bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhancing interactivity and automation through finite element neighbours
Authors: Hoole S. Ratnajeevan H. 
Published: August 2005

AbstractIn finite element analysis, each element is defined by a set of node numbers and stored. In this paper, it is shown that by storing the three neighbouring triangles of each triangular element, In addition to the three vertices, the interactivity and automation of the design station may be greatly enhanced. This enhancement results from the use of the data on neighbours in:

Identifying triangles pointed to on a graphics screen, through a digitizer. This is used for extracting potentials and field intensities at points, for refining meshes by adding points, and for imposing Neumann boundary conditions on the boundary edges and performing integrations, such as of force, over trianggles.
Following a path defined as a straight line for extracting graphs of potential and field intensity and performing contour integrations, like Maxwell stress, along such lines.
Checking the optimality of the mesh using the Delaunay criterion.
Determining discontinuities of field intensity at material interfaces.
Comparing the field intensities in adjacent triangles to measure error for adaptive refinement.
Alternatively, in an environment where memory for storing the neighbours is scarce, such as when using microcomputers, it is shown that the values may be computed when they are required, at the expense of speed.
On the use of a standard quadratic element in the analysis of consolidation following external loading
Authors: Thomas H. R. , Harb H. M. 
Published: August 2005

AbstractThe use of a standard quadratic element in the analysis of consolidation following external loading is explored. It is shown that such an element can produce satisfactory results for both instantaneous and ramp loading one‐dimensional problems. A double calculation procedure is proposed for the establishment of initial conditions under instantaneous loading. Simple refinement of the mesh, in the region of the free draining boundary, is shown to eliminate problems associated with ramp loading.
A method for infinite integrals of oscillating functions
Authors: Zhongjin Yang 
Published: August 2005

AbstractInfinite integrals of oscillating functions are often used in scientific research. The general numerical methods can only provide infinite integrals of strictly monotonic functions, which cannot be used while the integrand is an oscillating function. In this paper, we utilize the zero point distribution of the integrand to give a useful method for infinite integrals of oscillating functions as well as its error estimate.
The performance of ITPACK on vector computers for solving large sparse linear systems arising in sample oil reseervoir simulation problems
Authors: Oppe Thomas C. , Kincaid David R. 
Published: August 2005

AbstractResults are presented of the performance of two different versions of the ITPACK software package on large sparse linear systems arising in the solution of sample oil reservoir simulation problems using three different large vector computers (Cyber 205, Cray X‐MP48 and Amdahl VP1200). The main focus of this paper is on the necessary changes in the package that were made for efficiency when going from a memory‐to‐memory computer to a register‐to‐register computer. We feel that these are typical changes that must be considered when moving software of this type between vector computers. The execution times presented should not be considered to be representative of the overall performance of these computers.
A network method for nonlinear transient eddy current problems
Authors: Wong C. C. 
Published: August 2005

AbstractMaxwell's curl equations for a conducting region are simulated by the impedance network. A set of simultaneous first‐order ordinary differential equations is developed for the network which can be used to solve linear or nonlinear, transient or static eddy current problems. The resulting set of equations is solved by the explicit fourth order Runge–Kutta method and in some cases by an implicit method based on the central difference scheme for time discretization. A number of examples, including eddy current losses in a saturated steel plate, are described to illustrate the applications of the method. It is found that the explicit method is more suitable for nonlinear problems, whereas the implicit method is more efficient for linear problems.
Use of double nodes in the numerical simulation of multilayered flows of immiscible fluids
Authors: Mitsoulis Evan 
Published: August 2005

AbstractThe use of double nodes in side‐by‐side flows of immiscible fluids is introduced. The double nodes are required to satisfy the interface boundary conditions of continous velocities and stresses. The implementation of the technique in finite element simulations of two viscous immiscible fluids is illustrated through a typical example of co‐extrusion.
Patch test verification of a triangular thin‐shell element based on discrete Kirchhoff theory
Authors: Murthy S. Sridhara , Gallagher R. H. 
Published: August 2005

AbstractA new curved triangular thin‐shell finite element, based on nonconforming displacement fields, has demonstrated its effectiveness in a variety of numerical examples.8 The patch test is applied to that element in the present paper. The element formulation is outlined, the special characteristics of the patch test for curved thin‐shell elements are described, and that test is performed for the conditions of the inextensional bending, membrane stretching and rigid body displacements. Excellent results are obtained for element subtending angles up to 16 degrees.
A general mixed finite element for Timoshenko beams
Authors: Kolberg U. 
Published: August 2005

AbstractStarting from the principle of virtual work and applying the transformation of Legendre, a mixed finite element method is presented. This is done for the geometrically linear and nonlinear beam analysis including shear deformation. Lagrange polynomials of order six are chosen as element shape functions, and several examples are calculated, in order to show the efficiency of the numerical algorithm.
Exact singularity cancelling for the potential kernel in the boundary element method
Authors: Aliabadi M. H. , Hall W. S. , Hibbs T. T. 
Published: August 2005

