B. Pichler¹, H.A. Mang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 43-55, 2000, DOI:10.3970/cmes.2000.001.345

Abstract In order to avoid a fully nonlinear analysis to obtain stability limits on nonlinear load-displacement paths, linear eigenvalue problems may be used to compute estimates of such limits. In this paper an asymptotic approach for assessment of the errors resulting from such estimates is presented. Based on the consistent linearization of the geometrically nonlinear static stability criterion – the so-called consistently linearized eigenvalue problem – higher-order estimation functions can be calculated. They are obtained from a scalar post-calculation performed after the solution of the eigenproblem. Different extensions of these higher-order estimation functions are presented. An ab initio criterion for the… More >

F. M. A. El-Saeidy¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 33-42, 2000, DOI:10.3970/cmes.2000.001.335

Abstract In rotating radial ball bearings supported on elastic casings with the bearing outer ring lightly fitted into the housing, the force due to the ball elastic contact is indeed a rotating load rolling over the housing. For accurate estimation of the dynamic deformations of the casing annulus (hole), which in turn affect the bearing tolerances and hence the magnitudes of the generated forces, effect of the load rotation (motion) should be considered. Considering the integral casing and the outer ring to be a plate, an isoparametric plane stress finite-element (FE) based analytical procedure is presented for the dynamic analysis of… More >

H.-G. Kim, S. N. Atluri¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 11-32, 2000, DOI:10.3970/cmes.2000.001.313

Abstract The truly meshless local Petrov-Galerkin (MLPG) method holds a great promise in solving boundary value problems, using a local symmetric weak form as a natural approach. In the present paper, in the context of MLPG and the meshless interpolation of a moving least squares (MLS) type, a method which uses primary and secondary nodes in the domain and on the global boundary is introduced, in order to improve the accuracy of solution. The secondary nodes can be placed at any location where one needs to obtain a better resolution. The sub-domains for the shape functions in the MLS approximation are… More >

J.T. Katsikadelis¹, M.S. Nerantzaki¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 1-9, 2000, DOI:10.3970/cmes.2000.001.303

Abstract A boundary-only method is presented for the solution of the vibration problem of non-homogeneous membranes. Both free and forced vibrations are considered. The presented method is based on the Analog Equation Method (AEM). According to this method the second order partial differential equation with variable coefficients of hyperbolic type, which governs the dynamic response of the membrane, is substituted by a Poisson's equation describing a quasi-static problem for the homogeneous membrane subjected to a fictitious time dependent load. The fictitious load is established using BEM. Several numerical examples are presented which illustrate the efficiency and the accuracy of the method. More >

V . Bontozoglou¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.2, pp. 133-142, 2000, DOI:10.3970/cmes.2000.001.293

Abstract Laminar, gravity-driven flow of a liquid down an inclined wall with large-amplitude sinusoidal corrugations is studied numerically by a spectral spatial discretization method. The synchronous resonance between the wall and the free surface is investigated for corrugations with wavelength 0.002 m, which – according to linear theory – lead to strongest interaction. Free surface profile and flow structure are studied as a function of the film Reynolds number and the wall amplitude. Streamline patterns are computed and conditions leading to flow reversal are established. The distribution of the shear stress along the wall and of the normal velocity gradient close… More >

J. Lufrano¹, P. Sofronis¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.2, pp. 119-132, 2000, DOI:10.3970/cmes.2000.001.279

Abstract Transient hydrogen diffusion and hydride formation coupled with material deformation are studied in Zr-2.5Nb alloys used in the pressure tubes of CANDU nuclear generating stations. The energetics of the hydride formation is revisited and the terminal solid solubility of hydrogen in solution is defined on the basis of the total elastoplastic work done on the system by the forming hydride and the external loads. Probabilistic precipitation of hydride is modeled in the neighborhood of a crack tip under mode I plane strain loading and a uniform initial hydrogen concentration below the stress free terminal solid solubility. Finite element analysis is… More >

M. Kailasam¹, N. Aravas², P. Ponte Castañeda³

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.2, pp. 105-118, 2000, DOI:10.3970/cmes.2000.001.265

Abstract A constitutive model for a porous metal subjected to general three-dimensional finite deformations is presented. The model takes into account the evolution of porosity and the development of anisotropy due to changes in the shape and the orientation of the voids during deformation. A methodology for the numerical integration of the elastoplastic constitutive model is developed. Finally, some sample applications to plane strain extrusion and compaction of a porous disk are considered using the finite element method. More >

A.J. Yiotis¹, J.T. Katsikadelis¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.2, pp. 95-104, 2000, DOI:10.3970/cmes.2000.001.255

Abstract The Analog Equation Method is applied to the static and dynamic analysis of thin cylindrical shell panels. The Fl\"{u}gge theory is adopted. The three displacement components are established by solving two membrane and one plate bending problems under the same boundary conditions subjected to "appropriate'' (equivalent) fictitious loads. Numerical results are presented which illustrate the efficiency and the accuracy of the proposed method. More >

V. Tvergaard¹, T. Ørts Pedersen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.2, pp. 89-94, 2000, DOI:10.3970/cmes.2000.001.249

Abstract The development of fatigue damage in a tool-steel metal matrix discontinuously reinforced with TiC particulates is analysed using a numerical cell model. The material is subjected to cyclic loading, and the matrix material is represented by a cyclic plasticity model, which uses a superposition of kinematic and isotropic hardening, with continuum damage mechanics incorporated to model fatigue damage evolution. The cell model represents a material with transversely staggered particulates. With focus on low cycle fatigue, the effect of balanced as well as unbalanced cyclic loading is studied. More >

J.C. Michel¹, H. Moulinec, P. Suquet

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.2, pp. 79-88, 2000, DOI:10.3970/cmes.2000.001.239

Abstract An iterative numerical method based on Fast Fourier Transforms has been proposed by \cite{MOU98} to investigate the effective properties of periodic composites. This iterative method is based on the exact expression of the Green function for a linear elastic, homogeneous reference material. When dealing with linear phases, the number of iterations required to reach convergence is proportional to the contrast between the phases properties, and convergence is therefore not ensured in the case of composites with infinite contrast (those containing voids or rigid inclusions or highly nonlinear materials). It is proposed in this study to overcome this difficulty by using… More >