bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elasto‐plastic finite element analysis
Authors: Kalev I. , Gluck J. 
Published: August 2005

AbstractAn elasto‐plastic finite element small displacement procedure to predict the behaviour of structures under cyclic loads is presented. The solution combines incremental procedure with correction for equilibrium and iterative scheme. Applications are made for a rectangular strip and a notched bar under cyclic axial loads. Flow theory of plasticity with either isotropic hardening or kinematic linear hardening is used.
An isoparametric Hermitian element for the solution of field problems
Authors: Frind Emil O. 
Published: August 2005

AbstractA two‐dimensional isoparametric Hermitian element is investigated for use in potential field problems with irregular geometry. Nodal degrees‐of‐freedom are the potential, the gradients in the directions normal and tangential to the element sides, and the twist. In applying the isoparametric principle a simple approximation is used which in general guarantees C1 continuity only at the element corners. The present version is restricted to 90‐degree interior angles.The element is applied in the Galerkin solution of the steady‐state continuity equation and several examples are presented. It is found that in cases where the potential field is simple but the element is strongly distorted, gradients obtained from the Hermite are not as accurate as those from the Lagrange‐type cubic element having the same number of degrees‐of‐freedom. When the potential field is complex and the distortion is small, the Hermitian gradients are comparable to those of the Lagrange cubic; with increasing distortion they are comparable at the boundaries but less so in the interior. The errors in the potentials themselves are very similar, both elements giving a high degree of accuracy.Since all of its degrees‐of‐freedom are shared by four elements in the interior of a grid, the Hermite element is approximately 20 per cent more efficient than the Lagrange cubic for all but the smallest grids. Also, since the Hermite uses fewer nodes, data handling is greatly reduced. The element appears to be attractive at least in the area of groundwater flow.
Numerical analysis of flow with or without wake past a symmetric two‐dimensional profile without incidence
Authors: Bourgat J. F. , Duvaut G. 
Published: August 2005

AbstractFormulated in the hodograph plane, the bi‐dimensional flow of a perfect fluid past a symmetric body leads to an elliptic variational inequality. By this way we show the existence of a one‐parameter family of solutions. Furthermore the study gives us a simple and effective method for calculating the solutions. The results obtained with some typical profiles are given and compared with previous works.
Optimization methods applied to hydrodynamic bearing design
Authors: Dowson D. , Blount G. N. , Ashton J. N. 
Published: August 2005

AbstractOptimization techniques are applied to the design of both hydrodynamic journal and tilting pad thrust bearings. Fletcher's adaptation of Davidon's gradient search method is further modified to deal with non‐linear constraints in journal bearing design. A form of the Sequential Simplex is used for tilting pad thrust bearings. Penalty functions and variable transformations are used in both cases. Composite objective functions are included and the effect of weighting on each component of the composite function is investigated.
Optimization of non‐unimodal systems
Authors: Wang Bi‐Chong , Luus Rein 
Published: August 2005

AbstractTwo direct search algorithms for the optimization of non‐unimodal systems are presented. One method is interior in nature by using boundary relaxation with pseudo one‐dimensional search in the feasible region; the other one is an exterior method which allows the violation of constraints followed by the use of a penalty function to drive the search back into the feasible region. These two methods are usually capable of leaving local optima to reach a better solution if such exists. The application of the proposed approaches to several non‐unimodal systems shows that they are better than the existing methods. The proposed methods are also attractive because of the ease of programming and the high probability of reaching the global optimum.
A hybrid stiffness matrix for orthotropic sandwich plates with thick faces
Authors: Kraus Hans Dieter 
Published: August 2005

AbstractA stiffness matrix is derived for a rectangular orthotropic sandwich plate element with thick faces by the assumed stress hybrid approach.It will be demonstrated that an independent polynomial can be used for the internal forces of the sandwich plate by the membrane theory (assumption of thin faces) and also for the additional moments and shear forces of the faces.The boundary displacements are approached solutions of the homogeneous differential equation of a sandwich beam.
An unconditionally stable explicit algorithm for structural dynamics
Authors: Trujillo D. M. 
Published: August 2005

AbstractThis paper presents an unconditionally stable explicit algorithm for the direct integration of the structural dynamic equations of motion. The algorithm is restricted to a diagonal mass matrix and positive definite symmetric stiffness and damping matrices. The algorithm is based on splitting the stiffness and damping matrices into strictly lower and upper trangular form. Unconditional stability is proven, but only for the undamped case and a completely symmetric splitting of the stiffness matrix. An alternate splitting method is also presented and numerical examples indicate superior performance over the symmetric splitting, but only a conditional stability. A spring‐mass‐dashpot model is used to illustrate the algorithm.
Newtonian die swell evaluation for axisymmetric tube exits using a finite element method
Authors: Allan W. 
Published: August 2005