AbstractIt is known that the transformation of a triangular curved element to a local plane square introduces a Jacobian which is effective in dealing with the numerical problems of evaluating the singular integrands arising from the presence of the inverse distance potential kernel in the boundary element method. It is shown that exact cancelling of the singularity occurs for triangular elements with linear, quadratic or cubic shape function representions.
A cost‐efficiency analysis of boundary flow calculations from a finite element solution to grounwater flow problems
Authors: Matthews R. S. , Wood W. L. 
Published: August 2005

AbstractThis paper uses examples with exact solutions to demonstrate that boundary flows with 8‐node finite elements are more cost effectively calculated by extrapolation from the Barlow points than by direct sampling at the boundary. The boundary flows are used to calculate the mass balance, and the use of the error in this as a measure of solution accuracy is discussed.
Isoparametric quadrilaterals and hexahedrons for mesh‐grading algorithms
Authors: McDill J. M. , Goldak J. A. , Oddy A. S. , Bibby M. J. 
Published: August 2005

AbstractTwo‐dimensional (2‐D) and three‐dimensional (3‐D) mesh‐grading finite elements for problems with localized phenomena are presented. These quadrilaterals and hexahedrons permit mesh grading without element distortion and, if desired, can be used in a convenient recursive form. They are particularly well suited to adaptive finite element methods. Constraints associated with mesh grading are embedded in the basis functions, making the elements computationally efficient and easy to implement in standard finite element programs. Dramatic computational savings have been achieved. The computational complexity for an implicit analysis of a point load on a 3‐D uniform mesh is O(n7). For the equivalent graded mesh it is O(log2n). The corresponding 2‐D analyses have computational complexities of O(n4) and O(log2n).
Computation of pressure from the finite element vorticity stream‐function approximation of the stokes problem
Authors: Caussignac Ph. 
Published: August 2005

AbstractFor the two‐dimensional steady‐state Stokes problem, the mixed velocity–pressure–vorticity formulation is used to compute the pressure from the known vorticity. By defining appropriate weighting functions in the finite element space for the velocity, the pressure is obtained on each element by solving a local variational problem. Numerical results are presented to compare this method with the usual one, which consists in solving a Poisson equation.
Three‐field mixed approximation and the plate bending problem
Authors: Zienkiewicz O. C. , Lefebvre D. 
Published: August 2005

AbstractThe three‐field mixed approximation is typical of Reissner–Mindlin plates, Hu–Washizu elasticity form, etc. A simple stability requirement is presented which, when used with a ‘conceptual’ patch test, shows why some of the currently used elements fail and how improved element forms can be generated.
Thickness effect on the spectral properties of thick plates
Authors: Hassan Kamal 
Published: August 2005

AbstractIn this paper is shown the effect of plate thickness on the spectral properties of the stiffness matrix which is obtained from finite element representation. The results confirm the very stiff properties associated with the strain energy based on Reissner and Mindlin theories in the case of thin plates. On the other hand, the Bergan and Wang approach converges to exactly the classical thin plate solution as the thickness decreases.
Numerical method for the resolution of nonlinear heat transfer problems
Authors: Jordan A. , Bouayed F. , Borucki A , Benmouna M. 
Published: August 2005

AbstractWe solve a nonlinear heat transfer problem using a general formalism based on the combination of the finite element and the optimal linearization methods. The results are compared with an ‘exact’ numerical iterative solution and the agreement is found to be good.
Contact mechanical algorithms
Authors: Kalker J. J. 
Published: August 2005

AbstractAn algorithm is given and proved for the solution of a strictly convex minimization problem with linear equality and inequality constraints, in a finite number of steps. It is used to solve frictionless and frictional problems in contact elastostatics, and it has the property that each step can be interpreted mechanically. It is believed that an adaptation of the algorithm will also work for large deformations, and in a non‐elastic setting.
Geometric sensitivity analysis with local coordinate transformations
Authors: Brockman R. A. 
Published: August 2005

AbstractThe dimensionality of truss, beam, membrane and shell finite elements is often less than that of the global co‐ordinate system, and element calculations must be performed in local co‐ordinates. Design parameters which affect the nodal co‐ordinates in such elements control both the element dimensions and orientation, and element design sensitivity calculations must account for both effects. The influence of geometric design variables may be separated into two distinct contributions, which must be applied at separate stages of the sensitivity calculation. The paper includes a description of the appropriate algorithms, examples for one‐ and two‐dimensional elements, and a sample Fortran routine.
A refined Hermitian isoparametric plate bending element
Authors: Virtanen S. , Pramila A. 
Published: August 2005

