservative least‐squares finite element method for the stokes problem
Authors: Nelson John J. , Chang C. L. 
Published: August 2005

AbstractIn the paper the simulation of incompressible flow in 2D by the least‐squares finite element method (LSFEM) in the velocity‐vorticity‐pressure version is studied. A problem with this method is that it does not conserve mass exactly, i.e. div uh ≠ 0 exactly. In the paper a modified LSFEM is developed which enforces a near zero residual of mass conservation, i.e. div u is nearly zero at every point of the discretization. This is accomplished by adding an extra restriction in the divergence free equation through the Lagrange multiplier strategy.
Treatment of distributed sources in the stochastic boundary element method
Authors: Kaljević I. 
Published: August 2005

AbstractThe contributions of distributed sources to the mathematical expectations and variances of the response variables are analysed in the paper using the stochastic boundary element method. The validity and the accuracy of the particular integral approach in representing statistical properties of the domain are investigated. To this end domain integration techniques to calculate the contributions of the distributed sources and their derivatives with respect to random variables that may represent both random configuration of the domain and random material parameter are developed. Several models for the random interior are presented and their influence on the response statistics is investigated. The accuracy of the particular integral approach is demonstrated through numerical comparisons with the direct integration formulation.
An accurate numerical algorithm for advective transport
Authors: Manson J. R. , Wallis S. G. 
Published: August 2005

AbstractThe paper describes a new numerical algorithm for pure advection at large Courant numbers. The DISCUS scheme uses an accurate and proven control volume algorithm (QUICKEST) within a Lagrangian treatment of advection. By being in sympathy with the information flow dictated by characteristic lines, the scheme performs exceedingly well at Courant numbers greater than one. In contrast to existing Lagrangian schemes which use the characteristics to determine the grid points from which concentrations are interpolated, in DISCUS the characteristics are used to determine the appropriate location for the control volume. The scheme is of comparable accuracy to Eulerian schemes at Courant numbers less than one, but it increasingly outperforms them as the Courant number increases. Indeed, the results reported illustrate the futility of using an Eulerian scheme at high Courant numbers.
Growth behaviour of bulk GaN single crystals grown with various flux ratios using solvent‐thermal method
Authors: Shin T. I. , Yoon D. H. 
Published: August 2005

AbstractBulk GaN single crystals were grown using a solvent‐thermal method. They were grown for 200 h at 600 °C and 800 °C using 8 MPa of N2 gas and 1–3 mm sized pyramid GaN single crystals. Pure Na, NaN3 and Ca were used as the flux. The mole fraction of the [flux]/([flux] + [Ga]) was 0.30–0.67. The growth behavior differed according to the flux ratio. The quality of the bulk GaN single crystals was improved by increasing the flux ratio. The bulk GaN single crystals formed by spontaneous nucleation were deposited on the BN crucible wall and bottom during the first step of synthesis. The wurtzite structure of the GaN grown single crystal was confirmed by x‐ray diffration. The chemical composition was analyzed by electron probe microanalysis. The quality and optical properties of the GaN single crystal were examined by Raman spectroscopy and photoluminesence analysis. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Morphological lattice complexes
Authors: Hauck J. , Mika K. , Sager W. 
Published: August 2005

AbstractBinary and pseudobinary compounds AB like NaCl and CaCO3, with the center of charge at carbon position, are characterized by self‐coordination numbers of nearest, second and third neighborsT1T2T3of A and B positions. The maximum Madelung factor of compounds with identicalTivalues of A and B atoms is obtained for a maximum of B positions at the border of the A–A Dirichlet domain. The A and B positions form a packing with differentTivalues, if all B positions are on the border of the Dirichlet domain. This packing like the primitive cubic packing of Na and Cl atoms withTivalues 6 12 8 or the rhombohedrally distorted packing 6 8 6 of CaCO3as morphological lattice complexes can be related to cubic NaCl crystals or the cleaved rhombohedron of calcite. A different habit of crystals is expected for sphere, rod or layered packings. Many well‐defined nanoparticles can be obtained from microemulsions at variation of temperature, water content or water partial pressure. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interactions between pairs of DNA‐binding dyes: Results and implications for chromosome analysis
Authors: Latt Samuel A. , Sahar Elhanan , Eisenhard Michael E. , Juergens Lois A. 
Published: August 2005

AbstractA number of DNA‐binding dyes, with spectral properties making them suitable as components of energy donor‐acceptor pairs, are described. If such pairs are used to stain metaphase chromosomes, and if the energy acceptor (e.g., actinomycin D or methyl green) has a binding specificity opposite to the binding or fluorescence specificity of the donor (e.g., 33258 Hoechst, quinacrine or chromomycin A3), contrast in donor fluorescence can be enhanced, leading to patterns selectively highlighting standard or reverse chromosome bands or particular polymorphic regions. Such results presumably reflect chromosomal regions enriched in 10–20 base pair clusters to which the donor binds and fluoresces but to which the acceptor cannot bind. For other pairs, involving counterstains such as netropsin or echinomycin, which are not suitable as energy acceptors, specific changes observed in polymorphic region fluorescence are most likely due to binding competition between dyes. Dye pairs producing contrast by either method can be used to differentiate between homologous chromosomes or to facilitate detection of specific chromosomal rearrangements. Preliminary data indicate that contrast enhancement generated in fixed metaphase chromosomes spread on microscopic slides can also be observed in suspensions of unfixed metaphase chromosomes, reinforcing the expectation that the methodology described will be of use in flow cytometry.