AbstractUsing a finite element method, a value of 13.2 per cent is obtained for the die swell of a highly‐viscous Newtonian fluid flowing at very low Reynolds number from a circular tube of constant radius. The same method is then used to obtain die swell values for a variety of axisymmetric tube exits. It is found that, in general, conical constrictions at or near the tube exit result in a decrease in die swell, while conical expansions increase the die swell.
A finite element Laplace transform solution technique for the wave equation
Authors: Aral Mustafa M. , Gülçat Ülgen 
Published: August 2005

AbstractA technique is described for the solution of the wave equation with time dependent boundary conditions. The finite element solution accompanied by the numerical Laplace inversion process seems to be an efficient procedure to treat such problems. The programming involved is straightforward in the sense that numerical Laplace inversion routines can be directly used as a time integration procedure after obtaining standard finite element differential equation solutions in the transformed domain.Some results are presented for one‐ and two‐ dimensional applications, such as wave propagation in longitudinal bars and wave propagation in harbours.
An investigation of the stability of numerical solutions of the equations of viscoelasticity
Authors: Booker J. R. , Small J. C. 
Published: August 2005

AbstractIn this paper the correspondence principle is used to reduce the equations of viscoelasticity to the equations of elasticity by means of a Laplace transform.The finite element technique is used to approximate these equations in Laplace transform space. The approximating equations are then inverted to obtain a set of simultaneous Volterra integral equations. It is then shown how the introduction of certain auxiliary variables can be used to develop an integration scheme which considerably reduces computer storage requirements.The conditions under which this integration scheme is conditionally stable and unconditionally stable are both investigated and illustrated by means of examples.
A finite element formulation for creep analysis
Authors: Kim Hong Ou , Kuhlemeyer Roger L. 
Published: August 2005

AbstractAs an alternative to the initial strain method, a variable stiffness method is presented for creep analysis. The method is developed by incorporating the change in stress state during a time interval in determining the creep strain increments concurrent with the change. It is shown by means of examples that this method provides solution stability for relatively large time intervals for which the initial strain method may fail to function properly.
Continuous elements in the finite element method
Authors: Rukos Eduardo A. 
Published: August 2005

AbstractThe discretization of the media at all spatial co‐ordinates but one is presented here. This partial discretization leads to continuous finite elements as opposed to fully discrete ones and the problem resolves, for the cases presented here, into a set of linear differential equations rather than algebraic equations. The general problem of first derivative functionals in elastostatics is considered and it is shown, in general, how the continuous finite elements required for the solution may be obtained. Plane states, axisymmetric and three‐dimensional continuous elements are obtained to illustrate application to particular cases.Different methods of solution for the set of differential equations are discussed and it is shown that several existing and widely used finite element related techniques are particular cases of this local partial discretization. Three numerical examples are solved to demonstrate the good comparison obtained between the numerical and the exact solutions. The semi‐infinite examples included also illustrate the treatment of these types of problems without the use of fictitious boundaries.
Discussion of a paper by E. O. Frind
Authors: Brockman R. A. 
Published: August 2005

AbstractIn a recent paper, Dr. Frind has formulated a two‐dimensional isoparametric finite element based upon the Hermite bicubic interpolation scheme. The present discussion focuses upon certain simplifications in the derivation which appear to have diminished the accuracy of the resulting element, and suggests a simpler approach to the element formulation. This author agrees strongly with Dr. Frind's recommendation of the Hermite parametric element as an efficient and useful tool for general field problems; the present comments are offered to point out that, in fact, the accuracy comparisons presented by Dr. Frind are biased against the Hermite finite element.
A hybrid element method for diffraction of water waves by three‐dimensional bodies
Authors: Yue Dick K. P. , Chen Hsuan S. , Mei Chiang C. 
Published: August 2005

AbstractA hybrid element method developed recently for two‐dimensional problems of water waves in an infinite fluid is extended to three dimensions. In this method only a limited fluid domain close to irregular bodies is discretized into conventional finite elements, while the remaining infinite domain is treated as one element with analytical representations of high accuracy. Continuity at the junction surface is treated as natural boundary conditions in a variational principle. Computation experience and numerical results for several ocean structures are presented.
Cold rolling of a laminated composite sheet—A numerical solution
Authors: Batra R. C. 
Published: August 2005

AbstractThe problem of cold rolling of a composite sheet which consists of alternate layers of viscoelastic and elastic materials is studied by the finite element method. Results computed and presented graphically include the pressure distribution at the contact surface, the normal stress distribution at the middle surface and the asymmetric deformation of the surface of the sheet in contact with the roller.
The generalized problem of confined seepage
Authors: Cecchi M. M. , Mancino O. G. 
Published: August 2005

