bluuebunny/crossref_metadata_2025_split huggingface dataset:
Large deflection inelastic pseudo‐transient analysis of laminated composite plates
Authors: Kant T. , Kommineni J. R. 
Published: August 2005

AbstractA pseudo‐transient (static) linear, geometric, material and combined geometric and material non‐linear analyses of composite laminates are presented. A nine‐noded isoparametric quadrilateral finite element belonging to the Lagrangiar family is used in space discretization. An explicit time marching scheme is employed for time integration of the resulting discrete ordinary differential equations with the special forms of diagonal fictitious mass and/or damping matrices. Elasto‐plastic material behaviour is incorporated using the flow theory of plasticity. In particular, a modified version of Hill's initial yield criterion is used in which anisotropy parameters of plasticity are introduced. The shear deformation is accounted for by assuming a constant transverse shear strain across the thickness of the laminate and the geometric non‐linearity is considered in the sense of von Karman strains. The layered element approach is adopted for the treatment of plastic behaviour through the thickness. A wide range of numerical examples is presented to demonstrate the validity and efficiency of the present approach. The results for combined non‐linearity are also presented. The variety of results presented here, which are based on realistic material properties of often‐used advanced laminated composite plates, and especially those for combined non‐linear analysis, should serve as a reference for future investigations.
A variationally coupled FE–BE method for transient problems
Authors: Belytschko T. , Lu Y. Y. 
Published: August 2005

AbstractA variationally coupled finite element–boundary element method is developed for transient problems. A single variational statement is obtained for the entire domain and the unknown tractions, which may be discontinuous on the interface and are often a source of difficulties, are eliminated. Moreover, no interface conditions need be taken into consideration at the level of the discretized equation. The discrete equations for the coupled system can be obtained directly without any intermediate steps. The method generalizes a coupling method previously developed by the authors for statics. Numerical examples show that the solutions obtained by the present method agree very well with those obtained by analytical solutions.
An accelerated subspace iteration method
Authors: Rajendran S. , Narasimhan M. V. 
Published: August 2005

AbstractThe subspace iteration method is widely used for the computation of a few smallest eigenvalues and the corresponding eigenvectors of large eigenproblems. Under certain conditions, this method exhibits slow convergence. For improving the convergence of the method, a few acceleration techniques are already available in the literature. In this paper, yet another method is presented. The method has been applied for the computation of a few smallest eigenpairs of some typical eigenprobiems. The results indicate that the acceleration method is efficient for large eigenproblems. Simplicity, ease of computer implementation, absence of parameters whose values are to be chosen based on experience and effectiveness for large problems are the attractive features of the proposed method.
A new eight‐node quadrilateral shear‐bending plate finite element
Authors: Polit O. , Touratier M. , Lory P. 
Published: August 2005

AbstractA new eight‐node quadrilateral shear‐bending Reissner–Mindlin plate finite element for the very thin and thick plates without locking and spurious zero‐energy modes is presented. The element has very good convergence characteristics both for thin and thick plates, is hardly insensitive to mesh distortions, and passes the patch tests. The formulation of the element is derived from a displacement variational principle and some general criteria to compute inconsistent transverse shear strains. These criteria have been applied with success to four‐ and eight‐node quadrilateral plate finite elements and could be applied to construct triangular elements. The eight‐node quadrilateral shear‐bending plate finite element proposed has been found to be very efficient.
A forward gradient time integration procedure for an internal variable constitutive model of Sn–Pb solder
Authors: Busso E. P. , Kitano M. , Kumazawa T. 
Published: August 2005