AbstractA refined version of the Hermitian isoparametric element which avoids the difficulties with derivative parameters in the geometric mapping is presented. The accuracy of the element is compared with the DKT‐triangle, which is considered to be the most accurate 9 degrees‐of‐freedom plate bending element. The present element compares rather well with the DKT element. Moreover, comparisons are also made in some ‘non‐standard’ cases (circular plate with concentrated load off the centre and elliptical plate) which suggest that the accuracy of all the elements considered is slightly poorer in these than in the standard cases.
The stokes sieve problem
Authors: Conca Carlos 
Published: August 2005

AbstractThis paper presents a brief survey of some theoretical results concerning the motion of a viscous incompressible fluid in a domain containing a periodically perforated wall (or sieve). By studying a model problem, and using homogenization theory, the paper gives a complete description of the asymptotic behaviour of this kind of fluid flow as the sieve becomes finer and finer.
Some useful data structures for the generation of unstructured grids
Authors: Löhner Rainald 
Published: August 2005

AbstractSeveral data structures for the generation of unstructured grids are described. Their usefulness stems from the fact that they enable the necessary search operations to be performed in an optimal way. In particular, we describe heap lists, quad‐ and octrees, and linked lists. Combining these data structures, the important problem of interpolating information between unstructured grids is also solved.
Adaptive and hierarchical weighted residual and least‐squares time integration of convection‐diffusion problems
Authors: Wiberg Nils‐Erik 
Published: August 2005

AbstractIn order to obtain an adaptive procedure for integration in time for convection‐diffusion problems we make the integration by use of hierarchical approximation of the variation in time. Different hierarchical functions can be used for different types of problem. Both weighted residual and least‐squares formulations are applied. A combination of those two gives a penalty method with a constraint equation corresponding to the least‐squares method. A whole class of different methods is obtained, suitable for an adaptive procedure due to the hierarchical approximation in time. A combination of Galerkin in space and least‐squares in time gives a number of higher order schemes in time. Some special cases of the general procedures can be identified. If a linear discontinuous hierarchical basis function is used in the Petrov‐Galerkin weak formulation, the method obtained corresponds to the discontinuous Petrov‐Galerkin method in time useful for convection‐dominated problems. The streamline‐diffusion method is found as the penalty method mentioned.
Some conjugate gradient methods for symmetric and nonsymmetric systems
Authors: Prakhya K. V. G. 
Published: August 2005

AbstractThe performance of Stiefel's conjugate gradient (CG) method and a reformulated three‐parameter CG are compared for structural analysis problems having varying condition numbers. It has been found that diagonal preconditioning in the three‐parameter CG method is efficient when high condition numbers are encountered.
The convex hull problem for the selection of load cases in reinforced concrete cross‐section analysis
Authors: Recuero A. , Moran F. 
Published: August 2005

AbstractExact methods are presented for the problem of the convex hull in two and three dimensions. Given a set of points in the plane or in a three‐dimensional space, the convex hull problem consists in the determination of the points of the set which are vertices of the minimum convex polygon or polyhedron which contains all the points of the set.Both algorithms have been implemented as subroutines in Microsoft BASIC for PC‐compatible microcomputers. Execution times for these subroutines vary almost linearly with the number of points of the set, for the plane, and with the product of the number of points of the set and the number of vertices of the polyhedron, for the space.These methods can be used for the selection of load cases for the design or testing of reinforced concrete cross‐sections subjected to symmetrical bending and compression (plane) or to biaxial bending and compression (space). The load cases corresponding to internal points can be eliminated as a consequence of the convexity of the interaction diagram or surface.
An integration algorithm and the corresponding consistent tangent operator for fully coupled elastoplastic and damage equations
Authors: Benallal Ahmed , Billardon René , Doghri Issam 
Published: August 2005

AbstractThis paper deals with the implementation in finite element calculations of complex elastoplastic constitutive equations exhibiting non‐linear kinematic and isotropic hardening, and fully coupled to a continuous ductile damage evolution model. The Newton method is used to solve the non‐linear global equilibrium equations as well as the non‐linear local equations obtained by fully implicit integration of the constitutive equations. The consistent local tangent modulus is obtained by exact linearization of the algorithm. The procedure described has been implemented in the general purpose code ABAQUS.
General form of the generalized variational principle in elasticity
Authors: Shikui Liu , Zhongxiang Jiang 
Published: August 2005

AbstractA new method for establishing generalized variational principles, called the undetermined coefficient method, is presented. A more general form of functional for the generalized variational principles in elasticity and a concept of energy functional space are given. Based on the present functional, a general formulation for a hybrid/mixed element is established.
Analysis of unbounded field problems using dampers
Authors: Sharan Shailendra K. 
Published: August 2005

