bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic analysis of concrete pavements resting on a two‐parameter medium
Authors: Zaman Musharraf , Alvappillai Arumugam , Taheri Michael R. 
Published: August 2005

AbstractAn analysis procedure based on the finite element method is presented to solve moving‐load problems of rigid pavements. The algorithm presented considers the dynamic pavement‐aircraft interaction effects. The pavement‐foundation system is modelled by thin‐plate, non‐conforming finite elements resting on a two‐parameter elastic medium. The moving aircraft loads are represented by masses supported by a spring‐dashpot system moving at a specified initial horizontal velocity and acceleration. The accuracy of the finite element program developed is verified by comparing the numerical results of a static problem with the available solution. A parametric study is conducted to determine the effects of the various parameters on the dynamic response of pavements. Emphasis is placed on identifying the influence of fictitious edge and corner forces acting on the plate due to the deformation of the soil medium outside the plate.
Transient analysis of geometrically linear and non‐linear structures by a combined finite‐element‐Riccati‐transfer substructure method
Authors: Zhu Jinghua , Xue Huiyu 
Published: August 2005

AbstractThe combined finite‐element‐Riccati‐transfer substructure method is applied to the transient analysis of the structures under various excitations with small and large displacements, respectively. The advantages include reductions in the order of standard transfer equation systems, in the computational efforts, and in the propagation of round‐off errors produced in recursive multiplications of the transfer matrices. Meanwhile, a methodology for analysing transfer substructures is, in combination with exact dynamic condensation and generalized Riccati transformation, proposed to develop the finite element and transfer matrix (FETM) techniques. The Newmark method and Wilson‐θ method are used for time integrations with respect to linear and non‐linear problems. The modified Newton‐Raphson method is employed for equilibrium iteration in each time step.Numerical examples are presented to demonstrate the high efficiency and accuracy of the proposed method for the transient responses of plates. The results from these examples agree well with those obtained by other methods.
Hybrid hexahedral element for solids, plates, shells and beams by selective scaling
Authors: Sze K. Y. , Ghali A. 
Published: August 2005

AbstractA robust two‐field hexahedral element capable of handling plate/shell, beam and nearly incompressible material analyses without locking are presented. Starting with the assumed stress element of Pian and Tong,7 parasitic strain components leading to locking in plate, shell and beam analyses are first identified. Locking can be alleviated by scaling down selectively the parasitic strain components in the leverage matrix. Unfortunately, the element then fails the patch test. However, patch test correction and reduction in computation can be achieved by the recently proposed admissible matrix formulation. The resulting element is lock‐free and very efficient. All matrices involved in constructing the stiffness matrix can be derived explicitly. The accuracy of the element is tested by popular bench‐mark problems.
A survey of quasi‐Newton methods with reduced storage
Authors: Papadrakakis M. , Pantazopoulos G. 
Published: August 2005

AbstractA family of non‐linear solution methods is investigated based on limited‐memory quasi‐Newton updates. Depending upon the number of updates and the updating formula, a number of solution schemes may be constructed such as the conjugate‐ and secant‐Newton methods, the conventional and modified Newton‐Raphson methods and a variety of quasi‐Newton updates. Under the proposed implementation, the preconditioned truncated Lanczos method is used for the solution of the linearized problem in each non‐linear iteration. The complete factorization of the stiffness matrix is avoided and large‐scale problems can be solved efficiently both in terms of computing time and storage. The non‐linear iterative scheme is properly modified to account for loading variation inside the increment in order to be able to trace post‐critical equilibrium paths.
Analysis of the anisotropic viscoplastic‐damage response of composite laminates—continuum basis and computational algorithms
Authors: Saleeb A. F. , Wilt T. E. 
Published: August 2005