AbstractA self‐correcting forward gradient time integration procedure is formulated for the integration of a new unified visco‐plastic constitutive model for an eutectic solder alloy using a tensorial internal state variable. The procedure has been implemented numerically into a commercial FE code through a user‐material subroutine and is well suited to deal with numerically stiff constitutive equations. This is accomplished through an automatic subincrementation procedure controlled by a maximum allowed equivalent inelastic strain increment per time step.For illustration purposes, two examples are discussed: (i) uniaxial test simulations to reveal the optimum combination of the user‐specified tolerance and the prescribed load step size to obtain a desired accuracy at a minimum cost, (ii) a large‐scale three‐dimensional analysis of an integrated circuit (IC) package's solder joint to show the capability of the proposed procedure to deal with thermomechanical loading.
A parallel finite element contact/impact algorithm for non‐linear explicit transient analysis: Part II—Parallel implementation
Authors: Malone James G. , Johnson Nancy L. 
Published: August 2005

AbstractA parallel implementation of the contact algorithm discussed in Part I of this paper has been developed for a non‐linear dynamic explicit finite element program to analyse the response of three‐dimensional shell structures. The parallel contact algorithm takes advantage of the fact that in general only some parts of the structure will actually be in contact at any given time. Special interprocessor communication routines and a method which enables individual processors to dynamically build local contact domains during execution have been developed. The performance of the parallel contact algorithm has been studied by executing the program on 128 processors of a distributed‐memory multiprocessor computer.
On stability and convergence of finite element approximations of Biot's consolidation problem
Authors: Murad Márcio A. , Loula Abimael F. D. 
Published: August 2005

AbstractStability and convergence analysis of finite element approximations of Biot's equations governing quasistatic consolidation of saturated porous media are, discussed. A family of decay functions, parametrized by the number of time steps, is derived for the fully discrete backward Euler–Galerkin formulation, showing that the pore‐pressure oscillations, arising from an unstable approximation of the incompressibility constraint on the initial condition, decay in time. Error estimates holding over the unbounded time domain for both semidiscrete and fully discrete formulations are presented, and a post‐processing technique is employed to improve the pore‐pressure accuracy.
About the numerical simulation of the sheet metal stamping process
Authors: Gontier C. 
Published: August 2005

AbstractThe following is a summary of several years' research work devoted to the development of a sheet metal forming computer program. A few aspects of the membrane formulation are discussed, leading to the conclusion that instability problems cannot be avoided. Then a complete formulation including bending, based on the large‐displacement equations of plates, is developed. An expression for the tangent matrix is obtained. Elastic behaviour, yield equation and the plastic flow rule are reformulated in a suitable basis. A reliable method for stress projection on the yield surface, based on a ‘dichotomic’ algorithm, is presented. Many other features of the simulation problem are discussed: contact and frictional effects, thickness updating and geometry definitions. Finally, three illustrative test cases are presented.
Structural optimization based on preconditioned conjugate gradient analysis methods
Authors: Schmit Lucien A. , Lai Ye‐Chen 
Published: August 2005

AbstractAn efficient method for structural optimization is presented. Instead of classical direct decomposition methods, Preconditioned Conjugate Gradient (PCG) methods, in conjunction with two proposed starting‐vector generation schemes, are used to solve the systems of linear equations associated with the finite element analysis and behaviour sensitivity analysis problems. These inherently iterative analysis procedures are then used to carry out the analyses needed at the beginning of each stage in an approximation concepts approach to structural optimization. This technique has been implemented in a research program and used to solve a collection of minimum weight truss sizing design problems subject to static deflection and stress constraints. The effectiveness of the PCG methods of analysis in structural optimization is demonstrated. Comparison among different preconditioners is made. The effect of the proposed starting‐vector generation schemes is shown. The comparative merits of analytical sensitivity analysis and finite difference sensitivity analysis, when using PCG methods of analysis, are assessed. The parallel computation potential of PCG methods is discussed. Because of the iterative nature of PCG analysis methods and the prospects they offer for parallel computation, it is found that PCG analysis methods show promise in the context of structural optimization.
Boundary element discretization of plane elasticity and plate bending problems
Authors: Aristodemo M. , Turco E. 
Published: August 2005

