Jin Yeon Cho¹, Jae Mo An², You Me Song¹, Seungsoo Lee¹, Dong Whan Choi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.9, No.1, pp. 1-18, 2005, DOI:10.3970/cmes.2005.009.001

Abstract A displacement welding technique is proposed to carry out coupled analysis of the integrated whole model which consists of independently modeled finite element substructures. In the proposed method, the incompatible displacement fields in the interfaces of independently modeled substructures are directly welded together through a blended function that is newly defined in the transient region of mismatching interface. To construct the blended function, the moving least squares function, which does not require well-defined nodal connectivity, is utilized along with the original finite element shape function. The meshless character of the moving least squares function makes More >

J. Sladek¹, V. Sladek¹, J. Krivacek¹, Ch. Zhang²

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.3, pp. 259-270, 2005, DOI:10.3970/cmes.2005.008.259

Abstract A meshless method based on the local Petrov-Galerkin approach is presented for stress analysis in three-dimensional (3-d) axisymmetric linear elastic solids with continuously varying material properties. The inertial effects are considered in dynamic problems. A unit step function is used as the test functions in the local weak-form. It is leading to local boundary integral equations (LBIEs). For transient elastodynamic problems the Laplace-transform technique is applied and the LBIEs are given in the Laplace-transformed domain. Axial symmetry of the geometry and the boundary conditions for a 3-d linear elastic solid reduces the original 3-d boundary More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.3, pp. 231-258, 2005, DOI:10.3970/cmes.2005.008.231

Abstract Using a group-theoretical approach in the Minkowski space we explore kinematic hardening rules from a viewpoint of the Poincaré group. The resultant models possess two intrinsic times q₀^a and q₀^b; the first q₀^a controls the on/off switch of plasticity, and the second q₀^b controls the pace of back stress during plastic deformation. We find that some existent kinematic hardening rules, including the modifications from the Armstrong-Frederick kinematic hardening rule, can be categorized into type I, type II and type III, which correspond respectively to q₀^b = 0, q₀^b = q₀^a and q₀^b ≠ q₀^a. Based More >

Aleksandr N. Guz¹

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.3, pp. 217-230, 2005, DOI:10.3970/cmes.2005.008.217

Abstract The ultrasonic non-destructive method of determination of stresses in near-the-surface layers of solid bodies is based on the regularities of elastic surface wave propagation in bodies with initial (residual) stresses. Above mentioned regularities are received in the framework of the 3-D linearized theory of waves propagation in bodies with initial (residual) stresses. Computational methods are used for solution of the dispersion equations as applied to problems under consideration. Description of the non-destructive method and information on instruments and devices for measurements are presented. Some examples of non-destructive determination of stresses in near-the-surface layers of materials More >

W. J. Ferguson¹, B. Palananthakumar²

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.3, pp. 201-216, 2005, DOI:10.3970/cmes.2005.008.201

Abstract Environmental and safety issues associated with landfill gas require the control of off-site migration. Mathematical modelling can assist in the understanding of the processes and mechanisms controlling gas migration from municipal waste disposal sites. This paper presents the development and application of a mathematical model that simulates landfill gas migration within a partially saturated soil. This model accounts for two-phase flow and incorporates multi-component (methane, carbon dioxide, dry air and moisture) transport in the gas and liquid phases together with concomitant heat migration. The governing system of fully coupled non-linear partial differential equations of the… More >

F. Cosmi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.3, pp. 191-200, 2005, DOI:10.3970/cmes.2005.008.191

Abstract The Cell Method is a recently developed numerical method that is giving interesting results in several fields of physics and engineering. In this paper, first a brief description of the method for elasticity problems is given and successively the elastodynamics formulation is derived. The method leads to an explicit solution system, combining the advantages of a diagonal mass matrix and the possibility of using unstructured meshes. The convergence rate has been tested in reference to the problem of free harmonic vibrations in a system with one degree of freedom, showing that the Cell Method has More >

Wen-Hwa Chen¹, Cheng-Hung Chen²

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.3, pp. 177-190, 2005, DOI:10.3970/cmes.2005.008.177

Abstract An enriched meshless method, using meshless interpolations and a global Galerkin approach, is developed for the analysis of three-dimensional fracture problems. The displacement field which accounts for the stress singularity nearby the crack front and the boundary layer effect at the intersection between the crack front and the free surface of the structure is adopted to enrich the trial functions. The three-dimensional stress intensity factors can thus be treated as independent unknown parameters and calculated with the nodal displacements directly. To estimate the accuracy of the method developed, several representative three-dimensional cracks are analyzed. These More >

J. Purbolaksono¹, M. H. Aliabadi^2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.1, pp. 73-90, 2005, DOI:10.3970/cmes.2005.008.073

Abstract This paper presents the dual boundary integral equations for the buckling analysis of the shear deformable cracked plates. The domain integrals which appear in this formulation are transferred to boundary integrals using the dual reciprocity method. The plate buckling displacement and hypersingular traction integral equations are presented as a standard eigenvalue problem, which would allow direct evaluation of the critical load factor and buckling modes. Several examples with different geometries and boundary conditions are presented to demonstrate the accuracy of the proposed formulation. More >

Y.S. Lian¹, M.S. Liou²

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.1, pp. 61-72, 2005, DOI:10.3970/cmes.2005.008.061

Abstract This paper focuses on integration of computational methods for design optimization based on data mining and knowledge discovery. We propose to use radial basis function neural networks to analyze the large database generated from evolutionary algorithms and to extract the cause-effect relationship, between the objective functions and the input design variables. The aim is to improve the optimization process by either reducing the computation cost or improving the optimal. Also, it is hoped to provide designers with the salient design pattern about the problem under consideration, from the physics-based simulations. The proposed technique is applied More >

Igor Karšaj¹, Carlo Sansour², Jurica Sorić¹

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.1, pp. 45-60, 2005, DOI:10.3970/cmes.2005.008.045

Abstract In this paper, a free energy-based formulation incorporating the effect of kinematic hardening is proposed. The formulation is able to reproduce symmetric expressions for the back stress while incorporating the multiplicative decomposition of the deformation gradient. Kinematic hardening is combined with isotropic hardening where an associative flow rule and von Mises yield criterion are applied. An accurate and trivial wise objective integration algorithm employing the exponential map is developed. In order to ensure a high convergence rate in the global iteration approach, an algorithmic tangent operator is derived. The computational algorithm is implemented and applied More >