AbstractThe mathematical structure underlying the rate equations of a recently‐developed constitutive model for the coupled viscoplastic‐damage response of anisotropic composites is critically examined. In this regard, a number of tensor projection operators have been identified, and their properties were exploited to enable the development of a general computational framework for their numerical implementation using the Euler fully‐implicit integration method. In particular, this facilitated (i) the derivation of explicit expressions of the (consistent) material tangent stiffnesses that are valid for both three‐dimensional as well as subspace (e.g. plane stress) formulations, (ii) the implications of the symmetry or unsymmetry properties of these tangent operators from a thermodynamic standpoint, and (iii) the development of an effective time‐step control strategy to ensure accuracy and convergence of the solution. In addition, the special limiting case of inviscid elastoplasticity is treated. The results of several numerical simulations are given to demonstrate the effectiveness of the schemes developed.
A new family of continuous/discontinuous three‐dimensional boundary elements with application to acoustic wave propagation
Authors: Silva J. J. Rêgo , Wrobel L. C. , Telles J. C. F. 
Published: August 2005

AbstractThis paper presents a new family of continuous/discontinuous three‐dimensional boundary elements which has been implemented in a computer system for acoustic wave propagation in the frequency domain. The system includes elements of different geometrical shapes, 'order of interpolation and degree of continuity. Results of several tests are included to show the efficiency of the family of elements.
Superelement method for transient dynamic analysis of structural systems
Authors: Belyi M. V. 
Published: August 2005

AbstractA superelement algorithm for the transient dynamic analysis of structural systems is presented. The method represents a generalization of existing static and dynamic superelement (substructure) algorithms. Natural frequencies and modal shapes of a fixed boundary substructure are used to obtain equations of motion of a superelement. An implicit time‐stepping algorithm is presented for the numerical solution of a resulting superelement system of equations of motion. Numerical examples are given to illustrate the presented approach. The method is believed to be effective for large‐scale problems of structural analysis.
Neural networks for computing in structural analysis: Methods and prospects of applications
Authors: Kortesis S. , Panagiotopoulos P. D. 
Published: August 2005

AbstractA neural network model is proposed and studied for the treatment of structural analysis problems. Both the cases of bilateral and unilateral constraints are considered and Hopfield‐like neural models are proposed. Moreover, new results, generalizing the results of Hopfield and Tank,10 are obtained.Numerical applications illustrate the theory and show clearly the advantages of the neural network approach. Finally, the parameter identification problem is formulated and solved as a ‘learning’ problem for a neural network.
Curvilinear fatigue crack reliability analysis by stochastic boundary element method
Authors: Lua Yuan Jie , Liu Wing Kam , Belytschko Ted 
Published: August 2005

AbstractIn this paper, the stochastic boundary element method, which combines the mixed boundary integral equations method explored in Reference 1 with the first‐order reliability method, is developed to study probabilistic fatigue crack growth. Due to the high degree of complexity and non‐linearity of the response, direct differentiation coupied with the response‐surface method is employed to determine the response gradient. Three random processes, the mode I and mode II. stress intensity factors and the crack direction angle, are included in the expression of the response gradient. The sensitivity of these random processes is determined using a first‐order response model. An iteration scheme based on the HL‐RF method2 is applied to locate the most probable failure point on the limit‐state surface. The accuracy and efficiency of the stochastic boundary element method are evaluated by comparing the cumulative distribution function of the fatigue life obtained with Monte Carlo simulation. The reliability index and the corresponding probability of failure are calculated for a fatigue crack growth problem with randomness in the crack geometry, defect geometry, fatigue parameters and external loads. The response sensitivity of each primary random variable at the design point is determined to show its role in the fatigue failure. The variation of each primary random variable at the design point with the change of probability of failure is also presented in numerical examples.
Fragmentation algorithm for finite element failure simulation and analysis
Authors: Rice Darren L. , Ting Edward C. 
Published: August 2005