AbstractThe paper deals with the discretization of the integral equations arising in the boundary formulation of plane elasticity and plate bending problems. Particular attention is paid to the efficiency of the interpolation used in approximating the boundary quantities and to the precision and computational convenience in evaluating the boundary integrals. The proposed discretization model is based on the use of a quadratic B‐spline approximation to represent the boundary variables and on the results from the analytical integration to compute the boundary coefficients. The advantages are those of accuracy and the saving of computer time. Some numerical results allow an analysis of the performance of the model.
Investigation of regularization parameters and error estimating in inverse elasticity problems
Authors: Maniatty Antoinette M. , Zabaras Nicholas J. 
Published: August 2005

AbstractThe method of Tarantola1 based on Bayesian statistical theory for solving general inverse problems is applied to inverse elasticity problems and is compared to the spatial regularization technique presented in Schnur and Zabaras.2 It is shown that when normal Gaussian distributions are assumed and the error in the data is uncorrelated, the Bayesian statistical theory takes a form similar to the deterministic regularization method presented earlier in Schnur and Zabaras,2 As such, the statistical theory can be used to provide a statistical interpretation of regularization and to estimate error in the solution of the inverse problem. Examples are presented to demonstrate the effect of the regularization parameters and the error in the initial data on the solution.
An algorithm for the optimization of directionally stretched triangulations
Authors: Zhang Hou , Trépanier Jean‐Yves 
Published: August 2005

AbstractA procedure for the optimization of stretched triangular grids is described. The method is based on the construction and minimization of a function that represents a generalized version for stretched grids of a non‐linear spring system. The function is minimized using a gradient method based on the steepest descent. Examples are provided to show the applicability of the method to computational fluid dynamics problems.
Error estimators and enrichment procedures for the finite element analysis of thin sheet large deformation processes
Authors: Bonet Javier 
Published: August 2005

AbstractAn essentially geometric error measure capable of estimating the accuracy with which a faceted element mesh describes the continjous exact geometry of a deforming sheet is presented in this paper. This error is based on an estimated strain tensor between discrete and approximate geometries. Additionally, the paper describes the enrichment process which, at a reasonable computational cost, ensures that the error targets are met whilst generating as few elements as possible. In particular, the enrichment algorithm is based on a judicious combination of two simple operations, namely, side splitting and diagonal swapping. Finally, several applications relating to superplastic forming components are presented.
A new least‐squares finite element model for combined Navier–Stokes and Darcy flows in geometrically complicated domains with solid and porous boundaries
Authors: Nassehi V. , Petera J. 
Published: August 2005

AbstractIn this paper we present a novel method for linking Navier–Stokes and Darcy equations along a porous inner boundary in a flow regime which is governed by both types of these equations. The method is based on a least‐squares finite element technique and uses isoparametric C1 continuous Hermite elements for domain discretization. We show that our technique is superior to previously developed models for the combined Navier–Stokes/Darcy flows. The previous works use weighted residual finite element procedures in conjunction with C0 elements which are inherently incapable of linking Navier–Stokes and Darcy equations. The paper includes the application of our model to a geometrically complicated axisymmetric slurry filtration system.
Incompressibility and axisymmetry: A modified mixed and penalty formulation
Authors: Jinka Ashoka G. K. , Lewis Roland W. 
Published: August 2005

