V. Sladek¹, J. Sladek¹, M. Tanaka²

CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.1, pp. 69-84, 2005, DOI:10.3970/cmes.2005.007.069

Abstract An efficient numerical method is proposed for 2-d potential problems in anisotropic media with continuously variable material coefficients. The method is based on the local integral equations (utilizing a fundamental solution) and meshfree approximation of field variable. A lot of numerical experiments are carried out in order to study the numerical stability, accuracy, convergence and efficiency of several approaches utilizing various interpolations. More >

Yaxin Song¹, D. Michael McFarland¹, Lawrence A. Bergman¹, Alexander F. Vakakis²

CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.2, pp. 153-170, 2005, DOI:10.3970/cmes.2005.010.153

Abstract A general interface element is developed for dynamic response analysis of structures with jointed interfaces, which can account for damping due to both impact and friction. Contact effects are included through a segment-to-segment contact model which considers the stick-slip-slap behavior at every point along the joint interface. A nonlinear friction law is adopted at the interface to describe microscopic relative motion due to the deformation of the asperities on the interface. Numerical examples demonstrate that the general joint interface element is capable of accounting for both friction and impact damping in jointed interfaces, as well More >

Zhenyu Xue¹, Ashkan Vaziri¹, John W. Hutchinson¹

CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.1, pp. 79-96, 2005, DOI:10.3970/cmes.2005.010.079

Abstract A constitutive model for the elastic-plastic behavior of plastically compressible orthotropic materials is proposed based on an ellipsoidal yield surface with evolving ellipticity to accommodate non-uniform hardening or softening associated with stressing in different directions. The model incorporates rate-dependence arising from material rate-dependence and micro-inertial effects. The basic inputs are the stress-strain responses under the six fundamental stress histories in the orthotropic axes. Special limits of the model include classical isotropic hardening theory, the Hill model for incompressible orthotropic solids, and the Deshpande-Fleck model for highly porous isotropic foam metals. A primary motivation is application… More >

B. Šarler¹, R.Vertnik, J. Perko¹

CMC-Computers, Materials & Continua, Vol.2, No.1, pp. 77-84, 2005, DOI:10.3970/cmc.2005.002.077

Abstract The steady-state convective-diffusive solid-liquid phase change problem associated with temperature fields in direct-chill, semi-continuously cast billets and slabs from aluminum alloys has been solved by the Diffuse Approximate Method (DAM). The solution is based on formulation, which incorporates the mixture continuum physical model, nine-noded support, second order polynomial trial functions, and Gaussian window weighting functions. Realistic boundary conditions and temperature variation of material properties are included. Two-dimensional test case solution is shown, verified by comparison with the Finite Volume Method (FVM) results for coarse and fine grid arrangement. More >

S. Choi¹, M.D. Marcozzi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.3, pp. 201-212, 2004, DOI:10.3970/cmes.2004.005.201

Abstract The general intractability of derivative security pricing models to numerical techniques arguably remains one of the preeminant problems of mathematical finance. In particular, the valuations of such models may be represented as solutions of variational inequalities of evolutionary type typically characterized by their high number of degrees of freedom, unbounded domains, and asymptotic behavior. We consider the application of Multi-Quadratic Radial Basis Functions (MQ-RBF) to the problem of option pricing. More >

Youping Chen¹, James D Lee², Azim Esk,arian¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.1, pp. 35-44, 2004, DOI:10.3970/cmes.2004.005.035

Abstract This paper addresses the need of theories and simulations for material body of mesoscopic and microscopic sizes. An overview of polar theories is presented. The micropolar theory proposed by Eringen is introduced and compared with other polar theories. Constitutive equations of micropolar thermo-visco-elastic solid are derived. Finite element analyses have been performed for a few sample problems with wide range of length scales. Based on the discussion, comparison and computer simulations, the unique feature and applicability of micropolar theory are demonstrated. More >

X. Han^1,2,3, G. R. Liu^1,2, G. Y. Li ¹

CMC-Computers, Materials & Continua, Vol.1, No.1, pp. 39-50, 2004, DOI:10.3970/cmc.2004.001.039

Abstract An efficient hybrid numerical method is presented for investigating transient response of cross-ply laminated axisymmetric cylinders subjected to an impact load. In this hybrid numerical method, the laminated cylinder is divided into layered cylindrical elements in the thickness direction. The Hamilton principle is used to develop governing equations of the structure. The displacement response is determined by employing the Fourier transformations and the modal analysis. Numerical examples for analyzing transient waves have been provided in axisymmetric laminated cylindrical structures, both for thin cylindrical shells and thick cylinders.
A computational inverse technique is also presented for More >

C. J. Reddy¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 455-462, 2004, DOI:10.3970/cmes.2004.005.455

Abstract This paper presents an efficient algorithm to evaluate multi-spectral and multi-angular monostatic radar cross section (RCS) of large objects with very fine increments. The technique is based on the combination of Model Based Parameter Estimation (MBPE) method with hybrid frequency domain formulations. A general approach to formulation of MBPE is presented along with a similar approach called the Asymptotic Waveform Evaluation (AWE). Various numerical examples are presented for multi-spectral response calculations using method of moments (MoM) and the hybrid Finite Element-MoM technique in conjunction with MBPE. Example application of MBPE for hybrid MoM-Physical Optics approach More >

Raju R. Namburu¹, Eric R. Mark, Jerry A. Clarke

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 443-454, 2004, DOI:10.3970/cmes.2004.005.443

Abstract Computational electromagnetic (CEM) simulations of full-range military vehicles play a critical role in enhancing the survivability and target recognition of combat systems. Modeling of full-range military systems subjected to high frequencies may involve generating large-scale meshes, solving equations, visualization, and analysis of results in the range of billions of unknowns or grid points. Hence, the overall objective of this research is to develop and demonstrate a scalable CEM software environment to address accurate prediction of radar cross sections (RCS) for full- range armored vehicles with realistic material treatments and complex geometric configurations. A software environment… More >

V.K. Tewary², D.T. Read²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.4, pp. 359-372, 2004, DOI:10.3970/cmes.2004.006.359

Abstract An integrated Green's function and molecular dynamics technique is developed for multiscale modeling of a nanostructure in a semi-infinite crystal lattice. The equilibrium configuration of the atoms inside and around the nanostructure is calculated by using molecular dynamics that accounts for nonlinear interatomic forces. The molecular dynamics is coupled with the lattice statics Green's function for a large crystallite containing a million or more atoms. This gives a fully atomistic description of a nanostructure in a large crystallite that includes the effect of nonlinear forces. The lattice statics Green's function is then related to the… More >