AbstractAn algorithm which combines the techniques of numerical analysis and numerical simulation in the study of transient dynamic structural response is proposed. This is achieved by incorporating the ability to create new surfaces and separate fragments according to a defined failure criterion into a finite element procedure which uses explicit time integration. Thus, the algorithm not only provides accurate prediction of the structural failure and fragmentation pattern, but also evaluates accurate stress, velocity, acceleration and displacement values of each fragmented component.To develop a viable fragmental algorithm, other than the expected modification in storage and node bookkeeping, we found it necessary to introduce an efficient algorithm to handle extremely large displacements resulting from the fracture. In that regard, an updated corotational approach is introduced.
An analysis of some higher‐order triangular elements and their susceptibility to hourglassing in Lagrangian fluid simulations
Authors: Priestley A. 
Published: August 2005

AbstractIn Lagrangian codes two of the main problems are hourglassing with bilinear quadrilateral elements and mesh locking with linear triangular elements. Higher‐order triangular elements, with their greater number of degrees of freedom, should not suffer from mesh locking, Hourglassing, though, is caused by the interaction of the element and the quadrature used to evaluate the integrals of the derivatives on it. Higher‐order triangular elements, as we shall see, unlike their linear counterparts, also suffer from this spurious mode. A higher‐order element/quadrature combination is found that does not suffer from hourglassing. The main fault of this combination is the extra cost involved over the more usual linear or bilinear element with centroid quadrature combination. A short discussion is given regarding this point.
Geometrically non‐linear method of incompatible modes in application to finite elasticity with independent rotations
Authors: Ibrahimbegović Adnan , Frey Francois 
Published: August 2005

AbstractWe discuss a geometrically non‐linear method of incompatible modes. The model problem chosen for the discussion is the finite elasticity with independent rotations. The conditions which ensure the convergence of the method and the methodology to construct incompatible modes are presented. A detailed derivation of variational equations and their linearized form is given for a two‐dimensional plane problem. A couple of geometrically non‐linear two‐dimensional elements with independent rotational freedoms are proposed based on the presented methodology. The elements exhibit a very satisfying performance over a set of problems in finite elasticity.
Configuration design sensitivity analysis of built‐up structures part II: Numerical method
Authors: Twu Sung‐Ling , Choi Kyung K. 
Published: August 2005

AbstractA numerical method is presented for structural configuration design sensitivity calculations using established finite element analysis codes. The theoretical foundation of the configuration design sensitivity analysis is given in Part I of this paper1 using the continuum elasticity formulation. A linear approximation between design parameterizations and design velocity fields is derived for line and surface design components. A regular design velocity that avoids the calculation of corner terms at the boundary is implemented to show a unified configuration design sensitivity analysis. The design sensitivity analysis method is demonstrated using the post‐processing data of an existing finite element code. Configuration design sensitivity results of displacement, stress and eigenvalue performance measures are illustrated for several built‐up engineering structures.
Boundary integral equations for thin bodies
Authors: Krishnasamy Guna , Rizzo Frank J. , Liu Yijun 
Published: August 2005

AbstractA boundary integral equation formulation for thin bodies which uses CBIE (conventional BIE) only is well known to be degenerate. A mixed formulation for a thin rigid scatterer which combines CBIE and HBIE (hypersingular BIE) is motivated by examining the discretized form of the integral equations, and this formulation is shown to be non‐degenerate for thin non‐rigid inclusion problems. A near‐singular integration procedure, useful for singular integrals as well, is presented. Finally, numerical examples for acoustic wave scattering from rigid and soft scatterers are presented.
Higher‐order finite element modelling of laminated composite plates
Authors: Ahmed Nesar U. , Basu Prodyot K. 
Published: August 2005

AbstractP‐version finite elements based on higher‐order theory are developed for the two‐dimensional modelling of general bending and cylindrical bending of thin‐to‐thick laminated composite plates. In the case of general laminated plate elements, three displacement fields are used. In the special case of cylindrically bent laminated plate elements, two displacement fields are needed. In each case the displacement is expressed as the product of two functions—one in terms of out‐of‐plane co‐ordinates alone and the other in terms of in‐plane co‐ordinates. The shape functions used to build the displacement fields are based on integral of Legendre' polynomials. The quality and performance of the elements are evaluated in terms of convergence characteristics of displacements and stresses. The predicted response quantities are compared with those available in the published literature based on analytical as well as conventional finite element models.
Design of optimal process parameters for non‐isothermal forging
Authors: Cheng Huaining , Grandhi Ramana V. , Malas James C. 
Published: August 2005