AbstractThis paper describes a modified penalty and two‐field mixed formulation for the analysis of incompressible axisymmetric field problems, A discussion of the existing difficulties with incompressibility and axisymmetric formulations is covered in detail. To facilitate the exact satisfaction of incompressibility in axisymmetric bodies during finite element modelling procedures, a modified shape function is used in the description of radial displacement. Further, the modification to the radial displacement interpolation function overcomes the lacunae of the existing mixed and penalty formulations by eliminating the bias of the isoparametric element behaviour in a divergence free continuum state. A six‐noded triangular element, with a central bubble function, is considered to amplify the issues connected with incompressibility in axisymmetric geometries. The bilinear displacements, along with three reduced/selective integration rules in the case of the modified penalty method and three discontinuous pressure nodes in the element for the case of the modified mixed method, are shown to be equivalent in the case of a numerical study of the incompressible cylinder expansion problem. The displacements, stresses and pressure values obtained from the modified methods will be shown to be in close agreement with exact solutions available from the literature. The numerical treatment proposed in the present study clearly demonstrates the performance and the need for modified methods in the analysis of incompressible axisymmetric engineering problems.
Non‐linear analysis of thin‐walled structures using plate elements
Authors: Chin C. K. , Al‐Bermani F. G. A. , Kitipornchai S. 
Published: August 2005

AbstractThis paper presents a simple and efficient rectangular thin plate element for elastic geometric non‐linear analysis of thin‐walled structures. Based on the updated Lagrangian formulation and small strain hypothesis, this element can accurately predict the non‐linear pre‐ and post‐buckling load–deflection paths of a plate structure. Using symbolic manipulation, the linear and geometric stiffness matrices for the rectangular thin plate element are derived explicitly, thereby eliminating the need for numerical integration. The element contains 30 degrees of freedom (d.o.f.): 14 d.o.f. for the in‐plane (membrane) action and 16 d.o.f, for the out‐of‐plane (bending) action. Several examples involving the large deflection behaviour of thin‐walled structures are presented to demonstrate the accuracy, efficiency and versatility of the method.
Plate buckling loads by the boundary element method
Authors: Syngellakis S. , Elzein A. 
Published: August 2005

AbstractA boundary element solution of the plate buckling problem is extended and refined to accommodate any combination of loading and support conditions. It is complemented by a similar boundary element formulation yielding the prebuckling membrane state of stress for non‐uniform distributions of edge loads. Both continuous and discontinuous models of various orders of approximation for boundary as well as domain unknowns have been employed and their effect on the accuracy of the solution algorithm assessed. The computer code incorporates automatic mesh generation schemes for both the boundary and the domain through which a wide range of plate geometries can be discretized and analysed. Further, gains in both efficiency and accuracy are achieved by taking advantage of any support and loading symmetries and reducing the formulation to a standard eigenvalue problem. A large number of plate examples are solved to optimize the choice of various modelling parameters and to establish the reliability of the proposed analysis.
Robust boundary triangulation and delaunay triangulation of arbitrary planar domains
Authors: Subramanian G. , Raveendra V. V. S. , Kamath M. Gopalakrishna 
Published: August 2005

AbstractA simple and robust boundary triangulation algorithm is proposed and, based on it, completely automatic Delaunay mesh generation procedures are developed. The algorithm is equally applicable to convex, non‐convex and multiply connected planar domains. In this approach, given the nodes, the number of triangles formed is precisely known and any desired control over mesh generation is possible.
Time‐space method for multidimensional melting and freezing problems
Authors: Saitoh T. S. , Nakamura M. , Gomi T. 
Published: August 2005

AbstractIn this paper, the time–space method (TSM) for multidimensional melting and solidification problems is proposed. In the proposed TSM, the timewise co‐ordinate is incorporated into one of the spatial co‐ordinates, thereby transforming the usual transient 2‐D (or 3‐D) problems into steady 3D (or 4‐D) boundary‐value problems.Since time integration is not necessary, the TSM has a feature that eliminates the so‐called numerical instability which has been a great concern in the principal numerical methodologies in the past. That is, no error propagation in the timewise direction occurs in the TSM calculation.The TSM is applicable to almost all transient heat transfer and flow problems. The computer running time will be reduced to only 1/100th–1/1000th of the existing schemes for 2‐D or 3‐D problems. The sample calculations are presented for a 2‐D melting problem in a square cavity and the validity of the present method is examined.
Self‐similar solutions for axisymmetric jets using two turbulence models
Authors: Ghazzawi N. A. , Rabadi N. J. 
Published: August 2005