AbstractThe problem of confined seepage of water under a hydraulic structure, through a porous medium, is considered in an appropriate abstract space. Existence and uniqueness of the solution are proved. The numerical solution is derived by means of the finite element method. An error estimate is given. A sample problems in included.
A numerical method to obtain optimal quadrature formulas
Authors: Wang A. H. , Klein R. L. 
Published: August 2005

AbstractThis paper present a numerical method to obtain optimal quadrature formulas of Gauss type and Radau type in the sense of Sard. Using the relation between optimal quadrature formulas and nonospline functions, the optimal quadrature formula can be obtained by solving a set of no‐linear simultaneous algebraic equations induced from the interpolatory conditions of the monospline. In attempting to solve this set of non‐linear algebraic equations for numbers of knots and degrees of interpolution required in estimation problem applications insurmountable numerical errors were encountered. This paper solves the numerical problem by first reducing the number of unknowns and equations to approximately one half the original number. This is accomplished by showing and then using a symmetry property of the monospline. Second an iteration scheme which partitions the reduced order set of non‐linear algebraic equations into a linear subsystem and a non‐linear subsystem is developed to numerically solve the equations. This iteration algorithm provides the advantages of reducing the computational complexity, dynamically checking the convergence and explicitly evluating the resulting accuracy.
Application of dynamic programming to the general inverse problem
Authors: Trujillo D. M. 
Published: August 2005

AbstractThe general inverse problem is one for which measurements are made on some of the state variables and it is desired to find the forcing functions. This problem is a natural one for the method of dynamic programming. The formulation and solution of the problem are presented in matrix form, together with two illustrative examples of an inverse heat conduction problem and an inverse structural dynamics problem.
A non‐circular arc roll force model for gold rolling
Authors: Grimble M. J. , Fuller M. A. , Bryant G. F. 
Published: August 2005

AbstractA long established approximation, normally invoked in the development of classical rolling theory, is that the work roll‐strip interface assumes a circular profile. Although valid for a wide range of practical rolling conditions, the approximation is definitely suspect for instance in the last and penultimate stand of a thin sheet tandem mill, and algorithms based on classical theory may fail to converge. This paper computing solutions. In deriving the algorithm it is convenient to employ the formalism of functional One notable feature is that the gradients have to be carefully defined with respect to the correct ‘space’, in order that physically inadmissible discontinuties are not introduced during the hill‐climbing. Computed roll gap solutions sometimes display elastic deformation regions embedded within the normal plastic deformation zone. It is thought that this is the first time this possibility has been allowed for in the formulation, or solutions obtained exhibiting this feature.
A split Band‐Cholesky equation solving strategy for finite element analysis of transisent field problems
Authors: Cooke Charlie H. 
Published: August 2005

AbstractAn efficient strategy is outlined for out‐of‐core solution of the large systems of equations which specify nodal point time derivatives in finite element models of transient flow problems. The positive definiteness, symmetry, and band structure of the finite element mass matrices, as well as the nature of the equation assemblage process, is exploited by the method. Computational results are indicated for systems on the order of several thousand unknowns in size.
A finite difference‐Galerkin finite element solution of compressible laminar boundary‐layer flows
Authors: Bismarck‐Nasr Maher N. 
Published: August 2005

AbstractA finite difference‐Galerkinfinite element method is presented for the solution of the two‐dimensional compressible laminar boundary‐layer flow problem. The streamwise derivatives in the momentum and energy equations are approximated by finite differences. An iterative scheme, due to the non‐linearity of the problem, in conjunction with the Galerkin finite element method is then proposed for the solution of the problem through the boundary‐layer thickness. Numerical results are presented and these are compared with other numerical and analytical solutions in order to show the applicability and the effectiveness of the proposed formulation. In all the cases here examined, the results obtained attained the same accuracy of other numerical methods for a much smaller number of points in the boundary‐layer.
On a numerical solution of the plastic buckling problem of structures
Authors: Gupta K. K. 
Published: August 2005

AbstractAn automated digital computer procedure is presented for the accurate and efficient solution of the plastic buckling problem of structures. This is achieved by a Sturm sequence method employing a bisection strategy, which eliminates the need for having to solve the buckling eigenvalue problem at each incremental (decremental) loading stage that is associated with the usual solution techniques. The plastic bucking mode shape is determined by a simple inverse iteration process, once the buckling load has been established.Numerical results are presented for plate problems with various edge conditions. The resulting computer program written in FORTRAN for the JPL UNIVAC 1108 machine proves to be most economical in comparison with other existing methods of such analysis.
Hierarchal finite elements and precomputed arrays
Authors: Rossow M. P. , Katz I. N. 
Published: August 2005