AbstractThis paper presents a state space model and an optimal design scheme for non‐isothermal metal forming processes. By selecting nodal velocity and temperature as the state variables, a non‐isothermal state equation with coupled deformation and thermal terms is established. Based on this state space model, a control design scheme is developed to obtain the optimal die velocity and initial die temperature which will ensure that the effective strain‐rate and temperature satisfy the design requirements. A titanium alloy engine disk forging is used to demonstrate two design examples. The results show that the proposed model and design scheme behave well for different design requirements.
An accurate shear‐deformable six‐node triangular plate element for laminated composite structures
Authors: Kosmatka J. B. 
Published: August 2005

AbstractA six‐node triangle plate/shell element is developed for the analysis of laminated composite structures. This model is formulated using Hamilton's principle along with a first‐order (Reissner/Mindlin) shear deformation theory. The element is based upon an isoparametric representation along with an interdependent interpolation strategy; bicubic polynomials for the transverse displacement and biquadratic polynomials for the element geometry, in‐plane displacements and rotations. The resulting element, which is evaluated using exact numerical integration, has correct rank and is free of shear ‘locking’. Numerical results are presented that validate the new element and prove its outstanding convergence capabilities in comparison to existing triangular elements using standardized test problems (elastic eigenvalue analysis, patch test, static simply supported square‐plate solutions) and experimentally measured vibration data of cantilevered isotropic and composite plates.
A unified theory for formulation of hybrid stress membrane elements
Authors: Yuan Kuan‐Ya , Wen Jyh‐Chung , Pian Theodore H. H. 
Published: August 2005

AbstractA theory is proposed in this paper to explain, in a unified manner, the three rational approaches using the incompatible displacements uλ in the hybrid element formulation. Limited to the plane stress case, the theory suggests that the introduction of uλ is to constrain the total value of the invariant I2(= σxσy – τ) of the assumed stresses over the element to zero. In the plane stress case, this is the well‐known condition for the stress distributions to be independent of the elastic constants of the material. The theory proposed is also used to explain the closeness of the performances of the four 4‐node hybrid stress membrane elements, 5β‐I, 5β‐II, 5β‐A and 5β‐C, that have been developed previously. The differences among them are shown to be of the second degree in the distortion measures of the element shape, when they are compared on the basis of the non‐vanishing total value of I2 of their respectively adopted assumed stress field. Several numerical examples are used to verify and to illustrate the proposed theory.
An upwind kinetic flux vector splitting method on general mesh topologies
Authors: Weatherill N. P. , Mathur J. S. , Marchant M. J. 
Published: August 2005

AbstractAn upwind flux vector splitting algorithm which utilizes the moments of the Boltzmann equation to derive the Euler equations for inviscid compressible flow has been used with a variety of grid types. Although the upwind approach offers the potential for accurate flow simulations, it is necessary to ensure that such procedures can be utilized on realistic grids. In this paper, an upwind algorithm is used with structured multiblock grids, unstructured grids of triangles and hybrid structured/unstructured grids to solve realistic compressible flow problems in two dimensions.
On stress interpolation for hybrid models
Authors: Bouzeghoub M. C. , Gunn M. J. 
Published: August 2005

AbstractA technique is proposed for the selection of stress interpolations for hybrid models. The present paper applies this approach to plane problems. The stiffness matrix is derived using the Hellinger–Reissner variational principle. This formulation uses infinitesimal equilibrium relationships and divides the assumed stress into its lower‐order and higher‐order parts. The patch test can be passed and the resulting elements are generally invariant. A plane four‐node quadrilateral element is described and compared with existing elements. Numerical studies show that the accuracy of the element is generally good.
Locking‐free curved beam element based on curvature
Authors: Lee Pal‐Gap , Sin Hyo‐Chol 
Published: August 2005