AbstractSimilarity solutions for incompressible axisymmetric jets using a k–ϵ and a constant eddy diffusivity turbulence models are considered. For the k–ϵ model, the governing equations are very complex. Therefore, a transformation that simplifies these equations and makes them amenable to efficient numerical solution is used. Results for the velocity, turbulent kinetic energy and dissipation rate are obtained. Also, velocity decay rate, growth rate, entrainment and kinetic energy decay rate are determined. A comparison with experimental data and other works utilizing a parabolic marching asymptotic solution to the full partial differential equations is made. This comparison shows that similarity solutions are more accurate than solutions using numerical marching procedures.
Efficient three‐dimensional Delaunay triangulation with automatic point creation and imposed boundary constraints
Authors: Weatherill N. P. , Hassan O. 
Published: August 2005

AbstractA method is described which constructs three‐dimensional unstructured tetrahedral meshes using the Delaunay triangulation criterion. Several automatic point creation techniques will be highlighted and an algorithm will be presented which can ensure that, given an initial surface triangulation which bounds a domain, a valid boundary conforming assembly of tetrahedra will be produced. Statistics of measures of grid quality are presented for several grids. The efficiency of the proposed procedure reduces the computer time for the generation of realistic unstructured tetrahedral grids to the order of minutes on workstations of modest computational capabilities.
On the non‐singular traction‐BIE in elasticity
Authors: Huang Q. , Cruse T. A. 
Published: August 2005

AbstractThe work reported herein develops a generalized traction‐BIE formulation which involves only weakly singular integrals (in the three‐dimensional problem) or totally regular integrals (in the two‐dimensional problem). The first step deals with the terms in the Somigliana displacement identity, and then the derivatives of these terms. The only conditions required for the existence of the traction‐BIE and the related Somigliana stress identity are weak continuity of the in‐plane derivatives of the surface displacements and of the surface tractions. It is shown that the Cauchy Principal Value (CPV) interpretations so commonly used in BIE developments are unnecessary. The formulation is established not only at a smooth boundary point, but also at a corner point. The extension of the non‐singular formulation to discontinuous boundary tractions and tangential derivatives of the boundary displacements applicable to a generalized problem statement as well as the usual BEM implementations is also shown. In the demonstrated formulation, the source points are located directly at the boundary nodes and non‐conformal elements are not needed.
Thermal postbuckling analysis of cylindrically curved composite laminates with a hole
Authors: Madenci E. , Barut A. 
Published: August 2005

AbstractA non‐linear finite element analysis including a new flat shell element has been developed to examine the response of laminated panels going through large deflections and rotations under uniform temperature change. The equilibrium path describing the relationship between temperature and deflection is sensitive to the material system, hole size, in‐plane boundary conditions and radius of curvature. Certain laminate configurations exhibit snap‐through and bifurcation along this path. The accuracy of the results for a cylindrically curved panel is established by considering numerous validation problems with known solutions. The method has been demonstrated to be highly effective for predicting the non‐linear response of thin composite shells subjected to uniform temperature change in the presence of large displacements and rotations and material anisotropy.
Reduced minimization theory in beam elements
Authors: Oak‐Key Min , Yong‐Woo Kim 
Published: August 2005

AbstractBy using the field‐consistency and least‐squares fit concepts, reduced minimization theory is proposed to show the effect of numerical integration on the behaviour of C0‐continuous beam elements when the Jacobian is constant within an element. The theory provides a unified viewpoint on the relationship between spurious constraint, the location of optimal sampling points and integration order. The conventional Uniformly Reduced Integration (URI) and Selective Reduced Integration (SRI) are redefined by using reduced minimization theory. We also present numerical reduced minimization theory, which explains the effects of more‐than‐two‐order‐lower reduced integration when Gaussian quadrature is employed.