AbstractA highly efficient damper technique, recently developed for the two‐dimensional finite element analysis of hydrodynamic pressures on structures vibrating in an incompressible fluid medium, is generalized and extended to three‐dimensional problems. Some numerical examples are presented to demonstrate the effectiveness and efficiency of the proposed damper. The damper technique has potential applications to a wide variety of other field problems.
A compact database scheme for the partitioned frontal solution algorithm
Authors: Lin Hong‐Tsung 
Published: August 2005

AbstractA compact and effective data structure for memory management is introduced for front partitioning under relatively small memory capacity. The algorithm indexes frontal equations in a special database form and provides the frontal solver with the necessary coefficients for the Gaussian elimination process. If symmetry exists in frontal equations, only the upper/lower‐triangular part is accessed. An adjustable memory buffer is implemented to minimize data input/output operations in the database file. Ease of implementation is demonstrated (about 100 FORTRAN statements) in an existing coding. This development is advantageous for (but not restricted to) micro/minicomputer environments because of the compactness in coding and the efficiency in the access to the mass storage (requires at most the size of coefficients of the largest frontal). Results obtained on microcomputers using this scheme are given, together with comparisons. Other possible applications of the scheme are discussed.
A numerical comparison of conjugate gradient‐like methods
Authors: Langtangen Hans Petter , Tveito Aslak 
Published: August 2005

AbstractThree second‐order, nonselfadjoint partial differential equations in two dimensions are discretized by the finite element method, leading to non‐symmetric systems of linear equations. The systems are solved by several conjugate gradient‐like methods, and compared for their computational cost. All methods are tested with and without preconditioning.
On the numerical instability of the smeared‐crack approach in the non‐linear modelling of concrete structures
Authors: González‐Vidosa F. , Kotsovos M. D. , Pavlović M. N. 
Published: August 2005

AbstractThis paper considers various possible problems that may be encountered in the course of structural‐concrete analyses by means of the brittle material model. Ways of dealing with such problems are suggested, and are illustrated by two examples which, in the past, have proved difficult to predict in a reliable manner.
Computation of electrostatic field distribution in a cable by least‐squares smoothing finite element method
Authors: Lakshmipathi R. , Rao Y. Narayana , Rao G. Sridhara 
Published: August 2005

AbstractThis paper presents a method for computing the electrostatic field distribution at the interface between two dissimilar dielectrics based on the least‐squares smoothing technique along with the potential‐based classical finite element method by suitably incorporating the interface nodal conditions. It is found to give accurate results when compared with the results obtained by classical finite element method, and also it gives the continuous field distribution at the nodes in the case of a homogeneous dielectric problem. By using this method, the electrostatic field distributions in a solid insulated single‐core cable with homogeneous dielectric and in a compressed sulphur hexafluoride (SF6) gas insulated disk‐type spacer cable are determined. Laboratory investigations have also been carried out on a disk‐type spacer cable by varying parameters like the spacer contact angle, the relative permittivity of the spacer material and the conductor diameter.
A computational procedure for automated flutter analysis
Authors: Murthy Durbha V. , Kaza Krishna Rao V. 
Published: August 2005

AbstractA direct solution procedure for computing the flutter Mach number and the flutter frequency is applied to the aeroelastic analysis of propfans using a finite element structural model and an unsteady aerodynamic model based on a three‐dimensional subsonic compressible lifting surface theory. An approximation to the Jacobian matrix that improves the efficiency of the iterative process is presented. The Jacobian matrix is indirectly approximated from approximate derivatives of the flutter matrix, which are updated only in the direction of the last move. Examples are used to illustrate the convergence properties. The direct solution procedure facilitates the automated flutter analysis in addition to contributing to the efficient use of computer time as well as the analyst's time.
Direct cubic spline with application to quadrature
Authors: Anwar M. N. , El‐Tarazi M. N. 
Published: August 2005

AbstractThis paper presents a formulation of a cubic spline that fits the first derivatives of a function at mesh points and the function value and its second derivative at the beginning of the interval. Error bounds for the function and its first three derivatives are derived over the whole interval. This formulation can be applied, in particular, to quadratures.
Behaviour of five solution algorithms on turbulent calculations
Authors: Chao Y. C. , Ho W. C. 
Published: August 2005

AbstractThe relative performances of five pressure‐velocity coupling solution algorithms, SIMPLE, CTS SIMPLE, SIMPLER. SIMPLEC and FIMOSE, are evaluated for three turbulent flow problems. The characteristics of these methods are investigated based on the computational effort required to reach certain levels of residuals in mass, momentum and turbulent kinetic energy. Comparisons of these methods used to solve turbulent flows in the present study and laminar calculations in previous literature are made to reveal the characteristic behaviour of these algorithms in the computation of these two flow regimes. It is found that SIMPLEC is the most efficient and stable method for solving the complex turbulent flows and its performance is not always identical to CTS SIMPLE. SIMPLER needs the fewest iterations.