AbstractThe formulation of a curved beam element with 3 nodes for curvature to eliminate the shear/membrane locking phenomenon is presented. The element is based on curvature so that it may represent the bending energy fully, and the shear/membrane strain energy is incorporated into the formulation by the equilibrium equations. To deal with general boundary conditions, a transformation matrix between nodal curvature and nodal displacement vector is introduced. Several examples are presented in order to verify the element formulation and its analytical capability. The solutions obtained reveal that the element describes the curved beam behaviour quite correctly and efficiently, showing no locking phenomena, and that it is also applicable to the analysis of both thin and thick curved beams.
Linked interpolation for Reissner‐Mindlin plate elements: Part III—An alternative quadrilateral
Authors: Xu Z. , Zienkiewicz O. C. , Zeng L. F. 
Published: August 2005

AbstractAn alternative quadrilateral element for Reissner—Mindlin plates, which extends the mixed formulation described in Part 1 using linked interpolations, is presented. Differently from element Q4BL presented in Part I, this element (Q4BLa) employs four internal rotation nodes and a linear approximation for transverse shear forces. It is shown that the element passes various patch tests, it does not possess any zero‐energy mode and its performance is good for both thick and thin plates.
Pre‐ and postbuckling response of curved, thin, composite panels with cutouts under compression
Authors: Madenci E. , Barut A. 
Published: August 2005

AbstractAnalytical predictions of the postbuckling response of curved composite panels are difficult, especially under in‐plane compression, because of the presence of snap‐back with a steep negative slope beyond the bifurcation point. In this study, the pre‐ and postbuckling response of curved laminated panels with cutouts is investigated by developing a new finite element based on the free formulation. This trianguiar, flat, shell element, in conjunction with the updated Lagrangian form of the co‐rotational approach, accounts for the coupling terms arising from general material anisotropy, as well as large displacements and rotations. The analysis predictions correlate well with the corresponding experimental data available in the literature. Review of the studies in this subject area reveal that none of the available methods, including the STAGS‐C1 finite element program, is capable of providing the full description of the postbuckling phenomenon beyond bifurcation for curved composite panels with small cutouts.
Node and element resequencing using the Laplacian of a finite element graph: Part I—General concepts and algorithm
Authors: Paulino Glaucio H. , Menezes Ivan F. M. , Gattass Marcelo , Mukherjee Subrata 
Published: August 2005

AbstractA Finite Element Graph (FEG) is defined here as a nodal graph (G), a dual graph (G*), or a communication graph (G˙) associated with a generic finite element mesh. The Laplacian matrix (L(G),L(G*) or L(G˙)), used for the study of spectral properties of an FEG, is constructed from usual vertex and edge connectivities of a graph. An automatic algorithm, based on spectral properties of an FEG (G, G* or G˙), is proposed to reorder the nodes and/or elements of the associated finite element mesh. The new algorithm is called Spectral PEG Resequencing (SFR). This algorithm uses global information in the graph, it does not depend on a pseudoperipheral vertex in the resequencing process, and it does not use any kind of level structure of the graph. Moreover, the SFR algorithm is of special advantage in computing environments with vector and parallel processing capabilities.Nodes or elements in the mesh can be reordered depending on the use of an adequate graph representation associated with the mesh. If G is used, then the nodes in the mesh are properly reordered for achieving profile and wavefront reduction of the finite element stiffness matrix. If either G* or G˙ is used, then the elements in the mesh are suitably reordered for a finite element frontai solver, A unified approach involving FEGs and finite element concepts is presented. Conclusions are inferred and possible extensions of this research are pointed out.In Part II of this work,1 the computational implementation of the SFR algorithm is described and several numerical examples are presented. The examples emphasize important theoretical, numerical and practical aspects of the new resequencing method.