AbstractTwo‐dimensional C° finite elements of arbitrary polynomial order are developed for a general functional which includes a least squares or potential energy functional as special cases. The elements are ‘hierarchal’ in the sense that the nodal variables for polynomial order p constitute a subset of the nodal variables for order p+1. It is shown that the elemental arrays for high polynomial order may be efficiently computed by using hierarchal elements together with precomputed arrays—i.e., arrays which are computed once, stored on permanent file, and then re‐used in all subsequent applications of the program. A number of example problems are solved. Comparisons are made of the relative efficiency of finite element convergergence with mesh refinement (polynomial order held fixed) and with increasing polynomial order (mesh held fixed). The latter approach is found superior.
The finite element solution of rapid cycling creep problems
Authors: Ponter A. R. S. , Brown P. R. 
Published: August 2005

AbstractThe paper describes a simplified finite element method for high temperature creep problems involving cyclic load and temperature. The principal assumptions, that the cycle time is small compared with characteristic material time scales, is appropriate for the moderate load levels which occur when structures are designed for life times measured in years and decades. Because of the simplicity of the method, thermal loading problems may be studied in some detail. A parametric study of a plane stress problem is presented. Characteristic deformation rates are related to reference stress and timperature quantities, thereby reducing the main features of the solution to a few important structural and material parameters.
Numerical solutions for a class of multi‐part mixed boundary value problems
Authors: Aksogan O. 
Published: August 2005

AbstractThis paper proposes a procedure for the extension of a widely used numerical method1−4 for the solution of systems of singular integral equations, from mixed boundary value problems with two or three parts to those having many parts. The procedure is applied to three previously solved mixed boundary value problems and the result are presented in graphical form. The effectiveness of the given procedure is observed through the results for some limiting and special cases found in the literature.
A study of quadrilateral plate bending elements with ‘reduced’ integration
Authors: Pugh E. D. L. , Hinton E. , Zienkiewicz O. C. 
Published: August 2005

AbstractThe accuracy of certain thick plate elements when used in the context of thin plate problems can be improved by the use of reduced integration of the stiffness matrices. A series of numerical experiments on five different quadrilateral thick plate elements demonstrates the use of reduced integration and indicates the main reason for its success. This is the relaxation of a constraint on the shear strains. It is shown that the performance of a nine‐noded Lagrangian element is near optimal.
Efficient implementation of anisotropic three dimensional boundary‐integral equation stress analysis
Authors: Wilson R. B. , Cruse T. A. 
Published: August 2005

AbstractThe boundary‐integral equation medthod is particularly well suited for solution of stress concentration and elastic fracture mechanics problems. The method was not previously applicable to anisotropic three dimensional problems because no efficient technique existed for calculation of the required point load solution for an infinite body. A technique has been developed to evaluate numerically the anisotropic point load soultions, and used to generate data bases for various materials. An intrpolation technique is used to evaluate the point load solutions efficiently within a higher order boundary‐intgral equation code. The effectiveness of the technique is verified by solution of problems involving both uniaxial stress states and stress concentrations.
Stability analysis of some finite difference schemes for the Navier‐Stokes equations
Authors: Rigal Alain , Aleix Georges 
Published: August 2005

AbstractWe study the stability of two standard finite differnce schemes for the unsteady Navier‐Stokes equations. We write a scheme for small values of Reynolds number, where teh diffusion is predominant, and another one for large values of Reynolds number, where convection is predominant. The purpose of this results may be extended to unsteady problems leading to mixed hyperbolic‐parabolic partia differenctial equations.
A numerical comparison of axisymmetric finite elements
Authors: Durocher Lawrence L. , Gasper Andrew , Rhoades Gene 
Published: August 2005

AbstractThe advantages and disadvantages of a variety of axisymmetric elements are examined by comparing various elements from accuracy, computer time, and stress interpretation viewpoints. In addition, various techniques of stress averaging and/or smoothing are discussed from an acuracy and a computational effort standpoint. Numerical results are presented for three problems having classical solutions.
A‐posteriori error estimates for the finite element method
Authors: Babuška I. , Rheinboldt W. C. 
Published: August 2005

AbstractComputable a‐posteriori error estimates for finite element solutions are derived in an asymptotic form for h → 0 where h measures the size of the elements. The approach has similarity to the residual method but differs from it in the use of norms of negative Sobolev spaces corresponding to the given bilinear (energy) form. For clarity the presentation is restricted to one‐dimensional model problems. More specifically, the source, eigenvalue, and parabolic problems are considered involving a linear, self‐adjoint operator of the second order. Generalizations to more general one‐dimensional problems are straightforward, and the results also extend to higher space dimensions; but this involves some additional considerations. The estimates can be used for a practical a‐posteriori assessment of the accuracy of a computed finite element solution, and they provide a basis for the design of adaptive finite element solvers.